US2597778A

US2597778A - Absorption refrigerating apparatus

Info

Publication number: US2597778A
Application number: US51555A
Authority: US
Inventors: Curtis C Coons
Original assignee: Hoover Co
Current assignee: Hoover Co
Priority date: 1948-09-28
Filing date: 1948-09-28
Publication date: 1952-05-20
Anticipated expiration: 1969-05-20

Description

May 20, 1952 c, c, coo s 2,597,778

ABSORPTION REFRIGERATING APPARATUS JNVENTOR. CurZL's (Z. Caons SDZM ATTORNEY.

May 20, 1952 c. c. cooNs 2,597,778

ABSORPTION REFRIGERATING APPARATUS 5 Sheets-Sheet 2 Filed Sept. 28. 1948 INVENTOR. Curtis C, Coons BY ATTORNEY.

May 20, 1952 Filed Sept. 28, 1948 C. C. COONS ABSORPTION REFRIGERATING APPARATUS 3 Sheets-Sheet 3 INVENTOR. 7 Curtis 6. 000125 B #4:? J, EWM

ATTORNEY.

l atented May 20, 195i UNITED STATES ABSORPTION REFRIGERATING APPARATUS Curtis C. Coons, North Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application September 28, 1948, Serial No. 51,555

17 Claims. 1

The present invention relates to the art of refrigeration and more particularly to refrigeratingapparatuses of the absorption type particularly designed to produce refrigeration at various temperature levels suitable for the preservation of fresh food stuffs, for the productionof ice and for preservation of sharp frozen food stuffs. This application contains certain subject matter originally disclosed in my Patent 2,489,752, issued on November. 29, 1949 for Refrigeration and to that extent is a continuation-impart of my aforesaid application.

The present invention particularly relates to refrigerating apparatus of the absorption type in which low temperature refrigeration is produced by flowing highly purified liquid refrigerant into the presence of inert gas having an extremely low refrigerant vapor content.

It is a particular object of the present invention to provide a refrigerating system in which absorbin solution denuded of refrigerant in a generator is passed first into intimate contact with a comparatively small volume of inert gas having an initial low refrigerant vapor content under most efficient absorbing conditions to strip the small volume of inert gas of refrigerant vapor to produce an inert gas having a very low refrigerant vapor content which inert gas is then utilized to produce the extremely low temperature refrigeration. The aforesaid process does not greatly add to the refrigerant content of the solution because of the small volume and low refrigerant content of the inert gas involved; hence the solution is still capable, of absorbing refrigerant vapor. The partially enriched solution is then led into contact with another, and larger, body of inert gas having a refrigerant vapor content greater than the refrigerant vapor content of the first body of inert gas to absorb an additional greater quantity of refrigerant vapor before returning tothe genera-ting apparatus to complete its cycle.

Other objects and advantagesof the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing in which:'

Figure 1 is a vertical sectional side elevation of a refrigerator cabinet with a refrigerating apparatus shown partly schematically associated therewith;

Figure 2 shows a modified form of the invention;

Figure 3 illustrates a second modified form of the invention; and

Figure 4 illustrates-another modified form of the invention shown associated with certain cabinet constructions with which it will be used in operation.

Referring now to the drawing in detail and first to Figure 1 thereof, the refrigerating apparatus'shown is of the inert gas absorption type which is charged with a refrigerant such as ammonia, an absorbent therefor such as water and a pressure equalizing medium which is inert with respect to the refrigerant and absorbent such as nitrogen.

The apparatus comprises a generatorB containing a solution of refrigerant in the absorbent. The boiler is heated by suitable means, not shown, to evolve refrigerant vapor from the solution. Vapor so evolved in the generator B passes upwardly through an analyzer D in which it is brought into intimate contact with rich solution supplied from a source to be described hereinafter. After passing through the analyzer the vapors are conducted by a conduit II to a primary condenser C wherein the vapors are liquefied by heat exchange with atmospheric air. Liquid so produced flows through a liquid sealed gas trap [2 into a jacket I3 which surrounds the conduit I I. Since the liquid supplied to the jacket i3 is in direct contact with the pipe H carrying the hot vapors to the condenser the vapors are rectified and some of the liquid is vaporized to provide highly purified refrigerant vapor. This refrigerant vapor is substantially anhydrous ammonia and is suitable for extremely low temperature refrigeration. The anhydrous vapors formed in the jacket I3 flow through a conduit [4 into the upper portion of a secondary condenser C wherein they are re-condensed and are conveyed through a conduit l5 into a low temperature evaporator conduit l6.

As shown herein the conduit [6 is simply a substantially horizontal sinuous conduit. It may however take any desired shape or configuration depending upon the particular type best suited to a specific design repuirement.

Lipuid refrigerant which is not evaporated in the jacket I3, the major portion of the refrigerant liquid, is conducted therefrom by a conduit [8 sinuous conduit 22 which forms a solution pre-' cooler into a solution reservoir S. The absorbing solution is then conveyed for the reservoir S through a U-shaped conduit 24 having a vertically extending, finned, leg 25 adapted to function as a gas lift pump and secondary absorber. Pumping gas is supplied through the conduit 25 from an inert gas circulating pump F which is driven by an hermetically sealed electrical motor drive M. Inert gas under pressure discharges from the pump F through a conduit 2e forming part of a principal inert gas circuit to be described hereinafter. A portion of the gas under pressure supplied to the conduit 28 is diverted through the conduit 21 which supplies pumping gas to thegas lift pum p absorber 25.

