US2312619A - Refrigeration - Google Patents

Description

- I px-k.

March 2, 1943.

M. E. BIXLER REFRIGERAT IbN Filed Jan. 25, 1939 2 Sheets-Sheet l INVENTOR Milo E. Bixler ATTORNEY March 2, 19 3- M. E. BIXLER REFRIGERATION Filed Jan. 25, 1939 2 Sheets-Sheet 2 R m mr mm X i E 1 m ATTORNEY Patented Mar. 2, 1943 UNITED STATES PATENT OFFICE REFRIGERATION Milo E. Bixler, North Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application January 25, 1939, Serial No. 252,745

It is a principal object of the invention to provide a refrigerating system including an evaporator of the type in which the liquid refrigerant is propelled from the bottom to the top portion .thereof under the impetus of the inert gas stream into which the refrigerant is evaporating and to utilize some or all of the elevating conduits between substantially horizontal evaporator sections for the purpose of refrigerating the air within the food storage compartment.

It is a further object of the invention to provide an evaporator of the above referred to character which is so constructed and arranged that the same basic construction can be varied slightly to produce structures having a wide range of air refrigerating capacities. It is a further object of the invention to provide an evaporator of the above referred to type in which the lifting conduits at the rear of the evaporator coil structure are preferably but not necessarily contacted by a'singie large first to Figure 1 thereof, there is disclosed a refrigerating apparatus comprising a boiler B, an analyzer D, an air-cooled rectifier R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger G, an absorber A, a liquid heat exchanger L, a solution reservoir S, and a circulating fan F which is driven by an electrical motor M. These elements are suitably connected by various conduits to'form a plurality of gas plate or fin which will serve to refrigerate the air within the storage compartment but .without adding materially to the space normally occupied by the evaporator.

It is a further object of the invention to provide an evaporator of the type above referred to which is provided with a plurality ofair refrigerating elements operating at different temperature levels.

It is a further object of the invention to provide an evaporator so constructed and arranged that it does not appreciably add to the compartment space occupied by the freezing section of the evaporator, provides a free low resistance path for air flow in the storage chamber and which is simple and economical to manufacture.

It is a further object of the invention to provide an evaporator for three-fluid absorption refrigerating systems in which the box-cooling element is positioned to allowv free air flow over all parts thereof and which does not add substantially to anydimension of the evaporator.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawings, in which:

Figure l is a diagrammatic representation of a three-fluid absorption refrigerating system embodying the present invention in which the evaporator is illustrated on an enlarged scale and in perspective.

Figure 2 is an enlarged scale perspective view of a modified evaporator construction.

Referring now to the drawings in detail and and liquid circuits constituting a complete refrigerating system to which reference will be made in more detail hereinafter.

The above described refrigerating system will be charged with a suitable refrigerant, such as ammonia, a suitable absorbent, such as water, and an inert pressure equalizing medium, preferably a dense inert gas like nitrogen.

The boiler B may be heated in any suitable manner as by a combustible fuel burner or an electrical cartridge heater.

The apparatus, especially the motor- M and, .the heater for the boiler B, may be QilfilOlldi-f in any desired manner. A preferred control is" disclosed and claimed in the co-pending application of Curtis C. Coons, Serial No, 148,424, filed June 16, 1937, now Patent No. 2,228,343,

issued January 14, 1941.

The application of heat to the boiler B liberates refrigerant vapor from the strong solution normally therein contained. The vapor so liberated passes upwardly through the analyzer D in counterfiow to strong solution being supplied to the boiler. Further refrigerant vapor is generated in the analyzer D from the strong solution by the heat of condensation of absorbent vapor generated inthe boiler. The refrigerant vapor is conveyed from the upper portion of the analyzer D to the upp r portion of the condenser C by the conduit II which includes the rectifier R. The rectifier serves to condense vapor of absorption solution which may pass v through the analyzer D.

The refrigerant vapor supplied to the condenser is liquefied therein and drains from the bottom portion of the condenser into the bottom portion of the evaporator E by a conduit [2 which includes a U-shaped gas-sealing portion. The condenser side of the conduit I2 is vented by means of a conduit l3 to the rich gas discharge side of the gas heat exchanger G.

