US20070245752A1 - Refrigerating Apparatus and Air Conditioner - Google Patents
Refrigerating Apparatus and Air Conditioner Download PDFInfo
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- US20070245752A1 US20070245752A1 US11/630,104 US63010405A US2007245752A1 US 20070245752 A1 US20070245752 A1 US 20070245752A1 US 63010405 A US63010405 A US 63010405A US 2007245752 A1 US2007245752 A1 US 2007245752A1
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- Prior art keywords
- refrigerant
- heat source
- heat exchanger
- utilization
- refrigerating machine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B39/00—Evaporators; Condensers
- F25B39/02—Evaporators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
- F24F3/06—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B31/00—Compressor arrangements
- F25B31/002—Lubrication
- F25B31/004—Lubrication oil recirculating arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
- F25B2341/001—Ejectors not being used as compression device
- F25B2341/0016—Ejectors for creating an oil recirculation
Abstract
An air conditioner has a refrigerant circuit and a first oil returning circuit. The refrigerant circuit has a plurality of utilization refrigerant circuits each having a utilization heat exchanger and a utilization expansion valve connected to a heat source refrigerant circuit that includes a compression mechanism, a heat source expansion valve and a heat source heat exchanger configured so that a refrigerant flows in from below and flows out from above when the heat source heat exchanger functions as an evaporator. The heat source refrigerant circuit uses a combination of a refrigerating machine oil and a refrigerant that does not separate into two layers in a temperature range of 30° C. or below. The first oil returning circuit is connected to a lower portion of the heat source heat exchanger and returns the refrigerating machine oil accumulated inside the heat source heat exchanger to the compression mechanism together with the refrigerant.
Description
- The present invention relates to a refrigerating apparatus and an air conditioner, and particularly relates to a refrigerating apparatus and an air conditioner provided with a refrigerant circuit that has an evaporator configured so that refrigerant flows in from below and flows out from above.
- Conventionally, there has been a refrigerating apparatus disposed with a vapor compression-type refrigerant circuit including a heat exchanger configured such that refrigerant flows in from below and flows out from above as an evaporator of the refrigerant (e.g., see Patent Document 1). In order to prevent refrigerating machine oil from accumulating inside the evaporator, the refrigerating apparatus is configured to extract, from the vicinity of the surface of the refrigerant, the refrigerating machine oil accumulating in a state where it floats on the surface of the refrigerant as a result of the refrigerating machine oil and the refrigerant separating into two layers because the specific gravity of the refrigerating machine oil is smaller than that of the refrigerant, and to return the refrigerating machine oil to the intake side of the compressor.
- Further, as an example of a refrigerating apparatus disposed with a vapor compression-type refrigerant circuit, there is an air conditioner disposed with a vapor compression-type refrigerant circuit including: a heat source refrigerant circuit including plural heat source heat exchangers; and plural utilization refrigerant circuits connected to the heat source refrigerant circuit (e.g., see Patent Document 2). In this air conditioner, heat source expansion valves are disposed so that the flow rate of the refrigerant flowing into the heat source heat exchangers can be regulated. Additionally, in this air conditioner, when the heat source heat exchangers are caused to function as evaporators during a heating operation or during a simultaneous cooling and heating operation, for example, control is conducted to reduce the evaporating ability by reducing the openings of the heat source expansion valves as the overall air conditioning load of the plural utilization refrigerant circuits becomes smaller. Moreover, when the overall air conditioning load of the plural utilization refrigerant circuits becomes extremely small, control is conducted to reduce the evaporating ability by closing some of the plural heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators or to reduce the evaporating ability by causing some of the plural heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators.
- Further, in the aforementioned air conditioner, when the heat source heat exchangers are caused to function as condensers during a cooling operation or during the simultaneous cooling and heating operation, control is conducted to reduce the condensing ability by increasing the amount of liquid refrigerant accumulating inside the heat source heat exchangers and reducing the substantial heat transfer area by reducing the openings of the heat source expansion valves connected to the heat source heat exchangers as the overall air conditioning load of the plural utilization refrigerant circuits becomes smaller. However, when control is conducted to reduce the openings of the heat source expansion valves, there is the problem that there is a tendency for the refrigerant pressure downstream of the heat source expansion valves (specifically, between the heat source expansion valves and the plural utilization refrigerant circuits) to drop and become unstable, and control to reduce the condensing ability of the heat source refrigerant circuit cannot be stably conducted. In order to counter this problem, control has been proposed to raise the refrigerant pressure downstream of the heat source expansion valves by disposing a pressurizing circuit that causes high-pressure gas refrigerant compressed by the compressor to merge with refrigerant whose pressure has been reduced in the heat source expansion valves and is sent to the utilization refrigerant circuits (e.g., see Patent Document 3).
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Patent Document 1 -
- Japanese Patent Application Publication No. S63-204074
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Patent Document 2 -
- Japanese Patent Application Publication No. H03-260561
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Patent Document 3 -
- Japanese Patent Application Publication No. H03-129259
- In the aforementioned air conditioner, there are cases where a heat exchanger such as a plate heat exchanger configured such that the refrigerant flows in from below and flows out from above when functioning as an evaporator of the refrigerant is used as the heat source heat exchangers. In these cases, in order to prevent the refrigerating machine oil from accumulating inside the heat source heat exchangers, it is necessary to maintain the level of the refrigerant inside the heat source heat exchangers at a constant level or more. However, even if one tries to reduce the amount of refrigerant flowing through the heat source heat exchangers by reducing the openings of the heat source expansion valves when the heat source heating exchangers are caused to function as evaporators with little evaporating ability, such as when the air conditioning load in the plural utilization refrigerant circuits becomes extremely small, the evaporating ability cannot be sufficiently controlled just by regulating the openings of the heat source expansion valves because the openings of the heat source expansion valves cannot be reduced that much due to the restriction of the level of the refrigerant inside the heat source heat exchangers. As a result, it becomes necessary to conduct control to reduce the evaporating ability by closing some of the plural heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators or to reduce the evaporating ability by causing some of the plural heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators.
- For this reason, there are the problems that increases in the number of parts and cost arise as a result of disposing plural heat source heat exchangers, the amount of the refrigerant compressed in the compressor increases in correspondence to the amount of refrigerant condensed by the heat source heat exchangers when some of the plural heat source heat exchangers are caused to function as condensers to reduce the evaporating ability, and the COP becomes poor in an operating condition where the overall air conditioning load of the plural utilization refrigerant circuits is small.
- Further, in the aforementioned air conditioner, when a pressurizing circuit is disposed in the refrigerant circuit to cause the high-pressure gas refrigerant compressed by the compressor to merge with the refrigerant whose pressure has been reduced in the heat source expansion valve and which is sent to the utilization refrigerant circuits when the heat source heat exchangers are caused to function as condensers of the refrigerant, the refrigerant sent from the heat source expansion valve to the utilization refrigerant circuits becomes a gas-liquid two-phase flow. Moreover, the gas fraction of the refrigerant after the high-pressure gas refrigerant has merged therewith from the pressurizing circuit becomes larger the more the openings of the heat source expansion valves are reduced, and drift arises between the plural utilization refrigerant circuits, resulting in the problem that the openings of the heat source expansion valves cannot be sufficiently reduced. As a result, similar to when the heat source heat exchangers are caused to function as evaporators of the refrigerant, when plural heat source heat exchangers are disposed in the heat source refrigerant circuit and the overall air conditioning load of the plural utilization refrigerant circuits becomes extremely small, it becomes necessary to conduct control to reduce the condensing ability by closing the plural heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators or to reduce the condensing ability by causing some of the plural heat source heat exchangers to function as evaporators to offset the condensing ability of the heat source heat exchangers functioning as condensers.
- For this reason, there are the problems that increases in the number of parts and cost arise as a result of disposing plural heat source heat exchangers, the amount of the refrigerant compressed in the compressor increases in correspondence to the amount of refrigerant evaporated by the heat source heat exchangers when some of the plural heat source heat exchangers are caused to function as evaporators to reduce the condensing ability, and the COP becomes poor in an operating condition where the overall air conditioning load of the plural utilization refrigerant circuits is small.
- It is an object of the present invention to provide a refrigerating apparatus and an air conditioner comprising a refrigerant circuit that has an evaporator configured so that refrigerant flows in from below and flows out from above, wherein the control width is expanded when the condensing ability of an evaporator is controlled by an expansion valve.
- A refrigerating apparatus pertaining to a first invention comprises a refrigerant circuit and an oil returning circuit. The refrigerant circuit is configured by the interconnection of a compression mechanism, a condenser, an expansion valve, and an evaporator configured so that refrigerant flows in from below and flows out from above, and uses a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below. The oil returning circuit is connected to a lower portion of the evaporator and returns the refrigerating machine oil accumulated inside the evaporator to the compression mechanism together with the refrigerant.
- In this refrigerating apparatus, a refrigerant circuit having an evaporator configured so that refrigerant flows in from below and flows out from above is provided, and a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below is used as the refrigerating machine oil and refrigerant in the refrigerant circuit. Here, the evaporation temperature of the refrigerant in the evaporator is 30° C. or below when water, air, or brine is used as the heat source. For this reason, in this refrigerating apparatus, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the evaporator, but rather accumulates inside the evaporator in a state where it is mixed with the refrigerant. The refrigerating machine oil accumulated inside the evaporator is returned to the compression mechanism together with the refrigerant by way of the oil returning circuit connected to the lower portion of the evaporator. For this reason, there is no longer a need to keep the surface of the refrigerant inside the heat source heat exchanger at a constant level or higher in order to prevent the refrigerating machine oil from accumulating inside the evaporator, as is the case of conventional refrigerating apparatuses.
- Thus, in this refrigerating apparatus, even if control is conducted to reduce the evaporating ability of the evaporator by reducing the opening of the expansion valve in accordance with the refrigerating load so that as a result the level of the refrigerant inside the evaporator drops, the refrigerating machine oil does not accumulate inside the evaporator. For this reason, the control width when the evaporating ability of the evaporator is controlled by the expansion valve can be expanded.
- A refrigerating apparatus pertaining to a second invention comprises the refrigerating apparatus pertaining to the first invention, wherein the refrigerating machine oil and refrigerant used in the refrigerant circuit are a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −5° C. or below.
- In this refrigerating apparatus, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −5° C. or below is used as the combination of refrigerating machine oil and refrigerant. For this reason, in this refrigerating apparatus, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the evaporator, but rather accumulates inside the evaporator in a state where it is mixed with the refrigerant. In this case as well, the refrigerating machine oil can be prevented from accumulating inside the evaporator.
- A refrigerating apparatus pertaining to a third invention comprises the refrigerating apparatus pertaining to the second invention, wherein the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit is ethereal oil and R410A.
- In this refrigerating apparatus, ethereal oil is used as the refrigerating machine oil, and R410A is used as the refrigerant. With this combination of refrigerating machine oil and refrigerant, separation into two layers does not occur in a temperature range of −5° C. or below. In this case as well, the refrigerating machine oil can be prevented from accumulating inside the evaporator.
- A refrigerating apparatus pertaining to a fourth invention comprises the refrigerating apparatus pertaining to any of the first to third inventions, and further comprises a pressure difference increasing mechanism for increasing the pressure difference before the merging of the refrigerating machine oil and the refrigerant returned to the compression mechanism from the lower portion of the heat source heat exchanger through the oil returning circuit.
- In the refrigerating apparatuses of the first to third inventions, the flow rate of refrigerating machine oil and refrigerant returned to the compression mechanism from the lower portion of the evaporator through the oil returning circuit is determined in the oil returning circuit in accordance with the pressure loss between the lower portion of the evaporator and the compression mechanism. For this reason, in cases where, for example, the pressure loss inside the evaporator and inside the pipe from the refrigerant outlet side of the heat source heat exchanger to the intake side of the compression mechanism is small and the pressure loss in the oil returning circuit ends up becoming small, cases can arise where the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger cannot be returned to the compression mechanism from the lower portion of the heat source heat exchanger through the oil returning circuit.
- In this refrigerating apparatus, however, refrigerating machine oil and refrigerant, which have a flow rate that is sufficient to prevent refrigerating machine oil from accumulating inside the evaporator, can be reliably returned from the lower portion of the evaporator to the compression mechanism by way of the oil returning circuit. This can be achieved because the flow rate of the refrigerating machine oil and refrigerant returned from the lower portion of the evaporator to the compression mechanism by way of the oil returning circuit can be increased by providing a pressure difference increasing mechanism.
- A refrigerating apparatus pertaining to a fifth invention comprises a refrigerant circuit and an oil returning circuit. The refrigerant circuit is configured by the interconnection of a compression mechanism, condensers, an expansion valve, and an evaporator configured so that refrigerant flows in from below and flows out from above, and uses a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the evaporator. The oil returning circuit is connected to a lower portion of the evaporator and returns the refrigerating machine oil accumulated inside the evaporator to the compression mechanism together with the refrigerant.
- In this refrigerating apparatus, a refrigerant circuit having an evaporator configured so that refrigerant flows in from below and flows out from above is provided and a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the evaporator is used as the refrigerating machine oil and refrigerant in the refrigerant circuit. For this reason, in this refrigerating apparatus, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the evaporator under conditions corresponding to the evaporation temperature of the refrigerant in the evaporator, but rather accumulates inside the evaporator in a state where it is mixed with the refrigerant. The refrigerating machine oil accumulated inside the evaporator is returned to the compression mechanism together with the refrigerant by way of the oil returning circuit connected to the lower portion of the evaporator. For this reason, there is no longer a need to keep the surface of the refrigerant inside the heat source heat exchanger at a constant level or higher in order to prevent the refrigerating machine oil from accumulating inside the evaporator, as is the case of conventional refrigerating apparatuses.
