US20130186593A1

US20130186593A1 - Split-air flow cooling and dehumidification system

Info

Publication number: US20130186593A1
Application number: US13/744,952
Authority: US
Inventors: Ian Martin Shapiro; Crista Nicole Shopis
Original assignee: Synairco Inc
Current assignee: Synairco Inc
Priority date: 2012-01-20
Filing date: 2013-01-18
Publication date: 2013-07-25
Also published as: DE102013200784A1; FR2986059A1; JP2013148343A

Abstract

A split-air arrangement for cooling and dehumidifying air in an indoor conditioned space includes separate first and second courses created from an entering air stream. The first course passes through a desiccant device to remove humidity from the air, the air leaving the desiccant device passing through a first cooling coil to cool the air and the air leaving the first cooling coil entering a supply air plenum. The second course is directed through a first side of a heat exchanger, the air leaving the heat exchanger being heated by a heater element prior to picking up moisture from the desiccant device. Air leaving the desiccant device passes through a second side of the heat exchanger, and subsequently passes through a second cooling coil to cool and dehumidify the air in the second course. Exiting air is mixed with the first course air and returned to the conditioned space in which the process air flow is maximized relative to the regenerative air flow while still permitting effective latent cooling.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon U.S. Patent Application No. 61/588,965, filed Jan. 20, 2012, pursuant to relevant paragraphs of 35 USC §119.

TECHNICAL FIELD

This application relates generally to the field of heating and cooling and more specifically to a system in which a source of relatively warm water, such as geothermally cooled water, shallow lake water or near-shore ocean water, is used to remove sensible heat from indoor air for cooling thereof, the system further including a desiccant device for removing humidity wherein an incoming air stream from a space to be cooled is split into first and second air streams for removing both heat and humidity. In the present application, various improvements are herein discussed as to the optimization of a split-air stream cooling/dehumidification arrangement for increasing system efficiency, as well as for providing enhanced versatility.

BACKGROUND AND RELATED ART

As described in U.S. Pat. No. 7,654,101B2, Applicant has previously developed a cooling/dehumidification system in which a received air stream (i.e., building air) is split into first and second air streams or courses. Entering air flowing along the first course passes through a desiccant device, such as a rotating desiccant wheel, in order to remove the humidity of the indoor air. Moisture leaving the desiccant device is picked up by air flowing along the second course. This latter regenerative air stream is heated prior to picking the moisture that had been picked up from the first air stream from the desiccant device. The second air course then passes through a heat exchanger in order to remove the sensible heat. Then the air moving along the second course, which has a much higher dewpoint temperature having picked up moisture, can then be easily dehumidified in a coil that is cooled by relatively warm (about 50-60 degrees Fahrenheit) water.
Though Applicant's described system provides sensible cooling and dehumidification to a conditioned space, there are certain constraints that prevent maximizing the efficiency of the system, the latter being typically expressed as the coefficient of performance (COP), reflecting the ratio of heat removed from the cold reservoir divided by the input heat. Among these constraints is the ratio of the amount of sensible cooling per amount of dehumidification (latent cooling). Ideally, this latter ratio (referred to as sensible cooling divided by total cooling) should be approximately 70-75 percent. If this ratio is too high, then inadequate dehumidification may have resulted. Utilization of a relatively warm cooling source having a temperature between about 50 and 60 degrees Fahrenheit inherently makes it difficult to achieve this ratio. To that end, there is a need to optimize the presently known split-air system in order to provide a higher COP, while still providing an adequate balance of cooling and dehumidification using a relatively warm source for cooling.
Still further, there are a number of environments in which a conditioned space may require dehumidification but in which the air present may already be at a temperature that does not require cooling. Similarly, there are other environments in which the room air may be adequately dry, but in which cooling may still be required. As a result, there is a further need to provide a system that selectively enables sensible cooling and/or dehumidification.