The weak solution formed in the boiler by the generation of refrigerant vapor is conveyed therefrom through a conduit l5, the outer path of the liquid heat exchanger L and a conduit II, which also functions as a solution precooler by reason of the fins mounted thereon, into the solution reservoir S. The lean solution which accumulates in the solution reservoirs is conveyed therefrom into the bottom portionof the fan inlet or suction conduit l8 which communicates with the top portion of the tubular inclined air-cooled absorber A at its lower end by :means of ages lift pump conduit IS. The gas lift pump 19 is operated by gas diverted from the discharge conduit '26 of the circulating fan F through a small bleed conduit 2| which connects to the pump [3 below the liquid level normally prevailing in the boiler-analyzer system whereby the solution is elevated into the absorber by gas lift action. A small vent conduit 22 is connected between the suction conduit l6 and the solution reservoir S whereby the gas lift pump i9 operates under the maximum gas pressure differential available within the entire apparatus.

Lean solution flows downwardly through the absorber A in counterflow relationship with rich gas flowing upwardly therethrough. The absorption solution absorbs the refrigerant vapor content of the rich gas and the heat absorption is rejected to cooling air flowing over the exterior walls of the absorber tubing and in contact with the fins thereon. The strong solution formedin the .absorber flows from the bottom portion thereof from which point it is returned to the top portion of the analyzer D by way of conduit 24, the inner path of the liquid heat exchanger L and the conduit 25.

The lean gas discharged from the absorber into the suction inlet of the circulating fan F through the conduit 18 is placed under pressure 311are connected by a riser conduit and boxcooling construction comprising a horizontal conduit 46 lying in the plane of the coil section 36 which merges into a rising conduit section 41 by the fanF and is discharged through the conduit 20 into the outer path of the gas heat exchanger G. After passing through the gas heat exchanger the gas is conveyed by means of the conduit 23 into the bottom-portion of the evaporator E. The exact construction and operation of the evaporator E will be described in detail hereinafter. For the present it is sufiicient to note that the inert gas under pressure is supplied through the conduit 23 and the liquid refrigerant supplied through the conduit I2 both enter the evaporator proper at substantially the same point and that the liquid refrigerant is propelled by the inert gas through the evaporator as it is evaporating into the gas to produce refrigeration. The rich gas formed in the evaporator by the production of refrigeration is discharged therefrom into the top portion of the inner path of-the gas heat exchanger G by means of a conduit 3|. After'passing through the gas heat exr changer G the rich gas is conveyed by means of a conduit 32 to the bottom portion of the absorber A through which it flows upwardly in counterflow with the absorption solution in the manner previously described.

The evaporator E comprises three substantially horizontal vertically spaced parallel coil sections 35, 36 and 31. Each of the coil sections is formed of two U-shaped conduit elements having the inner legs thereof serially connected at the rear of the evaporator and with the outside legs of each coil forming the gas inlet and outlet connections thereto. The inert gas supply conduit 29 joins the left-hand, as viewed in Figure l,

outer leg of the coil section 35. The liquid refrigerant supply conduit l2 also joins this leg of the coilsection 35. The right hand outer legs of the coil sections and 36 are connected by a riser conduit 40. Though the riser conduit 43 has been shown as lying in the plane defined by the outer legs of the coil sections 35 and 36, it may, if desired, be turned inwardly into the plane of the rear wall of the evaporator.

The left-hand outer leg of the coil section 36 and the right-hand outer leg of the coil section terminating in a second horizontal conduit 'element 48 which lies substantially midway between the coil sections 36 and 31. The conduit 48 merges into a rising conduit 49 which terminates in a third horizontal conduit section 53 lying in the plane of the coil section 31 and joining the outer right-hand leg thereof. The left-hand outer leg of the coil section 31 terminates in the rich gas discharge conduit 3|.

It will be noted that the conduit elements 46 to 50, inclusive, lie in a planeparallel to a plane defined by the rear end of the coil sections 35, 36 and 31 and spaced slightly rearwardly thereof.