- Thus, in this refrigerating apparatus, even if control is conducted to reduce the evaporating ability of the evaporator by reducing the opening of the expansion valve in accordance with the refrigerating load so that as a result the level of the refrigerant inside the evaporator drops, the refrigerating machine oil does not accumulate inside the evaporator. For this reason, the control width when the evaporating ability of the evaporator is controlled by the expansion valve can be expanded.
- An air conditioner pertaining to a sixth invention comprises a refrigerant circuit and an oil returning circuit. The refrigerant circuit has a structure in which a plurality of utilization refrigerant circuits configured by the interconnection of a utilization heat exchanger and a utilization expansion valve are connected to a heat source refrigerant circuit configured by the interconnection of a compression mechanism, a heat source heat exchanger configured so that refrigerant flows in from below and flows out from above when functioning as an evaporator, and a heat source expansion valve, and in which a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below is used. The oil returning circuit is connected to a lower portion of the heat source heat exchanger and returns the refrigerating machine oil accumulated inside the heat source heat exchanger to the compression mechanism together with the refrigerant.
- This air conditioner comprises a heat source refrigerant circuit having a heat source heat exchanger configured so that the refrigerant flows in from below and flows out from above, and a refrigerant circuit configured by the interconnection of a plurality of utilization refrigerant circuits. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below is used as the refrigerating machine oil and refrigerant in the refrigerant circuit. Here, the evaporation temperature of the refrigerant in the heat source heat exchanger is 30° C. or below when water, air, or brine is used as the heat source. For this reason, in this air conditioner, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the heat source heat exchanger, but rather accumulates inside the heat source heat exchanger in a state where it is mixed with the refrigerant. The refrigerating machine oil accumulated inside the heat source heat exchanger is returned to the compression mechanism together with the refrigerant by way of the oil returning circuit connected to the lower portion of the heat source heat exchanger. For this reason, there is no longer a need to keep the surface of the refrigerant inside the heat source heat exchanger at a constant level or higher in order to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger, as is the case of conventional air conditioners.
- Therefore, in this air conditioner, even if control is conducted to reduce the evaporating ability of the heat source heat exchanger by reducing the opening of the heat source expansion valve in accordance with the air conditioning load of the plurality of utilization refrigerant circuits so that as a result the level of the refrigerant inside the heat source heat exchanger drops, the refrigerating machine oil does not accumulate inside the heat source heat exchanger. For this reason, the control width when the evaporating ability of the heat source heat exchanger is controlled by the heat source expansion valve can be expanded.
- Additionally, in this air conditioner, it becomes unnecessary to conduct control, as in conventional air conditioners disposed with a plurality of heat source heat exchangers, to reduce the evaporating ability by closing some of the heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators when the heat source heat exchangers are caused to function as evaporators or to reduce the evaporating ability by causing some of the heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators. For this reason, a wide control width of the evaporating ability can be obtained by a single heat source heat exchanger.
- Thus, because simplification of the heat source heat exchanger becomes possible in an air conditioner where simplification of the heat source heat exchangers could not be realized by restricting the control width of the control of the evaporating ability of the heat source heat exchangers, increases in the number of parts and cost that had occurred in conventional air conditioners as a result of disposing plural heat source heat exchangers can be prevented. Further, the problem of the COP becoming poor can be eliminated in an operating condition where, when some of the heat source heat exchangers are caused to function as condensers to reduce the evaporating ability, the amount of refrigerant compressed in the compression mechanism increases in correspondence to the amount of refrigerant condensed by the heat source heat exchangers and the air conditioning load of the utilization refrigerant circuits is small.
- An air conditioner pertaining to a seventh invention comprises the air conditioner pertaining to the sixth invention, wherein the refrigerating machine oil and refrigerant used in the refrigerant circuit are a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −5° C. or below.
- In this refrigerating apparatus, a combination of refrigerating machine oil and refrigerant that does not separate into tow layers in a temperature range of −5° C. or below is used as the combination of refrigerating machine oil and refrigerant. For this reason, in this refrigerating apparatus, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the heat source heat exchanger, but rather accumulates inside the heat source heat exchanger in a state where it is mixed with the refrigerant, even when the evaporation temperature of the refrigerant is low in the heat source heat exchanger functioning as an evaporator. In this case as well, the refrigerating machine oil can be prevented from accumulating inside the heat source heat exchanger.
- An air conditioner pertaining to an eighth invention comprises the air conditioner pertaining to the seventh invention, wherein the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit is ethereal oil and R410A.
- In this air conditioner, ethereal oil is used as the refrigerating machine oil, and R410A is used as the refrigerant. This combination of refrigerating machine oil and refrigerant does not separate into two layers in a temperature range of −5° C. or below, and the refrigerating machine oil can therefore be prevented from accumulating inside the heat source heat exchanger.
- An air conditioner pertaining to a ninth invention comprises the air conditioner pertaining to any of the sixth to eighth inventions, and further comprises a pressure difference increasing mechanism for increasing the pressure difference before the merging of the refrigerating machine oil and the refrigerant returned to the compression mechanism from the lower portion of the heat source heat exchanger through the oil returning circuit.
- In the air conditioner pertaining to any of the sixth to eighth inventions, the flow rate of refrigerating machine oil and refrigerant returned to the compression mechanism from the lower portion of the heat source heat exchanger functioning as an evaporator through the oil returning circuit is determined in the oil returning circuit in accordance with the pressure loss between the lower portion of the heat source heat exchanger functioning as an evaporator and the compression mechanism. For this reason, in cases where, for example, the pressure loss inside the heat source heat exchanger functioning as an evaporator and inside the pipe from the refrigerant outlet side of the heat source heat exchanger to the intake side of the compression mechanism is small and the pressure loss in the oil returning circuit ends up becoming small, cases can arise where the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger cannot be returned to the compression mechanism from the lower portion of the heat source heat exchanger through the oil returning circuit.
- However, in this air conditioner, refrigerating machine oil and refrigerant, which have a flow rate that is sufficient to prevent refrigerating machine oil from accumulating inside the evaporator, can be reliably returned from the lower portion of the evaporator to the compression mechanism by way of the oil returning circuit. This can be achieved because the flow rate of the refrigerating machine oil and refrigerant returned from the lower portion of the evaporator to the compression mechanism by way of the oil returning circuit can be increased by providing a pressure difference increasing mechanism.
- An air conditioner pertaining to a tenth invention comprises the air conditioner pertaining to any of the sixth to ninth inventions, wherein the oil returning circuit has a control valve. The control valve is closed when the heat source heat exchanger functions as a condenser, and is open when the heat source heat exchanger functions as an evaporator.
- In this air conditioner, by disposing a control valve in the oil returning circuit and adjusting the control value to a closed state when the heat source heat source heat exchanger is caused to function as a condenser, the flow rate of the refrigerant fed to the utilization refrigerant circuit can be prevented from being reduced after the refrigerant has been condensed in the heat source heat exchanger.
- An air conditioner pertaining to an eleventh invention comprises the air conditioner pertaining to the tenth invention, wherein the control valve is opened when the heat source expansion valve is at or below a prescribed position.
- In this air conditioner, it is not necessary to use the oil returning circuit until the level of the refrigerant inside the heat source heat exchanger reaches a constant level or more where there is no accumulation of refrigerating machine oil. For this reason, the opening of the heat source expansion valve corresponding to a level of the refrigerant where accumulation of the refrigerating machine oil can occur inside the heat
source heat exchanger 23 is set as a predetermined opening, and the control valve is opened and the air conditioner operates only when the opening of the heat source expansion valve becomes equal to or less than this predetermined opening, whereby the amount of refrigerant sent to the compression mechanism can be prevented from increasing without the refrigerant being evaporated in the heat source heat exchanger. - An air conditioner pertaining to a twelfth invention comprises the air conditioner pertaining to any of the sixth to eleventh inventions, wherein the heat source heat exchanger uses as a heat source water fed at a constant rate without regard to the flow rate of refrigerant that flows inside the heat source heat exchanger.
- In this air conditioner, the heat source heat exchanger uses as a heat source water fed at a constant rate without regard to the flow rate of refrigerant that flows inside the heat source heat exchanger, and the evaporating ability in the heat source heat exchanger cannot be controlled by controlling the amount of water. However, in this air conditioner, since the control width is expanded when the evaporating ability of the heat source heat exchanger is controlled by the heat source expansion valve, the control width can be assured when the evaporating ability of the heat source heat exchanger is controlled without controlling the amount of water.
- An air conditioner pertaining to a thirteenth invention comprises the air conditioner pertaining to any of the sixth to twelfth inventions, wherein the heat source heat exchanger is a plate heat exchanger.
- In this air conditioner, a plate heat exchanger is used as the heat source heat exchanger, and in terms of the structure thereof, it is difficult for the refrigerating machine oil accumulating in a state where it floats on the surface of the refrigerant to be extracted from the vicinity of the surface of the refrigerant in order to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger. However, in this air conditioner, it suffices simply for the refrigerating machine oil to accumulate inside the heat source heat exchanger in a state where it is mixed with the refrigerant and for the refrigerating machine oil accumulating inside the heat source exchanger to be extracted from the lower portion of the heat source heat exchanger together with the refrigerant. For this reason, it is easy to dispose the oil returning circuit even when a plate-type heat exchanger is used.
- The air conditioner pertaining to a fourteenth invention has a refrigerant circuit and an oil returning circuit. The refrigerant circuit has a structure in which a plurality of utilization refrigerant circuits configured by the interconnection of a utilization heat exchanger and a utilization expansion valve are connected to a heat source refrigerant circuit configured by the interconnection of a compression mechanism, a heat source heat exchanger configured so that refrigerant flows in from below and flows out from above when the heat source heat exchanger functions as an evaporator, and a heat source expansion valve; and uses a combination of refrigerating machine oil and refrigerant that does not separate into two layers inside the heat source heat exchanger when the heat source heat exchanger functions as an evaporator. The oil returning circuit is connected to a lower portion of the heat source heat exchanger and returns the refrigerating machine oil accumulated inside the heat source heat exchanger to the compression mechanism together with the refrigerant.
- In this air conditioner, a refrigerant circuit is provided that configured by the interconnection a plurality of utilization refrigerant circuits and a heat source refrigerant circuit having a heat source heat exchanger configured so that refrigerant flows in from below and flows out from above when the heat source heat exchanger functions as an evaporator. Used as the refrigerating machine oil and refrigerant used in the refrigerant circuit is a combination of refrigerating machine oil and refrigerant that does not separate into two layers inside the heat source heat exchanger when the heat source heat exchanger functions as an evaporator. For this reason, in this air conditioner, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the heat source heat exchanger under conditions corresponding to the evaporation temperature of the refrigerant in the heat source heat exchanger functioning as an evaporator, but rather accumulates inside the heat source heat exchanger in a state where it is mixed with the refrigerant. The refrigerating machine oil accumulated in the heat source heat exchanger is returned to the compression mechanism together with the refrigerant through the oil returning circuit connected to the lower portion of the heat source heat exchanger. For this reason, there is no longer a need to keep the surface of the refrigerant inside the heat source heat exchanger at a constant level or higher in order to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger as is the case of conventional air conditioners.
- Thus, in this air conditioner, even when control is conducted to reduce the evaporating ability of the heat source heat exchanger by reducing the opening of the heat source expansion valve in accordance with the air conditioning load of the plurality of utilization refrigerant circuits so that as a result the level of the refrigerant inside the heat source heat exchanger drops, the refrigerating machine oil does not accumulate inside the heat source heat exchanger. For this reason, the control width when the evaporating ability of the heat source heat exchanger is controlled with a heat source expansion valve can be expanded.
- In this air conditioner, it becomes unnecessary to conduct control, as in conventional air conditioners disposed with plural heat source heat exchangers, to reduce the evaporating ability by closing some of the heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators when the heat source heat exchangers are caused to function as evaporators or to reduce the evaporating ability by causing some of the heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators. For this reason, a wide control width of the evaporating ability can be obtained by a single heat source heat exchanger.
- Thus, because simplification of the heat source heat exchanger becomes possible in an air conditioner where simplification of the heat source heat exchangers could not be realized by restricting the control width of the control of the evaporating ability of the heat source heat exchangers, increases in the number of parts and cost that had occurred in conventional air conditioners as a result of disposing plural heat source heat exchangers can be prevented. Further, the problem of the COP becoming poor can be eliminated in an operating condition where, when some of the heat source heat exchangers are caused to function as condensers to reduce the evaporating ability, the amount of refrigerant compressed in the compression mechanism increases in correspondence to the amount of refrigerant condensed by the heat source heat exchangers and the air conditioning load of the entire plurality of utilization refrigerant circuits is small.
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FIG. 1 - A schematic diagram of a refrigerant circuit of an air conditioner of an embodiment pertaining to the invention.
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FIG. 2 - A diagram showing the overall schematic structure of a heat source heat exchanger.
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FIG. 3 - An enlarged view of portion C in
FIG. 2 showing the schematic structure of a lower portion of the heat source heat exchanger. -
FIG. 4 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner during a heating operating mode.
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FIG. 5 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner during a cooling operating mode.
-
FIG. 6 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner during a simultaneous cooling and heating operating mode (evaporation load).
-
FIG. 7 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner during a simultaneous cooling and heating operating mode (condensation load).