The inert gas supplied to the conduit 27 is what is ordinarily termed in this art lean gas, that is, it is inert gas which has traversed an absorber for the purpose of removing refrigerant vapor therefrom, hence its refrigerant vapor content is small, however, this gas when introduced into the conduit 25 is brought into the most intimate possible contact with the leanest absorbing solution available in the system. In the conduit 25 the pumping gas is most intimately admixed with the lean solution. Additionally, the volume of inert gas supplied to the conduit 25 is comparatively small compared to the volume of inert gas which is ordinarily brought into contact with absorbing solution in the absorber of refrigerating systems of the type forming the subject matter of the present inven# tion.

It has been found by experiment that the conduit 25 is a most efficient absorber under the foregoing conditions, that is, conditions in which the volume of inert gas is small comparedto the volume of absorbing solution with'which it is brought into intimate contact. It has additionally been found that the pumping gas supplied to the conduit 25, though what is customarily denominated as lean gas in this part, has its re-' frigerant content very appreciably lowered in its passage through the combined gas lift pump and secondary absorber conduit 25. The inert gas used to operate the pump-absorber 25 will have an absolute refrigerant vapor content as low as one percent by volume. The increase in the refrigerant content of the absorbing solution which traverses the conduit 25 represents the refrigerant vapor which it has absorbed from the pumping gas.- This increase in refrigerant content of the lean solution will customarily not amount to more than approximately five percent whereas the total solution concentration range between the weakest and strongest solutions available in the system will vary approximately twenty to twenty-five percent, hence the enrichment which occurs in the pumping conduit 25 is comparatively small. The highly stripped inert gas which discharges into the gas separation chamber 28 along with the lean absorbing solution is ideal for the production of low temperature refrigeration' due to its extremely low refrigerant vapor content which will permit extremely low temperature evaporation of refrigerant therei'nto.

The inert gas which discharges into the cham ber 28'i's conducted to'the low temperature evaporator It by means of a conduit 30 which passes in heat exchange relationship with the inert gas discharge conduit 3| of the evaporator l6 and in heat exchange relationship with the primary evaporator I9. This two stage cooling of the inert gas'enroute to the low temperatureevapcrator 16 almost completely condenses-vapors of absorbing solution and also supplies very cold gas to the low temperature evaporator [6 so thatthat evaporator is not called upon to carry a substantial load which represents merely cooling of the inert gas. Condensate formed in conduit 3!! drains back to chamber 28 or is removed to the strong solution conduit 34 by a drain conduit 32. The inert gas and liquid refrigerant supplied through the conduits 3i] and [5 respectively to the evaporator i5 produce refrigeration therein. at extremely low temperatures in the order of 5 F. and therebelow which are sufficient for the preservation of sharp frozen foods. It is to be borne in mind in this connection that the quantity of inert gas supplied to the evaporator l6 and the quantity of liquid refrigerant supplied therer to are both smallcompared to the quantity custor It maintains extremely low temperatures but it is not normally called upon to sustain a heavy refrigerating load because food stuffs which are placed in its compartment for preservation are almost invariably already thoroughly frozen andneed only be maintained at a low temperature.

The absorbing solution supplied to the separa tion chamber 28 flows therefrom through a U-sh'aped gas sealing conduit 33 into the upper end of a tubular air-cooled absorber A. As shown in Figure 1 this is a conventional type of tubular air-cooled absorber though other types of absorber may obviously be utilized without de parting from the invention. In the absorber A the solution flows downwardly by gravity in contact with and in 'counterflow relationship with the inert gas refrigerant vapor mixture which is flowing upwardly through the vessel. The absorbing solution in the absorber is enriched in refrigerant content to produce so called strong liquor. This strong liquor is then con-' ducted from the lower end of the absorber A through the conduit 34, the inner passage of the liquid heat exchanger 2| and conduit 35 into the upper portion or the analyzer D through which it flows into contact with and counterfiow relationship to the vapors liberated in the generator B. This completes the absorbing solution circuit of the apparatus.

The so called lean inert gas refrigerant vapor mixture which is formed in the absorber- A flows from the upper portion thereof through the com duit 3t into the suction or low pressure inlet of the circulating fan F wherein it is placed under pressure and discharged through the conduit 25 as described heretofore.

With the exception of the inert gas which is diverted through the conduit 21, the inert gas in conduit 26 enters theouter passage of a gas heat exchanger G, fio'ws therethrough and is conducted" therefrom by a conduit 31' to the prin= cipal evaporator l9. As shown in Figure 1, the 2 liquid refrigerant supply conduit ['8 actually joins the evaporator 19 at the point at which that evaporator connects to the inert gas supply con duit 31. The inert gas entering through the conduit 3'! is under pressure and the evaporator is so" designed that the inert gas circulates the liquid refrigerant through the evaporator as the liquid is evaperating to produce the'refrig'erating effect. This evaporator is of'the'ge'ner'al type disclosed in U. S. Patent No. 2,328,196 issued August 31, 1943. The evaporator is shown schematically in Figure 1 as consisting of a sinuous coil having two horizontal coil sections connected by a vertical lift pipe 38. It will be understood however that other forms of evaporator conduits may be utilized where: design or refrigerating conditions dictate their use. The inert gas and refrigerant liquid circulate through the various portions of the evaporator IS in which the refrigerant liquid evaporates to produce a refrigerating effect. This process charges the inert gas with refrigerant vapor to produce the so called rich gas which is conveyed from the gas outlet portion of the evaporator through a conduit 39, the inner passage of the gas heat exchanger G and a conduit 40 to the lower end of the absorber A through which it passes in contact with the absorbing solution in a manner heretofore described- .This process completes the principal inert gas circuit. o l p The inert gas which has traversed the evaporator l6 and is removed therefrom through the conduit 3| joins the conduit 40 adjacent the point at which itexits from the gas heat exchanger G.

