US2240175A - Absorption refrigeration apparatus - Google Patents

Description

Patented 29,

ABSORPTION REFRIGERATION APPARATUS Curtis 0. Coons, North Canton, Ohio, and Rudolph S. Nelson, Larchmont, N. Y., assignors to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application December 30, 1936, Serial No. 118,286

, 38 Claims.

This invention relates to continuous absorption refrigeration apparatus and more particularly,

to means for circulating fluids therein. This application is a continuation in part of our co-pending applications for Letters Patent Serial No. 5

97,562 filed on August 24, 1936, and Serial No. 97,942 filed on August 26, 1937.

More particularly, this invention deals with that type of apparatus in which a motor driven fan is utilized to circulate an inert gas between condenser above the evaporator assembly in order that liquid refrigerant might flow thereto by gravity. The disadvantages of this construction or more points along the condenser into the top of one or more evaporator chambers. Still more specifically, it is an object of the invention to employ adense, inert gas such as nitrogen in absorption refrigeration apparatus of the types just mentioned.

Another object of the invention is tov provide for a positivev circulation of both the inert gas and the condensate within a multi-fiuid absorption refrigeration system, and more particularly to provide means whereby said fluids may be circulated at the proper relative'rates for the most efiicient operation of the system. Still more specifically, it is an objectof the invention to produce a positive circulation of the fluids by simply creating a pressure differential between spaced points along the inert gas circuit. I

A further important object of the invention is to provide a condenser-evaporator assembly are obvious. Designers were given practically no which is much more compact, Particularly in freedom whatever in locating the evaporator within the cabinet, and it was impossible for them to locate the evaporator so as to make the most efiicient use of the space within the box.

Moreover, great difficulties were experienced in obtaining sufficient condensing area in the space allowed in the upper portion of the cabinet.

According to our invention, it is possible to employ a very efficient condenser occupying much more space than was heretofore possible in .com-

mercial practices. Moreover, according to our invention, the evaporator assembly may be located within the box, so as to permit not only the most efficient use of the space within the cabinet, but also to provide more eflicient cooling and better circulation of the air. Furthermore it is also possible to employ a plurality of evaporator chambers at spacedpoints within the box. Moreover, these chambers may be, if desired,

identical in form and in operating characteristics,

' provide a construction in which a common means is utilized to circulate the inert gas or pressure equalizing medium, and the liquid refrigerant or condensate. of this invention to provide a motor driven fan to circulate the inert gas between the absorber and the evaporator, and to bleed off a portion of the inert gas from the discharge side of the fan More specifically, it is an object vertical extent, than heretofore, and yet one which permits a far greater flexibility in the arrangement of parts.

Other objects and advantages reside in certain novel features of the arrangement and construction of parts which will be apparent from the following description taken in connection with the accompanying drawing in which: I Figure 1 is a diagrammatical elevation view of the invention showing some parts broken away;

Figure 2' isa diagrammatical elevation view showing modified embodiments of the invention.

The drawing is not drawn to scale and the ves-,

gas separating chamber S, a rectifier R, a con-- denser C, and evaporator assembly E E, a gas pump F, liquid gas lift pumps P and P and an 5 absorber A, as essential elements, these elements being connected to form the complete refrlgera tion apparatus, by various conduits, some of which are in heat exchange relation.

The boiler B may be of any desired construction, and may be heated by any suitable means such as by a fluid fuel burner. A vapor lift conduit I0 leads from the boiler into the gas separating chamber in a well-known manner, and functions to elevate absorption fluid from for the purpose of lifting condensate from one the boiler into the gas'separating chamber. A