SUMMARY OF THE DISCLOSURE

Therefore and according to a first aspect, there is provided an arrangement for cooling and dehumidifying air in an indoor conditioned space, the cooling arrangement comprising first and second courses created from an entering air stream from a conditioned space, in which the first course passes through a desiccant device to remove humidity from the air, the air leaving the desiccant device passing through a first cooling coil to cool the air and the air leaving the first cooling coil entering a supply air plenum;
and in which said second course is directed through a first side of a heat exchanger, the air leaving the heat exchanger being heated by a heater element and passing through said desiccant device to pick up moisture from said first air stream, the air leaving the desiccant device passing through a second side of said heat exchanger, and the air leaving the second pathway of said heat exchanger passing through a second cooling coil to cool and dehumidify the air in the second course, and the air exiting the second course passing to said supply air plenum, where it mixes with air of the first course, and then returns to the conditioned space;
said cooling arrangement further including means for adjusting the amount of process air flow relative to regenerative air flow of the first and second air streams in said system in order to increase overall efficiency.
For purposes of the herein described system, it has been determined that the ratio of process air flow to regenerative air flow should be between about 75/25 and 90/10 to increase system efficiency while still providing adequate dehumidification; that is, in order to maintain a viable sensible cooling ratio. According an idealized version, the foregoing ratio of process air flow to regeneration air flow is about 84/16 or greater.
Controlling air flow can be accomplished through sizing of the relative components; i.e., the heat exchangers, airflow passages, etc in order to encourage more airflow through the process side of the system and less air flow through the regeneration side. It has been determined that even with optimal sizing constraints that there is too much regeneration air flow. Therefore and according to one version, control of the above air flow ratio can be realized through the use of at least one damper, said at least one damper being preferably positioned in the second air stream in order to adequately control air flow therein. In another version or in combination with appropriate sizing and damping, air blower or fan speed can also he augmented in the respective air streams to improve the air flow ratio and improve efficiency.
According to another aspect, improvements in system efficiency can be achieved by physically splitting the desiccant wheel, wherein a larger portion of the desiccant wheel is provided for dehumidification. For example, the desiccant wheel can be physically split to a 90 to 10 configuration or according to another version to at least an 80 to 20 configuration.
The rotational speed of the desiccant wheel can also be adjusted. Preferably, the speed of rotation of the desiccant wheel can be slowed from about a typical rate of about 24 revolutions per hour to a rate of about six (6) revolutions per hour. Though changing the physical split of the desiccant wheel and/or slowing the rotational speed thereof actually decreases dehumidification, these decreases are acceptable given the gains in efficiency that can be realized in the herein described system and in which a suitable sensible cooling ratio can still be realized.
According to another aspect of the disclosure, there is provided a method for sensibly cooling and dehumidifying a conditioned space using a relatively warm cooling source, said method including the steps of:
ducting air from the conditioned space and separating said air into respective first and second air streams;
moving the first air stream through one side of a desiccant wheel to remove moisture from said air stream;
moving the first air stream through a first cooling coil cooled by a relatively warm source and then moving the first air stream back into the conditioned space;
moving said second air stream through one side of a regenerative heat exchanger and then through a heat source and the second side of the desiccant wheel, said second air stream picking up moisture removed from the first air stream;
moving said second air stream through the second side of the regenerative heat exchanger, and subsequently to said second cooling coil, each of said first and second cooling coils being connected to a geothermal or other source of relatively warm water; and
moving said air from said second cooling coil to the conditioned space, said method including the additional steps of adjusting the amount of process air flow relative to the amount of regenerative air flow of the first and second air streams in order to increase efficiency and to optimize the split-air system.
In one version, the ratio of process air flow to regenerative air flow is between at least 75/25 and 90/10. In an idealized version of the herein described method, a ratio of 84/16 or higher is achieved, the foregoing ratios accomplishing the goals of minimizing the heat (cost) required for regeneration and maximizing system efficiency (COP), while still permitting adequate cooling and dehumidification.
According to yet another aspect, there is provided a control system for a split-air cooling and dehumidification arrangement, said control system enabling the cooling and dehumidification arrangement to be operated in a plurality of modes. The split-air arrangement creates first and second air courses from a received air stream in which the first air course passes through a desiccant device that strips moisture therefrom, the first air course further passing to a first cooling coil that sensibly cools the air prior to supplying the air to a conditioned space. The second air course is initially heated to pull the moisture from the first air stream in which the second air stream passes through a heat exchanger to give off heat prior to passing said second air stream to a second cooling coil to cool the second air stream prior to mixing with the first air stream and returning the air to the conditioned space and in which the control system is configured to enable the arrangement to be operated in a plurality of modes.
The control system is enabled to operate as either a thermostat and/or as a dehumidistat. In a first mode, the system is operated to provide both sensible and latent cooling by enabling the desiccant device and application of heat to the first and second air streams flowing in the system. According to a second “free cooling” only mode, no heat is applied to the system and the desiccant device is not utilized so as to allow moisture of moving air to pass freely through the system. In a third “latent cooling” mode, no or very little water flow is caused to flow to the process heat exchanger (cooling coil). As a result, significant dehumidification with no cooling or with at most a very slight net heating of the air occurs.
In one version, the flow rate of water from the cooling source to the cooling coil can be adjusted to permit sufficient flow to offset the heat rise of the first air stream caused by the desiccant device in the above-described third mode.
One advantage realized using the above system is that sensible cooling and dehumidification can be more effectively and efficiently realized using a dual or split air stream system.
Another advantage provided by the present system is that an increase in efficiency provides reduced energy costs for the user.
Yet another advantage realized by the present system is that of versatility in terms of operational features for a particular environment.
These and other technical features and advantages will be readily apparent from the following Detailed Description, which should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a known split-air cooling/dehumidification system;