From, the foregoing it will be seen that the secondary inert gas circuit including the secvented to the inert gas discharge conduit 39 of the evaporator [9 by the vent conduits 4| and 42 respectively. This purges .the condensers of any non-condensable or non-condensed material which passes therethrough and also subjects the generator B and analyzer D substantially to the pressure prevailing at the suction inlet of the circulating fan'F increased by the small pressure drops in the gas heat exchanger (3- and the absorber A. The pressure in these parts of the system is a subtantially constant quantity in that it is principally governed by the substantially constant suction pressure of the circulating pump F. In a similar manner the upper portion of the solution reservoir S is vented by a conduit 43 to the suctionconduit 36 of the circulating fan F.

Thisserves also as a vent conduit for any vapors which may be liberated in the vessel S.

The principal evaporator I9 is provided with the usual overflow drain connection 45 which connects to the gas heat exchanger G.

The quantity of. inert gas which is diverted through the secondary absorber gas lift pump 25 isvery accurately controlled by that element to a fixed proportion of the total amount of inert gas discharged from the circulating pump F, hence a fixed proportion of the inert gas is always diverted from the pressure outlet of the circulating pump, is additionally reduced in refrigerant vapor content to a very low value, and is then supplied to the low temperature evaporator 16.

It is apparent from the foregoing that the present'invention is particularly designed to provid a comparatively small volume of very highly stripped inert gas capable of producing extremely low refrigerating temperatures by intimately admixing such inert gas with a comparatively large volume of lean absorbing solution in an air cooled absorber under conditions such that complete stripping of the inert gas will only partially enrich'the absorbing solution.

The apparatus includes an insulated refrigerator cabinet having an opening 5| in a rear or sidewall thereof through which the evaporating apparatus I6-I9 and the various connecting conduits can be inserted into the interior of the insulated compartment. The opening 5| is closed by an insulated closure 52 which is carried by the 6 1 refrigerating system proper and is assembled with the rest of'the cabinet only when it is also assembled with the refrigerating apparatus. v The evaporator I6 lies in ,the top portion of the interiorof the refrigerating chamber 50 and the closure element 52 cooperated with an in-. sulatedpartition 53 to form an insulated comture. By placing the coil 16 in the top of the chamber 55, all parts of that cha mber are maintained at safe temperatures and the high level location of the conduit [6 tends to keep the air therein in circulation to maintain substantially uniform. low temperatures.

In the form of the invention just described it has been found that the gas lift pump conduit 25' is a highly efiicientabsorber which ideally serves the purpose for supplying extremely stripped'inert gas to a low temperature evaporator. This arrangement 'of parts, which imposes a double function upon the gas lift pump, ispreferred where circumstances permit it, however, the latitude permitted the designer'in thisIarrangement is somewhat limited because of the limit upon the amount of inert gas which can be passed through the gas lift pump. The primary limit is the quantity of gas required to performthe'purely pumping function. The amount of gas'may be varied somewhat by varying the point of juncture between the

conduits

25 and 27, that is, the depth of immersion of the pump, but this again does not offer the designer a very wide choice, hence this typeof apparatus, while preferred, is usable only where the needs of the low temperature compartment for inert gas fall with in the limits of the amount of inert gas which can be utilized in thegas lift pump.

In the form of the invention shown in Fig ure 2' aconstruction .is schematically illustrated which avoids the limitations inherent in the gas lift pump arrangement of Figure 1.

Only so much of the apparatus of Figure 2, as is different from the apparatus of Figure 1 is illustrated herein. It will be understood that all otherparts of the apparatus are identical with those shown in Figure 1. Those portions of the apparatus actually illustrates in Figure 2 which are identical with portions of the apparatus of Figure 1 are identified with the same reference characters distinguished by the addition of a prime.

In'the form of the'invention illustrated in Figure 2the solution reservoir doubles as an absorber. The lean inert gas discharging from the absorber A. flows through the conduit 36 into the circulating pump F' wherein it is placed under' pressure and discharged through the conduit 26'. The major portion of this inert gas. fiowsthrough the gas heat exchanger just as in o the case of the conduit 26 in Figure 1 and then traverse the rest of its circuit'identically therewith. A portion of the inert gas supplied to'the conduit 26 flows through a. conduit 60 which: opens into the bottom of a combined solution The portion 62 of the conduit El is pro-U geis carii -ass tliioiig-F sire i this into afie hr nsg-h t" qysr sqlutibn scammed in the solution r'servdif '6 fii e 1' construction a)- large" ildlinfi 6f is" i 's'ii' t6 strip-e; cdni TH iHSBIQ v tisu y as smi- 'th8Lf SI -idWf1 i-il Ffg'iil 1' elf-1d hasflb'ii l'lbdlitfe' ifift gs" Stnfibd slibtirit "e 'sdine' dg ree; ea iii the" absorber 61 is conveyed ii-en's the fidrfii ofi Of the Vessel i l tIi'IO u g-h the cell 30 to the lbw temperature ahsorfier' the mannssdsserib'sds ave in connection with Fi se-1. lit-52in solution from" the enera-tor" is sub plied' to the reserves assert-er 61'- from the solih olihg bond-nit 2 hence the leiriest 1- able-in" thesystni is snpbl-ied w ne aBso'rlier-receiver' 61'. The glosorbing solution which is somewhat enriched" int-he absorber-re: c'ei vi e r-isecnveye's to the principal bsqrber'A' his di-iduit 6 3 which includes a gas lift numn s Piiinpinggas is suppliedto the pig-mi) fiduit 65 which connects to the gas co' n The'i irt-gas which has traversed the pump asis admixed with the inert as exiting-from the 'ahso'rber A". In view of the fzi irfihatthis g's is il'r'yjle'aiii it does no" ha m sdimk'ed with the lean inert gas dis:

