US2303816A

US2303816A - Refrigeration

Info

Publication number: US2303816A
Application number: US274891A
Authority: US
Inventors: George A Brace
Original assignee: Hoover Co
Current assignee: Hoover Co
Priority date: 1939-05-22
Filing date: 1939-05-22
Publication date: 1942-12-01
Anticipated expiration: 1959-12-01

Description

G. A. BRACE REFRIGERATION Filed May 22 G. A. BRACE REFRIGERATION Dec. l, 1942.

INVENTOR ATTORNEY Patented Dec. 1, 1942l REFRIGERATION George A. Brace, Winnetka, Ill., assignor to The Hoover Company,l North Canton, Ohio, a corporation of Ohio Application May 22,1939, serial 10.274,391'

24 claim.` (C1. i2-119.5)

Thisfinvention relates to the art of refrigeration and more particularly to a novel three-fluid absorption refrigerating system.

ln previous three-fluid absorption refrigerating systems it is customary to supply liquid refrigerant to an evaporator through which the liquid flows in a thin stream in contact with a gas stream. This possesses the disadvantage that the area of liquid to metal contact is extremely small as the stream of liquid flowing through the evaporator amounts only to a thin trickle. Also' the area of gas and liquid Contact is extremely small as the surface of the trickle of liquid refrigerant flowing through the evaporator amounts to but a small fraction of the interior surface area of the evaporator conduit. This arrangement produces an ineihcient apparatus because heat transfer between the inert gas and the metal wall of the evaporator conduit is poor and the area of the conduit which is wetted by the liquid is small as noted above, wherefore inefficient evaporation results and a sharp temperature differential is maintained between the exterior Wall of the evaporator and the gas stream flowing therethrough. In addition to the above factors the gas stream is discharged from the evaporator at a very low temperature which represents just so much wasted reirigerative effort.

Various means have been utilized in an attempt 'to remedy this condition but all of these means cause additional complications in the apparatus and are not entirely successful. Among such means may be mentioned the provision of wicking material in the evaporator, the insertion of metal wires and the insertion of metal ribbons. These devices tend to distribute the liquid refrigerant but they impede the flow of the inert gas, require a larger conduit, add very greatly to the cost of the evaporator and they form an additionallink in the path through which the heat is conducted from the exterior walls of the evaporator to the liquid refrigerant therein contained. The net result of these constructions is that the additional' length of the heat conducting path and the additional flow resistance practically offsets the advantages gained by enlarging the area of the liquid refrigerant in contact with the inert gas.

Accordingly, it is a principal object Aof the present invention to provide an evaporator in which an unbroken lm of liquid refrigerant is maintained uniformly throughout the exterit of the evaporator upon and across which the inert gas flows whereby to provide direct liquid to metal heat transfer throughout the entire extent of the evaporator wall and also to provide the maximum possible gas and liquid heat contact area without the introduction of any structural elements into the interior of the evaporator conduit which would tend to impede the heat transfer or to interfere withthe gas flow therethrough.

It is another object of the invention to provide a three-fluid absorption refrigerating system in which the liquid refrigerant circulates through the evaporator-by gas lift action in contact with the gas into which it evaporates.

It is a further object of the invention to provide a. three-fluid absorption refrigerating system including an evaporator which is practically independent of the elevation at which the condenser is located.

It is another object of the invention to provide a refrigerating system in which a very large body of cold liquid refrigerant is continuously circulated throughthe evaporating portion of the apparatus.

It is another object of the present invention to provide a three-fluid absorption refrigerating system in which foreign bodies, such as absorption solution, finding their way into the evaporator are periodically purged therefrom.

It is a still furtherobject of the present invention to provide a three-fluid absorption refrigerating system in which spaced bodies of gas circulate through the evaporator alternating with spaced bodies of liquid and in contact with a thin film of liquid which adheres to the entire inner wall of the evaporator conduit.

I 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 1 is a partly diagrammatic broken view illustrating the invention.

Figure 2 is a sectional view on an enlarged scale illustrating a detail of the invention.

Figure 3 is a. diagrammatic partial sectional perspective view of a. modified form of the invention.