FIG. 2 is a psychrometric chart of the known split-air cooling/dehumidification system of FIG. 1;

FIG. 3 is a schematic system view of an installation employing the embodiment of FIGS. 1 and 2;

FIG. 4 is a diagrammatic view of a cooling/dehumidification system in accordance with an exemplary embodiment;

FIG. 4( a) is a partial view of a desiccant device used in the prior art system of FIG. 1;

FIG. 4( b) is a partial view of a desiccant device used in the system of FIG. 4;

FIG. 5 is a psychrometric chart illustrating an improvement of the cooling/dehumidification system according to one version;

FIG. 6 is a diagrammatic view of a control system in accordance with another exemplary embodiment; and

FIG. 7 is a flow chart depicting the control system of FIG. 6.

DETAILED DESCRIPTION

The following description relates to various improvements to Applicant's previously patented split-air flow cooling system in order to improve the overall efficiency thereof. In the description that follows, a number of terms are used in order to establish a suitable frame of reference in regard to the accompanying drawings. These terms, however, should not be narrowly interpreted in terms of the inventive concepts that are described herein. In addition, it should be noted that each of the drawings are not shown or intended to be shown to scale for purposes of the following description.
In terms of background, the prior known arrangement or system is illustrated according to FIG. 1, the system including a return air duct or inlet 10 which receives warm and moist air from a room or other confined space that is to be conditioned. According to this system, the air entering the system from the return duct 10 is initially split into respective first and second air flows or courses, for example, using a pair of blowers or fans (not shown) or other porting means thereby moving the air. The first air stream, herein labeled as A, is caused to pass through one side of a desiccant wheel 14, and more specifically through the dehumidification or drying side 14A thereof, wherein the desiccant materials that are provided within the wheel pick up moisture from the first air stream A passing therethrough. The desiccant wheel 14 is concentrically rotated so as to convey the moisture to the second air stream in which the latter air stream is initially heated and caused to pass through the rotated or “wet” side 14B of the desiccant wheel 14 to pick up the moisture from the contained desiccant.
The dehumidified first air stream leaving the desiccant wheel 14 is passed through a cooling coil 16A, in order to provide sensible cooling of that air. The air is cooled by the cooling coil 16A at a temperature below the temperature of the room air, preferably by means of a geothermal sink 18 such as a well or other suitable cooling source, and is sent according to this version to a supply air plenum 20 or alternatively a blower or other means (not shown), which passes the air back into the conditioned space as cooled and dehumidified air. A chiller 30 may optionally be provided in connection with the cooling coil 16A.
In the meantime, the second air stream, labeled as B, is initially moved such as by a fan (not shown) through an incoming air side of an air-to-air or other suitable regenerative heat exchanger 22. The entering air passing through the incoming air side is heated by air passing through the return side of the heat exchanger 22, which in turn cools the air on that side. The air leaving the incoming side of the heat exchanger 22 is then heated by a heating element 24 to a temperature that is sufficient for picking up moisture from the first air stream A from the rotating desiccant wheel 14. This heated air is then passed through the wet side 14B of the rotating desiccant wheel 14. The air leaving the desiccant wheel 14 then passes through the return side of the heat exchanger 22, so that some of the heat from the heating element 24 can be recovered and transferred to the incoming air. This also cools the second air stream before it leaves the heat exchanger 22 and passes through a second cooling coil 16B. The second cooling coil 16B removes heat from the second air stream, cooling this air and also condenses and removes the humidity that had been transferred to it from the first air stream by the desiccant wheel 14 as well as its own initial humidity.
Preferably, each of the first and second cooling coils 16A, 16B are supplied with water that has been returned from a geothermal well 18 or other source of cool water, such as near-shore ocean water or shallow lake water, in which the water temperature is in the vicinity of about 50° F. to 60° F. The air leaving the second cooling coil 16B passes to the supply plenum 20 or supply blower (not shown), where the second air stream mixes with the first air stream and flows back into the conditioned space as cooled and dehumidified air. A condenser 32 may optionally be provided to collect the condensate from the second air stream and direct same to the heating element 24. The condenser 32 can also be connected to the chiller 30 that exhausts heat to the water returning the cooling source. Details regarding the latter features are described in previously incorporated U.S. Pat. No. 7,654,101 B2.