-
FIG. 8 - A schematic diagram of a refrigerant circuit of an air conditioner pertaining to
modification 1. -
FIG. 9 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner of
modification 1 during a heating operating mode. -
FIG. 10 - A schematic diagram of the refrigerant circuit describing the operation of the air conditioner of
modification 1 during a cooling operating mode. -
FIG. 11 - A schematic diagram of a refrigerant circuit of an air conditioner pertaining to
modification 2. -
FIG. 12 - A schematic diagram of a refrigerant circuit of an air conditioner pertaining to
modification 3. -
FIG. 13 - A schematic diagram of a refrigerant circuit of an air conditioner pertaining to
modification 4. -
FIG. 14 - A schematic diagram of the refrigerant circuit of the air conditioner pertaining to
modification 4. -
FIG. 15 - A schematic diagram of the refrigerant circuit of the air conditioner pertaining to
modification 4. -
FIG. 16 - A schematic diagram of the refrigerant circuit of the air conditioner pertaining to
modification 4. -
- 1 Air Conditioner (Refrigerating Apparatus)
- 12 Refrigerant Circuit
- 12 a, 12 b, 12 c Utilization Refrigerant Circuits
- 12 d Heat Source Refrigerant Circuit
- 21 Compression Mechanism
- 23 Heat Source Heat Exchanger (Evaporator)
- 24 Heat Source Expansion Valve (Expansion Valve)
- 31, 41, 51 Utilization Expansion Valves
- 32, 42, 52 Utilization Heat Exchangers (Condensers)
- 101 First Oil Returning Circuit (Oil Returning Circuit)
- 101 b Control Valve
- 111 Pressurizing Circuit
- 121 Cooler
- 122 Cooling Circuit
- 131, 141 Pressure-Reducing Mechanism (Pressure Difference Increasing Mechanism)
- 151 Pump Mechanism (Pressure Difference Increasing Mechanism)
- 161 Ejector Mechanism (Pressure Difference Increasing Mechanism)
- An embodiment of an air conditioner pertaining to the invention will be described below on the basis of the drawings.
-
FIG. 1 is a schematic diagram of a refrigerant circuit of anair conditioner 1 of an embodiment pertaining to the invention. Theair conditioner 1 is an apparatus used to cool and heat the indoors of buildings and the like by conducting a vapor compression-type refrigerating cycle. - The
air conditioner 1 is mainly disposed with oneheat source unit 2; a plurality of (three in the present embodiment)utilization units connection units utilization units refrigerant communication pipes heat source unit 2 and theutilization units connection units air conditioner 1 is configured such that it can conduct a simultaneous cooling and heating operation in accordance with the requirements of indoor air conditioned spaces where theutilization units type refrigerant circuit 12 of theair conditioner 1 of the present embodiment is configured by the interconnection of theheat source unit 2, theutilization units connection units refrigerant communication pipes - Additionally, in the present embodiment, a combination of refrigerating machine oil and refrigerant is used that does not separate into two layers in a temperature range of −20° C. or below in the
refrigerant circuit 12 of theair conditioner 1. For example, a combination of R410A and polyvinyl ether (PVE) or another ethereal oil is used as such a combination of refrigerant and refrigerating machine oil. Following are the reasons for using a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of −20° C. or below. - First, in view of the fact that the maximum value of the evaporation temperature of the refrigerant is 30° C. when the heat source heat exchanger 23 (described later) of the
heat source unit 2 is caused to function as an evaporator, the refrigerant and refrigerating machine oil accumulated inside the heatsource heat exchanger 23 are not allowed to separate in at least a temperature range that is equal to or below the maximum value (i.e., 30° C.) of the evaporation temperature, and the refrigerating machine oil can thereby be extracted together with the refrigerant from the lower portion of the heatsource heat exchanger 23 and returned to the compression mechanism 21 (described later) of theheat source unit 2. - More preferably, in view of the minimum value of the evaporation temperature of the refrigerant when the heat source heat exchanger 23 (described later) of the
heat source unit 2 is caused to function as an evaporator, the refrigerant and refrigerating machine oil accumulated inside the heatsource heat exchanger 23 are not allowed to separate into two layers in a temperature range that is equal to or less than the minimum value of the evaporation temperature, whereby the refrigerating machine oil can be extracted together with the refrigerant from the lower portion of the heatsource heat exchanger 23 and returned to the compression mechanism 21 (described later) of theheat source unit 2. When water is used as the heat source of the 23, the minimum value of the evaporation temperature is −5° C. When air is used as the heat source of the heatsource heat exchanger 23, the minimum value of the evaporation temperature is −15° C. When brine (e.g., one that includes 40 to 50 wt % ethylene glycol) is used as the heat source of the heatsource heat exchanger 23, the minimum value of the evaporation temperature is −20° C. - <Utilization Units>
- The
utilization units utilization units heat source unit 2 via therefrigerant communication pipes connection units refrigerant circuit 12. - Next, the configuration of the
utilization units utilization unit 3 has the same configuration as those of theutilization units utilization unit 3 will be described here, and in regard to the configurations of theutilization units utilization unit 3, and description of those respective portions will be omitted. - The
utilization unit 3 mainly configures part of therefrigerant circuit 12 and is disposed with autilization refrigerant circuit 12 a (in theutilization units utilization refrigerant circuits utilization refrigerant circuit 12 a is mainly disposed with autilization expansion valve 31 and autilization heat exchanger 32. In the present embodiment, theutilization expansion valve 31 is an electrically powered expansion valve connected to a liquid side of theutilization heat exchanger 32 in order to regulate the flow rate of the refrigerant flowing inside theutilization refrigerant circuit 12 a. In the present embodiment, theutilization heat exchanger 32 is a cross fin-type fin-and-tube heat exchanger configured by a heat transfer tube and numerous fins, and is a device for conducting heat exchange between the refrigerant and the indoor air. In the present embodiment, theutilization unit 3 is disposed with a blower fan (not shown) for taking in indoor air to the inside of the unit, heat-exchanging the air, and thereafter supplying the air to the indoors as supply air, so that the indoor air and the refrigerant flowing through theutilization heat exchanger 32 can be heat-exchanged. - Various types of sensors are also disposed in the
utilization unit 3. Aliquid temperature sensor 33 that detects the temperature of liquid refrigerant is disposed at the liquid side of theutilization heat exchanger 32, and agas temperature sensor 34 that detects the temperature of gas refrigerant is disposed at a gas side of theutilization heat exchanger 32. Moreover, an RAintake temperature sensor 35 that detects the temperature of the indoor air taken into the unit is disposed in theutilization unit 3. Further, theutilization unit 3 is disposed with autilization control unit 36 that controls the operation of the respective portions configuring theutilization unit 3. Additionally, theutilization control unit 36 is disposed with a microcomputer and memory disposed in order to control theutilization unit 3, and is configured such that it can exchange control signals and the like with a remote controller (not shown) and exchange control signals and the like with theheat source unit 2. - <Heat Source Unit>
- The
heat source unit 2 is disposed on the roof or the like of a building or the like, is connected to theutilization units refrigerant communication pipes refrigerant circuit 12 between theutilization units - Next, the configuration of the
heat source unit 2 will be described. Theheat source unit 2 mainly configures part of therefrigerant circuit 12 and is disposed with a heat sourcerefrigerant circuit 12 d. The heat sourcerefrigerant circuit 12 d is mainly disposed with thecompression mechanism 21, afirst switch mechanism 22, the heatsource heat exchanger 23, a heatsource expansion valve 24, areceiver 25, asecond switch mechanism 26, aliquid closing valve 27, a high-pressuregas closing valve 28, a low-pressuregas closing valve 29, a firstoil returning circuit 101, a pressurizingcircuit 111, a cooler 121, and acooling circuit 122. - The
compression mechanism 21 mainly includes acompressor 21 a, anoil separator 21 b connected to a discharge side of thecompressor 21 a, and a secondoil returning circuit 21 d that connects theoil separator 21 b and anintake pipe 21 c of thecompressor 21 a. In the present embodiment, thecompressor 21 a is a positive-displacement compressor whose running capacity can be varied by inverter control. Theoil separator 21 b is a container that separates the refrigerating machine oil accompanying the high-pressure gas refrigerant compressed and discharged in thecompressor 21 a. The secondoil returning circuit 21 d is a circuit for returning the refrigerating machine oil separated in theoil separator 21 b to thecompressor 21 a. The secondoil returning circuit 21 d mainly includes anoil returning pipe 21 e, which connects theoil separator 21 b and theintake pipe 21 c of thecompressor 21 a, and acapillary tube 21 f, which reduces the pressure of the high-pressure refrigerating machine oil separated in theoil separator 21 b connected to theoil returning pipe 21 e. Thecapillary tube 21 f is a narrow tube that reduces, to the refrigerant pressure of the intake side of thecompressor 21 a, the pressure of the high-pressure refrigerating machine oil separated in theoil separator 21 b. In the present embodiment, thecompression mechanism 21 only has the onecompressor 21 a but is not limited thereto, and may also be one where two or more compressors are connected in parallel in accordance with the connection number of utilization units. - The
first switch mechanism 22 is a four-way switch valve that can switch between flow paths of the refrigerant inside the heat sourcerefrigerant circuit 12 d such that when the heatsource heat exchanger 23 is caused to function as a condenser (below, referred to as a condensation operating state), thefirst switch mechanism 22 connects the discharge side of thecompression mechanism 21 and the gas side of the heatsource heat exchanger 23, and when the heatsource heat exchanger 23 is caused to function as an evaporator (below, referred to as an evaporation operating state), thefirst switch mechanism 22 connects the intake side of thecompression mechanism 21 and the gas side of the heatsource heat exchanger 23. Afirst port 22 a of thefirst switch mechanism 22 is connected to the discharge side of thecompression mechanism 21, asecond port 22 b of thefirst switch mechanism 22 is connected to the gas side of the heatsource heat exchanger 23, athird port 22 c of thefirst switch mechanism 22 is connected to the intake side of thecompression mechanism 21, and afourth port 22 d of thefirst switch mechanism 22 is connected to the intake side of thecompression mechanism 21 via acapillary tube 91. Additionally, as mentioned previously, thefirst switch mechanism 22 can conduct switching that connects thefirst port 22 a and thesecond port 22 b and connects thethird port 22 c and thefourth port 22 d (corresponding to the condensation operating state; refer to the solid lines of thefirst switch mechanism 22 inFIG. 1 ), and connects thesecond port 22 b and thethird port 22 c and connects thefirst port 22 a and thefourth port 22 d (corresponding to the evaporation operating state; refer to the dotted lines of thefirst switch mechanism 22 inFIG. 1 ). - The heat
source heat exchanger 23 is a heat exchanger that can function as an evaporator of the refrigerant and as a condenser of the refrigerant. In the present embodiment, the heatsource heat exchanger 23 is a plate heat exchanger that exchanges heat with the refrigerant using water as the heat source. The gas side of the heatsource heat exchanger 23 is connected to thesecond port 22 b of thefirst switch mechanism 22, and the liquid side of the heatsource heat exchanger 22 is connected to the heatsource expansion valve 24. As shown inFIG. 2 , the heatsource heat exchanger 23 is configured such that it can conduct heat exchange as a result ofplural plate members 23 a formed by pressing or the like being superposed via packing (not shown) so thatplural flow paths plate members 23 a, whereby the refrigerant and water alternately flow inside theseplural flow paths flow paths 23 b and the water flows inside theflow paths 23 c; refer to arrows A and B inFIG. 2 ). Additionally, theplural flow paths 23 b are mutually communicated at their upper end portions and lower end portions, and are connected to agas nozzle 23 d and aliquid nozzle 23 e disposed on the upper portion and the lower portion of the heatsource heat exchanger 23. Thegas nozzle 23 d is connected to thefirst switch mechanism 22, and theliquid nozzle 23 e is connected to the heatsource expansion valve 24. Thus, as shown by arrow A inFIG. 2 , when the heatsource heat exchanger 23 functions as an evaporator, the refrigerant flows in from theliquid nozzle 23 e (i.e., from below) and flows out from thegas nozzle 23 d (i.e., from above), and when the heatsource heat exchanger 23 functions as a condenser, the refrigerant flows in from thegas nozzle 23 d (i.e., from above) and flows out from theliquid nozzle 23 e (i.e., from below). Further, theplural flow paths 23 c are mutually communicated at their upper end portions and lower end portions, and are connected to awater inlet nozzle 23 f and awater outlet nozzle 23 g disposed on the upper portion and the lower portion of the heatsource heat exchanger 23. Further, in the present embodiment, the water serving as the heat source flows in as supply water CWS from thewater inlet nozzle 23 f of the heatsource heat exchanger 23 through a water pipe (not shown) from a cooling tower facility or a boiler facility disposed outside theair conditioner 1, is heat-exchanged with the refrigerant, flows out from thewater outlet nozzle 23 g, and is returned as discharge water CWR to the cooling tower facility or the boiler facility. Here, a constant amount of the water supplied from the cooling tower facility or the boiler facility is supplied without relation to the flow rate of the refrigerant flowing inside the heatsource heat exchanger 23. - In the present embodiment, the heat
source expansion valve 24 is an electrically powered expansion valve that can regulate the flow rate of the refrigerant flowing between the heatsource heat exchanger 23 and theutilization refrigerant circuits refrigerant communication pipe 9, and is connected to the liquid side of the heatsource heat exchanger 23. - The
receiver 25 is a container for temporarily accumulating the refrigerant flowing between the heatsource heat exchanger 23 and theutilization refrigerant circuits receiver 25 is connected between the heatsource expansion valve 24 and the cooler 121. - The
second switch mechanism 26 is a four-way switch valve that can switch between the flow paths of the refrigerant inside the heat sourcerefrigerant circuit 12 d such that when theheat source unit 2 is used as a heat source unit for a simultaneous cooling and heating machine (refer to FIGS. 4 to 7) and sends the high-pressure gas refrigerant to theutilization refrigerant circuits second switch mechanism 26 connects the discharge side of thecompression mechanism 21 and the high-pressuregas closing valve 28, and when theheat source unit 2 is used as a heat source unit for a cooling and heating switching machine (modification 1; refer to FIGS. 8 to 10; below, referred to as a cooling/heating switching time cooling operating state) to conduct a cooling operation, thesecond switch mechanism 26 connects the high-pressuregas closing valve 28 and the intake side of thecompression mechanism 21. Afirst port 26 a of thesecond switch mechanism 26 is connected to the discharge side of thecompression mechanism 21, asecond port 26 b of thesecond switch mechanism 26 is connected to the intake side of thecompression mechanism 21 via acapillary tube 92, athird port 26 c of thesecond switch mechanism 26 is connected to the intake side of thecompression mechanism 21, and afourth port 26 d of thesecond switch mechanism 26 is connected to the high-pressuregas closing valve 28. Additionally, as mentioned previously, thesecond switch mechanism 26 can conduct switching that connects thefirst port 26 a and thesecond port 26 b and connects thethird port 26 c and thefourth port 26 d (corresponding to the cooling/heating switching time cooling operating state; refer to the solid lines of thesecond switch mechanism 26 inFIG. 1 ), and connects thesecond port 26 b and thethird port 26 c and connects thefirst port 26 a and thefourth port 26 d (corresponding to the heating load requirement operating state; refer to the dotted lines of thesecond switch mechanism 26 inFIG. 1 ). - The