Referring now to the drawings in detail and first to Figure l thereof, there is illustrated a three-huid absorption refrigerating system comprising la boiler B, an analyzer D, an air-cooled rectier R., a tubular air-cooled condenser C, an. evaporator E, a gas heat exchanger G, an inclined tubular air-cooled absorber A, a liquid heat exchanger L, a solution reservoir S, and a circulating fan F which is driven by an electrical motor M. llihese elements are suitably interconnected by various'conduitsto form'a complete refrigerating system including a number of gas audliqheating means, such'as an electrical' cartridge heater, a'gas burner or a liquid fuel burner.

Thenapplication of heat to the boileriB generates refrigerant v 'apor from therefrigerant absorbing solution therein contained. @The vapor so generated lpasses upwardly through the/analyzer D in counteriiowtoj strong solution vflmting downwardly therethrough whereby' further refrigerantrvapor isfgeneratedby theheat of cbn densation' of absorption solution v apor carried into the analyzer.' The'r'efrigrant vapor is then conveyedfrorn-f'thev analyzer D tothe upper'portion detail hereinafter.

evaporator in a manner to be described in more For the present it is sumcient to note that the liquid refrigerant and inert gas flow upwardly through the evaporator as the `refrigerant is evaporating thereinto to produce refrigeration. The evaporator E also includes an upper finned tubular box-cooling section 30 which discharges into the vessel. 28. The rich gas is `then conveyed from the vessel 28 to the inner path of the gas heat exchanger G by means of the conduit 3| and is conveyed from the inner 'path of the gas heat exchanger G to the bottom portion of the absorber A by means of the conduit 32. The inert gas refrigerant vapor mixture flows upwardly through the absorber A in counterflow to the absorption solution in the manner heretofore described. l

of the condenser Cbymeans of-Aa conduit/[I which f includesfthe rectifier R. v

The weak solution formed ing-:the .boiler by the generation of refrigerantfvapor'therefrom isco'nveyed fromthe boiler to the solution reservoir S by way ofthe conduit VI4, the liquid heat exchangerY L and a"finnedlprecooling conduit I6.

. The liquid level' prevailing in the boiler-analyzer reservoir system is appreciably below the upper f portion of the absorber wherefore a gas lift pump conduit is provided to convey the lean solution from the bottom portion of the reservoir S into the upper portion of the absorber A. A small gas bleed conduit |8 is connected between the discharge conduit i9 of the circulating fan F and the gas lift pump` I1 below the liquid level normally prevailing therein in order to supply pumping gas to the conduit I1. The` upper portion ofthe so- 1 lution reservoir S is vented by means of a small conduit 28 tothe conduit 2| which is connected.

' Specifically considered, the evaporator comprises a conduit which may be coiled in any desired manner, for example, to form a plurality of substantially horizontal shelf-like portions upon which ice tray supporting shelves may be rested. The evaporator also includes the upper rearward- 1y inclined large diameter finned box-cooling section 30. It will be understood that the evaporator will be completely enclosed in any suitable form of casing in thev usual manner though that has been omitted from the present illustration for purposes of clarity.- If desired, the evaporator may be shaped substantially like the coils shown in Figure 3 to be described more fully hereinafter.

' The bottom portion 35 of the evaporator is prodirectly to the suction side of the circulating fan y F whereby the gas lift pump is enabled to operate with the maximum pressure differential available 'in the system.

The lean solution supplied to the absorber A flows downwardly therethrough by gravity in counterow relationship to a mixture of pressure equalizing medium and refrigerant vapor which flows upwardly therethrough and is supplied from the evaporator. The solution absorbs the refrigerant vapor content of the mixture and the heat of absorption is rejected to cooling air flowing across the fins provided on the exterior walls of the absorber conduit.

The strong solution which is formed in the absorber as a result of the absorbing action flows to the bottom portion thereof from which point it is conveyed to the' upper part of the analyzer D by way of the conduit 23, the liquid heat exchanger L, and the conduit 25.

The lean inert gas formed inthe absorber is conveyed from the upper end thereof through the pipe 2| into the suction side of the circulatl ing fan F in which it is placed under pressure and is discharged through the conduit I8 into the outer path of the gas heat exchanger G from which the lean gas is conveyed by means of the condenser C by way of the conduit is liquefied in the condenser and is discharged therefrom into a reservoir and separation vessel 28 by means of a conduit 28. The liquid refrigerant is conveyed from the reservoir into the bottom portion of the b.

vided with a downwardly extending U-shaped continuation 36 which terminates in a downwardly facing goose necked portion 3l within the vessel 28. The lean gas conduit 26 opens into the evaporator side of the U-shaped conduit 36 a short distance below the level of the bottom 8l of the evaporator E.