' mine absorber A; 7 Thi's 'forin of the invention previgles' a high 'de' gie' bf fiiiibilitj with respect to' the 'qufiriti ty bf th-ga'swhich is hjr-pas's'ed to the second absorber wherein it is substantially stripped of refrigerant vapor.

inert gas diverted from the main inert as circuit for-'snnply' to the low' temperature evaporator is accomplished by a; proper choice of size of the pipe 66; size of the perforations in the section fi thereof and the depth by which the pipe section 62 is submerged in solution in the reservoir ab: sorber 6 I. Once the capacityiof the low teinperzituie evaporator is determined'the requisite quantity of gas is" res-any calculablet When" that i the resistance of the gas flow which must be offered by the total gas circuitcomprising" the ei t ratbr'l'fi isfthe'n' adjusted to give'the' requisite getsfiow'thre'through'.

fiefii'ing nowto Figure} there is di'sclosedp;

mod'iiiatipn f theirf ventibn designeii 'to" rovid Highly stripped inert gas forth e low'tenif etspdratmsimilarly to the form or the icfsnt'icsiwitn thalt' illustrated in Figure" 1 except in connection with certain portions of thesec onde triinert as; circuit only those portions" thereoi ireil strate'd which a're necessary tpdisclose s ettheremaiining portion of the apparatus is t in eve -y respect with thait'illu'strated thisforni of the inyehtionithos h i iwiw mh; are ide fi with. e-

.t l, 1 'eisiha ia t -s di'sji'iiigiiislie by theolilitiDh of s dbiibl'e p je. ii Eig'tire ii thefcdnduit' 22" does not disc arge directly intofthe'solutionreservoir S, instead" it be s1" {reservoir fist no ence s g le with absorbingsol except su'c'h' The inert gas WHich is" illustrated in Fighters 1 3111 12. Since of the invention is substantially rerices therebetwe'en; It willbennder sei it. meme-s under pressure-bfihhls-jiit vessel 10; I m ss-is 251 "of the circ p' 14mg ratt Eh g gfi eth ths's l t fi fl w n fi' 'b he v5 my With th'i arrangement conn erficiw r solution ans ere gas" is prqi ided while n gas is" -bnbbliiig into and through the solution. For-"thiseasor'ij the vessel t0 iriust haire etc! 5' et'er mgje efio igntqpieve'nt gas lift 15m n) so that the 'ge'sfwil notte'nd to phr'np theliq iii a re se direction} Similarly the lower if) non o the conduit any which conv ys in '7 gas minei w tmpsramre superstar in'ust are a d'iinieter sfiifiicien't' toprevent the lllfiift'flS fie s I I h v k v tne-sng'h il incnned essel 10; In this form of the invention the metering of In each or the" three forms of the mv nt reviously de'scrib'eii the system isicn rac ri by th'eprovisidn of a structiirei'n' which a par of the inert ga sjwhich hastratersed theprin absorber is bubbled into ndthidusht' j quantity of absorbing solution 'circuiat 'i I system and is 'b'roiig'ht into most shipwith the principal evaporator of aiter" whichitcontetcts" the anhydroii's V, liquid supplied to the low temperature evaporiitqr,

In each instance" thesecondztry 'orfs'tfippin'g absorption step" is sc 'osipus e by bi' heat "of atbsorfition" to the The relative quantities or inert gets tifhhfisg ten percent ammonia. The strong solution flowing to the generator contained approximately thirty-two percent ammonia. Approximately one-fourth of the total quantity of refrigerant liquid produced was supplied to the evaporator which refrigerated the sharp frozen food compartment. The inert gas exiting from the pri mary absorber and the inert gas entering the secondary absorber contained approximately ten percent by volume of ammonia. The inert gas leaving the secondary absorber and flowing to the evaporator for refrigerating the sharp frozen food compartment contained approximately'one and one-half percent ammonia by volume. Approximately thirty percent of the inert gas discharged by the circulating pump was diverted to the sec ondary stripping absorber.

The foregoing figures are purely illustrative and are not limiting, all are subject to variation to meet the needs of variant design and operating conditions. In general, the weakest available solution in full volume and lean inert gassuch as inert gas which has traversed the primary absorbershould be supplied to the stripping absorber to facilitate its operation. The proportions of inert gas and refrigerant liquid diverted to the stripping absorber and low ternperature evaporator respectively are variable to satisfy variant conditions, in general from fifteen to forty percent of the inert gas and from twenty to fortypercent of the liquid refrigerant may be so diverted.

In any event the stripping absorber will be supplied with inert gas which contains a low percentage of refrigerant vapor and with the full stream of absorbing solution circulating through the system. Even if the inert gas were denuded of all admixed refrigerant'vapor the solution resulting would be weak, that is, only partially enriched. The combination of inert gas which is initially lean and small 'in volume com'pa'red'to the volume of inert gas customarily brought into contact with absorbingsolution' produces the extremely stripped inert gas provided for the low temperature evaporator in accordance with this invention. The quantity of refrigerant evaporated in the low temperature evaporator is not necessarily equal to the quantity absorbed in the stripping absorber since all of the inert gas circulating in the system passes through the primary absorber.

Under the conditions enumerated above the refrigerator was found to maintain temperatures in the region of F; and below in the sharp frozen food compartment and to refrigerate the remaining portions of the cabinet construction in conventional temperature ranges and capacities.

