US2900798A - Heat-exchanger in which a multi-component medium is cooled - Google Patents

Description

Aug. 25, 1959 c. o. JONKERS 2,900,798

HEAT-EXCHANGER IN WHICH A MULTI-COMPONENT MEDIUM IS COOLED Filed May 29. 1953 4 Sheets-Sheet 1 IN VEN TOR CORNELIUS OTTO 'JONKERS AGENT Aug. 25, 1959 cjo. JONKERS 2,900,793

HEAT-EXCHANGER IN WHICH A MULTI-COMPONENT MEDIUM IS COOL-ED Filed May 29. 1953 4 Sheets-Sheet 2 INVENTOR CORN ELIUS OTTO JONKERS AGENT g- 25, 1959 c. o. JONKERS 2,900,798

HEAT-EXCHANGER IN WHICH A MULTI-COMPONENT MEDIUM IS COOLED Filed May 29. 1953; 4 Sheets-Sheet 3 Z. IIIIIIIIIIII,

zzrzczri Z Y 7 i 6 INVENTOR. CORNELIUS 0. JONKERS AGENT Aug. 25, 1959 c. o. JONKERS HEAT-EXCHANGER IN WHICH .A MULTI-COMPONENT MEDIUM IS COOLED 4 Sheets-Sheet 4 Filed May 29. 1953 IN VEN TOR CORNELIUS OTTO JONKERS AGENT HEAT-EXCHANGER IN WHICH A MULTl- CONEONENT MEDIUM IS COOLED Cornelius Otto .Ionirers, Eindhoven, Netherlands, assignor,

by mesne assignments, to North American Philips Company, Inc, New York, N.Y., a corporation of Delaware Application May 29, 1953, Serial No. 358,317

Claims priority, application Netherlands April 22, 1953 12 Claims. (Cl. 62--42) The invention relates to a device in which a medium constituted by a plurality of components is cooled, one or more of the components being separated out from the medium. The device may, for example, be used, if impurities, such as water vapour and carbonic acid have to be extracted from a gaseous medium, for example air.

One of the conventional methods to remove components from a medium is realized by leading the medium through chemical substances forming a chemical or physical compound with the components, for example, with the impurities. This method has in general satisfactory results, but it has a limitation in that it is complicated and that the chemical substances must be replaced by new substances from time to time, so that in certain cases the method may be comparatively costly. Moreover, the device by means of which this method is carried out is, in general, bulky.

By a further method the medium is led through a heat exchanger formed as a recuperator. In this recuperator the medium from which a component is to be extracted is in thermal contact with a further meditun, from which it is separated by an intermediate partition. Consequently, these recuperators always require a cooling medium. If the recuperator is used in gas fractionating systems, the medium to be cooled may, for example, be air and the cooling medium one of the fraction produced in the gas fractionating column.

In certain cases such a cooling medium is not available or only available to an inadequate extent, so that the re cuperators can then not be used or used with reduced efliciency. Particularly in these cases the heat exchanger according to the invention is an expedient, since with this heat exchanger any source of cold of adequately low temperature may be used. In the aforesaid recuperators the temperature drops gradually from the hot end of the recuperator Where the medium to be cooled enters, to the cold end Where this medium leaves the heat exchanger. This gradually decreasing temperature has been found to be very desirable. If the medium to be cooled would come into contact with walls of too low temperature, the component to be extracted might be separated out before contacting with the wall. Thus the component would 'adhere less tightly to the wall and leave the heat exchanger together with the medium. It has furthermore been found that the medium should be set into turbulence to an extent such that the whole medium engages the Wall as frequently as possible. This may be realized by. providing extensions on the wall of the heat exchanger.

The heat exchanger according to the invention exhibits the feature that the carrier is provided with a plurality of fins, with which the medium is in thermal contact, the heat of the fins being conducted away for at least 25% by conduction via the carrier to the cold side thereof, while at least on some of these fins the component(s) to be extracted is (are) deposited, so that near these extensions the composition of the medium is modified and the temperature at which the component(s) can be extracted is reduced, the mean temperature of each of atent O starts is not more than 20 0, preferably not more than 10 C. lower than the point of extraction of the component(s) in the medium, supplied to this fin.

In the heat exchanger described above such a quantity of solid substance will have deposited on the fins that it is not necessary to remove it until a comparatively long time has passed. The removal may, for example, be carried out by heating slightly the heat exchanger, so that the solid substance will be volatilized or become liquid. A substantial portion of the heat is thus conducted away via a carrier to a cold space at some dis tance, operating as a source of cold.