The liquid refrigerant formed in the condense is discharged into the lower'portion of the vessel 28 through the conduit 29.

The box-cooling section 30 of the evaporator E discharges into the upper portion of the vessel 28 directly into a cup 39 provided therein. 'I'he upper portion of the cup is open to allow the gas discharged from the section 30 to escape there- -from andthe bottom portion of the cup is drained by means of a conduit 4D directly to the bottom portion of the vessel 28. v

The evaporator and the liquid supply conduit may be constructed froma -continuous tube which is bent into any desired shape or from a plurality of pre-formed sections which are secured together as by welding.

A vertically extending purge conduit 45 extends from a point adjacent the bottom portion of the vessel 28 upwardly therein through a point slightly above the halfway mark of the vessel 28 where it joins an inwardly extending portion 46 of a drain conduit 4 1 which terminates in the strong gas conduit 32 leading directly to the liquid discharge portion of the absorber A. The upper portion of thel conduit 45 within the ves--4 sel 28 also connects to a short overturned and downwardly opening conduit 5|). A small vent conduit 52 connects the upper portion of the condenser discharge conduit 29' to the upper portion of the vessel 28.

The apparatus will be charged with the refrigerant absorbent and inert gas in the usual manner with the following exception. The vessel 28 will be charged directly with liquid refrigerant up to approximately the level o f the line marked As shown in Figure 1 the apparatus will be incorporated in a suitable insulated cabinet 60.

which is provided with a suitable insulated door 8i and a rear air-cooling ilue 62. The rear wall of the cabinet G is provided with an opening 63 which is closed by an insulated insert element 84, A suitable sealing gasket 65 is provided around the edges of the insert 64. The vessel 28 and portions ofthe conduit connected thereto and the upper ,portion of the gas heat exchanger G are encased within the insulation of the insert 64. The lower portion of the cabinet has .not been shown but it will be understood to ,be of a conventional type'in which the absorber lies in an inclined position and extends forwardly and downwardly from beneath the lower end of the ue 62 into the mechanism compartment.

The operation of this form of the invention except as the same has been described hereinabove is as follows: When the apparatus is initially started the liquid refrigerant stands in the vessel 28 and in the evaporator E at a level within the limits of the lines marked b and c. When inert gas is suppliedto the upwardly extending portion of the conduit 36 it enters thereinto in separated slugs in the well known gas lift phenomena and elevates the liquid. refrigerant upwardly through the evaporator E into the box-cooling conduit 30 through which the gas and liquid flow in parallel relationship, the liquid flows by gravity through the conduit 30 as the diameter thereof is so great that the separation between the slugs of liquid and slugs of gas no longer are maintained. Obviously by this means the quantlty of liquid circulated per unit of time through the evaporator is several times greater than that which can be evaporated into the inert gas and this excess liquid collects in the cup 39 within the vessel 28 and is'returned by the conduit 40 to the very bottom portion of the vessel 28. This gas lift circulation of the liquid refrigerant from the vessel 28 through the goose neck 31, the con- `duit 36, the evaporator E, the box-cooling conduit 38, the cup 38 and conduit 40 continues unabated so long as the control mechanism energizes the circulating motor M and the heater for the boiler B. Liquid refrigerant is continuously supplied to the vessel 28 through the conduit 28 .to make up for that portion of the liquid circulating through the evaporator E which is evaporating.

It has been found from long experience in opi erating the type of system herein disclosed that smallquantities of absorption solution will find their way into the evaporator and that these should be removed before too great an accumulation is permitted. A strong solution of ammonia and water has a greater density than pure ammonia and in such a system the strong solution tends to settle at the bottom of the contain- "ing vessel. .This phenomenon is facilitated if the tion'which nds its way into the evaporator is continually returned to the bottom portion of the vessel 28 by the conduit 40. The goose neck 81 feeds refrigerant liquid rising from the bottom 0f the vessel and supplied from the conduit 29 which has a very low absorption solution concen-tration into the evaporator.