conduit leads from the top of the gas separating chamber through rectifier R and into the top of the condenser C. The condenser may be cooled in any desired manner such as bylaircooled heat radiating fins. A conduit l2 connects the bottom portion of the condenser with a U-shaped tube l3 having legs I4 and I5 con nected to an upper portion of evaporator chambers E and E respectively. Interposed between the two legs H and I5 of the U-shaped conduit I3 is located another U-shaped conduit 32 which is inverted. The two legs of this inverted U- shaped conduit 32 are connected to the two legs of U-shaped conduit l3 at a level which is, below the liquid refrigerant level' normally existing in the lower part of condenser C. The high pressure side of the gas pump F is connected by conduits 2| and 3| to the conduit 82 at the point shown in the drawing. Thus two liquid gas lift pumps P and P are formed. In view of the structural similarity and functional interdependence of these two pumps, we have found it convenient to refer to the same as a twin gas lift pump. When the gas pump F is in operation, inert gas is forced through conduits 2| and 3| and into conduit 32 where the gas stream splits, part of it entering theleft leg I of U- shaped conduit l3 to elevate liquid refrigerant into the top section of evaporator E and the remainder of the inert gas entering the right leg I5 of U -shaped conduit I3 to elevate liquid refrigerant into the top section of evaporator-E.

As shown, evaporator chambers E and E are similar in shape and size and contain baffles l6 over which liquid condensate flows in a thin film. It will be understood, of course, that the evaporator chambers may be of any preferred form, and may be dissimilar. According to the construction of Figure 1 the evaporator chambers are interconnected at the top and bottom by gas conduits l1 and i8 respectively.

An absorber A is positioned below the evaporator and may be of any desired construction, the one shown being an inclined cylindrical vessel having heat radiating fins IS on the exterior thereof. This vessel may have baflies or other means on its interior for bringing the absorption fiuid and the gases flowing therethrough into intimate surface contact. The absorber is connected to the evaporator chambers by a gas circuit consisting of conduits 20, 2| and 22; conduits and 22 being shown in heat exchange relation at 23. Conduit 20 is connected with conduit I! which interconnects the tops of evaporators E and E and below is connected to conduit 2| through the gas pump F. Conduit 2| leads into the lower end of the absorber A and conduit 22 leads from the upper end of the absorber and serves to conduct the inert gas back to conduit I8 which interconnects the bottom evaporator chambers, as is clearly shown in the drawing.

The absorption fluid circuit consists. of a U- shaped conduit 24 leading from gas separation chamber S into the top portion of absorber A. The conduit 25 conveys absorption fluid from the lower end of the absorber into a receiving vessel 26, which may be omitted if desired, while a conduit 21 leads from vessel 26 back to boiler B. U tube 24 and conduit 21 are preferably in heat exchange relation as indicated at 28.

We have discovered that a miniature fan operating at relatively low speeds is capable of producing a pressure differential equivalent to several inches of water when operating in a gaseous medium having a relatively high molecular weight (for. example, nitrogen) when under a pressure such as that employed in a three fluid refrigerating system. If an inert gas of low molecular weight like hydrogen is used, it is necessary to employ a fan many times larger than is the case with a dense gas in order to produce a given pressure differential. The larg-. er fan, of course, would require a larger motor and consume more power than the miniature fan and motor used in' our construction. The significance of the foregoing will be apparent when it is realized that for the same amount of useful work, a tremendous saving in operating and construction costs may be made by employing a dense inert gas rather than a light gas. Moreover, since it is desirable to circulate forcibly the pressure equalizing medium in a refrigeration system, and since the volume of gas circulated is much greater than the quantity of liquid refrigerant flowing, it is possible to utilize a small part of the gas to elevate the liquid refrigerant from the condenser into the evaporator without appreciably increasing the power input to the gas circulating means.

Gas pump F accordingly comprises a very small motor 29 operatively connected to a small fan 30, preferably of the centrifugal type, although it will be understood that other types of fans may be used. In the average size household refrigeration system, the power required to drive the .fan is about that used by a very small motor.

Such a fan is capable of producing a suflicient pressure differential in a dense gas circuit not only to circulate the inert gas, but also to elevate liquid condensate from one or more points on the condenser into the evaporator assembly.