liquid closing valve 27, the high-pressuregas closing valve 28 and the low-pressuregas closing valve 29 are valves disposed at ports connected to external devices/pipes (specifically, therefrigerant communication pipes liquid closing valve 27 is connected to the cooler 121. The high-pressuregas closing valve 28 is connected to thefourth port 26 d of thesecond switch mechanism 26. The low-pressuregas closing valve 29 is connected to the intake side of thecompression mechanism 21. - The first
oil returning circuit 101 is a circuit that returns the refrigerating machine oil accumulating inside the heatsource heat exchanger 23 to thecompression mechanism 21 together with the refrigerant during the evaporation operating state, i.e., when the heatsource heat exchanger 23 is caused to function as an evaporator. The firstoil returning circuit 101 mainly includes anoil returning pipe 101 a that connects the lower portion of the heatsource heat exchanger 23 and thecompression mechanism 21, acontrol valve 101 b connected to theoil returning pipe 101 a, acheck valve 101 c, and acapillary tube 101 d. Theoil returning pipe 101 a is disposed such that one end can extract the refrigerating machine oil together with the refrigerant from the lower portion of the heatsource heat exchanger 23. In the present embodiment, as shown inFIG. 3 , theoil returning pipe 101 a is a pipe extending inside theflow paths 23 b through which flows the refrigerant of the heatsource heat exchanger 23 through the inside of the pipe of theliquid nozzle 23 e disposed in the lower portion of the heatsource heat exchanger 23. Here, communication holes 23 h are disposed in theplate members 23 a in the heatsource heat exchanger 23 in order to allow theplural flow paths 23 b to be communicated with each other (the same is true of theplural flow paths 23 c). For this reason, theoil returning pipe 101 a may also be disposed such that it penetrates theplural flow paths 23 b (refer to theoil returning pipe 101 a indicated by the dotted lines inFIG. 3 ). Further, in the present embodiment, the other end of theoil returning pipe 101 a is connected to the intake side of thecompression mechanism 21. In the present embodiment, thecontrol valve 101 b is an electromagnetic valve that is connected to ensure that it can use the firstoil returning circuit 101 as needed, and can circulate and cut off the refrigerant and the refrigerating machine oil. Thecheck valve 101 c is a valve that allows the refrigerant and the refrigerating machine oil to flow just inside theoil returning pipe 101 a toward the intake side of thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23. Thecapillary tube 101 d is a narrow tube that reduces, to the refrigerant pressure of the intake side of thecompression mechanism 21, the pressure of the refrigerant and the refrigerating machine oil extracted from the lower portion of the heatsource heat exchanger 23. - The pressurizing
circuit 111 is a circuit that causes the high-pressure gas refrigerant compressed in thecompression mechanism 21 to merge with the refrigerant that is condensed in the heatsource heat exchanger 23, pressure-reduced in the heatsource expansion valve 24, and sent to theutilization refrigerant circuits source heat exchanger 23 is caused to function as a condenser. The pressurizingcircuit 111 mainly includes a pressurizingpipe 111 a that connects the discharge side of thecompression mechanism 21 and the downstream side of the heat source expansion valve 24 (i.e., between the heatsource expansion valve 24 and the liquid closing valve 27), acontrol valve 111 b connected to the pressurizingpipe 111 a, acheck valve 111 c, and acapillary tube 111 d. In the present embodiment, one end of the pressurizingpipe 111 a is connected between the outlet of theoil separator 21 b of thecompression mechanism 21 and thefirst ports second switch mechanisms pipe 111 a is connected between the heatsource expansion valve 24 and thereceiver 25. In the present embodiment, thecontrol valve 111 b is an electromagnetic valve that is connected to ensure that it can use the pressurizingcircuit 111 as needed, and can circulate and cut off the refrigerant. Thecheck valve 111 c is a valve that allows the refrigerant to flow just inside the pressurizingpipe 111 a toward the downstream side of the heatsource expansion valve 24 from the discharge side of thecompression mechanism 21. Thecapillary tube 111 d is a narrow tube that reduces, to the refrigerant pressure of the downstream side of the heatsource expansion valve 24, the pressure of the refrigerant extracted from the discharge side of thecompression mechanism 21. - The cooler 121 is a heat exchanger that cools the refrigerant that is condensed in the heat
source heat exchanger 23, pressure-reduced in the heatsource expansion valve 24, and sent to theutilization refrigerant circuits source heat exchanger 23 is caused to function as a condenser. In the present embodiment, the cooler 121 is connected between thereceiver 25 and theliquid closing valve 27. In other words, the pressurizingcircuit 111 is connected such that the pressurizingpipe 111 a is connected between the heatsource expansion valve 24 and the cooler 121, so that the high-pressure gas refrigerant merges with the refrigerant whose pressure has been reduced in the heatsource expansion valve 24. A double tube heat exchanger, for example, can be used as the cooler 121. - The
cooling circuit 122 is a circuit connected to the heat sourcerefrigerant circuit 12 d such that during the condensation operating state, i.e., when the heatsource heat exchanger 23 is caused to function as a condenser, thecooling circuit 122 causes some of the refrigerant sent from the heatsource heat exchanger 23 to theutilization refrigerant circuits refrigerant circuit 12 d and be introduced to the cooler 121, cools the refrigerant that is condensed in the heatsource heat exchanger 23, pressure-reduced in the heatsource expansion valve 24, and sent to theutilization refrigerant circuits compression mechanism 21. Thecooling circuit 122 mainly includes a lead-inpipe 122 a that introduces to the cooler 121 some of the refrigerant sent from the heatsource heat exchanger 23 to theutilization refrigerant circuits circuit expansion valve 122 b connected to the lead-inpipe 122 a, and a lead-outpipe 122 c that returns, to the intake side of thecompression mechanism 21, the refrigerant passing through the cooler 121. In the present embodiment, one end of the lead-inpipe 122 a is connected between thereceiver 25 and the cooler 121. Further, in the present embodiment, the other end of the lead-inpipe 122 a is connected to the inlet of thecooling circuit 122 side of the cooler 121. In the present embodiment, the coolingcircuit expansion valve 122 b is an electrically powered expansion valve that is connected to ensure that it can use thecooling circuit 122 as needed, and can regulate the flow rate of the refrigerant flowing through thecooling circuit 122. In the present embodiment, one end of the lead-outpipe 122 c is connected to the outlet of thecooling circuit 122 side of the cooler 121. Further, in the present embodiment, the other end of the lead-outpipe 122 c is connected to the intake side of thecompression mechanism 21. - Further, various types of sensors are disposed in the
heat source unit 2. Specifically, theheat source unit 2 is disposed with anintake pressure sensor 93 that detects the intake pressure of thecompression mechanism 21, adischarge pressure sensor 94 that detects the discharge pressure of thecompression mechanism 21, adischarge temperature sensor 95 that detects the discharge temperature of the refrigerant of the discharge side of thecompression mechanism 21, and a cooling circuitoutlet temperature sensor 96 that detects the temperature of the refrigerant flowing through the lead-outpipe 122 c of thecooling circuit 122. Further, theheat source unit 2 is disposed with a heatsource control unit 97 that controls the operation of the respective portions configuring theheat source unit 2. Additionally, the heatsource control unit 97 includes a microcomputer and a memory disposed in order to control theheat source unit 2, and is configured such that it can exchange control signals and the like with theutilization control units utilization units - <Connection Units>
- The
connection units utilization units connection units utilization units heat source unit 2 together with therefrigerant communication pipes refrigerant circuit 12. - Next, the configuration of the
connection units connection unit 6 has the same configuration as those of theconnection units connection unit 6 will be described here, and in regard to the configurations of theconnection units connection unit 6, and description of those respective portions will be omitted. - The
connection unit 6 mainly configures part of therefrigerant circuit 12 and is disposed with aconnection refrigerant circuit 12 e (in theconnection units connection refrigerant circuits 12 f and 12 g, respectively). Theconnection refrigerant circuit 12 e mainly includes aliquid connection pipe 61, agas connection pipe 62, a high-pressuregas control valve 66, and a low-pressuregas control valve 67. In the present embodiment, theliquid connection pipe 61 connects the liquidrefrigerant communication pipe 9 and theutilization expansion valve 31 of theutilization refrigerant circuit 12 a. Thegas connection pipe 62 includes a high-pressuregas connection pipe 63 connected to the high-pressure gasrefrigerant communication pipe 10, a low-pressuregas connection pipe 64 connected to the low-pressure gasrefrigerant communication pipe 11, and a junctiongas connection pipe 65 that merges the high-pressuregas connection pipe 63 and the low-pressuregas connection pipe 64. The junctiongas connection pipe 65 is connected to the gas side of theutilization heat exchanger 32 of theutilization refrigerant circuit 12 a. Additionally, in the present embodiment, the high-pressuregas control valve 66 is an electromagnetic valve that is connected to the high-pressuregas connection pipe 63 and can circulate and cut off the refrigerant. In the present embodiment, the low-pressuregas control valve 67 is an electromagnetic valve that is connected to the low-pressuregas connection pipe 64 and can circulate and cut off the refrigerant. Thus, when theutilization unit 3 conducts the cooling operation, theconnection unit 6 can function to close the high-pressuregas control valve 66 and open the low-pressuregas control valve 67 such that the refrigerant flowing into theliquid connection pipe 61 through the liquidrefrigerant communication pipe 9 is sent to theutilization expansion valve 31 of theutilization refrigerant circuit 12 a, pressure-reduced by theutilization expansion valve 31, evaporated in theutilization heat exchanger 32, and thereafter returned to the low-pressure gasrefrigerant communication pipe 11 through the junctiongas connection pipe 65 and the low-pressuregas connection pipe 64. Further, when theutilization unit 3 conducts the heating operation, theconnection unit 6 can function to close the low-pressuregas control valve 67 and open the high-pressuregas control valve 66 such that the refrigerant flowing into the high-pressuregas connection pipe 63 and the junctiongas connection pipe 65 through the high-pressure gasrefrigerant communication pipe 10 is sent to the gas side of theutilization heat exchanger 32 of theutilization refrigerant circuit 12 a, condensed in theutilization heat exchanger 32, pressure-reduced by theutilization expansion valve 31, and thereafter returned to the liquidrefrigerant communication pipe 9 through theliquid connection pipe 61. Further, theconnection unit 6 is disposed with aconnection control unit 68 that controls the operation of the respective portions configuring theconnection unit 6. Additionally, theconnection control unit 68 includes a microcomputer and a memory disposed in order to control theconnection unit 6, and is configured such that it can exchange control signals and the like with theutilization control unit 36 of theutilization unit 3. - As described above, the
refrigerant circuit 12 of theair conditioner 1 is configured by the interconnection of theutilization refrigerant circuits refrigerant circuit 12 d, therefrigerant communication pipes connection refrigerant circuits air conditioner 1 of the present embodiment can conduct a simultaneous cooling and heating operation, such as theutilization unit 5 conducting a heating operation while theutilization units - Additionally, in the
air conditioner 1 of the present embodiment, as will be described later, the control width is expanded when the evaporating ability of the heatsource heat exchanger 23 is controlled by the heatsource expansion valve 24 by using the firstoil returning circuit 101 when the heatsource heat exchanger 23 is caused to function as an evaporator, so that a wide control width of the evaporating ability can be obtained by the single heatsource heat exchanger 23. Further, in theair conditioner 1, as will be described later, the control width when the condensing ability of the heatsource heat exchanger 23 is controlled by the heatsource expansion valve 24 is expanded by using thepressurizing circuit 111 and the cooler 121 when the heatsource heat exchanger 23 is caused to function as a condenser, so that a wide control width of the condensing ability can be obtained by the single heatsource heat exchanger 23. Thus, in theair conditioner 1 of the present embodiment, simplification of the heat source heat exchanger, which had been plurally disposed in conventional air conditioners, is realized. - Next, the operation of the
air conditioner 1 of the present embodiment will be described. - The operating modes of the
air conditioner 1 of the present embodiment can be divided in accordance with the air conditioning load of each of theutilization units utilization units utilization units utilization units utilization units source heat exchanger 23 of theheat source unit 2 is caused to function and operate as an evaporator (evaporation operating state) and when the heatsource heat exchanger 23 of theheat source unit 2 is caused to function and operate as a condenser (condensation operating state). - The operation of the
air conditioner 1 in the four operating modes will be described below. - <Heating Operating Mode>
- When all of the
utilization units refrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 4 (refer to the arrows added to therefrigerant circuit 12 inFIG. 4 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, thefirst switch mechanism 22 is switched to the evaporation operating state (the state indicated by the dotted lines of thefirst switch mechanism 22 inFIG. 4 ) and thesecond switch mechanism 26 is switched to the heating load requirement operating state (the state indicated by the dotted lines of thesecond switch mechanism 26 inFIG. 4 ), whereby the heatsource heat exchanger 23 is caused to function as an evaporator such that the high-pressure gas refrigerant compressed and discharged in thecompression mechanism 21 can be supplied to theutilization units refrigerant communication pipe 10. Further, the opening of the heatsource expansion valve 24 is regulated to reduce the pressure of the refrigerant. It will be noted that thecontrol valve 111 b of the pressurizingcircuit 111 and the coolingcircuit expansion valve 122 b of thecooling circuit 122 are closed so that the high-pressure gas refrigerant is caused to merge with the refrigerant flowing through the heatsource expansion valve 24 and thereceiver 25, the supply of the cooling source to the cooler 121 is shut off, and the refrigerant flowing between thereceiver 25 and theutilization units connection units gas control valves gas control valves utilization heat exchangers utilization units utilization units utilization expansion valves utilization heat exchangers liquid temperature sensors gas temperature sensors - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thesecond switch mechanism 26. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. The high-pressure gas refrigerant sent to thesecond switch mechanism 26 is sent to the high-pressure gasrefrigerant communication pipe 10 through thefirst port 26 a and thefourth port 26 d of thesecond switch mechanism 26 and the high-pressuregas closing valve 28. - Then, the high-pressure gas refrigerant sent to the high-pressure gas