As a result of this construction the liquid in thel Q line marked a. When this level in the apparatus has been reached the liquid will overflow through the conduits 45,- 46 and 41 thereby tol form a syphon which will remove the liquid in the very bottom portion of the vessel 28 until the liquid level thereinhas been reduced to the level of the line marked c at which timethe syphon breaker conduit 50 will be opened to the gas in the upper portion of the vessel 28, the syphon column will be broken and the syphonic action will cease.

These levels have been chosen solely for purposes of illustration as various proportions will be used for different conditions depending upon the nature or size of the system, the nature of the refrigerant and the operative-conditions to which it is subjected. As illustrated herein, the dash line marked e represents substantially the maxilmum amount of strong-solution which will ever flood the vessel 28. However,`a greater amount of liquid is periodically removed from the apparatus, namely the quantity represented by the distance between the lines a and c in 'order to insure the removal of absorption solution therefrom. The liquid level in the vessel 28 will periodically fluctuate between the lines a and c. However, the gas lift action'in the evaporator will operate eiiiciently and without material differentiation between the levels indicated.

The syphon purging apparatus will not abso- `lutely rid the apparatus of absorption solution Vbut it-will keep the concentration thereof in the liquid in the vessel 28 at a level low enough to prevent difficulty therefrom.

Of course thev liquid which is continuously circulating through the evaporator becomes very cold wherefore the contents of the vessel 28 are very cold and it is for this reason that the vessel 28 is embedded in the heavy insulation in the window insert 64 in order to prevent decrease in the emclency of the system by warming this liquid which in eiect is a cold accumulator for the entire system. The vessel 28- also serves a a pre-cooler for the liquid discharged by the condenser. l

The operation of the evaporator itself can bestv rator and with the inert gas slugs flowing therethrough.

Therefore, the liquid refrigerant and inert gas are circulated through the evaporator by gas lift action in the form of separated alternate gas and liquid slugs, but the gas is in continuous contact with a thin lm of the liquid refrigerant which slugs oi' the liquid 66 and of course some evapoiae,"

tion occurs directly from the bodies of liquid 66 to the bodies of gas 61 which aids in lowering the temperature of the bodies of liquid.

The thin continuous lm of liquid with which the gas is in intimate contact is provided without introducing any structure of any nature into the interior of the evaporator and without introducing anything which would impede heat transfer or free flow of gas and liquid.

By reason of the fact that the liquid refrigerant is supplied to the bottom portion of the evaporator and is elevated therethrough by the inert gas, the relative positions of the evaporator and the condenser C are independent within practical limits. For example, the condenser C may be placed in the top portion of the iiue 62 and the evaporator may be placed in the direct top portion of the storage cabinet 60 without necessitat-vl ing the provision of condenser sections extending above the top portion of the cabinet 60 and 4without introducing complications such as a tapped condenser or multiple condensers. Also, the condenser C may extend substantially to the level of the bottom portion of the evaporator without in any way interferring with the operation of the evaporator or requiring additional construction.

All nuids in the system are circulated by the inert gas; that is, the absorption solution is circulated by the gas lift pump i1 and the liquid refrigerant is circulated through the evaporator by gas lift action, thereby assuring that the rates of circulation of all fluids in the system will be properly proportioned relative to each other and relative to the rates which the inert gas is circulated.

Referring now to Figure 3 there is disclosed a 4modified form of the invention. In some types of systems and under some operating conditions, such as those which are encountered for example tion of the evaporator E' and'-the box-cooling sectioniiil'` thereof. The inert gas `'which is discharged into the chamber iii flows directly into the conduit 3D v'and the liquid refrigerant which l is supplied thereto is drained back to the vessel.v 28 through a conduit 1i including a U-shaped vliquid sealing portion 12. Liquid refrigerant is supplied to the forward end of the box-cooling conduit-'30 by means of a conduit 'I4 which is connected to an intermediate portion of the condenser C' through a U-shaped liquid sealing portion 15. A small diameter bleed conduit 'I1 is connected between the vessel 10 and the inert gas supply conduit 26 to supply a small amount of inert gas to the vessel 10 which will reduce the concentration of refrigerant vapor in the gas in the conduit 30' to insure eflicient evaporation of the regulated quantity of liquid supplied by the conduit 14. y

Except in the above 'noted respect the form of the invention illustrated in Figure 3 operates in exactly the same manner and is embodied in exactly the same construction as that described and illustrated in connection with Figures 1 and 2.