In order to provide the desired temperature at the fins, the carrier in a further embodiment of the invention comprises portions each having a different heat resistance.

The heat exchanger according to the invention may be used not only for freezing out components 1 nt also for further cooling of the medium from which the components are extracted. For this purpose the heat exchanger has the feature that the conductor is provided with a plurality of fins at which the component(s) is (are) separated out and with a plurality of fins by means of which the medium from which the component(s) is (are) extracted is cooled.

In a further embodiment of the invention the heat exchanger through which passes during normal operation a medium containing a plurality of components to be extracted of relatively diiferent extraction ranges has a conductor provided with at least two groups of fins used for extracting one or more components, while the component(s) of one extraction range is (are)primarily separated 'out at one group of fins and the component(s) of the other extraction range is (are) separated out on the other group of fins. The fins of one group have in succession a temperature diiference of not more than 20 C., preferably not more than 10 C.

Since, in general, there will be a comparatively high temperature difierence between the extraction ranges, it is advantageous in a further embodiment of the invention to provide a further group of fins between the twogroups of fins, this group serving mainly to cool the medium. Since no material or only a small quantity of material will be deposited on these fins the aforesaid temperature differences need not be observed for these fins. For the same reason the fins may be arranged comparatively close to one another, so that this part will occupy comparatively little space. In a further embodiment of the invention the fins of the various groups are arranged after one another in a closed sequence. Thusthe temperatures of the heat exchanger vary little with the quantity of medium passing through it.

The desired temperatures at the fins may be obtained by constructing the conductor in a manner such that its portions have the required heat resistance. This resistance may be realized by providing the desired dimensions such as thickness or length for the carrier or by making a carrier from special material. tive embodiment of the invention, at least some of the fins may have ditferent heat resistances. In this case the heat resistance of the carrier need not fulfil special requirements. I

' The heat exchanger according to the invention may be used isuccessfully for freezing out impurities contained in gaseous media. The heat exchanger will frequently be used as a freezerin' a cold-gas refrigerator. The term cold-"gas refrigerator is to be understood to mean here- Patented Aug. 25, 1959 However, in an alternain a refrigerator operating on the reversed hot-gas engine principle. These cold-gas refrigerators comprise an element which conducts away the cold produced by the apparatus to the outside; this element is termed freezer. By means of the cold the temperature of a medium may be reduced in this freezer.

Ina further embodiment of the invention cold is withdrawn from the heat exchanger via the conductor, which is, on its cold side, in thermal contact with the wall of the cold-gas refrigerator, which bounds the cold space thereof.

The heat exchanger according to the invention may be constructed in various ways. In one embodiment the conductor is provided with fins, constructed in the form of transverse plates and forming the boundaries of spaces from the hot side of the heat exchanger to the cold side thereof, these spaces communicating with one another through apertures, so that via these apertures the medium is allowed to flow through the spaces from the hot side of the heat exchanger to the cold side thereof. In this embodiment it is desirable for the apertures to be such that the medium flowing through the heat exchanger is set into turbulence, so that the medium frequently comes into close contact with the extensions.

The desired turbulence may be obtained, if the heat exchanger comprises a conductor and a wall spaced apart therefrom by a certain distance, the conductor being provided with fins shaped in the form of transverse plates, apertures being provided between these transverse plates and the wall.

In a further preferred embodiment of the invention the heat exchanger comprises a carrier and a wall spaced apart therefrom by a certain distance, the conductor being provided with transverse plates extending to engage the wall, the transverse plates being provided with apertures. In a further embodiment of the invention the apertures in each transverse plate are preferably provided at least in part opposite a wall portion of the adjacent transverse plate. Particularly in this case an intensive turbulence of the medium is ensured.

The heat exchanger may be provided with a conductor, in which all fins are arranged in a sequence in the direction of length. of the conductor. Such a heat exchanger will, in general, be in need of only a comparatively small cross sectional area, but its height will be comparatively great. For structural reasons it will, however, be sometimes desirable to provide a smaller height for the heat exchanger, while in these cases the cross sectional area may be larger. Such a construction is obtained, if in a further embodiment of the invention the heat exchanger comprises at least two concentrical portions, each of which comprises a conductor provided with fins and thermally connected to one another.

In order-that the invention may be readily carried intoeffect, it will be described with reference to the accompanying drawing, which shows a few diagrammatical embodiments.

Fig. 1 shows a cold-gas refrigerator comprising a heat exchanger according to the invention.