According to our invention, a small portion of the dense gas is bled from conduit 2| on the lowing manner:

The system may be charged in accordance with known practices, with any suitable fluids such as ammonia as the refrigerant, water as the absorbent, and any dense inert gas, such as nitrogen, which serves as the pressure equalizing medium. A boiler B containing a mixture of ammonia and water may be heated in any desired manner, and as a result ammonia vapor will be liberated from the solution. The ammonia vapor generated in the boiler is under a pressure higher than that existing in the gas separating chamber S. Accordingly, absorbent liquid is elevated by the vapor lift pump l0 into the gas separation chamber 8. At this point, the ammonia vapor flows upwardly through conduit rectifier R and into the top of condenser C. Herein the ammonia condenses and collects in the lower part of the condenser C and also in the lower portion of U be I3.

Due to the operation 01 the gas pump F nitrogen will be circulated between the absorber and the evaporator chambers in the direction indicated on the drawing. A small portion of this inert nitrogen gas is by-passed upwardly through conduit 3|, through inverted U tube 32, and bubbles into the liquid refrigerant standing in legs I4 and I6 of U tube l3. While conduit 3| is shown connected to conduit 2| of the inert medium circuit, it is obvious that it could be connected to conduit 22 if desired. Since the gas pressurein conduit 32 is greater than that existing in the top sections of evaporators E and E liquid condensate is elevated by the liquid gas lift pumps P and P into the evaporator. It will be noted that the single stream of. condensate flowing from the condenser is divided into two streams as it is elevated by the twin gas lift pump, and part is delivered to evaporator E and part to evaporator E As the condensate flows downwardly over baffles "5, it evaporates into the stream of pressure equalizing medium and is then conveyed into the lower end of the absorber.

Meanwhile, weak aqua is flowing downward from the gas separating chamber S, through conduit 24 and into the top of absorber A through which it flows downwardly absorbing ammonia from the rich inert gas flowing in counterflow therewith. The enriched absorption fluid passes from the absorber through conduit 25 into receiving vessel 26. From this point, the enriched absorption fluid passes through conduit 21 back to boiler B after first passing in heat exchangerelation at 28 with weak aqua in conduit 24.

Attention is called to vent pipe 34 leading from an intermediate point in the condenser into some other part of the system such as into the top of the U-shaped inert gas pipe 32. An overflow pipe 33 for condensate also leads from an intermediate point-in the condenser to some other part of the system such as the absorption fluid conduit 21. Attention is directed at this point to the fact that all the ammonia vapor should be condensed in the condenser C above the point where vent pipe 34 joins the condenser, the condenser being so designed as to function in this manner.

Referring now to Figure 2, it will be seen that the general arrangement of parts is very similar to that just described in Figure 1, the principal differences being that only a single evaporator chamber is shown, and that one instead of two gas lift pumps is employed to elevate the condensate into the top of the evaporator.

Preferably, the arrangement of Figure 2 consists of a vapor lift pump leading from the boiler B into the gas separation chamber S where the ammonia vapor separates from the liquid and flows upwardly from conduit 5! and rectifier R, and into the top of condenser C. Conduit 52 leads from the bottom of the condenser into the liquid trap 53 which in turn, is connected to the top of the evaporator E by means of conduit 54. The inert gas circuit consists of a conduit 55 leading from the top of the evaporator E through gas pump F, conduit 56, theabsorber A, and then through conduit 51 back to the lower part of the evaporator. Conduits 55 and 51 are pref erably in heat exchange relation at 58. A conduit 29 leads from conduit 56 on the discharge side of gas'pump F to conduit 54. A loop 66 in conduit 59, is similar to inverted U tube 32 in Figure 1 and serves to prevent condensate from overflowing into conduit 59. As will be seen from Figure 2, loop 66 connects into conduit 54 at a point somewhat below the normal condensate ration chamber S into the top of absorber A. A

conduit 62 leads from the lower end of the absorber into receiving vessel 63. From vessel 63, the enriched absorbent is conveyed to boiler B through conduit 64, this conduit being in heat exchange relation at with weak aqua conduit 6|. Condenser C is provided with a vent conduit 66,

v and an overflow conduit 61 which serve functions similar to those of conduits 34 and 33 in Figure 1. The invention shown in Figure 2 operates in substantially the same manner as the preferred embodiment hereinabove fully described and illustrated.