Accordingly, there is provided an absorption refrigeratng system in which all fluids are circulated by gas lift action, in which provision is in climates having a relatively low year around temperature, the large quantity of cold liquid refrigerant supplied to the box-cooling portion of the evaporator in addition to the evaporation which occurs therein may cause the box-cooling portion of the evaporator to operate at a temperature too low for ideally satisfactory food storage condition. For this reason the apparatus Y illustrated in Figure 3 has been provided.

This form of the invention further provides a construction permitting the use of -a relatively high evaporator without imposing too heavy a lifting load on the inert gas circulator. The freezing section of the4 evaporator may be designed to take full advantage of the lifting power of the inert gas. The additional height of the evaporator represented by the box-cooling conduit does not burden the inert gas circulator as the refrigerant flows therethrough by gravity and is supplied directly by gravitythrough a made for a periodic purge of the evaporator system to relieve the same of foreign material such as absorption solution and in which evaporation occurs from a thin continuous film of refrigerant covering the entire inner surface of the evaporator. There is a direct heat transfer between the wall of the evaporator and the liquid refrigerant without the intervention of any interior construction in the evaporator and without impeding the flow of gas and liquid therethrough. Another feature of the invention resides in the fact that the large cold body of liquid refrigerant which is present in the evaporator and in the storage purging vessel has a stabilizing influence on the systemand tends to reduce the frequency of the operative periods of the apparatus when the same is operated as an intermittent cycle system.

Though the invention has been illustrated and described in considerable detail, it is not to be construed as being limited thereto as various changes may be made in the construction, arrangement special condenser connection which also serves to control the quantity of refrigerantsupplied to the box-cooling element.

and proportion of parts without departing from the spirit of the invention or the scope of the appended claims.

I claim:

l. Absorption refrigerating apparatus comprising a solution circuit including an absorber and a boiler, a pressure equalizing medium circuit including an evaporator and said absorber, means for supplying refrigerant vapor generated in said boiler to said evaporator in liquid phase, means for circulating the pressure equalizing medium through said pressure equalizing medium circuit, said evaporator comprising a continuous conduit, a storage vessel connected to the inlet and outlet portions of said evaporator for holding a quan tity of liquid refrigerant, and means for supply- I ing .the pressure equalizing medium and the liquid Certain portions of the apparatus illustrated 7| refrigerant to the lower portion of said evaporator in such fashion that the same operates as a su lift pump to circulate refrigerant from said storage vessel.

' 2. Absorption refrigerating'apparatus comprisinga solution circuit including an absorber and a boiler, a pressure equalizing medium circuit including an evaporator and said absorber, means for supplying refrigerant Vapor generated in said boiler to said evaporator in liquid phase, means for circulating the pressure -'equalizing medium through said pressure equalizing medium circuit, said evaporator comprising a continuous conduit, a storage. vessel connectedk to the inlet and outlet portions of said evaporator for holding a. quantity vof liquid refrigerant, means for supplying the pressure equalizing medium and the liquid refrigerant to the lower portion of said evaporator in such fashion that the same operates as a gas lift pump to circulate refrigerant from said storage vessel, and means for periodically conveying a quantity of liquid in the bottom of said storage vessel into another portion of the system.

3. Three fluid absorption refrigerating apparatus comprising an upstanding evaporator constructed from `a continuous conduit, a separation chamber connected to the upper endthereof, a second evaporator connected to said separation chamber, a storage vessel connected to said second mentioned evaporator, means for supplying liquid refrigerant from said vessel to the lower portion of said first mentioned evaporator, means for introducing an inert gas into the liquid refrigerant supplied to the lower portion of said evaporator to cause the same to circulate upwardly therethrough to said chamber by gas lift action, means for conveying liquid refrigerant from said separation chamber into said vessel, means for supplying inert gas directly to said chamber, and means for supplying liquid refrigerant to said second evaporator from a source of supply.