A large air-cooling plate or fin 52 is mounted in heat transfer relationship with the conduit elements 46 to '56, inclusive. The plate 62 is provided with indented portions 53 corresponding to the conduit elements 46 to 50, inclusive, and adapted to embrace approximately one-half the circumference of said conduits. may be secured to the conduits 46 to 56, inclusive, in any suitable manner as by clamping, welding, brazing,soldering, etc. to provide a good thermal bond therebetween. It is not essential that the plate '52 be intended to receive the conduit elements 46 to 50; it is only necessary to provide a thermal bond between these elements. For example, the plate 52 may be plane in which event a ,welded, brazed or tinned bond is preferred. If the plate 52 is plane, the heat transfer thereto can be improved by depositing metal as by welding between the plate and the channels formed with the associated evaporator conduits.

The evaporator is drained by means of .a conduit 55 which connects the strong solutionreturn line 24 and the top half of the coil section 35 adjacent its point of connection to the riser conduit 40. This drain functions merely as an overflow device in order to prevent blockage of the bottom coil section with liquid refrigerant and in normal operation it will not discharge any refrigerant provided the system is properly charged. This drain construction is fully described and claimed in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No, 220,189, filed July 20, 1938.

The coil sections 35, 36 and 31 will be enclosed in a suitable evaporator housing which is indicated by the dotted line 51.. Suitable shelves may be placed upon and thermally bonded to the coil sections 35 and 36 to accommodate ice and dessertfreezing and like receptacles. The air cooling plate 52 will be spaced rearwardly of housing 51 which may be insulated and .between the housing 51 and the rear wall of the cabinet whereby air to be-cooled contacts both sides of the plate.

The distance between the coil sections 36 and 31 is appreciably greater than the distance between the coil sections 35 and .36 whereby doubleculating fan F at a velocity suflicient to drag or sweep the liquid refrigerant supplied to the bot- The plate 52- tom portion of the evaporator upwardly therethrough as it is evaporating to produce refrigeration. The evaporator may be constructed from continuous tubing bent into the desired shape or from pre-formed conduit sections which are welded or brazed together as desired.

The action of the inert gas on the liquid refrigerant is as follows: In substantially horizontal and slightly inclined conduits the gas stream passes over the surface of a small stream of the liquid which it propels through the conduit by the dragging or frictional action exerted on the liquid by the gas. In rising and steeply inclined conduits the action is somewhat different, the

liquid refrigerant collect to some extent and is ?& again propels the liquid in a stream as mentionedabove.

The three horizontal and two vertical lift conduits which form the means for conveying the inert gas and liquid refrigerant from the coil 1 section 36 and the coil section 31 not only serve as conveying elements but they also serve as refrigerating elements for the food storage compartment and, further, they permit the relatively great height which exists between the coil sections 36 and 31. The refrigerating action of these elements is enhanced by reason of the fact that the instant type of evaporator exhibits aitendency to produce a largequantity of refrigeration adjacent to and within the riser conduits, such as the conduits l and 45. The instant invention takes full advantage of this phenomenon without increasing the height of the evaporator and thereby permitting the box-cooling conduit and fins normally positioned on the top portion of the evaporator to be eliminatedin their entirety.

the size of the fan which is undesirable because of the increase in depth of the mechanism compartment at the rear of the refrigerator cabinet, the increase in the cost of construction of the fan and the increase in the cost of operating the same. The present invention obviates this difllculty without measurably increasing the pressure drop between the gas inlet and outlet connections of the evaporator by taking the higher lift between the coil sections 38 and 31 in two stages of relatively small extent. The reason that this construction permits a greater lifting height without ameasura-ble increase in pressure drop appears to be due to the fact that the major portion of the throttling action of the inert gas in the evaporator occurs in the vertical lift portions thereof and that the throttling action increases more rapidly than a straight line function with increasing lifting height. Therefore, by using two small lifts instead of a single lift, the liquid may be elevated through a height greater than that possible with a single lift with the same pressure differential. This is highly advantageous and makes the evaporator'construction more flexible in the The propelling action of the inert gas is a function of its density, pressure, and velocity of flow.