The foregoing constructions are not well suited to gravity type systems in which the sole force available to circulate the inert gas is the density differential between the warm lean gas leaving the absorber and the cold rich gas leaving the evaporator. The pressure available in gravity systems is usually inadequate to bubble a portion of the gas into a body of absorbing solution. In such systems gas and liquid surface contact type absorbers are utilizable for this purpose; but these absorbers are inherently less effective as gas and liquid contact devices per se than the bubble type absorbers above described and will not strip the inert gas at the same degree. The advantages of the invention are realizable in gravity systems by using a secondary surface contact type absorber which is chilled to a low temperature by the primary evaporator in the system.

With this arrangement the requisite stripped inert gas can be obtained by passing all of the lean solution through the absorber into contact with a comparatively small quantity of initially lean inert gas.

Referring now to Figure 4 a modification of the invention is illustrated in which the inert gas circulation is by gravity as above described.

This form of the invention will be associated with an insulated refrigerator cabinet similar to that illustrated in connection with Figure 1. For simplicity in illustration the cabinet structure is indicated here by the broken line 18.

The apparatus comprises a generator 80 which is heated by any suitable means,'not shown. The vapor formed from' the rich solution in the generator 86 operates a vapor lift pump conduit 8| which serves to pump the lean solution into a separation vessel 82. The lea'n solution is conveyed from the vessel 82 to a secondary absorber 83 by the conduit 84, the innerpath of the liquid heat exchanger 85, conduit 86, the inner path of a second liquid heat exchanger 81 and a conduit 88. The absorber 83 consists of a sinuous elongated conduit which is in contact substantially throughout its length with a sinuous elongated primary evaporator conduit 89. In the absorber 83 the lean absorbing solution flows into contact and counterfiow relationship with inert gas which is circulating through the absorber in a comparatively small volume. The inert gas and absorbing solution flowing through the absorber 83 are maintained at a low temperature by the evaporator 89 and the refrigerant vapor content of the inert gas is reduced to a comparatively low value. The stripped inert gas is conveyed from the upper portion of the absorber 83 into the outer path of a gas heat exchanger 90 and then to the low temperature evaporator 9| through'the conduit '92. The low temperature evaporator 9| is positioned within an insulated low temperature chamber 94 which preferably will be positioned within the refrigerator cabinet- The refrigerant vapor discharged into the separation chamber 82 is conducted therefrom to a condenser 95 by a conduit 96 which includes'a finned rectifying section 91' to reduce the water vapor content of the vapors supplied to the condenser 95. The condensate formed in the condenser 95 flows through a U-shaped conduit 98 into the upper portion of the evaporator 9| through which it flows in counterflow relationship and contact withthe inert gas flowing upwardly through the evaporator 9 The inert gas which has traversed the evaporator 9| flows through a portion of a conduit 98 exteriorly of the insulated chamber 94 in which place the inert 'gas evaporatively cools the liquid refrigerant flowing to the evaporator 9| before such liquid actually enters the chamber 94. Inert gas which has traversed the evaporator 9| is returned to the lower portion of the absorber 83 by the conduit 99 which passes through the inner passage of gas heat exchangertil and connects to the lowermost point in the absorber 83. This completes the secondary inert gas circuit which links the low temperature evaporator 9| and the absorber 83.

The quantity of the refrigerant actually evaporated in the evaporator 9| is comparatively small accounting for approximately twenty' to forty percent of the total quantity of refrigerant condensed in condenser 95 depending upon the design and operating conditions.

The absorbing solution which has traversed the l l absprber 83- is' conveyedtherefrom to the principal; absorber I60. by theconduit I0]; liquidheat exchanger- 81' and the u-shaped gass'ealconduit I021 The partially enriched absorbing-solution suppliedto-absorber I00 fiowsdownwardly therethrough by gravity in surface contact with and in counterflo-wrelationship-with; inert gas. flowing upwardly through thatrabsorber. The. absorbing solutionis'enriched inthe absorber I90 to form theso ca-lled strong-liquor. After traversingabsorber I001 the enriched solution is, conveyed therefrom to the generator 89 by way of conduit [03; solution reservoir [04, conduit H35, solution heat exchanger 85am]; conduit I96 to complete the absorbing solution circuit.

Inert: gas deprived: of refrigerant-vapor inthe absorber I00 is=conveyeditherefrom to thelower portion of-the-principal evaporator 89. by; way; of

conduit I08; the gas: heat exchanger I09 and;

conduit H0. The inert gas flows upwardly through the evaporator 89 in contact with and counterfiow relationship with liquid refrigerant flowing downwardly therethrough. Liquid refrigerant which is unevaporatecl in:the evaporator- 91', the major portion ofthe liquid condensed in the condenser 95, fiowsfrom thelovver portion thereof'to 4 the upper portion of the evaporator 89 by=way of the conduit H l, the heat exchanger [12,. which surrounds one leg of: conduit. to-

pre-coolliquid refrigerant flowing to evaporator 9i, and' trap'sealed conduit H3; The evaporator 89 refrigerates the ice: freezing compartment I14, the absorber 83", and the air within the food storage-compartmentof the refrigerator cabinet. P

shall be supplied with anhydrous refrigerant by I a double condenser arrangement such as that illustrated-in connection with Figure 1.