4. Absorption refrigerating apparatusV comprising an insulated cabinet having a rear air cooling flue and an opening between the flue and the interior of the cabinet, a gas lift evaporator adapted to pass through said opening, a storage vessel connected to said evaporator to supply refrigerant thereto and to receive unevaporated refrigerant liquid, means for supplying fresh refrigerant to said vessel, means for supplying a pressure equalizing medium to said gas lift evaporator to circulate refrigerant therethrough as it is evaporating to produce useful refrigeration and an insulated closure for said opening housing said vessel.

5. That method of producing refrigeration which includes the steps of circulating a quantity of liquid in excess of that required to sustain the refrigerating demand through a cooling zone by the pressure of an inert gas, evaporating a portion of the liquid from a thin film substantially surrounding the evaporating zone into the inert gas, and periodically purging the liquid in the evaporating system of foreign materials.

6. Refrigerating apparatus comprising a tubular evaporator, a storageand recirculation vessel connected to receive material discharged from said evaporator, a U-shaped liquid seal conduit connected to convey liquid from said vessel into said evaporator, means for introducing a pressure equalizing gas into the evaporator side of said conduit to circulate a large quantity of liquid through said evaporator, means for separating the gas and unevaporated liquid in the storage vessel, means for removing the gas from the storage vessel, and means for supplying fresh liquid to the storage vessel.

7. Refrigerating apparatus comprising la tubu' lar evaporator, a storage and recirculation vessel connected to receive material discharged from said evaporator, a U-shaped liquid seal conduit connected to convey liquid from said vessel into said evaporator, means for introducing a pressure equalizing gas into the evaporator side of said conduit to circulate a large quantity of liquid through said evaporator, means for separating the gas and unevaporated liquid in the storage vessel, means.

for removing the gas from the storage vessel, means for supplying fresh liquid to the storage vessel, and means for periodically reducing the concentration of foreign material in said evaporator and vessel without discontinuing the operation thereof. l

8. An evaporator comprising means forming a continuous passageway, means for supplying refrigerant to the lower portion thereof, means for introducing a pressure 'equalizing medium into the lower portion of the passageway tocirculate the refrigerant therethrough by gas lift action, and means for returning unevaporated liquid to the lower portion of the passageway to be recirculated therethrough.

9. Refrigerating apparatus comprising a tubular evaporator, a storage and recirculation vessel connected to receive material discharged from said evaporator, a liquid seal conduit connected to convey liquid from vsaid vessel into said evaporator, means for introducing a pressure equalizing gas into the evaporator side of said` conduit to circulate a large .quantity of quid through said evaporator, lmeans for separ ting the gas and unevaporated liquid in the storage vnected in series with a high temperature section, and means for supplying liquid refrigerant and an inert gas to one of said sections, said last named means being operative to circulate the gas and liquid first through the low temperature sec..

tion and then through the high temperature section by gas lift action and to recirculate un- -evaporated liquid until the same hasbecome evaporated.

11. That improvement in the art of refrigeration which includes the steps of expelling refrigerant from solution` by the application of heat thereto, liquefying the'refrigerant expelled from solution by abstraction of heat therefrom', circulating the liquefied refrigerant through an evaporation zone together with liquid refrigerant cooled by previous traversal of the evaporating zone by introducing pressure equalizing medium under pressure into the refrigerant liquid to propel the refrigerant liquid by gas lift action, recirculating unevaporated liquid through the evaporating zone, conveying pressure equalizlng medium and admixed refrigerant vapor from the evaporating zone into contact with solution previously weakened by expulsion of refrigerant culation -of absorption solution therebetween,

means connected to receive refrigerant vapor ex- -pelled from solution in said generator for liquefying`such vapor, means arranged to receive cold unevaporated liquid from said evaporator, and

' means arranged to convey liquid discharged by said liquefyingmeans mixed with cold liquid from said receiving means to said evaporator, said absorber and evaporator being so connected that inert gas flows from said absorber and is in-' troduced into the liquid refrigerant to circulate the same through said evaporator by gaslift action.