able to develop approximately 4 of water pressure across the circulating fan F' for refrigerators adapted to be used in conventional size domestic cabinets. Of this total resistance drop in the inert as circuit, only between 2/ to 3" of water pressure may be used up between the gas inlet and outlet connections to the evaporator as the remainder of the pressure drop is used up t force the gas to flow through the various conduits, the gas heat exchanger and the absorber. It has also been found with a system using nitrogen and with a system pressure ranging between 2'70 and 400 pounds per square inch that this pressure drop will circulate the liquid through an evaporator of approximately '10" or 11" in height and arranged to receive a double depth ice tray resting upon the shelf placed above the coil sections 35 and 33; however, it is desirable to stack two single depth ice trays between the coil sections 36' and 31. This necessitates an increase in the evaporator height of a magnitude of /2" to 1" depending upon the particular design. However, it has been found that a single lift. such as the conduit 40 extending between the coil sections 36 and 35, is not altogether reliable in operation if the extra height is added between the coils 33 and 31 and that continued operation under these conditions can be assured only by increasing the pressure drop of the inert gas across the evaporator, which hands of the designer and, as heretofore noted, permits the'utilization of double depth ice trays in the bottom portion of the evaporator and of. two single depth ice trays in the upper portion thereof, thus giving the housewife a reasonable choice of tray capacity when ice cubes are in demand. I

The single plate fin construction characteristic of this form of the invention possesses a large number of desirable features. Because of the fact that the vertical fin is positioned laterally of the freezing compartment, box-cooling air may flow thereover without appreciable or material interference from the storage compartment and with relatively very little flow resistance because of the shape of the cooling fin.- -Moreover, with the present fin structure it is unnecessary to thread tubes through the fins, to cut out the fins, to position a plurality of fins or to proceed with any of the other steps normally followed in the manufacture of multi-fin heat exchangers which reto its economy and ease of manufacture andefilciency, the present iln structure is very simple to clean. Though the coil element which is bonded to the fin 52 operates at a low temperature frost deposition is minimized because of the rapid heat transfer provided by the large plate and the large v volume of air flowing thereover.

of course necessitates an increase in the speed or 7 By mounting'the cooling air fin on the lifting conduit interconnecting the two top freezing sections of the evaporatona large quantity of refrigeration is available in the finned conduit and the top freezing section does not operate at an extremely low temperature which is advantageous because the top freezing section normally is not the same manner. Certain portions of the apparatus disclosed in Figure 2 are identical with apparatus disclosed in Figure 1 and are given the same reference characters primed.

In Figure 2 the horizontal conduit section 50' merges into an S-shaped coil 6| which terminates in a riser conduit 62 at the forward portion of the evaporator. The riser conduit 62 opens into an enlarged connecting chamber 63 which is connected to an S-shaped coil 65 identical in shape with the coil 6| but constructed of larger diameter tubing. The coil 65 terminates in the rich gas return conduit 3 I which communicates with the rich gas inner passage of the heat exchanger This form of the invention is particularly designed and intended to be utilized in connection with refrigerating systems in which an extraordinarily heavy storage space refrigerating load is to be carried with respect to the freezing or ice production load. To this end, the elevating conduits 46' to 50', inclusive, are provided with a plurality of spaced vertically extending fins 68 and the upper large diameter s-shaped coil section 65 is also provided with a plurality of spaced apart vertically positioned fins 69.

The enlarged chamber 63 which forms the junction between the small diameter S-shaped coil 62 and the large diameter 8-shaped coil 65 is very important. It has been found from experiment that a very .large resistance to gas .fiow is introduced into the evaporator if the conduits 62 and 65 are connected directly through a reducing connection or by turning the conduit 62 into a blank end wall on the conduit 65. It has further been found that by introducing an enlarged chamber at this'point the resistance to flow of the inert gas stream through the evaporator can be decreased without interfering with the operation thereof or the discharge of liquid ammonia into the S-shaped coil 65.