Inthis form of the invention the leanest solution in the system is first broughtinto contact with inert gas in a secondary inert gascircuit.

under conditions such that thesolution is called upon to strip. only acomparatively. small'volume of inert gas which does not contain a large amount ofrefrigerant vaporinitially. The refrigerant vapor concentrationrange in the inert gas circuit linking the evaporator 9|. and the secondary-absorber 83twill be in a comparativelynarrow-rangeand of low absolute value. Thus the=inert gas exiting from the absorber 83 may contain no more than: three or four percent refrigerant: vapor by volume. and be. enriched to ten to fifteen percent of refrigerant vapor by volume in the evaporator 91. The foregoing figuresq constitute: the. approximate limits of the concentration range which exists inthe. sec

ondary inert gas circuit. On the other hand, the absorbing=solution enteringtheabsorber 83 may have-a refrigerant-content of five or six percent and be increasedtoano more than tenortwelve percent inits passage therethroug-h:

In the. principal: inert .52 .ci-rpuitrz linking the principal; evaporator; 83 an. absorber mo the.:,leam inert gasfleavi-ngatheabsor r m y 0 tainzasmuch asternor eleven per entirefrieeran vaporxbyvolumezandrbe enriched:inrtheprincipal evaporaton to; a; much. higherzzfigure; dependin on; the total: refrigeratingload- The absorbing solution; enterin ;the:.-absorbjer:.l 0.0,; williha-vea; the same;.concentratiomasz, the. solution: leaving. the absorber -83; 'andiitsz; concentration may; be; increased. in: -the.;absorber: I00; to: approximately thirtye wo percent; refrigerant;

In this; form. of: t e. invention: like those; previouslydescribed the: quantity: of: inert; gas. circulating: perunitofatimein the lpw-temperature circuit may equal; fifteen:,to-.forty percent-of the quantity of inert gas circulatingf per unityoftime in. theprincipalninert gas; Circuit; Since: all of h b rb solutioni circulatin through. the system is; brought: into, absorbing relations with thiscomparatively small. volume .of: comparative- 1y leaninertgasin a: lowtemperatureabsorber,

iGO

the -,desirable: highly-stripped: inert gas; is: provided; for. the; low; temperature evaporator and the solution ismnly partially enriched, Theosolution;v would be only; partially; enrichedi if s it; absorbed-mall the; refrigerant vapor. admixed: with the. inert: gas;

In accordance; with; the, present. invention I have .providediconstructionsz by which 1 extremely low' temperature refrigeration can; conveniently be secured in inert gas three fluid typerabsorption. refrigerating. systems. Where they design of' the. systems. permits; an. extremely; highly stripped. inert; gas; can besupplied to thelow temperature. evaporator by; an. absorber which is air cooled. 1 This: canbe. accomplished; effectivrelyv bybubbling or.- introducing a comparatively small quantity. of lowa refrigerant vapor content, lean inert gas. into. all: of the: absorbing solution circnlatingdnzthe system so that substantially complete stripping; of the gas. does not. greatly enrich the. solution, that. is, the. solutionislean solutionas that-:term isrused in this arteven after it .has traversedrthe initial absorben. In: systems inwhich the aforementioned highly emcientrtype of absorber is notefeasible iti-has been found desirable. to .cool: the absorber; for the low. temperature evaporatorbyl-placing the samein heat .exchange relationship with the: principal evaporator of the system. In this arrangementtalso. a small volume of low. refrigerant contentvinert gas contacting a large.volumeofabsorbing-solution-.isused-to.strip the inert gasxw-ithouteunduly enriching; the absorbing, solution.-

It will'be understood that all of the contact type. absorberssuchas A, A; A"; 83' and I00 above described may be; and preferably are; provided. with known typeset-inserts, bafflesand the like to agitatesthe inert gas andabsorbingsolution which areaflowing therethrough.

While I -have illustrated and described the-invention inconsiderable detail; it ais to-beiunderstood that various changes may.- be made the arrangement, proportion and construction of parts without departing. from the. spirit-oft the invention or the-scope of the appendediclaims.

I claim:

1. In a refrigerating apparatus ofthe pressure equalized absorption type, a pair of 'evaporators, an absorber; a genera-tor, means for liquefying refrigerant vapor evolvedin said generator and for supplying refrigerant liquid to said evaporators, means for conducting inert-gas through said absorber and toone of said-evaporators; means of such mixture to the minimum value in a second concentration range which -for convfeying absorbing solution from said generator to said absorber including a gas lift pump, means for introducing inert gas into said gas lift pump to operate the same and means for conveying pumping gas which has traversed said gas 1) lift pump to said second evaporator.

2. In a refrigerating apparatus of the pressure equalized absorption type, a pair of evaporators, an absorber, a generator, means for liquefying refrigerant vapor evolved in said generator and m for supplying refrigerant liquid to said evaporators, means for conducting inert gas through said absorber and to one of said evaporators, means for conveying absorbing solution from said generator to said absorber including a gas lift pump} means for withdrawing a part of the inert gas which has traversed said absorber from the means conducting inert gas to said one evaporator and for introducing such withdrawn gas into said gas lift pump to operate the same and means for conveying pumping gas which has traversed said gas lift pump to said second evaporator.

3. That improvement in the art of refrigeration which includes the steps of applying heat to a solution of refrigerant in absorbent to liberate refrigerant vapor therefrom, flowing the solution from which refrigerant vapor has been liberated into contact with an inert gas refrigerant vapor mixture to reduce the refrigerant vapor content of said mixture to the minimum value of a first concentration range, flowing the inert gas refrigerant vapor mixture into contact with refrigerant liquid to increase its refrigerant vapor content to the maximum value in said first concentrationrange, flowing the partially enriched absorb- 2%. ing solution into contact with an inert gas refrigerant vapor mixture having a larger volume than the inert gas refrigerant mixture in said first concentration range to reduce the concentration i0 is higher than said first mentioned minimum value, flowing the inert gas of said minimum value of said second concentration range into contact with refrigerant liquid to increase the refrigerant concentratiomgs to the maximum value of said second concentration range which is higher than the maximum value of said first concentration range.