13. Absorption refrigerating apparatus comprising an upstanding coiled evaporator conduit, a vessel connected to the upper portion of said evaporator conduit to receive unevaporated refrigerant liquid therefrom, means for producing refrigerant liquid, means for conveying refrigerant liquid from said producing means and from said vessel to the lower portion of said conduit,

-and means introducing an inertgas into the liquid refrigerant supplied to the lower portion of said evaporator to circulate the'refrigerant through the lower portion thereof by gas lift action, and means for supplying refrigerant liquid from an intermediate portion of said condenser to the upper portion of said evaporator to evaporate in contact with inert gas`and refrigerant vapor which is discharged from the lower portion of said evaporator. A

16. That improvement in the art of absorption refrigeration which includes the steps of applying heat to a solution of a refrigerant in an absorbent to expel vapor ofthe refrigerant, condensing the refrigerant vapor to substantially pure liquid refrigerant by passing the vapor in heat exchange relationship but out of contact with a cooling medium, conducting the refrigerant liquid to a place of evaporation having an extensive heat transfer-surface, evaporating the liquid into a pressure equalizing medium to produce a. refrigerating effect from a thin film on the heat transfer surface of the place of evaporation, maintaining the said film of liquid and providing for now of the pressure equalizing medium thereacross by introducing pressure equalizing medium into the liquid refrigerant in said .place of evaporation to circulate 'a quantity of liquid therethrough by gas lift action, said appa'-` ersed said evaporator when inert gas and refrig- 4 erant liquid from said refrigerant liquid producing means are not being introduced intosaid evaporator.

14. That improvement in the art of refrigeration which includes the steps of expelling refrigerant vapor from solution in an absorbent by the application of heat thereto, liquefying a first p0rtion and a second portion of said refrigerant vapor by the abstraction of heat therefrom, circulating said second portion of refrigerant liquid through an evaporating zone together with refrigerant liquid cooled by previous traversal of the evaporating zone by gas lift action by introducing inert gas into the refrigerant liquid, recirculating unevaporated refrigerant liquid through the evaporatingzone, conveying said first portion of refrigerant liquid into a second evaporating zone in contact with inert gas and refrigerant vapor discharged from said rstvmentioned evaporating zone, and conducting unevaporated refrigerant liquid from said second mentioned evaporating zone into said first-mentioned evapcrating zone.

l5. Absorption refrigerating apparatus comprising an opstanding evaporator andan absorber connected for circulation of inert gas therei tion below the upper portion of said evaporator means arranged to supply refrigerant liquid from the bottom of said condenser and liquid previously circulated through said evaporator to the lower portion of said evaporator, said evaporatorV and absorber being so connected that the inert gas is introduced into the liquid refrigerant supplied to said evaporator to circulate the liquid liquid in excess of that required to maintain said iilm across said surface by gas lift action, and absorbing refrigerant vapor produced in the place of evaporation from pressure equalizing medium which has traversed the 'place of evaporation by contacting the pressure equalizing medium and admixed refrigerant vapor withA absorbent from which refrigerant vapor has been expelled.

17, That improvment in the art of absorption refrigeration which includes the steps of applying heat to a solution of a refrigerant in an absorbent to expel-'vapor of the refrigerant, condensing the refrigerant vapor tc substantially pure liquid refrigerant by passing the vapor in 'heat exchange relationshipbut out of Acontact with a cooling medium,- conducting the refrigerant liquid to a place of evaporation having anl extensive heat transfer surface, evaporating the liquid into a pressure equalizing medium to produce a refrigerating effect from a thin film on the heat transfer surface of the place of evaporation, m intaining the said film of liquid and providing or flow of the pressure equalizing medium thereacross by introducing pressure equalizing medium into the liquid 'refrigerant in'fsaid place of evaporation to circulate a' quantity 'of liquid in excess of that required to maintain said lm across said surface by gas lift action, collecting unevaporated liquid which has traversed said l place of evaporation and returning the same to said place of evaporation for recirculation therethrough, and absorbing refrigerant vapor produced in the -place of evaporation from pressure equalizing medium which has traversed the place of evaporation by contacting the pressure equalizing medium and admixed refrigerant vapor with absorbent from which refrigerant vapor 'has been expelled.

18. .absorption refrigerating apparatus comprising a generator, an absorber, means providing for circulation of absorption solution between said generator and said absorber, a condenser connected to receive refrigerant vapor from said generster, an elongated evaporator conduit including a substantially horizontal segment, means for conveying refrigerant liquid from said condenser to said evaporator, means for conveying lean inert gas from said absorber and forintroducing the gas into said evaporator below the level of liquid refrigerant therein' to elevate the liquid refrigerant through said evaporator by gas lift action, and means for conveying rich inert gas from said evaporator to said absorber.