The cross-sectional area of the S-shaped coil 65 is greater than that of the other portions of the evaporator in order that the gas and liquid streams may fiow therethrough at a lower ve- 31 could be replaced by an S-shaped coil, such as the coil 6| which either discharged directly into the conduit 3| or into a connecting chamber and upper large diameter coil, such as the coil 65 provided with additional fins for box-cooling purposes. Obviously, the evaporator construction illustrated in Figure 2 is also susceptible of similar modifications. The single plate aircooling construction of Figure 1 may be combined with the multiple fin construction of Figure 2 to increase the air-cooling capacity of the unit by attaching a plurality of narrow vertically extending fins to the large plate at right angles to the plane thereof. Such additional fins may be attached to either or both sides of the large plate. If the additional fins are attached to both sides of the large plate they may be utilized to mount the large plate on the evaporator coil. This may be accome plished by providing the additional fins with edge slots which engage the coil and with flange; firmly attached to the plate.

As a further variant of the arrangements illustrated the lifting conduits may be enclosed evaporator at the rear thereof efficient use is made of space normally wasted and the rear cabinet wall opening through which the evaporator is inserted in assembly need be no larger in area than the cross-sectional area of the encased freezing portion of the evaporator. An additional advantage results from the fact that neither the cooling unit nor foodstuffs stored adjacent thereto can materially interfere with free fiow of air across the box-cooling element.

In each form of the invention the functions of box-cooling and freezing at distinct temperature gradients are performed by distinct thermally remote vertically co-extensive sections of a single evaporating unit. There is relatively little heat transfer along the length of the evaporator conduits and the evaporator casing, such as 51, whether insulated or not serves to isolate the finned portions of the evaporator from the freezing portions thereof.

Though in each form of the invention herein illustrated the rising conduit between the two lower evaporator sections has been shown as utilized by the evaporator to be decreased by the amount previously utilized by the; fins on top of the evaporator casing. Moreover, the single plate cooling element does not require any additional space at the rear of the evaporator over and above that normally provided therein, and free evenly distributed flow of air over all portions of the box-cooling element is provided.

Though the invention has been disclosed in some detail, many modifications are obviously possible without departing from the spirit of the invention or the scope thereof. For example, in the construction illustrated in Figure 1 the coil 31 could either be eliminated entirely, in which event the conduit 50 which is charged directly into the conduit 3! or the coil being free of the box-cooling fins, that is by no means necessary for this conduit too may be turned inwardly into the plane of the rear of the evaporator and finned, if desired.

While the invention has been illustrated and described herein in considerable detail, it is not to be limited to the construction and arrangement illustrated, as various changes may be made in the construction, arrangement and proportionsections, conduit means including a plurality of vertical lifting and horizontal connecting sections connected to one of said freezing sections and spaced therefrom, and a single large area vertically extending plate thermally bonded to said connecting sections.

including a plurality of serially connected vertically spaced conduits, heat transfer means thermally bonded to said evaporator intermediate said serially connected conduits, another conduit having a cross-sectional area greater than the cross-sectional area of said first-mentioned conduits and means for serially connecting said conduit of large cross-sectional area to the highest of said first-mentioned conduits including an enlarged chamber, means for supplying refrigerant to the bottom portion .of said evaporator, and means for propelling a pressure equalizing medium upwardly therethrough at a velocity suflicient to circulate the refrigerant.

4. Refrigerating apparatus comprising an evaporator having a pair of horizontal freezing coils, an upstanding box-cooling coil serially connecting said freezing coils, a horizontal box-cooling coil connected serially to one of said freezing coils, and means for supplying refrigerant and inert gas to the freezing coil not directly connected to said horizontal box-cooling coil.

5. Refrigerating apparatus comprising an evaporator having a pair of freezing sections, a plane coil serially connecting said freezing sections and spaced laterally therefrom and a large plate formed to partially embrace said plane coil and thermally bonded thereto, said plate lying in a plane parallel to said plane coil and being thermally isolated from said freezing sections.