The above system relies upon the concept of splitting the entering air into separate air streams in order to provide both sensible cooling and dehumidification using a cooling source, such as a geothermal well or equivalent source of relatively warm (about 50° F. to 60° F.) water and a desiccant device. FIG. B is a representative psychometric chart illustrating the two air courses A and B in terms of the principles embodied by the system. Specific portions are labeled herein for ease of convenience according to the circled portions 1-9, which are also indicated in FIG. 1 and refer to stagepoints of each of the respective air flows. In terms of reference in regard to the chart of FIG. 2, the dry bulb temperature is shown along the ordinate, enthalpy is shown on the scale along the left and top of the chart, the diagonal lines are lines of constant wet bulb temperature and the hyperbolic (curved) lines represent lines of constant relative humidity, wherein the saturation curve is at the upper left of the chart.
The first air stream, shown between the return air duct and the supply plenum 20, is represented by the lines beginning at point 1 and extending to points 7, 8 and 9. The second air flow or air stream is represented by the lines also beginning at point 1 and extending to points 2, 3, 4, 5, 6 and 9.
More specifically, heating of moist air between points 1 and 2 occurs at constant humidity through the regenerative heat exchanger 22 and then between points 2 and 3 in which the heater element 24 adds a quantity of thermal energy at rate Q to the moving air. Transfer of moisture from the first air stream to the second air stream occurs between points 3 and 4, where the second air stream picks up the moisture from the first air stream via the rotating desiccant wheel 14. Sensible heat transfer of the incoming air in the second air stream to the air leaving the desiccant wheel 14 is represented between points 1 and 2 and points 4 and 5, in which the latter portion of the process gives up heat to process 1-2. This latter process occurs along lines of constant moisture content, as shown in FIG. 2.
The portion of the process occurring from points 5 to 6; i.e., the passage of the air of the second air stream through the water supplied cooling coil 16B, is made of two distinct phases. According to a first process occurring between points 5 and 5A, the second air stream is cooled at constant humidity content until it reaches saturation (point 5A). In the second part occurring between points 5A and 6, cooling of the second air stream follows the saturation curve, where condensation also takes place, in order to remove the humidity that was picked up from the rotating desiccant wheel 14 as well as humidity initially in the regeneration air stream.
In the first air stream, air passing through the desiccant wheel 14 between points 1 and 7 causes the air to be warmed as the desiccant materials in the rotating wheel absorb moisture from the air. When the second air stream passes the wet side of the desiccant wheel 14 between points 3 and 4, the process cools the air as the desiccant material gives up the moisture to the warmer air stream.
In the first air stream between points 7 and 8, the desiccant wheel 14 removes humidity and then the air temperature is reduced (cooled) as the air stream passes through the first cooling coil 16A, which is cooled using the geothermal source (well 18, FIG. 1) or other source of water.
Finally, the portions of the process occurring between points 8 and 9 and 6 and 9, respectively, of the first and second air streams represent the flow of each air stream to the supply plenum 20 and their mixing before discharge back into the conditioned space. Additional details in regard to this prior known split-air system are described in Applicant's prior patent, U.S. Pat. No. 7,654,101B2, the entire contents of which are herein incorporated by reference.
A broad schematic representation of the prior system in a use condition is shown in FIG. 3 for a conditioned space herein labeled as C, clearly depicting the split process and regenerative air flows and movement of air in relation to the rotating desiccant wheel 14, heat exchanger 22 and cooling coils 16A, 16B, each of the latter being cooled by the geothermal well 18 or other source of water, as well as fans or blowers 12A, 12B which are used to direct the first and second air streams from the entering air flow.
Referring now to FIG. 4, there is depicted a split-air cooling/dehumidification system that is made in accordance with an exemplary embodiment. Similarly to the prior discussed system, a return duct 110 or similar porting means is provided to receive air from a space that is to be conditioned by the system. Also and as previously discussed, a set of blowers 112A and 112B channel the received air into respective first and second air streams or courses. Alternatively, other porting means, such as locating a single blower downstream of all components, can be substituted for the blowers 112A and 112B. Additionally, utilization of a variable speed blower, particularly relative to the second air stream, is particularly useful as described herein.