Figs. 2 and 3 show one embodiment in which the heat exchanger comprises two concentrical portions.

Fig. 4 shows a heat exchanger in which the conductor is surrounded by a wall, apertures being provided between the fins and the wall.

In the embodiment shown in Fig. 5 some of the extensions of the heat exchanger have relatively different heat resistances.

Figs. 6 and 7 show one embodiment in which the heat is conducted away from a source of cold and'from a medium brushing past the carrier.

In the cold-gas refrigerator shown in- Fig. 1 a quantity of working medium, for example, hydrogen, performs a closed thermodynamic cycle. The working space of the apparatus comprises a freezing space 1, ducts 2 in the freezer 3, a regenerator 4 and ducts 5 in a cooler 6 and a cooled space 7. The volume of the freezing space 1 is varied by means of a displacer piston 8 and the volume of the cooled space 7 is varied both by the motions of the displacer piston 8 and those of a piston 9. The displacer piston 8 and the piston 9 reciprocate, for this purpose, with a substantially constant phase difference, of for example 90". By means of a connecting rod mechanism 10 the displacer piston is coupled with a crank of a crank shaft 11 and the piston 9 is coupled with cranks of the same crank shaft by means of a connecting rod system 12. The cold-gas refrigerator is driven by means of a motor, for example, an electric motor 13, as is shown in the figure. The freezer comprises two portions, i.e. one portion 14, associated with the ducts 2, and the portion formed by the conductor 15 having the fins constructed in the form of transverse plates 16. These transverse plates are provided with apertures 17, which are arranged in staggered position relatively to one another, as is also shown in Fig. 3. The heat exchanger comprises four portions, i.e. one portion 18, in which one component of the medium to be cooled may be separated out, one portion 19 in which the temperature of the medium is further reduced, one portion 20 in which a second component may be extracted from the medium and the portion 14 in which the temperature of the medium may be further reduced.

If the cold-gas refrigerator is used for liquifying air, it will, in general, be desirable to extract the impurities, such as water vapour and the carbonic acid, from the air. The extraction range of water vapour extends to about 60, 0.0006% by weight of water vapour being still left, while the extraction range of the carbonic acid extends from l40 C. to l C., 4.l0 by weight of carbonic acid being left. The Water vapour is separated out in the portion 18, so that the fins of this portion are spaced apart from one another by a comparatively large distance, while these fins also have the aforesaid required temperature difference of for example 8. The air freed from the water vapour is cooled in the portion 19 from 60 C. to l40 C. During this cooling substantially no extraction of components occurs, so that in this portion the small temperature difference between the fins need not be maintained, it being permitted moreover to arrange the fins nearer one another. If desired, the small temperature difference between the fins may be maintained, so that the temperature difference of the first fins varies less if the quantity of medium is varied.

The carbonic acid is separated out in the portion 20, so that also here the fins are more remote from one another, while the temperatures of the fins exhibit a slight difference, of for example 10 C. In the portion 14 the air thus cooled is cooled further until liquid is formed, which is conducted away through a duct 21. In order to attain the required temperature level of the fins, the carrier. or conductor 15 comprises portions having different wall thicknesses, as is evident from the figure. The heat exchanger is surrounded by a screen 22 having heat-insulating properties, this screen being provided with an aperture 23 at the top, through which the air is supplied. The outlet duct 21 is also surrounded by a heat-insulating layer. The air may be supplied by means of the pressure difference prevailing between the uncooled air and the cooled air. The heat exchanger described above has the property that the temperature of the first fins varies comparatively little with the quantity of medium passing through the heat exchanger. In view thereof it is desirable that the temperature differences of the extensions not intended forseparating out a component shouldv not be too high. It has furthermore been found that the layer of ice'on the fins constitutes such a smallinsulation that the extraction of the component may be continued until the whole space between, the fins is locally filled out.

In the construction shown in Figs. 2 and 3 the heat exchanger comprises two portions which are arranged concentrically to one another. Fig. 3 is a cross sectional view taken on the line IIIIII of Fig. 2. Also in this case the heat exchanger is secured to a head 30 of a coldgas refrigerator. The conductor comprises three portions, i.e. a portion 31, a portion 32 and a portion 33. The heat resistances of these conductor portions differ. The wall thickness of the conductor portion 31 is materially larger than that of the portion 32 and the wall thickness of the latter portion exceeds that of the portion 33. The portions 32 and 33 are connected by means of a connecting piece 34 of good thermal conductivity to one another. The conductor portions are provided with fins formed in the shape of transverse plates, in which provision is made of apertures. As is evident from Fig. 3, these apertures are arranged in staggered position. The transverse plates 35 with the apertures 36 of the conductor portion 31 and the transverse plates 37 with the apertures 38 of the conductor portion 32 extend to engage a wall 39 surrounding these conductor portions, while the transverse plates 40 with the apertures 41 of the conductor portion 33 extend to engage a wall 42. The conductor portion 33 is insulated from the wall 39. The heat exchanger is surrounded by a wall 43, having heatinsulating properties.