19. Absorption vrefrigerating 'apparatus comprising a generator, an absorber, means providing for circulation of absorption solution between said generator and said absorber, a condenser connected to receive refrigerant vapor from said generator, an elongated evaporator conduit including a substantially horizontal segment and a substantially vertical segment, means for conveying refrigerant liquid from said condenser to said evaporator, means forv conveying lean inert gas from said absorber and for introducing the inert gas into said evaporator below the level of liquid refrigerant therein to elevate the liquid refrigerant through said evaporator by gas lift action, and means for conveying rich inert gas from said evaporator to said absorber.

20. Absorption refrigerating apparatus comprising a generator, an absorber, means providing for circulation of absorption solution between said generator and said absorber, a condenser connected to receive refrigerant vapor from said generator, an elongated gas and liquid passageway forming an evaporator, means for conveying refrigerant liquid from said condenser to said evaporator, means for conveying lean inert gas from said absorber and for introducingthe inert gas into said evaporator below the level of liquid from said evaporator to said absorber.

refrigerant therein toelevate the liquid refrigervant through said evaporator by`gas lift action,

and means for conveying rich inert gas from said evaporator to said absorber.

2l. Absorption refrigerating vapparatus comprising a generator, an absorber, means providing for circulation of absorption solution between said generator and said absorber, a condenser connected to receive `refrigerant vapor from said generator, an elongated evaporator conduit arranged to form a plurality of horizontal vertically superposed shelf-like serially connected coils 4adapted to underlie and refrigerate ice trays,

means for conveying refrigerant liquid from said condenser to said evaporator, means for conveym ing lean inert gas from said absorber and for introducing the inert gas into said evaporator `below the level of liquid refrigerant therein to levate the liquid refrigerant through said evaporator by'gas lift action, and means for conveying rich inert gas from said evaporator to said abi sorber.

23. In a refrigerating apparatus a cabinet structure including an insulated storage chamber and an insulated mechanism compartment, an absorption refrigerating mechanism associated with lsaid cabinet including a generator, an air cooled absorber in said compartment connected for circulation of inert gas therebetween, an sir cooled condenser in said compartment connected to receive refrigerant vapor from said generator, an evaporator conduit in said chamber arranged to form a shelf-like coil portion adapted to support and refrigerate freezing receptacles, means for conducting refrigerant liquid from said condenser to said evaporator, means for conducting lean inert gas from said absorber to said evaporator and for introducing the' inert gas into the liquid refrigerant in said evaporator below the surface thereof whereby -the liquid refrigerant circulatesthrough said evaporator by gas lift action, a liquid refrigerant collecting vessel -mounted in the wall of said insulated chamber evaporator and to receive unevaporated liquid which has traversed said evaporator, and means for conducting rich inert gas from said evaporator to said absorber.

24. That improvement in the art of refrigerating systems utilizing a refrigerant, an absorbent for the refrigerant, and a gas inert with respect to the refrigerant and the absorbent which includes the steps of applying heat to a solution of vrefrigerant in the absorbent to expel vapor of the refrigerant from the solution, condensing the refrigerant vapor expelled from the solution to the liquid state at a place of condensation by passing the refrigerant vapor in heat transfer relationship but out of contact with a cooling medium to abstract heat from the refrigerant vapor, flowing the inert gas through a place of evaporation in contact with a continuous thin nlm of liquid refrigerant which lies on the entire inner surface of a liquid confining' wall defining the place of evaporation, Iand maintaining the nlm of liquid substantially constant by providing Ia substantially constant supply of fresh liquid refrigerant to the pla'ce of evaporation from the place of condensation.

GEO. A. BRACE.

CERTIFICATE CF CORRECTION; l A Patent No. 2,505,816. I December l, 1914.2.

GEORGE A. BRACE.

It is hereby certified that error appears in the printed specification of'the above numbered patentrequiring correction as follows: Page 5,' secl-l ond column, line 56, for i'serve-s a read --se'rves as page 7, setiorxd colnmn, line. 5b., claim 25, after the word "chamber" read ,--connec'ted to supfJly liquid refrigerant to said; and that the said Letters Patent should be read with this, correction therein that the same may conformV to the record of the case in the -Patent Office.

signed and 4sealed this 2nd day of February, A. D. 19115.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patente.