refrigerant communication pipe 10 is branched into three and sent to the high-pressuregas connection pipes connection units gas connection pipes connection units utilization heat exchangers utilization units gas control valves - Then, the high-pressure gas refrigerant sent to the
utilization heat exchangers utilization heat exchangers utilization units utilization heat exchangers utilization expansion valves liquid connection pipes connection units - Then, the refrigerant sent to the
liquid connection pipes refrigerant communication pipe 9 and merges. - Then, the refrigerant that has been sent to the liquid
refrigerant communication pipe 9 and merged is sent to thereceiver 25 through theliquid closing valve 27 and the cooler 121 of theheat source unit 2. The refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25, and the pressure of the refrigerant is thereafter reduced by the heatsource expansion valve 24. Then, the refrigerant whose pressure has been reduced by the heatsource expansion valve 24 is evaporated in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source, becomes low-pressure gas refrigerant, and is sent to thefirst switch mechanism 22. Then, the low-pressure gas refrigerant sent to thefirst switch mechanism 22 is returned to the intake side of thecompression mechanism 21 through thesecond port 22 b and thethird port 22 c of thefirst switch mechanism 22. In this manner, the operation in the heating operating mode is conducted. - At this time, there are cases where the heating loads of the
utilization units source heat exchanger 23 of theheat source unit 2 and balance the overall heating load of theutilization units utilization heat exchangers source heat exchanger 23 by conducting control to reduce the opening of the heatsource expansion valve 24. When control is conducted to reduce the opening of the heatsource expansion valve 24, the level of the refrigerant inside the heatsource heat exchanger 23 drops. Thus, in a heat exchanger configured such that the refrigerant flows in from below and flows out from above when the heat exchanger functions as an evaporator of the refrigerant (seeFIG. 2 andFIG. 3 ), like the heatsource heat exchanger 23 of the present embodiment, it becomes difficult for the refrigerating machine oil to be discharged together with the evaporated refrigerant, and it becomes easy for accumulation of the refrigerating machine oil to occur. - However, in the
air conditioner 1 of the present embodiment, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below (more preferably, the minimum value of the evaporation temperature or less) is used (i.e., a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the heat source heat exchanger when the heat source heat exchanger functions as an evaporator), and the firstoil returning circuit 101 is disposed. Additionally, thecontrol valve 101 b of the firstoil returning circuit 101 is configured to be opened during the heating operating mode (i.e., when thefirst switch mechanism 22 is in the evaporation operating state) such that it can extract, and return to thecompression mechanism 21, the refrigerating machine oil together with the refrigerant from the inside of the heatsource heat exchanger 23 from the lower portion of the heatsource heat exchanger 23 through theoil returning pipe 101 a. For this reason, even though the level of the refrigerant inside the heatsource heat exchanger 23 drops as a result of control being conducted to reduce the opening of the heatsource expansion valve 24 and it becomes difficult for the refrigerating machine oil to be discharged together with the evaporated refrigerant, accumulation of the refrigerating machine oil inside the heatsource heat exchanger 23 can be prevented. - It will be noted that it is preferable for the
control valve 101 b to be closed when thefirst switch mechanism 22 is in the condensation operating state and to be opened when thefirst switch mechanism 22 is in the evaporation operating state because when thecontrol valve 101 b is opened when the heatsource heat exchanger 23 functions as a condenser, some of the refrigerant condensed in the heatsource heat exchanger 23 is returned to thecompression mechanism 21 and the amount of refrigerant sent to theutilization refrigerant circuits control valve 101 b may also be configured such that when thefirst switch mechanism 22 is in the evaporation operating state, thecontrol valve 101 b is opened only when the level of the refrigerant inside the heatsource heat exchanger 23 drops as a result of control being conducted to reduce the opening of the heatsource expansion valve 24 and it becomes difficult for the refrigerating machine oil to be discharged together with the evaporated refrigerant. For example, the conditions under which thecontrol valve 101 b is opened may be when thefirst switch mechanism 22 is in the evaporation operating state and when the heatsource expansion valve 24 is equal to or less than a predetermined opening. The opening of the heatsource expansion valve 24 when the level of the refrigerant inside the heatsource heat exchanger 23 drops and it becomes difficult for the refrigerating machine oil to be discharged together with the evaporated refrigerant is found experimentally, and the predetermined opening is determined on the basis of the experimentally found opening. - <Cooling Operating Mode>
- When all of the
utilization units refrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 5 (refer to the arrows added to therefrigerant circuit 12 inFIG. 5 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, thefirst switch mechanism 22 is switched to the condensation operating state (the state indicated by the solid lines of thefirst switch mechanism 22 inFIG. 5 ), whereby the heatsource heat exchanger 23 is caused to function as a condenser. Further, the heatsource expansion valve 24 is opened. It will be noted that thecontrol valve 101 b of the firstoil returning circuit 101 is closed so that the operation of extracting, and returning to thecompression mechanism 21, the refrigerating machine oil together with the refrigerant from the lower portion of the heatsource heat exchanger 23 is not conducted. In theconnection units gas control valves gas control valves utilization heat exchangers utilization units utilization heat exchangers utilization units compression mechanism 21 of theheat source unit 2 become connected via the low-pressure gasrefrigerant communication pipe 11. In theutilization units utilization expansion valves utilization heat exchangers liquid temperature sensors gas temperature sensors - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thefirst switch mechanism 22. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. The high-pressure gas refrigerant sent to thefirst switch mechanism 22 is sent to the heatsource heat exchanger 23 through thefirst port 22 a and thesecond port 22 b of thefirst switch mechanism 22. Then, the high-pressure gas refrigerant sent to the heatsource heat exchanger 23 is condensed in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source. Then, the refrigerant condensed in the heatsource heat exchanger 23 passes through the heatsource expansion valve 24, the high-pressure gas refrigerant that has been compressed and discharged by thecompression mechanism 21 merges therewith through the pressurizing circuit 111 (the details will be described later), and the refrigerant is sent to thereceiver 25. Then, the refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25 and thereafter sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled as a result of heat exchange being conducted with the refrigerant flowing through the cooling circuit 122 (the details will be described later). Then, the refrigerant cooled in the cooler 121 is sent to the liquidrefrigerant communication pipe 9 through theliquid closing valve 27. - Then, the refrigerant sent to the liquid
refrigerant communication pipe 9 is branched into three and sent to theliquid connection pipes connection units liquid connection pipes connection units utilization expansion valves utilization units - Then, the pressure of the refrigerant sent to the
utilization expansion valves utilization expansion valves utilization heat exchangers gas connection pipes connection units - Then, the low-pressure gas refrigerant sent to the junction
gas connection pipes refrigerant communication pipe 11 through the low-pressuregas control valves gas connection pipes - Then, the low-pressure gas refrigerant that has been sent to the low-pressure gas
refrigerant communication pipe 11 and merged is returned to the intake side of thecompression mechanism 21 through the low-pressuregas closing valve 29. In this manner, the operation in the cooling operating mode is conducted. - At this time, there are cases where the cooling loads of the
utilization units source heat exchanger 23 of theheat source unit 2 and balance the overall cooling load of theutilization units utilization heat exchangers source heat exchanger 23 by conducting control to reduce the opening of the heatsource expansion valve 24. When control is conducted to reduce the opening of the heatsource expansion valve 24, the amount of the liquid refrigerant accumulating inside the heatsource heat exchanger 23 increases and the substantial heat transfer area is reduced, whereby the condensing ability becomes smaller. However, when control is conducted to reduce the opening of the heatsource expansion valve 24, there is a tendency for the refrigerant pressure downstream of the heat source expansion valve 24 (specifically, between the heatsource expansion valve 24 and theutilization refrigerant circuits refrigerant circuit 12 d. - However, in the
air conditioner 1 of the present embodiment, the pressurizingcircuit 111 is disposed which causes the high-pressure gas refrigerant compressed and discharged by thecompression mechanism 21 to merge with the refrigerant whose pressure is reduced in the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits control valve 111 b of the pressurizingcircuit 111 is configured to be opened during the cooling operating mode (i.e., when thefirst switch mechanism 22 is in the condensation operating state) such that it can cause the refrigerant to merge downstream of the heatsource expansion valve 24 from the discharge side of thecompression mechanism 21 through the pressurizingpipe 111 a. For this reason, the pressure of the refrigerant downstream of the heatsource expansion valve 24 can be raised by causing the high-pressure gas refrigerant to merge through the pressurizingcircuit 111 downstream of the heatsource expansion valve 24 while control is conducted to reduce the opening of the heatsource expansion valve 24. However, when the high-pressure gas refrigerant is simply caused to merge downstream of the heatsource expansion valve 24 through the pressurizingcircuit 111, the high-pressure gas refrigerant merges and the refrigerant sent to theutilization refrigerant circuits refrigerant communication pipe 9 to theutilization refrigerant circuits utilization refrigerant circuits - However, in the
air conditioner 1 of the present embodiment, the cooler 121 is further disposed downstream of the heatsource expansion valve 24. For this reason, control is conducted to raise the refrigerant pressure downstream of the heatsource expansion valve 24 by causing the high-pressure gas refrigerant to merge through the pressurizingcircuit 111 downstream of the heatsource expansion valve 24 while control is conducted to reduce the opening of the heatsource expansion valve 24, and the refrigerant whose pressure is reduced by the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits utilization refrigerant circuits air conditioner 1 of the present embodiment, because the pressurizingpipe 111 a is connected between the heatsource expansion valve 24 and thereceiver 25, the high-pressure gas refrigerant merges with the refrigerant downstream of the heatsource expansion valve 24, and the refrigerant whose temperature has risen as a result of the high-pressure gas refrigerant merging therewith is cooled by the cooler 121. For this reason, it is not necessary to use a low-temperature cooling source as the cooling source for cooling the refrigerant in the cooler 121, and a cooling source with a relatively high temperature can be used. Moreover, in theair conditioner 1 of the present embodiment, thecooling circuit 122 is disposed, the pressure of some of the refrigerant sent from the heatsource heat exchanger 23 to theutilization refrigerant circuits compression mechanism 21, and this refrigerant is used as the cooling source of the cooler 121. For this reason, a cooling source can be obtained which has a sufficiently lower temperature than the temperature of the refrigerant whose pressure is reduced in the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits source expansion valve 24 and which is sent to theutilization refrigerant circuits circuit expansion valve 122 b of thecooling circuit 122 is regulated in accordance with the flow rate and temperature of the refrigerant sent to theutilization refrigerant circuits source expansion valve 24, such as regulating the opening on the basis of the degree of superheat of the cooler 121 (calculated from the refrigerant temperature detected by the cooling circuitoutlet temperature sensor 96 disposed in the lead-outpipe 122 c of the cooling circuit 122). - <Simultaneous Cooling and Heating Operating Mode (Evaporation Load)>
- The operation will be described during the simultaneous cooling and heating operating mode where, for example, the
utilization unit 3 of theutilization units utilization units source heat exchanger 23 of theheat source unit 2 is caused to function and operate as an evaporator (evaporation operating mode). In this case, therefrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 6 (refer to the arrows added to therefrigerant circuit 12 inFIG. 6 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, similar to the aforementioned heating operating mode, thefirst switch mechanism 22 is switched to the evaporation operating state (the state indicated by the dotted lines of thefirst switch mechanism 22 inFIG. 6 ) and thesecond switch mechanism 26 is switched to the heating load requirement operating state (the state indicated by the dotted lines of thesecond switch mechanism 26 inFIG. 6 ), whereby the heatsource heat exchanger 23 is caused to function as an evaporator so that the high-pressure gas refrigerant compressed and discharged in thecompression mechanism 21 can be supplied to theutilization units refrigerant communication pipe 10. Further, the opening of the heatsource expansion valve 24 is regulated to reduce the pressure of the refrigerant. It will be noted that thecontrol valve 111 b of the pressurizingcircuit 111 and the coolingcircuit expansion valve 122 b of thecooling circuit 122 are closed so that the high-pressure gas refrigerant is not caused to merge with the refrigerant flowing between the heatsource expansion valve 24 and thereceiver 25 and the supply of the cooling source to the cooler 121 is cut off such that that the refrigerant flowing between thereceiver 25 and theutilization units connection unit 6, the high-pressuregas control valve 66 is closed and the low-pressuregas control valve 67 is opened, whereby theutilization heat exchanger 32 of theutilization unit 3 is caused to function as an evaporator, and theutilization heat exchanger 32 of theutilization unit 3 and the intake side of thecompression mechanism 21 of theheat source unit 2 become connected via the low-pressure gasrefrigerant communication pipe 11. In theutilization unit 3, the opening of theutilization expansion valve 31 is regulated in accordance with the cooling load of the utilization unit, such as the opening being regulated on the basis of the degree of superheat of the utilization heat exchanger 32 (specifically, the temperature difference between the refrigerant temperature detected by theliquid temperature sensor 33 and the refrigerant temperature detected by the gas temperature sensor 34), for example. In theconnection units gas control valves gas control valves utilization heat exchangers utilization units utilization units utilization expansion valves utilization heat exchangers 42 and 52 (specifically, the temperature difference between the refrigerant temperature detected by theliquid temperature sensors gas temperature sensors 44 and 54), for example. - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thesecond switch mechanism 26. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. The high-pressure gas refrigerant sent to thesecond switch mechanism 26 is sent to the high-pressure gasrefrigerant communication pipe 10 through thefirst port 26 a and thefourth port 26 d of thesecond switch mechanism 26 and the high-pressuregas closing valve 28. - Then, the high-pressure gas refrigerant sent to the high-pressure gas