The gas to be cooled is supplied through a duct 44 and flows through the apertures of the transverse plates 40 in upward direction, then through an aperture 45 in the connecting piece 34 and through the apertures 36 and 38 in the transverse plates 35 and 37 respectively and along vanes 46 in the head 30. The cooled medium leaves the heat exchanger as a liquid and is conducted away via the ducts 47 and 48. On the transverse plates 40 associated with the conductor portion 33 is deposited the water vapour, whilst the spaces 49 between these plates are so large that it takes a comparatively long time before they are completely filled with ice. In the spaces 50 between the transverse plates 35 carbonic acid may be separated out, the transverse plates 37 serving only for further cooling the medium. The temperature difference between the transverse plates 35 and 40 is such that the temperature difference between the successive transverse plates associated with one of these groups is not more than for example C. The temperature of the fin where the extraction starts is not more than C., preferably not more than 10 C. lower than the extraction point of that component in the medium as it is supplied to the fins. In accordance with the quantity of medium flowing through the heat exchanger the extraction will begin at one of the transverse plates located, for example at the bottom of the heat exchanger, where the medium enters. If after some time such a quantity of ice is separated out in the heat exchanger that some of the spaces 49 are more or less filled out, it will be desirable to cease the supply of medium to the heat exchanger, while at the same time no cold is any longer withdrawn from the heat exchanger. The solid carbonic acid in the spaces 50 will then volatilize, while the ice in the spaces 49 changes into water and may be conducted away through a duct 51.

In the embodiment described above substantially all the heat is conducted by conduction via the conductor to the cold side thereof. In particular embodiments part of this heat can be conducted away by means of a medium flowing along a wall partition.

In the embodiment shown in Fig. 4 the heat exchanger comprises a conductor 60, provided with annular fins 61. These extensions are surrounded by a wall 62, which may have heat-insulating properties. The fins 61 do not extend so far as to engage the wall 62, so that apertures 63 are left. The medium to be cooled is supplied at the top through the aperture 64 and the cooled medium may be conducted away at the bottom via the duct 64. The conductor 60 may be connected to a source of cold.

The heat is conducted away from the medium flowing along the fins via the fins and the conductor to the source of cold, for example, the head 66 of a cold-gas refrigerator. This may be provided with vanes 67. The operation of this heat exchanger corresponds furthermore completely to that of the heat exchanger described above.

Fig. 5 shows a heat exchanger in which the fins each have a difierent heat resistance. In this embodiment a conductor 70 has a constant heat conductivity and the heat exchanger comprises two portions, i.e. the portion having the extensions. 71 and a portion having the fins 72. The portion having the fins 71 serves to extract a component while the portion comprising the fins 72 is used only for further cooling of the medium. The fins 71 and 72 are provided with apertures 73 and 74 respectively and with a part 75 and 76 respectively having a definite heat resistance. This heat resistance is such that the temperature differences between the fins 71 are comparatively small. The parts 75 and 76 are provided in a layer 77 of heat-insulating material applied to the conductor. The fins are surrounded by a sheath 78, having heat-insulating properties.

. Figs. 6 and 7 show a heat exchanger in which part of the heat is conducted away via the conductor to a source of cold, while a further part of the heat is transferred to a medium flowing along the carrier. Fig. 7 is a sectional view taken on the line VIP-VII of Fig. 6. The heat exchanger comprises a conductor 80, secured to a head 81 of a cold-gas refrigerator. Both on the outer side and the inner side the conductor is provided with fins. On the outer side provision is made of the fins 82, having apertures 83 which are arranged in staggered position as is shown in Fig. 7. The fins 84 of the conductor are provided with apertures 85, one or two of these apertures being provided in every other partition respectively. At the bottom the conductor has apertures 86, through which the space about the conductor communicates with the space inside the conductor. The whole heat exchanger is surrounded by a screen 87, having heat-insulating properties and provided at the top with two inlet apertures 88 and with an outlet aperture 89. The medium to be cooled is supplied through the apertures 88 to the heat exchanger and brushes past the fins 82, where it is cooled, a component being thus separated out on the fins. Then the medium flows through the apertures 86 and is heated while flowing along the fins 84. In this embodiment at leat 25% of the heat conducted away from the fins is transferred via the conductor to the source of cold.