From the foregoing, it will be appreciated that we have devised new and novel refrigeration systems having not only the many advantages to be obtained by forcibly circulating the pressure equalizing medium, but we have devised means for utilizing the pressure differential obtained in such a system to elevate condensate from the condenser into the evaporator assembly in a novel and heretofore unknown manner. Moreover, according to our construction, the flow of inert gas and condensate may be so proportioned relative to one another byproper design of the various parts of the apparatus as to give a max-.

inium efiiciency without using any control devices whatever in the system.

Furthermore, it will be obvious that our system lends itself to automatic control by the simple expedient of starting and stopping the gas pump F, or by varying the speed of the pump.

, The relative rates of flow of inert gas and liquid remain substantially the same regardless of the change in the speed of the pump. The .flow of the pressure equalizing medium in the system is therefore seen to be independent of the differences in density between two columns of gas caused by either or both temperature or concentration difierences between the two gas columns.

We also wish it to be understood that two liquid gas lift pumps may be employed with a sinle evaporator chamber. It will also be apparent that a liquid gas lift pump can be utilized to elevate only a portion of the condensate into the top of the evaporator, the remaining portion flowing into a lower portion of the evaporator by gravity. Moreover a liquid refrigerant gas lift pump is in reality an evaporator as well as a pump for the liquid refrigerant being pumped partially evaporates into the inert gas also passing through the pump, and is thereby cooled.

Accordingly the liquid refrigerant gas liftpump may be considered as a precooler for the liquid refrigerant. An ammonia vapor lift pump operating to elevate liquid ammonia into an evaporator not only is less efiicient than a gas lift liquid ammonia pump, because the ammonia that is vaporized to form the vapor for operating the vapor pump is wasted for producing refrigerating, but also it does not act in the capacity of a pre-cooler for the liquid ammonia, as does the gas lift liquid refrigerant pump.

While only two embodiments of the invention have been described, herein, it is to be understood that various changes maybe made in the arrangement and construction of the parts without departing from the spirit of the invention or the scope of the annexed claims,

Although gas pump F has been shown in the rich inert medium conduit, it will be understood that equally satisfactory results can be obtained if it is located in some other part of the inert medium circuit, as for example the lean medium conduit as shown in our copending application Serial No. 118,284, filed concurrently herewith. It is only necessary that the gas inlet and the discharge ends of the gas lift pump be connected to ahigh and to a low pressure area respectively of the inert medium circuit. Since some refrigerant vapor willalways be present in all parts of the inert gas circuit, it will be apparent that the gas diverted to the gas lift pump will always be a mixture of refrigerant vapor and inert medium, and under all conditions of operation there will be a considerable preponderance of inert medium.

We claim:

1. Absorption refrigerating apparatus of the type in which an inert gas is employed as a pressure equalizing agent and including an evaporator, an absorber, a gas lift pump for conveying liquid into the evaporator, a gas conduit connecting the evaporator andabsorber for conveying inert gas and refrigerant gas from the evaporator to the absorber, a power driven pump located in said conduit for raising the pressure therein and means for removing some of the gas at the raised pressure from said conduit before it enters the absorber and for conveying it to said gas lift pump to cause liquid to flow upwardly therethrough.

2. Absorption refrigerating apparatus of the type in which an inert gas is employed as a pressure equalizing agent and including an evaporator, an absorber, a condenser having a portion located below the top of the evaporator, means for lifting liquid from said portion of the condenser to the top of said evaporator, a gas conduit for conveying inert gas and refrigerant gas from the evaporator to the absorber, a power driven gas pump in said conduit and a conduit for by-passing some of the gases around the absorber and for conveying the gases to said liquid lifting means to operate the same.

3. Absorption refrigerating apparatus of the type in which an inert gas is employed as a pressure equalizing agent and including an evaporator, an absorber, a condenser having a portion located below the top of the evaporator, means for lifting liquid from said portion of the condenser to the top of said evaporator, a gas conduit for conveying inert gas and refrigerant gas from the evaporator to the absorber, a power driven gas pump in said conduit and a conduit for by-passing some of the gas around the absorber and for conveying the gas to said liquid lifting means to operate the same, said liquid lifting means comprising a gas lift pipe having its lower end connected to the bottom of the condenser and its upper end connected to the top of the evaporator.