4. In a refrigerating apparatus of the pressure equalized absorption type including a first evapzgg orator, a first absorber connected to supply inert gas tosaid first evaporator, a second evaporator,

a second absorber connected to supply inert gas to said second evaporator, means for flowing lean absorbing solution through said first absorbergzm and thence through said second absorber, means for conducting a first body of inert gas refrigerant vapor mixture to said first absorber, means for conducting a second larger body of inert gas refrigerant vapor mixture to said second absorbermio and said means for conducting inert gas from said first absorber to said first evaporator passing in heat exchange relation with said second evaporator to condense absorbent vapors from said inert gas. (.565

5. That improvement in the art of refrigeration which includes the steps of applying heat to a solution of refrigerant in an absorbing solution to liberate refrigerant vapor therefrom until the absorbing solution contains approximately five'z'yo percent absorbed refrigerant, conducting said absorbing solution containing approximately five percent absorbed refrigerant into absorbing contact with an inert gas refrigerant vapor mixture containing not more than twelve percent refrigeims 14 erant vapor by volume and absorbing refrigerant fromsaid mixture into said absorbing solution to reduce the refrigerant vapor content of said mixture to not more than four percent refrigerant by volume and increasing the refrigerant content of said absorbing solution to approximately ten percent, conducting said absorbing solution containing approximately ten percent refrigerant into absorbing contact with an inert gas refrigerant vapor mixture to absorb refrigerant therefrom to reduce the refrigerant content ofsaid mixture to approximately ten percent refrigerant vapor by volume and to increase the refrigerant content of -said absorbing solution to approximately thirty-two percent, flowing said inert gas containing not more than four percent refrigerant vapor into contact with refrigerant liquid to produce a first refrigerating effect, and flowing said inert gas containing approximately ten-percent refrigerant vapor into contact with refrigerant liquid to produce a second refrigerating effect at a higher temperature level than said first refrigerating effect.

6. In an absorption refrigerating apparatus, a generator, a first air cooled absorber positioned below the surface level of absorbing solution in said generator, a second air cooled absorber, means for circulating absorbing solution through said generator and said first and second absorbers serially in the order named, first and second evaporators, means for conducting inert gas from said second evaporator to said second absorber, means for placing inert gas under pressure, means for conducting inert gas from said second absorber to said pressure creating means, means for conveying a portion of the inert gas placed under pressure by said pressure creating means to said second evaporator and for introducing another portion of the inert gas under pressure into the absorbing solution in said first absorber, and means for conveying inert gas from said first absorber to said first evaporator, and means for supplying refrigerant liquid to said evaporators.

'7. In an absorption refrigerating apparatus, a generator, a first air cooled absorber comprising an elongated air cooled conduit, a second air cooled absorber, means for circulating absorbing solution through said generator and said first and second absorbers serially in the order named, first and second evaporators, means for conducting inert gas from said second evaporator to said second absorber, means for placing inert gas under pressure, means for conducting inert gas from said second absorber to said pressure creating means, means for conveying a portion of the inert gas placed under pressure by said pressure creating means to said second evaporator and for introducing another portion of the inert gas under pressure into the absorbing solution in said first absorber in a manner to pass into and through the absorbing solution therein contained and to flow through said first absorber in counterfiow relation to the absorbing solution, means for conveying inert gas from said first absorber to said first evaporator and means for supplying refrigerant liquid to said evaporators.

3. Refrigerating apparatus comprising a cabinet structure including food storage and low temperature refrigerating chambers insulated from each other, a low temperature evaporator in the top portion of said low temperature refrigerating chamber, a second evaporator arranged to refrigerate said food storage chamber, a generator, a

first condenser, means for conveying refrigerant vapors from said generator to said first condenser,

meansior oouveums in said first condenser s. c said vapor 9 crime Inca d evaporator aseoo d rend u er. ductine'vanors revolved convevin niea s osai icrconveyine re :iserantliquid rom o condenser to said :first evaporator, a pair of absorbers, 'JIQEQILSQI'QY conducting in it gas from said evaporate-rate one of sai abso b rs. mean for conducting a part of theinertgas ch has traversed said one absorber direc l to saldon evaporator and the, remainder o s i inert gas through the other ofsaid absorbers and to said low mberature evaporator and me ns o citculgaqti-ng absorbing solution from said generator through said other and said one absorber in that orderand'baok to. said enerator.

' :9.,A refrigeratingapparatus comprising a cabinet structure including a low temperature insu- :lated' chamber an a higher temperature insulated chamber, a freezing compartment in said higher temperature chamber, an absorption rei ugeratingapparatusassociated with said cabinet structure including a first evaporator for refrigerating said low temperature chamber, a second evaporator for refrigerating said compartment and said higher temperature chamber, first and second air cooled absorbers positioned exteriorly of said insulated chambers, a generator, 'means :for conducting absorbing solution through said first and second absorbers seriallt in the order roamed, means providing a circuit for inert gas including said second evaporator and said second absorber, and-meansiorming a loy-pass circuit for inert gas around said second evaporator inwhich a portion of the inert gas which has traversed said second absorber is conducted through said first absorber and said first evaporator.