According to this version, a rotating desiccant wheel 114 is provided through which the first air stream passes. The desiccant wheel 114 is caused to rotate by means of a motor (not shown) having a shaft passing through the center of the desiccant wheel or alternatively a belt drive extends about the outer periphery of the wheel driven by an external motor (not shown). As opposed to the previously known system design, which provides for a 50/50 split between the humidification and dehumidification portions or sides 14A, 14B of the wheel 14, FIG. 4( a), or a 75/25 split per the chart shown in FIG. 2, the herein disclosed desiccant device is defined by a physically offset split design. According to one version shown in FIG. 4( b), a desiccant wheel 114 having a physical split of about 80/20 is used between the process and regenerative sides thereof, respectively, shown as 114 A and 114 B, respectively, although physical wheel splits in the range between about 80/20 to 95/5 or possibly greater are also acceptable. Therefore and according to this embodiment, the second air stream is permitted to access only 20 percent of the rotating desiccant wheel 114B. Although dehumidification is actually decreased using this physical split, a result increasing of COP (efficiency) is realized.
In another variation, the rotational speed of the desiccant wheel 114 can be suitably adjusted in tandem with the above physical split or in use with a conventional 50/50 split desiccant wheel. Typically, the speed of rotation of the desiccant wheel 114 is about 24 revolutions per hour. It has been determined that reducing the speed of rotation can produce efficiency gains in the system. Slowing the speed of rotation to about 6 revolutions per hour provides optimal results. Additionally slowing the desiccant wheel 114, though providing increased efficiency (COP), will cause insufficient dehumidification for the efficiency gain that is realized. That is, minimum dehumidification is still achieved in order to maintain a satisfactory sensible cooling ratio (between about 70-75 percent).
Moisture is caused to be stripped from the first air stream by the materials that are contained within the materials contained within the rotating desiccant wheel 114 in which the wheel is rotated about its center to enable the stripped moisture to be picked up by the passing second air stream. As in the preceding, the first air stream after passing through the desiccant device 114 is cooled by a first cooling coil 116A to a temperature that is cooler than that of the room air, by means of a geothermal sink 118 according to this embodiment, or alternatively other warm water cooling sources such as shallow lake and near-ocean shore sites having temperatures between about 50 and 60 degrees Fahrenheit.
The second air stream is caused to be moved into the first or process stage or airway of an air to air or other regenerative heat exchanger 122, in which the moving air stream is initially heated. It is preferred that the heat exchanger 122 utilized herein not include significant internal leaks. Use of a fixed plate heat exchanger is therefore a desirable option in order to meet this latter objective, which further improves overall efficiency.
Air exiting the first stage of the heat exchanger 122 is further heated by a heating element 124, such as a hot water coil, a gas furnace or other apparatus, to a suitable temperature for picking up the moisture from the first air stream on the wet side of the rotating desiccant wheel 114 through the application of additional thermal energy Q.
The moisture from the desiccant wheel 114 is then picked up by the second air stream wherein the air is moved to the second or regenerative side of the air to air heat exchanger 122. As noted and based on the split design of the desiccant wheel 114, FIG. 3( b), and optionally slower rotational speed of the desiccant wheel, the resulting amount of moisture is decreased. Heat is transferred to the first side of the heat exchanger 122 as the air passes through the second side thereof. The cooler air leaving the heat exchanger 122 is then additionally cooled by means of a second cooling coil 116B, which like the first cooling coil 116A is cooled by means of a geothermal or other suitable water cooling source 118.
Controlling air flow can be accomplished through sizing of the relative components; i.e., the heat exchangers, airflow passages, etc in order to encourage more airflow through the process side of the system and less air flow through the regeneration side. Use of a variable speed blower also provides a means of selectively controlling the amount of airflow. It has been determined that even with optimal sizing constraints that there is too much regeneration air flow. Therefore, at least one balancing damper can be positioned within the ducting of the second air stream and more particularly relative to the air stream leaving the first side of the heat exchanger 122 to better control airflow. It has been determined that optimizing the airflow passages in combination with the damper further improves efficiency gains in that less balancing (load) is therefore required by the damper. In terms of effects, balancing by component selection provides the least amount of damper activity/restriction/inefficiency. The damper is in the smaller airstream, such that the damper is smaller (cheaper) and the required airflow restriction (always undesirable from a point of view of wasted energy) is minimized.