4. In an absorption system using inert gas, and having an evaporator, an absorber and inert gas conduits connecting the same, the combination of a power driven gas pump for circulating the inert gas, means for lifting liquid into the evaporatorand means for by-passing some gas from said inert gas conduits around the absorber and to said liquid lifting means to operate the same.

5. The method of operating an absorption refrigeration apparatus which includes lifting substantially pure liquid refrigerant from a point of rest to an evaporation zone thereabove by means of a relatively small propelled stream of dense gas injected into a body of the liquid in column form, said small stream of gas being derived from a relatively large circulating stream a three fluid system wherein refrigeration is prounder pressure through the evaporating zone, bypassing a predetermined proportion of the dense inert gas before it reaches the evaporating zone, and lifting a quantity of liquid refrigerant to the evaporating zone proportional to the quantity of inert gas so diverted by introducing the diverted inert gas into a column of liquid refrigerant.

'7. In an almorption refrigerating system having a plurality of interconnected parts in open communication, two evaporators connected at their upper and lower ends respectively by conduits, a U-tube between the evaporators having the legs thereof opening into the upper portions of the evaporators, a conduit supplying liquid refrigerant to the lower portion of the U-tube, a gas pump circulating a dense inert gas under pressure through the evaporators, means diverting a portion of the dense inert gas circulated through the evaporator and introducing it into the lower portions of the legs of the U-tube to lift the liquid refrigerant into the evaporator.

8. An absorption refrigerating system having a plurality of interconnected parts in open communication, certain of said parts comprising a plurality of evaporator chambers connected in parallel, and means for supplying liquid refrigerant to each of said chambers comprising a U- tube connected at its upper end to each of said chambers, means supplying liquid refrigerant to the lower end of the U-tube, and means for sunplying a medium in gaseous phase to said U-tube to elevate liquid refrigerant to each of said chambers.

9. An absorption system of the type defined in claim 8 characterized by the fact that the gaseous medium supplied to said U-tube is non-condensable at temperatures and pressures normally prevailing in the system.

10. An absorption system of the type defined in claim 8 characterized by the fact that said gaseous medium is supplied to both legs of said U-tube in such manner that the refrigerant liquid is discharged alternately into the evaporator chambers.

11. That improvement in evaporators suitable for use in absorption refrigerators wherein a. pressure equalizing medium is circulated through a circuit including a path of flow-through the evaporator in counterflow to downwardly flowin liquid refrigerant, which improvement comprises diverting a part of the pressure equalizing medium and using the same to actuate a gas lift pump connected to and discharging into the top of the evaporator and operable to elevate refrigerant liquid from a point below the upper part of the evaporator into the evaporator.

12. That improvement in absorption refrigeration apparatus having an evaporator provided with means for circulating a pressure equalizing medium therethrough, a condenser for liquefying refrigerant vapor supplied thereto, means for elevating a portion of said liquefied refrigerant into the evaporator, said means including a gas lift pump, and means for supplying a non-condensing gaseous fluid to said pump to lift the liquid therein.

13. The improvement recited in claim 12 characterized by the fact that said gaseous fluid comprises nitrogen diverted from the main stream of gas circulating through the evaporator.

14. The improvement recited in claim 12 characterized by the fact that a part of the stream of pressure equalizing medium is diverted from the mainstream circulating through the evaporarich solution of refrigerant in an absorbent to generate refrigerant vapor, elevating weak solu-, tion by introducing into a column thereof retor and is injected into said liquid elevating said parts from a point therebelow, and means for supplying a dense non-condensing gas to said gas lift pump to operate the same.

16. A two part evaporator as recited in claim 15 characterized by the fact that the pressure equalizing medium and the liquid refrigerant flow through at least one of said evaporator parts in counterfiow relation.

17. A two part evaporator as recited in claim 15 wherein the pressure equalizing medium flows in counterfiow to the liquid refrigerant in both parts of the evaporator.