refrigerant communication pipe 10 is branched into two and sent to the high-pressuregas connection pipes connection units gas connection pipes connection units utilization heat exchangers utilization units gas control valves gas connection pipes - Then, the high-pressure gas refrigerant sent to the
utilization heat exchangers utilization heat exchangers utilization units utilization heat exchangers utilization expansion valves liquid connection pipes connection units - Then, the refrigerant sent to the
liquid connection pipes refrigerant communication pipe 9 and merges. - Then, some of the refrigerant that has been sent to the liquid
refrigerant communication pipe 9 and merged is sent to theliquid connection pipe 61 of theconnection unit 6. Then, the refrigerant sent to theliquid connection pipe 61 of theutilization unit 6 is sent to theutilization expansion valve 31 of theutilization unit 3. - Then, the pressure of the refrigerant sent to the
utilization expansion valve 31 is reduced by theutilization expansion valve 31, and the refrigerant is evaporated in theutilization heat exchanger 32 as a result of heat exchange being conducted with the indoor air and becomes low-pressure gas refrigerant. The indoor air is cooled and supplied to the indoors. Then, the low-pressure gas refrigerant is sent to the junctiongas connection pipe 65 of theconnection unit 6. - Then, the low-pressure gas refrigerant sent to the junction
gas connection pipe 65 is sent to the low-pressure gasrefrigerant communication pipe 11 through the low-pressuregas control valve 67 and the low-pressuregas connection pipe 64, and merges. - Then, the low-pressure gas refrigerant sent to the low-pressure gas
refrigerant communication pipe 11 is returned to the intake side of thecompression mechanism 21 through the low-pressuregas closing valve 29. - The remaining refrigerant excluding the refrigerant sent from the liquid
refrigerant communication pipe 9 to theconnection unit 6 and theutilization unit 3 is sent to thereceiver 25 through theliquid closing valve 27 and the cooler 121 of theheat source unit 2. The refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25, and the pressure of the refrigerant is thereafter reduced by the heatsource expansion valve 24. Then, the refrigerant whose pressure has been reduced by the heatsource expansion valve 24 is evaporated in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source, becomes low-pressure gas refrigerant, and is sent to thefirst switch mechanism 22. Then, the low-pressure gas refrigerant sent to thefirst switch mechanism 22 is returned to the intake side of thecompression mechanism 21 through thesecond port 22 b and thethird port 22 c of thefirst switch mechanism 22. In this manner, the operation in the simultaneous cooling and heating operating mode (evaporation load) is conducted. - At this time, there are cases where, in accordance with the overall air conditioning load of the
utilization units source heat exchanger 23 but the size thereof becomes extremely small. In such cases, similar to the aforementioned heating operating mode, it is necessary to reduce the refrigerant evaporating ability in the heatsource heat exchanger 23 of theheat source unit 2 and balance the overall air conditioning load of theutilization units utilization unit 3 and the heating loads of theutilization units source heat exchanger 23 must be extremely reduced. - However, in the
air conditioner 1 of the present embodiment, because the combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below (more preferably, the minimum value of the evaporation temperature or less) is used (i.e., a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the heat source heat exchanger when the heat source heat exchanger functions as an evaporator), and the firstoil returning circuit 101 is disposed, the accumulation of refrigerating machine oil inside the heatsource heat exchanger 23 can be prevented as previously mentioned in the description of the operation of the heating operating mode. - <Simultaneous Cooling and Heating Mode (Condensation Load)>
- The operation will be described during the simultaneous cooling and heating operating mode where, for example, the
utilization units utilization units utilization unit 5 conducts the heating operation, when the heatsource heat exchanger 23 of theheat source unit 2 is caused to function and operate as a condenser in accordance with the overall air conditioning load of theutilization units refrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 7 (refer to the arrows added to therefrigerant circuit 12 inFIG. 7 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, thefirst switch mechanism 22 is switched to the condensation operating state (the state indicated by the solid lines of thefirst switch mechanism 22 inFIG. 7 ) and thesecond switch mechanism 26 is switched to the heating load requirement operating state (the state indicated by the dotted lines of thesecond switch mechanism 26 inFIG. 7 ), whereby the heatsource heat exchanger 23 is caused to function as an evaporator so that the high-pressure gas refrigerant compressed and discharged in thecompression mechanism 21 can be supplied to theutilization unit 5 through the high-pressure gasrefrigerant communication pipe 10. Further, the heatsource expansion valve 24 is opened. It will be noted that thecontrol valve 101 b of the firstoil returning circuit 101 is closed so that the operation of extracting, and returning to thecompression mechanism 21, the refrigerating machine oil together with the refrigerant from the lower portion of the heatsource heat exchanger 23 is not conducted. In theconnection units gas control valves gas control valves utilization heat exchangers utilization units utilization heat exchangers utilization units compression mechanism 21 of theheat source unit 2 become connected via the low-pressure gasrefrigerant communication pipe 11. In theutilization units utilization expansion valves utilization heat exchangers 32 and 42 (specifically, the temperature difference between the refrigerant temperature detected by theliquid temperature sensors gas temperature sensors 34 and 44), for example. In theconnection unit 8, the low-pressuregas control valve 87 is closed and the high-pressuregas control valve 86 is opened, whereby theutilization heat exchanger 52 of theutilization unit 5 is caused to function as a condenser. In theutilization unit 5, the opening of theutilization expansion valve 51 is regulated in accordance with the heating load of the utilization unit, such as the opening being regulated on the basis of the degree of subcooling of the utilization heat exchanger 52 (specifically, the temperature difference between the refrigerant temperature detected by theliquid temperature sensor 53 and the refrigerant temperature detected by the gas temperature sensor 54), for example. - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thefirst switch mechanism 22 and thesecond switch mechanism 26. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. Then, the high-pressure gas refrigerant sent to thefirst switch mechanism 22 of the high-pressure gas refrigerant that has been compressed and discharged by thecompression mechanism 21 is sent to the heatsource heat exchanger 23 through thefirst port 22 a and thesecond port 22 b of thefirst switch mechanism 22. Then, the high-pressure gas refrigerant sent to the heatsource heat exchanger 23 is condensed in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source. Then, the refrigerant condensed in the heatsource heat exchanger 23 passes through the heatsource expansion valve 24, the high-pressure gas refrigerant that has been compressed and discharged by thecompression mechanism 21 merges therewith through the pressurizing circuit 111 (the details will be described later), and the refrigerant is sent to thereceiver 25. Then, the refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25 and sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled as a result of heat exchange being conducted with the refrigerant flowing through the cooling circuit 122 (the details will be described later). Then, the refrigerant cooled in the cooler 121 is sent to the liquidrefrigerant communication pipe 9 through theliquid closing valve 27. - The high-pressure gas refrigerant sent to the
second switch mechanism 26 of the high-pressure gas refrigerant that has been compressed and discharged by thecompression mechanism 21 is sent to the high-pressure gasrefrigerant communication pipe 10 through thefirst port 26 a and thesecond port 26 d of thesecond switch mechanism 26 and the high-pressuregas closing valve 28. - Then, the high-pressure gas refrigerant sent to the high-pressure gas
refrigerant communication pipe 10 is sent to the high-pressuregas connection pipe 83 of theconnection unit 8. The high-pressure gas refrigerant sent to the high-pressuregas connection pipe 83 of theconnection unit 8 is sent to theutilization heat exchanger 52 of theutilization unit 5 through the high-pressuregas control valve 86 and the junctiongas connection pipe 85. - Then, the high-pressure gas refrigerant sent to the
utilization heat exchanger 52 is condensed in theutilization heat exchanger 52 of theutilization unit 5 as a result of heat exchange being conducted with the indoor air. The indoor air is heated and supplied to the indoors. The refrigerant condensed in theutilization heat exchanger 52 passes through theutilization expansion valve 51 and is thereafter sent to theliquid connection pipe 81 of theconnection unit 8. - Then, the refrigerant sent to the
liquid connection pipe 81 is sent to the liquidrefrigerant communication pipe 9 and merges with the refrigerant sent to the liquidrefrigerant communication pipe 9 through thefirst switch mechanism 22, the heatsource heat exchanger 23, the heatsource expansion valve 24, thereceiver 25, the cooler 121 and theliquid closing valve 27. - Then, the refrigerant flowing through the liquid
refrigerant communication pipe 9 is branched into two and sent to theliquid connection pipes connection units liquid connection pipes connection units utilization expansion valves utilization units - Then, the pressure of refrigerant sent to the
utilization expansion valves utilization expansion valves utilization heat exchangers gas connection pipes connection units - Then, the low-pressure gas refrigerant sent to the junction
gas connection pipes refrigerant communication pipe 11 through the low-pressuregas control valves gas connection pipes - Then, the low-pressure gas refrigerant sent to the low-pressure gas
refrigerant communication pipe 11 is returned to the intake side of thecompression mechanism 21 through the low-pressuregas closing valve 29. In this manner, the operation in the simultaneous cooling and heating operating mode (condensation load) is conducted. - At this time, there are cases where, in accordance with the overall air conditioning load of the
utilization units source heat exchanger 23 but the size thereof becomes extremely small. In such cases, similar to the aforementioned cooling operating mode, it is necessary to reduce the refrigerant condensing ability in the heatsource heat exchanger 23 of theheat source unit 2 and balance the overall air conditioning load of theutilization units utilization units utilization unit 5 become about the same in the simultaneous cooling and heating operating mode, and in such cases the condensation load of the heatsource heat exchanger 23 must be made extremely small. - However, in the
air conditioner 1 of the present embodiment, control is conducted to raise the pressure of the refrigerant downstream of the heatsource expansion valve 24 by causing the high-pressure gas refrigerant to merge through the pressurizingcircuit 111 downstream of the heatsource expansion valve 24 while reducing the opening of the heatsource expansion valve 24, and the refrigerant whose pressure is reduced by the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits utilization refrigerant circuits - The
air conditioner 1 of the present embodiment has the following characteristics. - (A)
- The
air conditioner 1 of the present embodiment is provided with therefrigerant circuit 12 configured by the interconnection of the plurality ofutilization refrigerant circuits refrigerant circuit 12 d, which includes the heatsource heat exchanger 23 configured such that the refrigerant flows in from below and flows out from above when the heatsource heat exchanger 23 functions as an evaporator. A combination of refrigerating machine oil and refrigerant that does not separate into two layers in a temperature range of 30° C. or below (more preferably, the minimum value of the evaporation temperature or less) is used as the refrigerating machine oil and the refrigerant used in therefrigerant circuit 12. Here, the evaporation temperature of the refrigerant in the heatsource heat exchanger 23 is a temperature of 30° C. or below (more preferably, the minimum value of the evaporation temperature or less) when water, air, and brine are used as the heat sources. Specifically, a combination of refrigerating machine oil and refrigerant that does not separate into two layers in the heat source heat exchanger is used as the refrigerating machine oil and refrigerant in the refrigerant circuit when the heat source heat exchanger functions as an evaporator. For this reason, in theair conditioner 1, the refrigerating machine oil does not accumulate in a state where it floats on the surface of the refrigerant inside the heatsource heat exchanger 23, but rather accumulates inside the heatsource heat exchanger 23 in a state where it is mixed with the refrigerant. Additionally, the refrigerating machine oil accumulating inside the heatsource heat exchanger 23 is returned to the intake side of thecompression mechanism 21 together with the refrigerant by the firstoil returning circuit 101 connected to the lower portion of the heatsource heat exchanger 23. For this reason, it becomes unnecessary to maintain the level of the refrigerant inside the heat source heat exchanger at a constant level or more in order to prevent the refrigerating machine oil from accumulating inside the heat source heat exchanger, as in conventional air conditioners. - Thus, in the
air conditioner 1, even when control is conducted to reduce the evaporating ability of the heatsource heat exchanger 23 by reducing the opening of the heatsource expansion valve 24 in accordance with the air conditioning load of the plurality ofutilization refrigerant circuits source heat exchanger 23 drops, the refrigerating machine oil does not accumulate inside the heatsource heat exchanger 23. For this reason, the control width when the evaporating ability of the heatsource heat exchanger 23 is controlled with a heat source expansion valve can be expanded. - Additionally, in the
air conditioner 1, it becomes unnecessary to conduct control, as in conventional air conditioners disposed with plural heat source heat exchangers, to reduce the evaporating ability by closing some of the heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators when the heat source heat exchangers are caused to function as evaporators or to reduce the evaporating ability by causing some of the heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators. For this reason, a wide control width of the evaporating ability can be obtained by a single heat source heat exchanger. - Thus, because simplification of the heat source heat exchanger becomes possible in an air conditioner where simplification of the heat source heat exchangers could not be realized by restricting the control width of the control of the evaporating ability of the heat source heat exchangers, increases in the number of parts and cost that had occurred in conventional air conditioners as a result of disposing plural heat source heat exchangers can be prevented. Further, the problem of the COP becoming poor can be eliminated in an operating condition where, when some of the heat source heat exchangers are caused to function as condensers to reduce the evaporating ability, the amount of refrigerant compressed in the compression mechanism increases in correspondence to the amount of refrigerant condensed by the heat source heat exchangers, and the air conditioning load of the entire plurality of utilization refrigerant circuits is small.