Referring to the chart of FIG. 4 and according to one version, a damper 126 is provided in the second air stream relative to state point 3 adjacent the heating element 124. A damper could also be alternatively positioned at either of state points 2, 5 or 7, as shown, for example, by the locations denoted by reference numerals 128.
Referring to FIG. 5, a psychrometric chart is provided in regard to an alternative option in which the temperature of the second air stream is controlled to that which is simply sufficient to pull the humidity from the desiccant wheel 114, thereby adding a smaller amount of thermal energy Q supplied by heating element 124 and providing a cost benefit to the system user that is realized. For example, if the temperature at state point 3 is 200 F, a model shows an efficiency of 1.5 COP, whereas if the temperature at state point 3 is 150 F, the efficiency is increased to 2.0 COP. However, there are limits to which this temperature can be controlled. If the temperature is too low, then insufficient dehumidification results.
According to yet another alternative version of this system, the regulated flow rate of water entering either or each of the first and second cooling coils 116A and 116E from the geothermal well or other water source of cooling 118 can be suitably adjusted in order to further promote cooling and therefore increase efficiency of the herein described system. As in the preceding, greater cost savings can be realized by reducing the amount of regenerative air flow in the system but not at the expense of cooling and dehumidification.
According to yet another aspect and referring to FIGS. 6 and 7, the herein described split-air system can be operated in a plurality of various modes in order to provide enhanced versatility while optimizing use, based for example on the geographic location or environment of the installed system.
According to a first operating mode, 140, FIG. 7, the system can be operated to provide both sensible cooling and latent cooling (dehumidification), in the manner previously described herein using the split-air arrangement.
In a second operating mode, 144, FIG. 7, the system can selectively be operated to provide sensible cooling only. In this specific mode, the desiccant wheel 114 is not rotated and no external heat is applied to the second air stream using the heating element 124. The result is that the first air stream passes through the nonrotating desiccant wheel 114 and is cooled by the first cooling coil 116A. There is no dehumidification using this mode in which sensible cooling results, provided the room air is sufficiently dry. This specific mode creates substantial energy savings, providing an essentially “free cooling” mode.
According to a third operating mode, 148, FIG. 7, the system can also be operated to provide latent cooling (dehumidification) only. According to this mode, all or most water flow to the process heat exchanger (first cooling coil) is stopped. As a result, the desiccant wheel 114 pulls the moisture from the first air stream, which is then picked up by the second air stream. The second air stream is initially passed through the first side of the regenerative heat exchanger 122 and is further heated by heating element 124 to enable the moisture to be picked up as the second air stream passes through the desiccant wheel 114. As in the preceding, the second air stream is then passed through the second side of the regenerative heat exchanger 122 in which heat is given off to the first side of the heat exchanger. The air stream then passes to the second cooling coil 116B and the air is cooled by the water source 118 in which condensate is produced and given off. According to one version, this condensate can be directed to the heating element 124, for example, if the heating element is a hot water coil as a water source therefor. Otherwise, this dehumidified air mixing with the non-cooled air of the first air stream which is directed back into the conditioned space. The result of this latter mode creates a slight increase in temperature but significant latent cooling. Preferably, this latter mode is useful for room air that is already sufficiently cool but humid, found in climates, for example, such as Florida in which dehumidification is very desirable. In addition, the above mode can be used in environments having high moisture loads (e.g., theaters with many patrons, greenhouses, indoor pool areas, etc).
The control system 130 includes a microprocessor 134 having contained control logic for controlling each of the system components including each of the regenerative heat exchanger 120, the desiccant wheel 114, the cooling coils 116A and 116B, the heating element 124 and ducting/dampers of the system to which the microprocessor is electrically connected. A user interface 136 is also connected to the microprocessor 134, including various actuable control buttons (not shown). The user can therefore select the proper operating mode for the system based on the desired effects. It should be noted that additional modifications are possible. For example and as to the third dehumidification mode, this mode 148 can further permit (if needed) some cooling of the first air stream via the first cooling coil 116A by controlling the flow of water thereto to negate any heat rise in the first air stream from passing through the desiccant wheel 114. Other similar modifications and variations to the control system and various operating modes should be readily apparent.