What is claimed is:

1. A heat exchanger having a gas passing therethrough containing a plurality of components to be cooled and having at least one of said components precipitated out comprising a conductor enclosure containing a conductor and having a hot end and a cold end, said medium flowing from the hot end to the cold end thereof, a plurality of fins with which the medium is in thermal contact, means mounting said fins in said conductor enclosure in superposed relationship and substantially laterally to said conductor enclosure, an inlet duct for said medium at the hot end of said conductor enclosure, an outlet duct for said medium at the cold end of said conductor enclosure, a thermal sink adjacent to the cold end of the conductor enclosure formirrg a cold source for said conductor enclosure and directly connected thereto, said component to be separated being deposited on certain of said fins, the composition of the medium being modified and the temperature at which said component is to be precipitated being reduced, and the mean temperature of each of said fins being at the maximum 20 C. lower than that of successive fins, and the mean temperature of one of said fins at which said precipitation begins is not more than 20 C. lower than the precipitation point of said 7 component in the medium when it is supplied to said one of said fins.

2'. A heat exchanger as set forth in claim 1 wherein said conductor comprises portions which each have a different heat resistance.

3. A heat exchanger as set forth in claim 1 wherein said component is separated out on certain of the fins in said conductor, and primarily cooled by a plurality of other of fins in said conductor.

4. A heat exchanger having a gas passing therethrough containing a plurality of components to be cooled and at least one of said components to be precipitated out, said components having different extraction ranges comprising a conductor enclosure containing a conductor and having a hot end and a cold end, said medium flowing from the hot end to the cold end thereof, a plurality of fins with which the medium is in thermal contact, means mounting said fins in said conductor enclosure in superposed relationship and substantially laterally to said conductor enclosure, an inlet duct for said medium at the hot side of said conductor enclosure, an outlet duct for said medium at the cold end of said conductor enclosure, a thermal sink adjacent to the cold end of the conductor enclosure forming a cold source for said conductor enclosure and directly connected thereto, said fins being formed in at least two groups whereby at least one component associated with one extraction range is precipitated out in one group of fins and at least one component associated with another extraction range is precipitated out in another group of fins, and successive fins of any group having a temperature difference of not more than 20 C., said heat being extracted from said conductor at the cold end thereof.

5. A heat exchanger as set forth in claim 4 further comprising a third group of fins being positioned between said other two groups of fins, said third group serving primarily to cool said medium.

6. A heat exchanger as set forth in claim 4, wherein the groups of fins are arranged in said conductor in sequence.

7. A heat exchanger as set forth in claim 4 wherein 8 at least some of said fins have relatively different heat resistances.

8. A heat exchanger as set forth in claim 4 wherein a gaseous medium is present and the impurities therein are frozen out.

9. A heat exchanger as set forthin claim 4 wherein said conductor is provided with fins constructed in the form of transverse plates having apertures therein and bounding spaces from the hot end of the heat exchanger to the cold end thereof, said bounding spaces communicating with each other through said apertures whereby fluid medium may flow through said spaces and apertures from the hot end of said heat exchanger to the cold end thereof.

10. A heat exchanger as set forth in claim 4 wherein said conductor has a wall spaced therefrom a predetermined distance, said conductor being provided with a further group of transverse plates, said further group of transverse plates having apertures and being so arranged as to extend to a point adjacent to said wall.

11. A heat exchanger as set forth in claim 4 wherein said conductor has a wall spaced therefrom a predetermined distance, said conductor being provided with relatively long plates and said wall being provided with relatively short plates in staggered relationship to said long plates whereby openings between said plates and said wall are formed.

12. A heat exchanger as set forth in claim 4 further comprising two concentric portions, each of which comprises a conductor provided with a plurality of fins, said conductors being thermally in contact with each other.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,135 Lenning Oct. 21, 1931 1,794,030 Phelps Feb. 24, 1931 1,842,263 Gobert Jan. 19, 1932 1,882,640 Jones et al. Oct. 11, 1932 2,090,454 Mayor Aug. 17, 1937 2,097,434 De Baufre Nov. 2, 1937 2,648,205 Hufnagel Aug. 11, 1953

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