- (B)
- In the
air conditioner 1 of the present embodiment, thecontrol valve 101 b is disposed in the firstoil returning circuit 101, and theair conditioner 1 operates in a state where thecontrol valve 101 b is closed when the heatsource heat exchanger 23 is caused to function as a condenser, whereby the amount of refrigerant sent to theutilization refrigerant circuits source heat exchanger 23 can be prevented from being reduced. - Further, in the
air conditioner 1, it is not necessary to use the firstoil returning circuit 101 until the level of the refrigerant inside the heatsource heat exchanger 23 reaches a constant level or more where there is no accumulation of refrigerating machine oil. For this reason, the opening of the heatsource expansion valve 24 corresponding to a level of the refrigerant where accumulation of the refrigerating machine oil can occur inside the heatsource heat exchanger 23 is set as a predetermined opening, and thecontrol valve 101 b is opened and theair conditioner 1 operates only when the opening of the heatsource expansion valve 24 becomes equal to or less than this predetermined opening, whereby the amount of refrigerant sent to thecompression mechanism 21 can be prevented from increasing without the refrigerant being evaporated in the heatsource heat exchanger 23. - (C)
- In the
air conditioner 1 of the present embodiment, a plate-type heat exchanger is used as the heatsource heat exchanger 23, and in terms of the structure thereof, it is difficult for the refrigerating machine oil accumulating in a state where it floats on the surface of the refrigerant to be extracted from the vicinity of the surface of the refrigerant in order to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23. However, in theair conditioner 1 of the present embodiment, it suffices simply for the refrigerating machine oil to accumulate inside the heatsource heat exchanger 23 in a state where it is mixed with the refrigerant and for the refrigerating machine oil accumulating inside the heat source exchanger 23 to be extracted from the lower portion of the heatsource heat exchanger 23 together with the refrigerant. For this reason, it is easy to dispose the firstoil returning circuit 101 even when a plate-type heat exchanger is used. - (D)
- In the
air conditioner 1 of the present embodiment, the high-pressure gas refrigerant merges from the pressurizingcircuit 111 and the refrigerant to be sent to theutilization refrigerant circuits source expansion valve 24 rises when the pressure of the refrigerant that has been condensed in the heatsource heat exchanger 23 functioning as a condenser is reduced by the heatsource expansion valve 24 and the refrigerant is sent to theutilization refrigerant circuits utilization refrigerant circuits source expansion valve 24 cannot be sufficiently reduced. However, in theair conditioner 1, the refrigerant whose pressure is reduced by the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits utilization refrigerant circuits - Thus, in the
air conditioner 1, even if control is conducted to reduce the condensing ability of the heatsource heat exchanger 23 by reducing the opening of the heatsource expansion valve 24 in accordance with the air conditioning load of the plurality ofutilization refrigerant circuits circuit 111 to merge the high-pressure gas refrigerant and pressurize the refrigerant sent to theutilization refrigerant circuits utilization refrigerant circuits source heat exchanger 23 is controlled by the heatsource expansion valve 24 can be expanded. - Additionally, in the
air conditioner 1, it becomes unnecessary to conduct control, as in conventional air conditioners disposed with plural heat source heat exchangers, to reduce the evaporating ability by closing some of the heat source expansion valves to reduce the number of heat source heat exchangers functioning as evaporators when the heat source heat exchangers are caused to function as condensers or to reduce the evaporating ability by causing some of the heat source heat exchangers to function as condensers to offset the evaporating ability of the heat source heat exchangers functioning as evaporators. For this reason, a wide control width of the condensing ability can be obtained by a single heat source heat exchanger. - Thus, because simplification of the heat source heat exchanger becomes possible in an air conditioner where simplification of the heat source heat exchangers could not be realized by restricting the control width of the control of the condensing ability of the heat source heat exchangers, increases in the number of parts and cost that had occurred in conventional air conditioners as a result of disposing plural heat source heat exchangers can be prevented. Further, the problem of the COP becoming poor can be eliminated in an operating condition where, when some of the heat source heat exchangers are caused to function as evaporators to reduce the condensing ability, the amount of refrigerant compressed in the compression mechanism increases in correspondence to the amount of refrigerant condensed by the heat source heat exchangers, and the air conditioning load of the entire plurality of utilization refrigerant circuits is small.
- (E)
- In the
air conditioner 1 of the present embodiment, because the pressurizingcircuit 111 is connected between the heatsource expansion valve 24 and the cooler 121 such that the high-pressure gas refrigerant merges, refrigerant whose temperature has become higher as a result of the high-pressure gas refrigerant merging therewith becomes cooled by the cooler 121. Thus, it is not necessary to use a low-temperature cooling source as the cooling source for cooling the refrigerant in the cooler 121, and a cooling source with a relatively high temperature can be used. - Further, in the
air conditioner 1, because refrigerant whose pressure is reduced to a refrigerant pressure that can return, to the intake side of thecompression mechanism 21, some of the refrigerant sent from downstream of the heatsource expansion valve 24 to theutilization refrigerant circuits source expansion valve 24 to theutilization refrigerant circuits source expansion valve 24 to theutilization refrigerant circuits - (F)
- In the
air conditioner 1 of the present embodiment, water, of which a constant amount is supplied without relation to the control of the flow rate of the refrigerant flowing through the heatsource heat exchanger 23, is used, and the evaporating ability in the heatsource heat exchanger 23 cannot be controlled by controlling the water amount. However, in theair conditioner 1, because the control width when the evaporating ability or the condensing ability of the heatsource heat exchanger 23 is controlled by the heatsource expansion valve 24 is expanded, the control width when controlling the evaporating ability of the heatsource heat exchanger 23 can be ensured even if the water amount is not controlled. - In the
aforementioned air conditioner 1, theheat source unit 2 and theutilization units refrigerant communication pipes connection units FIG. 8 , theheat source unit 2 and theutilization units refrigerant communication pipes air conditioner 1 of the present modification is configured such that the low-pressure gasrefrigerant communication pipe 11 and theconnection units utilization units refrigerant communication pipe 9 and the high-pressure gasrefrigerant communication pipe 10, and by the switching of thesecond switch mechanism 26, the high-pressure gasrefrigerant communication pipe 10 is caused to function as a pipe through which flows the low-pressure gas refrigerant returned to theheat source unit 2 from theutilization units refrigerant communication pipe 10 is caused to function as a pipe through which flows the high-pressure gas refrigerant supplied to theutilization units heat source unit 2. - Next, the operation (the heating operating mode and the cooling operating mode) of the
air conditioner 1 of the present modification will be described. - First, the heating operating mode will be described. When all of the
utilization units refrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 9 (refer to the arrows added to therefrigerant circuit 12 inFIG. 9 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, thefirst switch mechanism 22 is switched to the evaporation operating state (the state indicated by the dotted lines of thefirst switch mechanism 22 inFIG. 9 ) and thesecond switch mechanism 26 is switched to the heating load requirement operating state (the state indicated by the dotted lines of thesecond switch mechanism 26 inFIG. 9 ), whereby the heatsource heat exchanger 23 is caused to function as an evaporator so that the high-pressure gas refrigerant that has been compressed in thecompression mechanism 21 and discharged can be supplied to theutilization units refrigerant communication pipe 10. Further, the opening of the heatsource expansion valve 24 is regulated to reduce the pressure of the refrigerant. It will be noted that thecontrol valve 111 b of the pressurizingcircuit 111 and the coolingcircuit expansion valve 122 b of thecooling circuit 122 are closed such that the high-pressure gas refrigerant is not caused to merge with the refrigerant flowing between the heatsource expansion valve 24 and thereceiver 25 and the supply of the cooling source to the cooler 121 is cut off so that the refrigerant flowing between thereceiver 25 and theutilization units utilization units utilization expansion valves utilization heat exchangers liquid temperature sensors gas temperature sensors - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thesecond switch mechanism 26. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. The high-pressure gas refrigerant sent to thesecond switch mechanism 26 is sent to the high-pressure gasrefrigerant communication pipe 10 through thefirst port 26 a and thefourth port 26 d of thesecond switch mechanism 26 and the high-pressuregas closing valve 28. - Then, the high-pressure gas refrigerant sent to the high-pressure gas
refrigerant communication pipe 10 is branched into three and sent to theutilization heat exchangers utilization units - Then, the high-pressure gas refrigerant sent to the
utilization heat exchangers utilization heat exchangers utilization units utilization heat exchangers utilization expansion valves refrigerant communication pipe 9, and merges. - Then, the refrigerant that has been sent to the liquid
refrigerant communication pipe 9 and merged is sent to thereceiver 25 through theliquid closing valve 27 and the cooler 121 of theheat source unit 2. The refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25, and the pressure of the refrigerant is thereafter reduced by the heatsource expansion valve 24. Then, the refrigerant whose pressure has been reduced by the heatsource expansion valve 24 is evaporated in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source, becomes low-pressure gas refrigerant, and is sent to thefirst switch mechanism 22. Then, the low-pressure gas refrigerant sent to thefirst switch mechanism 22 is returned to the intake side of thecompression mechanism 21 through thesecond port 22 b and thethird port 22 c of thefirst switch mechanism 22. In this manner, the operation in the heating operating mode is conducted. - In this case also, there are cases where the heating loads of the
utilization units oil returning circuit 101 is disposed, accumulation of the refrigerating machine oil inside the heatsource heat exchanger 23 can be prevented in the same manner as in the aforementioned heating operating mode of the air conditioner configured to be capable of simultaneous cooling and heating. - Next, the cooling operating mode will be described. When all of the
utilization units refrigerant circuit 12 of theair conditioner 1 is configured as shown inFIG. 10 (refer to the arrows added to therefrigerant circuit 12 inFIG. 10 for the flow of the refrigerant). Specifically, in the heat sourcerefrigerant circuit 12 d of theheat source unit 2, thefirst switch mechanism 22 is switched to the condensation operating state (the state indicated by the solid lines of thefirst switch mechanism 22 inFIG. 10 ) and thesecond switch mechanism 26 is switched to the cooling/heating switching time cooling operating state (the state indicated by the solid lines of thesecond switch mechanism 26 inFIG. 10 ), whereby the heatsource heat exchanger 23 is caused to function as a condenser so that the low-pressure gas refrigerant returned to theheat source unit 2 from theutilization units refrigerant communication pipe 10 can be sent to the intake side of thecompression mechanism 21. Further, the heatsource expansion valve 24 is opened. It will be noted that thecontrol valve 101 b of the firstoil returning circuit 101 is closed so that the operation of extracting, and returning to thecompression mechanism 21, the refrigerating machine oil together with the refrigerant from the lower portion of the heatsource heat exchanger 23 is not conducted. In theutilization units utilization expansion valves utilization heat exchangers liquid temperature sensors gas temperature sensors - In this configuration of the
refrigerant circuit 12, a large portion of the refrigerating machine oil accompanying the high-pressure gas refrigerant that has been compressed and discharged by thecompressor 21 a of thecompression mechanism 21 is separated in theoil separator 21 b, and the high-pressure gas refrigerant is sent to thefirst switch mechanism 22. Then, the refrigerating machine oil separated in theoil separator 21 b is returned to the intake side of thecompressor 21 a through the secondoil returning circuit 21 d. Then, the high-pressure gas refrigerant sent to thefirst switch mechanism 22 is sent to the heatsource heat exchanger 23 through thefirst port 22 a and thesecond port 22 b of thefirst switch mechanism 22. Then, the high-pressure gas refrigerant sent to the heatsource heat exchanger 23 is condensed in the heatsource heat exchanger 23 as a result of heat exchange being conducted with water serving as a heat source. Then, the refrigerant condensed in the heatsource heat exchanger 23 passes through the heatsource expansion valve 24, the high-pressure gas refrigerant that has been compressed and discharged by thecompression mechanism 21 through the pressurizingcircuit 111 merges therewith, and the refrigerant is sent to thereceiver 25. Then, the refrigerant sent to thereceiver 25 is temporarily accumulated inside thereceiver 25 and thereafter sent to the cooler 121. Then, the refrigerant sent to the cooler 121 is cooled as a result of heat exchange being conducted with the refrigerant flowing through thecooling circuit 122. Then, the refrigerant cooled in the cooler 121 is sent to the liquidrefrigerant communication pipe 9 through theliquid closing valve 27. - Then, the refrigerant sent to the liquid
refrigerant communication pipe 9 is branched into three and sent to theutilization expansion valves utilization units - Then, the pressure of the refrigerant sent to the
utilization expansion valves utilization expansion valves utilization heat exchangers refrigerant communication pipe 10 and merges. - Then, the low-pressure gas refrigerant that has been sent to the high-pressure gas
refrigerant communication pipe 10 and merged is returned to the intake side of thecompression mechanism 21 through the high-pressuregas closing valve 28 and thefourth port 26 d and thethird port 26 c of thesecond switch mechanism 26. In this manner, the operation in the cooling operating mode is conducted. - In this case also, there are cases where the cooling loads of the
utilization units source expansion valve 24 by causing the high-pressure gas refrigerant to merge through the pressurizingcircuit 111 downstream of the heatsource expansion valve 24 while conducting control to reduce the opening of the heatsource expansion valve 24, and the refrigerant whose pressure is reduced by the heatsource expansion valve 24 and which is sent to theutilization refrigerant circuits utilization refrigerant circuits - In the
aforementioned air conditioner 1, the firstoil returning circuit 101, the pressurizingcircuit 111, the cooler 121 and thecooling circuit 122 were disposed in theheat source unit 2 in order to expand both the control width of the control of the evaporating ability of the heatsource heat exchanger 23 with the heatsource expansion valve 24 and the control width of the control of the condensing ability of the heatsource heat exchanger 23 with the heatsource expansion valve 24. However, when the control width of the control of the condensing ability of the heatsource heat exchanger 23 is ensured and it is necessary to expand only the control width of the control of the evaporating ability of the heatsource heat exchanger 23, for example, just the first oil returning circuit 101 (i.e., omitting the pressurizingcircuit 111, the cooler 121 and the cooling circuit 122) may be disposed in theheat source unit 2 as shown inFIG. 11 (i.e., the pressurizingcircuit 111, the cooler 121 and thecooling circuit 122 may be omitted). - In the