PARTS LIST FOR FIGS. 1-7

1 process state point
2 process state point
3 process state point
4 process state point
5 process state point
6 process state point
7 process state point
8 process state point
9 process state point
10 return air inlet
12A fan or blower
12B fan or blower
14 desiccant wheel
14A drying side, desiccant wheel
14B wet side, desiccant wheel
16A cooling coil
16B cooling coil
18 geothermal well
20 supply air plenum
22 heat exchanger
24 heating element
30 chiller
32 condenser
100 system
110 return duct
112A fan or blower
112B fan or blower
114 desiccant wheel
114A drying side
114B wet side
116A cooling coil
116B cooling coil
118 geothermal well or water source of cooling
120 supply plenum
122 heat exchanger
124 heating element
126 damper
128 damper locations
130 control system
134 microprocessor
136 user interface
140 mode
144 mode
148 mode
A first air stream
B second air stream
C conditioned space

It will be readily apparent that there are other variations and modifications that will be readily apparent from the foregoing description and in accordance with the following claims:

Claims

1. A cooling arrangement for cooling and dehumidifying air in an indoor conditioned space, said cooling arrangement comprising first and second air streams created from an entering air stream from a conditioned space, in which said first course is directed through a desiccant device to remove humidity from the air, the air leaving the desiccant device passing through a first cooling coil to cool the air and the air leaving the first cooling coil entering a supply air plenum;

said second course being directed through a first side of a heat exchanger, the air leaving the heat exchanger being heated by a heater element and passing through said desiccant device, the air leaving the desiccant device passing through a second side of said heat exchanger, and the air leaving a second pathway of said heat exchanger passing through a second cooling coil to cool and dehumidify the air in the second course, and the air exiting the second course passing to the supply air plenum, where it mixes with air of the first course, and then returns to the conditioned space,

said arrangement further comprising means for adjusting the ratio of process air flow relative to the regenerative air flow of the first and second air streams so as to produce greater efficiency.

2. A cooling arrangement as recited according to claim 1, wherein the ratio of process air flow to regenerative air flow in said system is at least 75 to 25.

3. A cooling arrangement as recited according to claim 2, wherein the ratio of process air flow to regenerative air flow in said system is at least 84 to 16.

4. A cooling arrangement as recited according to claim 1, wherein said desiccant device is a rotating desiccant wheel, said wheel being defined by a physically split design.

5. A cooling arrangement as recited according to claim 4, wherein the physical split in said desiccant wheel is such that about 80 percent of the desiccant wheel is accessed by the first air stream and about 20 percent of the rotating desiccant wheel is accessed by the second air stream.