18. An evaporator comprising two parts, means for delivering a predetermined amount of liquid refrigerant to each of said parts from a common source of the liquid refrigerant, said means including a double gas lift pump having a discharge to each of said evaporator parts, and means for delivering gas under pressure to said double gas lift pump whereby liquid refrigerant is delivered to both of said evaporator parts.

19. An evaporator as defined in claim 18 wherein said double gas lift pump is so constructedand arranged that substantially equal amounts of liquid refrigerant are delivered to each of the evaporator parts.

20. An evaporator as defined in claim 18 wherein the liquid refrigerant is delivered to first one evaporator part and then to the other evaporator part.

21. That improvement in the art of continuous absorption refrigerating system using inert gas which includes the steps of propelling the inert gas stream by applying thereto a force produced externally of the system, bleeding off a part of said inert gas stream and introducing the inert gas-bled off into a column of liquid refrigerant.

22. The method of proportioning the amount of liquid refrigerant and the amount of inert gas supplied to the evaporator of a continuous absorption refrigerating system using inert gas which includes the steps of positively propelling the inert gas, diverting a fixed proportion of the inert gas so propelled, and lifting liquid refrigerant to a place of evaporation by introducing the diverted inert gas thereinto.

23. Absorption refrigeration apparatus comprising a generator, an evaporator, a condenser extending below the evaporator, an absorber, conduits connecting said elements to form a continuous absorption refrigerating system including a liquid line connecting the condenser and evaporator, an inert gas circuit including the absorber and evaporator, power-driven means for frigerant vapor, separating the vapor and weak solution, liquefying the refrigerant vapor, and elevating the liquid refrigerant to a place of evaporation by introducing thereinto a relatively small propelled stream of dense inert gas derived from a relatively large circulating stream of said dense inert gas.

25. In continuous absorption refrigerating apparatus using inert gas, an evaporator, a condenser extending below the evaporator, an absorber, a generator, an inert gas circuit including said evaporator and absorber, power-driven means for circulating inert gas through said circuit, a conduit connecting said evaporator and the bottom of said condenser, means leading a portion of the inert gas into said conduit above the level of the bottom of the condenser, means venting said condenser to the inert gas circuit, and overflow means connected to said condenser at a point above the level of the inert gas connection to the liquid column and to a portion of the system containing liquid refrigerant.

26. That improvement in the art of continuous absorption refrigerating systems utilizing inert gas which includes the steps of introducing a. propelled stream of inert gas into a rising column of liquid refrigerant to elevate the liquid to a place of evaporation and passing inert gas and liquid refrigerant through the place of evaporation in' counterflo-w relation.

27. That improvement in the art of continuous absorption refrigerating systems having an evaporator and an absorber connected to form an inert gas circuit and a condenser to liquefy vaporous refrigerant which includes the steps of forcibly propelling the inert gas through its circuit, diverting a portion of the inert gas so propelled and introducing it into a rising column of liquid refrigerant to elevate it into the evapo rator, and passing the liquid refrigerant through the evaporator in counterflow relation with the undiverted portion of the inert gas.

28. That improvement in the art of continuous absorption refrigeration which includes the steps of liquefying vaporous refrigerant, elevating the liquid refrigerant to a place of evaporation by injecting gas under pressure thereinto, conveying inert gas through the place of evaporation and venting the refrigerant liquefying zone to the place of evaporation adjacent the point at which inert gas exits therefrom.

29. Absorption refrigerating apparatus including a condenser, an evaporator, an absorber, conduits connecting said evaporator and absorber to form an inert gas circuit, a rising conduit connecting said condenser to the evaporator adjacent the rich gas outlet of the inert gas circuit, power-driven means circulating the inert gas, and means diverting a portion of the rich inert gas into saidrising conduit to elevate liquid refrigerant into the evaporator.

30. The method controlling a continuous absorption refrigerating system using inert gas which includes the steps supplying a propelled stream of inert gas to an evaporating zone, generating at least the maximum amount of refrigerant capable of being evaporated by the inert gas supplied to the place of evaporation, liquefying the refrigerant, elevating liquid refrigerant to the evaporating zone by introducing a portion of said propelled stream of inert gas into a rising column of liquid refrigerant, and maintaining a substantially constant pumping head in said column by venting non-condensable gases and excess liquid refrigerant from the liquefying zone.