aforementioned air conditioner 1, four-way switch valves were used as thefirst switch mechanism 22 and thesecond switch mechanism 26, but the switch mechanisms are not limited thereto. For example, as shown inFIG. 12 , three-way switch valves may also be used as thefirst switch mechanism 22 and thesecond switch mechanism 26. - In the
aforementioned air conditioner 1, the flow rate of the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 functioning as an evaporator through the firstoil returning circuit 101 is determined in the firstoil returning circuit 101 in accordance with the pressure loss between the lower portion of the heatsource heat exchanger 23 functioning as an evaporator and thecompression mechanism 21. For this reason, in cases where, for example, the pressure loss inside the heatsource heat exchanger 23 functioning as an evaporator and inside the pipe from the refrigerant outlet side of the heatsource heat exchanger 23 to the intake side of thecompression mechanism 21 is small and the pressure loss in the firstoil returning circuit 101 ends up becoming small, cases can arise where the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23 cannot be returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101. - In such cases, in order to ensure that the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heat
source heat exchanger 23 can be returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101, as shown inFIG. 13 , theair conditioner 1 may be further disposed with apressure reducing mechanism 131 that is connected between the refrigerant outlet side of the heatsource heat exchanger 23 and the intake side of thecompression mechanism 21 and can reduce, before the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101 merge, the pressure of the gas refrigerant evaporated in the heatsource heat exchanger 23 and returned to the intake side of the compression mechanism. - The
pressure reducing mechanism 131 mainly comprises acontrol valve 131 a, which comprises an electromagnetic valve connected to the pipe connecting thethird port 22 c of thefirst switch mechanism 22 and the intake side of thecompression mechanism 21, and a bypass pipe 131 b, which bypasses thecontrol valve 131 a. A capillary tube 131 c is connected to the bypass pipe 131 b. Thepressure reducing mechanism 131 can be operated such that when the firstoil returning circuit 101 is used, thecontrol valve 131 a is closed so that the gas refrigerant evaporated in the heatsource heat exchanger 23 flows just through the bypass pipe 131 b, and in other cases, thecontrol valve 131 a is opened so that the gas refrigerant evaporated in the heatsource heat exchanger 23 flows through both thecontrol valve 131 a and the bypass pipe 131 b. For this reason, when the firstoil returning circuit 101 is used, the pressure loss from the refrigerant outlet side of the heatsource heat exchanger 23 functioning as an evaporator to the intake side of the compression mechanism is increased (i.e., by causing thepressure reducing mechanism 131 to function as a pressure difference increasing mechanism that increases the pressure difference before the merging of the refrigerant and refrigerating machine oil returned from the lower portion of the heatsource heat exchanger 23 to thecompression mechanism 21 through the first oil returning circuit 101), and the flow rate of the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101 can be increased. Thus, the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23 can be returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101. It will be noted that the capillary tube 131 c is not used when the pressure loss in the bypass pipe 131 b can be appropriately set without connecting the capillary tube 131 c. - Further, rather than the
control valve 131 a and the bypass pipe 131 b of the above-describedpressure reducing mechanism 131, the pressure reducing mechanism acting as a pressure difference increasing mechanism may also be an electrically powered expansion valve connected to the pipe connecting thethird port 22 c of thefirst switch mechanism 22 and the intake side of thecompression mechanism 21, as shown inFIG. 14 . Thispressure reducing mechanism 141 is configured such that when the firstoil returning circuit 101 is used, control is conducted to reduce the opening, the pressure loss from the refrigerant outlet side of the heatsource heat exchanger 23 functioning as an evaporator to the intake side of thecompression mechanism 21 can be increased, and the flow rate of the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101 can be increased, and such that in other cases, control can be conducted to increase the opening (i.e., completely open), so that the refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23 can be reliably returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101. - A
pump mechanism 151 may be disposed as a pressure difference increasing mechanism, as shown inFIG. 15 , in the firstoil returning circuit 101 rather than using thepressure reducing mechanism 131 andpressure reducing mechanism 141 as described above. For example, a refrigerant pump can be used as thepressure reducing mechanism 151. Thepump mechanism 151 can increase the flow rate of the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101 by increasing the pressure of the refrigerating machine oil accumulated inside the heatsource heat exchanger 23 and sending the refrigerating machine oil to the first oil returning circuit 101 (i.e., by causing thepressure reducing mechanism 151 to function as a pressure difference increasing mechanism that increases the pressure difference before the merging of the refrigerant and refrigerating machine oil returned from the lower portion of the heatsource heat exchanger 23 to thecompression mechanism 21 through the first oil returning circuit 101). The refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23 can thereby be returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101. - An
ejector mechanism 161 may be disposed as the pressure difference increasing mechanism, as shown inFIG. 16 , in place of thepump 151. Theejector mechanism 161 mainly comprises an ejector 161 a disposed in the firstoil returning circuit 101, a branchingtube 161 b in which high pressure gas refrigerant as the driving fluid of the ejector 161 a branches from the discharge side (in the present modification, between theoil separator 21 b and thefirst port 22 a of the first switch mechanism 22) of thecompression mechanism 21, and acontrol valve 161 c disposed in the branchingtube 161 b. In thisejector 161, in the case that the firstoil returning circuit 101 is used, the flow rate of the refrigerating machine oil and the refrigerant returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101 can be increased by opening the control valve 161 a, feeding high pressure gas refrigerant as the driving fluid to the ejector 161 a from the discharge side of thecompression mechanism 21, using the high pressure gas refrigerant to draw in the refrigerating machine oil accumulated in the lower portion of the heatsource heat exchanger 23, and sending to into the first oil returning circuit 101 (i.e., by causing theejector 161 to function as a pressure difference increasing mechanism that increases the pressure difference before the merging of the refrigerant and refrigerating machine oil returned from the lower portion of the heatsource heat exchanger 23 to thecompression mechanism 21 through the first oil returning circuit 101). The refrigerating machine oil and the refrigerant of a flow rate sufficient enough to be able to prevent the refrigerating machine oil from accumulating inside the heatsource heat exchanger 23 can thereby be reliably returned to thecompression mechanism 21 from the lower portion of the heatsource heat exchanger 23 through the firstoil returning circuit 101. - Embodiments of the present invention were described above with reference to the diagrams, but the specific configurations are not limited to these embodiments, and modifications are possible that do not depart from the spirit of the present invention.
- In accordance with the present invention, the control width can be expanded when the evaporating ability of the evaporator is controlled by the expansion valve in a refrigerating apparatus and air conditioner provided with a refrigerant circuit that has an evaporator configured so that refrigerant flows in from below and flows out from above.
Claims (14)
1. A refrigerating apparatus, comprising:
a refrigerant circuit including a compression mechanism, a condenser, an expansion valve, and an evaporator, the evaporator being configured so that a refrigerant flows in from below and flows out from above, and the refrigerant circuit using a combination of a refrigerating machine oil and the refrigerant that does not separate into two layers in a temperature range of 30° C. or below; and
an oil returning circuit connected to a lower portion of the evaporator and configured to return the refrigerating machine oil accumulated inside the evaporator to the compression mechanism together with the refrigerant.
2. The refrigerating apparatus of claim 1 , wherein
the refrigerating machine oil and the refrigerant used in the refrigerant circuit are a combination of a refrigerating machine oil and a refrigerant that does not separate into two layers in a temperature range of −5° C. or below.
3. The refrigerating apparatus of claim 2 , wherein
the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit includes ethereal oil and R410A.
4. The refrigerating apparatus of claim 1 , further comprising
a pressure difference increasing mechanism for increasing a pressure difference before merging of the refrigerating machine oil and the refrigerant returned to the compression mechanism from the lower portion of the evaporator through the oil returning circuit.
5. A refrigerating apparatus, comprising:
a refrigerant circuit including a compression mechanism, a condenser, an expansion valve, and an evaporator, the evaporator being configured so that a refrigerant flows in from below and flows out from above, and the refrigerant circuit using a combination of a refrigerating machine oil and the refrigerant that does not separate into two layers in the evaporator; and
an oil returning circuit connected to a lower portion of the evaporator and configured to return the refrigerating machine oil accumulated inside the evaporator to the compression mechanism together with the refrigerant.
6. An air conditioner, comprising:
a refrigerant circuit including a plurality of utilization refrigerant circuits, each having a utilization heat exchanger and a utilization expansion valve and being connected to a heat source refrigerant circuit including a compression mechanism, a heat source expansion valve and a heat source heat exchanger, the heat source heat exchanger being configured so that a refrigerant flows in from below and flows out from above when the heat source heat exchanger functions as an evaporator, the heat source refrigerant circuit using a combination of a refrigerating machine oil and a refrigerant that does not separate into two layers in a temperature range of 30° C. or below; and
an oil returning circuit connected to a lower portion of the heat source heat exchanger and configured to return the refrigerating machine oil accumulated inside the heat source heat exchanger to the compression mechanism together with the refrigerant.
7. The air conditioner of claim 6 , wherein
the refrigerating machine oil and the refrigerant used in the refrigerant circuit are a combination of a refrigerating machine oil and a refrigerant that does not separate into two layers in a temperature range of −5° C. or below.
8. The air conditioner of claim 7 , wherein
the combination of refrigerating machine oil and refrigerant used in the refrigerant circuit includes ethereal oil and R410A.
9. The air conditioner of claim 6 , further comprising
a pressure difference increasing mechanism for increasing a pressure difference before merging of the refrigerating machine oil and the refrigerant returned to the compression mechanism from the lower portion of the heat source heat exchanger through the oil returning circuit.
10. The air conditioner of claim 6 , wherein
the oil returning circuit has a control valve, and
the control valve is closed when the heat source heat exchanger functions as a condenser, and is open when the heat source heat exchanger functions as an evaporator.
11. The air conditioner of claim 10 , wherein
the control valve is opened when the heat source expansion valve is at or below a prescribed position.
12. The air conditioner of claim 6 , wherein
the heat source heat exchanger uses as a heat source water fed at a constant rate without regard to a flow rate of refrigerant that flows inside the heat source heat exchanger.
13. The air conditioner of claim 6 , wherein
the heat source heat exchanger includes a plate heat exchanger.
14. An air conditioner, comprising:
a refrigerant circuit including a plurality of utilization refrigerant circuits, each having a utilization heat exchanger and a utilization expansion valve and being connected to a heat source refrigerant circuit including a compression mechanism, a heat source expansion valve and a heat source heat exchanger, the heat source heat exchanger being configured so that a refrigerant flows in from below and flows out from above when the heat source heat exchanger functions as an evaporator, the heat source refrigerant circuit using a combination of a refrigerating machine oil and a refrigerant that does not separate into two layers inside the heat source heat exchanger when the heat source heat exchanger functions as an evaporator; and
an oil returning circuit connected to a lower portion of the heat source heat exchanger and configured to return the refrigerating machine oil accumulated inside the heat source heat exchanger to the compression mechanism together with the refrigerant.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2004-195228 | 2004-07-01 | ||
JP2004195228 | 2004-07-01 | ||
PCT/JP2005/011930 WO2006003925A1 (en) | 2004-07-01 | 2005-06-29 | Freezer and air conditioner |
Publications (1)
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US20070245752A1 true US20070245752A1 (en) | 2007-10-25 |
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ID=35782733
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US11/630,104 Abandoned US20070245752A1 (en) | 2004-07-01 | 2005-06-29 | Refrigerating Apparatus and Air Conditioner |
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US (1) | US20070245752A1 (en) |
EP (1) | EP1780479A4 (en) |
JP (1) | JP4475278B2 (en) |
CN (1) | CN1981165A (en) |
AU (1) | AU2005258567B2 (en) |
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US20170115068A1 (en) * | 2014-06-10 | 2017-04-27 | Vmac Global Technology Inc. | Methods and apparatus for simultaneously cooling and separating a mixture of hot gas and liquid |
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WO2018152474A1 (en) * | 2017-02-17 | 2018-08-23 | Miles Mark W | Solar driven ejector heat pumps for supplemental heating and cooling resources |
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US10184676B2 (en) | 2012-12-28 | 2019-01-22 | Daikin Industries, Ltd. | Air conditioner having simultaneous heating and cooling |
US10571173B2 (en) * | 2016-06-14 | 2020-02-25 | Mitsubishi Electric Corporation | Air conditioning system |
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JP3861891B2 (en) * | 2004-08-04 | 2006-12-27 | ダイキン工業株式会社 | Air conditioner |
KR101340725B1 (en) * | 2006-10-17 | 2013-12-12 | 엘지전자 주식회사 | Water cooling type air conditioner |
JP4492638B2 (en) | 2007-05-09 | 2010-06-30 | 株式会社日立製作所 | Plasma display panel, substrate structure of plasma display panel |
DE102007041281A1 (en) | 2007-08-31 | 2009-07-23 | Airbus Deutschland Gmbh | An aircraft cooling system evaporator arrangement for two independent coolant circuits |
JP5017037B2 (en) * | 2007-09-26 | 2012-09-05 | 三洋電機株式会社 | Refrigeration cycle equipment |
JP5316074B2 (en) * | 2009-02-24 | 2013-10-16 | ダイキン工業株式会社 | Heat pump system |
JP5806940B2 (en) * | 2009-12-28 | 2015-11-10 | ダイキン工業株式会社 | Heat pump system |
JP5295330B2 (en) * | 2011-08-08 | 2013-09-18 | 三菱電機株式会社 | Plate heat exchanger and refrigeration air conditioner |
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Also Published As
Publication number | Publication date |
---|---|
JPWO2006003925A1 (en) | 2008-04-17 |
AU2005258567A1 (en) | 2006-01-12 |
JP4475278B2 (en) | 2010-06-09 |
EP1780479A4 (en) | 2013-12-11 |
AU2005258567B2 (en) | 2008-07-03 |
EP1780479A1 (en) | 2007-05-02 |
WO2006003925A1 (en) | 2006-01-12 |
CN1981165A (en) | 2007-06-13 |
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