10. Refrigerating apparatus of the pressure (equalized type charged with a refrigerant, an absorbent for the refrigerant and an inert gas comprising: a low temperature evaporator, a high temperature evaporator, an auxiliary absorber, .a principal:absorben-ineans for generating refrigierant vapor from solution in said absorbent, zneansfor liquefying refrigerant vaporevolved in said generating means and for supplying refrigerant'liquid to said evaporators, means providing for circulation of :said absorbent from said generating means through said auxiliary absorber and then through said principal absorber back lto said generating means; means providing a plurality .of :pathsof flow of inert gas and refrigsorber;

:era-nt "vapor mixture in which the refrigerant f5 rapor content of the mixture varies from a:max-

- imum to a minimum value, one of said paths of ilovl including means .for conveying apart of said mixture having a refrigerant content below said 'nraximum value from said principal absorberthrough said high temperature evaporator to increase the refrigerant content of the mixture :to said maximum value, and another :of said paths :of flow including means for conveying another part of :said mixture having a refrigerant content above said minimum value through said auxiliary absorber to reduce the refrigerantcontent thereof :to said minimum value and -to :f,1ow said mixture of minimum refrigerant content t-hrough said low temperature evaporator.

'11. Refrigerating apparatus of the pressure equalized type charged with a refrigerant, an absorbent for the refrigerant and an inert :gas comprising: a low temperature evaporator, a high temperature evaporator, an 1 auxiliary ab-q saidgenerating means and for supplying re lg.-

' erantl-iquid to, said evaporatorsrheansprov ng for circulation of said absorbent from said genera ing m an throu h sai a xiliary ab r an t an t rou h sai p i c a a sorber bac to, said g nerating means; me ns prov ding a p ural ty o h o flo of inert ass nd refri e an vapor mixt in which th -.r-efrig rant vapor content of the mixture varies from a maximum to war-min mum alue e. of said paths of flow inc ud n means for nveyin a ma or p opo tionof the total quantity of ma ur ircmatiu in said apparatus perunit of time and having a refri er n co t i te me iate said maximum and m nimum va u s m Sa d rinc pa abs be throughsaid high temperatureevaporator where-- the refrigerant vapor content ,of the mixture is incr a ed to s m x ue, an another of said paths-of flow including means. fornonvow ing a minor proportion of the total quantity of mixture circulating in said apparatus per -,unit of time and having a refrigerant vapor content intermediate said-maximum and minimumvalues through said auxiliary absorber to reducethe re- :fl'igerant contentof the mixture tosaidminimum value and then through said low temperature evaporator.

12. Refrigerating apparatus of. thev pressure equalized absorption type includin a first evaporator, a first absorber of the type normally containing a body of absorbing solution in operation, a second evaporator, asecond absorber, means for flowing lean absorbingsolution through said first absorber and thence through said second absorber, means providing a plurality .of paths of; flow of inert gas for circulating inert ,gas through said evaporators and saidabsorbers including means for introducing a minor proportionof the total quantity of inert gascirculating in the apparatus per unit of .timeinto said iirst absorber below the liquid level therein .to pass into and through the absorbingsolution therein and for then conveying such inert gasinto said first evaporator, and means for flowing themajor proportion of the inert gas circulating in said apparatus per unit of time through said second evaporator and then through said second ab- 13. That i nprovementin the art of refrigera tion-whiohincludes the steps of applying heat to a solution of refrigerant in an absorbent having :aymaximum-refrigerant content to evolve refrig- Torant vapor and reduce the refrigerant content wfirst; mentioned in r s f i eran vap mixture with a second inertgas refrigerant vap mixture having a higher refrigerant vapor content thanthe initialrefrigera nt vapor content of a d first mentioned inert gas reirieeran vapor gmixture to increase the :rciri erau QQQLQQE 9f said solution to said maximum value and to reduce the refrigerant content of said second mentioned inert gas refrigerant vapor mixture, and evaporating another part of said liquefied refrigerant into said second mentioned inert gas refrigerant vapor mixture to increase the refrigerant vapor content thereof to a maximum and to produce a second refrigerating effect.

14. A refrigerating apparatus comprising a cabinet structure including a low temperature insulated chamber and a higher temperature insulated chamber, a freezing compartment in said higher temperature chamber, an absorption refrigerating apparatus associated with said cabinet structure including a first evaporator for refrigerating said low temperature chamber, a second evaporator fer refrigerating said compartment and said higher temperature chamber, a first absorber of the type normally containing a body of liquid in operation positioned exteriorly of said insulated chambers, a second absorber positioned exteriorly of said insulated chambers, a generator, means for conducting absorbing solution from said generator through said first and second absorbers serially in the order named and back to said generator, means for circulating an inert gas through and between said second absorber and said second evaporator, and means for conducting a portion of the inert gas which has traversed said second absorber into said first absorber below the liquid level therein and thence through said first evaporator back to said second absorber.

15. Refrigerating apparatus ofthe pressure equalized type charged with a refrigerant, an absorbent for the refrigerant and an inert gas comprising: a low temperature evaporator, a high temperature evaporator, an auxiliary absorber, a principal absorber, means for generating refrigerant vapor from solution in said absorbent, means for liquefying refrigerant vapor evolved in said generating means and for supplying refrigerant liquid to said evaporators, means providing for circulation of said absorbent from said generating means through said auxiliary absorber and then through said principal absorber back to said generating means; means for flowing inert gas from said evaporators to said principal absorber means for flowing inert gas from said principal absorber to said high temperature evaporator, and means for flowing a minor part of the inert gas which has traversed said principal absorber through said auxiliary absorber and thence through said low temperature evaporator.

16. Apparatus according to claim 10 including means for conducting said inert gas refrigerant vapor mixture of maximum refrigerant content from said high temperature evaporator to said principal absorber and said means for conducting inert gas refrigerant vapor mixture to said auxiliary absorber is connected to receive said mixture from said low temperature evaporator.

1'7. Apparatus according to claim 10 in which said auxiliary absorber is in heat exchange relation with said principal evaporator.

CURTIS C. COONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Nov. 6, 1936