6. Refrigerating apparatus comprising a horizontal shelf-forming freezing coil, an upstanding plane coil serially connected t4. said freezing coil and positioned rearwardly thereof, and an upstanding plate lying in a plane substantially parallel to the plane of said upstanding coil and thermally bonded to said upstanding coil in spaced relationship with said freezing coil whereby said plate is thermally remote from said freezing coil and air to be cooled may traverse each side thereof.

7. Absorption refrigerating apparatus comprising a pressure equalizing medium circuit including an evaporator and an absorber, a solution circult including a boiler and said absorber, said evaporator comprising a substantially horizontal shelf-like freezing portion adapted to support freezing receptacles and an upstanding plane coil portion positioned laterally of said freezing portion, a heat conducting plate lying in a plane substantially parallel to the plane of said plane coil and thermally bonded thereto, and means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator,

8. Absorption refrigerating apparatus comprising an evaporator, a boiler, an absorber, means connecting said boiler and said absorber to form a solution circuit, means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator, aid evaporator including a horizontal shelf-like freezing portion, a horizontal finned air cooling portion positioned in spaced relationship to said freezing portion and a vertically positioned finned air-cooling portion positioned in spaced relationship to said freezing portion and said horizontal air-cooling portion, and means connecting said evaporator and said absorber for circulation of pressure equalizing medium therebetween.

9. Absorption refrigerating apparatus comprising an evaporator, a boiler, an absorber, means connecting said boiler and said absorber to form a solution circuit, means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator, said evaporator including a horizontal shelf-like freezing portion, a horizontal finned air-cooling portion positioned in spaced relationship to said freezing portion and a vertically positioned finned air-cooling portion positioned in spaced relationship to said freezing portion and said horizontal air-cooling portion, and means connecting said evaporator and said absorber for circulation of pressure equalizing medium therebetween. said last mentioned means including means for propelling the pressure equalizing medium through at least'a part of said evaporator with a velocity and pressure su-mcient to circulate the refrigerant liquid as it is evaporating.

l0. Absorption refrigerating apparatus comprising an evaporator, a boiler, an absorber, means connecting said boiler and said absorber to form a solution circuit, means'for liquefying refrigerant vapor produced in said boiler and for supplying thev liquid to said evaporator, means connecting said evaporator and aid absorber for circulation of pressure equalizing medium therebetween, said last mentioned means including means for propelling the pressure equalizing medium through at least a part of said evaporator with a velocity and pressure sufficient to circulate the refrigerant liquid as it is evaporating, said evaporator comprising a plurality of spaced freezing sections, conduit means serially connecting said freezing sections and positioned in spaced relationship therewith, and air cooling means in heat conducting relationship with said conduit means and positioned to be thermally isolated from said freezing sections.

ll. Absorption refrigerating apparatus comprising an evaporator, a boiler, an absorber,

with a velocity and pressure sufiicient to circulate the refrigerant liquid as it is evaporating, said evaporator comprising a plurality of spaced freezing sections, conduit means serially connecting said freezing sections and positioned in spaced relationship therewith, air-cooling means in heat conducting relationship with said conduit means and positioned to be thermally isolated from said freezing sections, and a finned air-cooling section positioned above and in spaced relationship with said freezing sections.

12. Refrigerating apparatus comprising a freezing chamber, a single heat conducting air-cooling plate positioned in a. plane spaced from and parallel to one wall of said freezing chamber and thermally-isolated therefrom, a cooling unit including a part arranged to refrigerate said chamber and another part for refrigerating said air cooling plate arranged in contact therewith, and means for supplying a cooling medium to said cooling unit.

13. A refrigerating apparatus comprising a plurality of vertically spaced freezing evaporators, evaporating means serially connecting said freezing evaporators including a pair of upstanding conduits connected by a horizontal conduit and heat transfer means thermally bonded to said conduits, means for supplying refrigerant to the lowest of said freezing evaporators, and means for propelling an inert gas upwardly through said evaporator with suflicient velocity and pressure to circulate the liquid refrigerant upwardly therethrough.