6. A cooling arrangement as recited according to claim 4, wherein the physical split in said desiccant wheel is at least 90/10.

7. A cooling arrangement as recited according to claim 1, wherein said desiccant device comprises a rotating desiccant wheel, and in which said system includes means for selectively adjusting the speed of rotation of said wheel.

8. A cooling arrangement as recited according to claim 1, further comprising means for selectively adjusting the rate of water from said source of cooling to each of said first and second cooling coils.

9. A cooling arrangement as recited according to claim 1, further including means for adjusting the temperature of air over said second course prior to picking up moisture from said desiccant device.

10. A method for sensibly cooling and dehumidifying a conditioned space using a geothermal cooling source, said method including the steps of:

ducting air from the conditioned space and separating said air into respective first and second air streams;

moving the first air stream through one side of a desiccant wheel to remove moisture from said air stream;

moving the first air stream through a first cooling coil;

moving said second air stream through one side of a regenerative heat exchanger and sequentially through a heat source and the second side of the desiccant wheel, said second air stream picking up moisture removed from the first air stream;

moving said second air stream through the second side of the regenerative heat exchanger, and subsequently to said second cooling coil, each of said first and second cooling coils being connected to a relatively warm source of water; and

mixing the second air stream and the first air stream and moving the mixed air to the conditioned space, said method including the additional step of

adjusting the ratio of process air flow relative to regenerative air flow of the first and second air streams in order to optimize system efficiency.

11. A method for improving efficiency according to claim 10, including the step of configuring process air flow to regenerative air flow such that the ratio of process air flow to regenerative air flow is at least 80/20.

12. A method for improving system efficiency according to claim 10, including the step of providing a desiccant wheel having a physically split design.

13. A method as recited according to claim 12, wherein the physical split in said permits at least 80/20 in which only 20 percent of the area of said wheel is accessible to said second air stream.

14. A method as recited according to claim 13, wherein the physical split in said desiccant wheel is at least 90/10.

15. A method as recited according to claim 12, wherein said desiccant device comprises a desiccant wheel, said method including the additional step of selectively adjusting the speed of rotation of said desiccant wheel.

16. A method as recited according to claim 15, including the step of slowing the speed of rotation of said desiccant wheel from a first speed of rotation to a second speed of rotation sufficient to maintain a sensible heat ratio of no more than 75 percent.

17. A method as recited according to claim 16, wherein said second speed of rotation is about 6 revolutions per hour.

18. A method as recited according to claim 10, including the additional step of selectively adjusting the rate of water from said source of cooling to each of said first and second cooling coils.

19. A method as recited according to claim 10, including the additional step of adjusting the temperature of air over said second course prior to picking up moisture from said desiccant device.

20. A method as recited according to claim 19, wherein said temperature adjusting step includes the step of minimizing the temperature of air in said second course to a value that still permits moisture to be picked up from the desiccant device.

21. A method as recited according to claim 10, including the additional step of inserting at least one balancing damper in the second air stream to permit reduction of said flow.

22. A control system for a split-air cooling arrangement, including first and air course from an indoor conditioned space, in which said first course passes through a desiccant device to remove humidity from the air, the air leaving the desiccant device passing through a first cooling coil to cool the air and the air leaving the first cooling coil entering a supply air plenum;

said second course being directed through a first side of a heat exchanger, the air leaving the heat exchanger being heated by a heater element and passing through said desiccant device, the air leaving the desiccant device passing through a second side of said heat exchanger, and the air leaving the second pathway of said heat exchanger passing through a second cooling coil to cool and dehumidify the air in the second course, and the air exiting the second course passing to the supply air plenum, where it mixes with air of the first course and then returns to the conditioned space, said control system enabling said system to operate in various modes.

23. A control system as recited in claim 22, including a microprocessor connected to each of the components of said arrangement, said microprocessor being programmed to enable each of said modes.

24. A control system as recited in claim 22, wherein said various modes includes a mode in which only sensible cooling is performed.

25. A control system as recited in claim 22, wherein said various modes includes a mode in which only latent cooling is performed.