31. That improvement in the art of continuous absorption refrigeration systems wherein refrigerant is expelled from solution by the application of heat, the vapor so produced is liquefied, the liquid is evaporated in the presence of an inert gas in an evaporating zone to produce refrigeration, and the refrigerant vapor is absorbed by transferring a mixture of inert gas and refrigerant vapor from the evaporating zone to an absorbing zone containing absorption solution. which includes the steps of collecting liquefied refrigerant, venting the liquefying zone to the evaporating zone, propelling portions of the collected liquid refrigerant to the evaporating zone by gas lift action, and returning excess refrigerant to said solution.

32. An evaporator adapted for use in an absorption refrigeration apparatus of the type employing a pressure equalizing medium, said evaporator comprising a chamber having an inlet at its lower extremity and an outlet at its upper eX- tremity for said pressure equalizing medium, means for elevating liquid refrigerant from a point below the upper part of the evaporator into the evaporator from which point it flows downwardly therethrough by gravity in counterflow to the pressure equalizing medium and evaporates into the pressure equalizing medium to produce refrigeration, said refrigerant liquid elevating means being a gas lift pump, and power operated means for supplying a non-condensing gas to said pump to operate the same.

33. An evaporator adapted for use in an absorption refrigeration apparatus of the type employing a pressure equalizing medium, said evaporator comprising a chamber having an inlet at its lower extremity and an outlet at its upper extremity for said pressure equalizing medium, and means for elevating liquid refrigerant from a point below the upper part of the evaporator into the evaporator from which point it flows downwardly therethrough by gravity in counterfiow to the pressure equalizing medium and evaporates into the pressure equalizing medium to produce refrigeration, said refrigerant liquid elevating means being a gas lift pump provided with means for supplying a non-condensable gas to said pump under pressure for elevating the refrigerant.

34. Refrigerating apparatus comprising a solu tion circuit including a boiler and an absorber,

an inert gas circuit including an evaporator and said absorber, a condenser extending below the refrigerant inlet to said evaporator and connected to receive refrigerant vapor from said boiler, a gas lift pump for elevating liquid refrigerant from said condenser into said evaporator inlet, and means for diverting inert gas from said inert gas circuit to operate said gas lift pump, said gas lift pump, evaporator and inert gas circuits being so connected that inert gas discharging into said evaporator from said pump is immediately removed therefrom.

35. That method of operating an absorption refrigerating system which includes the steps of lifting substantially pure liquid refrigerant from a point of rest to an evaporating zone thereabove by means of a small stream of dense inert gas projected into a body of the liquid in column form, and circulating another body of the dense inert gas through the evaporating zone.

36. Absorption refrigerating apparatus comprising a pressur equalizing medium circuit including an evaporator and an absorber having resistance to gas flow therethrough, means for raising the pressure of the pressure equalizing medium at a selected point in said circuit to produce a flowof pressure equalizing medium therethrough against the resistance thereof, means for short circuiting a portion of the circulating pressure equalizing medium around a portion of the resistance of said circuit from an area of relatively high pressure to an area of relatively low pressure, and means for introducing liquid refrigerant into the short circuit path to convey the liquid to such area of low gas pressure and to interpose sufflcient resistance in the shortcircuit gas path to limit gas flow therethrough.

37. Refrigerating apparatus comprising a solution circuit including a boiler and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, a condenser extending below th top portion of said evaporator, and means for diverting a portion of the rich gas enroute from said evaporator into a gas lift pump connected between the discharge portion of said condenser and the top portion of said evaporator.

38. Refrigerating apparatus comprising a solution circuit including a boiler and an absorber, a pressure equalizing medium circuit including an evaporator and said absorber, a condenser extending below the top portion of said evaporator, means for producing a pressure differential between different portions of said pressure equalizlng medium circuit to produce pressure equalizing medium flow therethrough, and means for diverting rich gas from a high pressure area into a gas lift pump connected between the discharge portion of said condenser and the top portion of said evaporator.

CURTIS C. COONS. RUDOLPH S. NELSON.

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