14. Refrigerating apparatus comprising a plurality of vertically spaced freezing evaporators, evaporating means serially connecting said freeZ- ing evaporators including a pair of upstanding conduits connected by a horizontal conduit and a large vertically extending plate of heat conducting material thermally bonded to said conduits, means for supplying refrigerant to the lowest of unit arranged to support and refrigerate a horizontal receptacle supporting shelf, a flat vertically extending air-cooling unit positioned laterally of one side of said freezing unit and in spaced said freezing evaporators, and means forpropellabove said freezing evaporators, a conduit connected at one end to the freezing evaporator directly beneath said coil and connected at its other end to a chamber having a large cross-sectional area relative to the cross-sectional areas of said coil and of said conduit, said chamber being connected to one end of said coil, means for supplying refrigerant to the lowest of said freezing evaporators, and means for propelling an inert gas upwardly through said freezing evaporators and said evaporator means with sufficient pressure and velocity to circulate the liquid refrigerant upwardly therethrough.

16. Absorption refrigerating apparatus com-- prising a plurality of cooling unit sections having a generally rectangular configuration and adapted to be enclosed within a freezing chamber, an

air cooling unit positioned laterally of said sections, a large area plate of heat conducting material in heat exchange relationship with said air-cooling unit and lying in a plane parallel to a vertical plane including the'laterally adjacent edges of said cooling unit sections, said plate being spaced from said cooling unit sections to form an air flow passageway therewith, and means for supplying a cooling medium to said air cooling unit and said cooling unit sections.

17. Refrigerating apparatus having a freezing relationship thereto, a vertically extending heat conducting plate arranged in heat conducting relationship with said air-cooling unit and positioned laterally of and in spaced relationship to the said one side of said freezing unit to form an air passageway between said plate and said freezing unit and to allow air to flow in contact with both sides of said plate, and means for supplying a cooling medium to each of said units.

18. Refrigerating apparatus comprising a horizontal evaporator conduit adapted to underlie and refrigerate a receptacle support, an elongated evaporator conduit positioned in spaced relationship to said horizontal evaporator conduit and connected to one end thereof, a large area heat conducting plate lying in a vertical plane spaced from said horizontal conduit to form an air passageway between said plate and said horizontal conduit and to allow air to flow in contact with both sides of said plate, one face of said plate being thermally bonded to said elongated conduit along a line parallel to the longitudinal axis of said elongated conduit, and means for supplying a refrigerant to said conduits.

19. Absorption refrigerating apparatus comprising a horizontal evaporator conduit adapted to refrigerate a receptacle support, an elongated evaporator conduit positioned in spaced relationship to said horizontal evaporator conduit and connected to one end thereof, a large area heat conducting plate lying in a vertical plane spaced from'said horizontal conduit, one face of said plate being thermally bonded to said elongated conduit along a line parallel to the longitudinal axis of said elongated conduit, means for supplying refrigerant liquid to said horizontal conduit, and means for propelling an inert gas through said horizontal conduit and then through said elongated conduit with a velocity and pressure uificient to circulate the refrigerant liquid through said conduits.

20. Refrigerating apparatus comprising a freezing coil, a. vertically extending air cooling coil positioned laterally of and serially connected to said freezing coil, means for supplying a refrigerant liquid to said freezing coil, and means for propelling a pressure equalizing medium through said freezing coil and then through said air cooling coil with sufficient velocity and pressure to propel the liquid refrigerant through said coils as the liquid is evaporating.

21. Refrigerating apparatus comprising an evaporator conduit having a first part formed into a sinuous horizontal coil adapted to underlie and refrigerate a receptacle suporting shelf and a second part comprising an elongated conduit serially connected to said first part and positioned in spaced relationship to said horizontal coil, a vertically extending large area plate of heat conducting material thermally bonded to said elongated conduit and positioned in spaced relationship with said sinuous coil, means for supplying refrigerant liquid to said first part of said evaporator conduit, and means for circulating inert gas through said evaporator conduit in a direction and with suflicient velocity and pressure to propel the liquid refrigerant through said sinuous coil and then through said elongated conduit.

MILO E. BIXLER.

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