US2787137A - Absorption refrigeration - Google Patents

Description

April 2, 1957 w. G. KOGE.. 2,787,137

ABSORPTION REFRIGERATION Original Filed Ju1y'14, 1949 lll ABSORPTIN REFRIGERATION' Wilhelm GeorgKogel, Stockholm, Sweden, assigner to Aktiebolaget Elelrtrolux,` Stockholm, Sweden, a` cor-` poration of Sweden Original application July 14, 1949, Serial No. 104,771, now Patent No. 2,655,010; dated ctober 13, 19de, Divided and this application December 23, `1952, Serial No.-327,`622

Claims priority, application Sweden luly4 22, 194g 6 Claims. (Cl. 62-119.5)

This invention relatesto refrigeration and is especially concerned with refrigeration systems of the absorption` circulating in the system and insure reliable operation under all operating conditions encounteredin practicegto provide in such a system an arrangementin which one component or member' forms a unitary or integral part ofV one or several other members; to combine several components or members in one unitary part whereby eflicient heat exchangeA may be effected between fluids circulating in the system; and to provide a new relation` ship of parts in the circuit for absorption liquid in which efficient heat exchange between fluids in such circuit is promoted and at the same time loss of heatfrom such fluids to the surroundings is minimized.

The novel features which are believed to be characteristic of the invention` are set forth with particularity in the claims. The invention, bothas to organization and method, together with the above and other objects and' advantages thereof, will be better understood by reference tothe following description taken in conjunction with the accompanying drawings forming a part of this specification, and of which:

Fig. 1 illustrates more or less dagrammatically an absorption refrigeration system of the inert gas typeembodying` the invention;` and Figs. 2 to 5 are fragmentary views diagrammatically illustrating modifications of the system shown in Fig. 1.

InFig. 1 the invention is shown embodied' in an absorption refrigeration system of a type employing an inert gas'or pressure equalizing agent. Systernsfof` this typeare well known andlinclude a generator orvapor expulsion unit' 1i?, a condenser 11, an evaporator 12 and absorber 14 which are connected to one` another to provide circuits for circuiation of refrigerant fluid, inert gas and absorption liquid. By way of example, aminonia may be employed as the refrigerant, hydrogen as thelinert gas and water as the liquid absorbent;

The vapor expulsion unit 10, which is enveloped within a body 9 of suitable insulating material, may comprise a boiler 15 `in the form of piping to which' heat is suppliedfrorn `a heating tube or liuc 16 thermally connected therewith at 17, as by welding, for example. The heating tube 1o may be heated in any suitable'manner, as by an electrical` heating element disposed within the lower part of the tube 16 or by a liquid or gaseousrfuel burner which is.` adapted to project its llame into the lower end of the tube.

States Patent O ice evaporator beingdiagrammatically shown and arrangedy to effect cooling of a thermally insulated space 21. In-

evaporator 12 liquid refrigerant evaporates and diiuses into an inert pressure equalizing gas, such as hydrogen,

which entersthrough' a conduit 22; Duetto evaporationof refrigerant fluidinto inert gas in evaporator 12 aV refrigerating' effect is produced with consequent absorption of heat' from the surroundings.

The richgasmixtureof refrigerant'vapor and inert gas formed in evaporator 12 ows from :the lower part thereof through one passage 23 of a gas heat exchanger 2,4Y

and conduits 25 and26 into the lower end of the absorber 14 whichis in the form of a looped coil having cooling` tins 6i) which also serve to dissipate heat from the condenser 113 In the absorber 14the rich gas mixture flows countercurrentto downwardly; owing absorption liquid which enters through a conduit Z7. The absorptionliquid absorbs refrigerant vapor from inert gas, and inert gas weak: in refrigerant flowsfrom thel upper end of absorber 14 through a conduit 23, another passage 2910i gas heat exchanger 24 andconduit 22 into the upper part of evaporator 12. is connected in the inert gas circuit just .described in such manner that parallel flow of inert gas and refrigerant fluid is effected in the evaporator.; However, `it should be` understood that the evaporator 12 may be connected in the gas circuittin any other desired manner so that, for example, inert gas and refrigerant lluid pass in counterow with` respect to one'another.

The circulation of gas in the gas circuit just described is `duetothe` difference in specific weight of the columns of gas rich and weak, respectively, in refrigerant Vapor.

Since the column ofV gas rich in; refrigerant` vapor and' flowingfrom` evaporator 12rto absorber 14K is heavier than boiler 15 absorption solution passes into the lower end of a vertically extending tube 31 in which liquid is raised` p by vapor-lift action, the tube 31 being heat conductively connected to the heating` tube lo, as by welding, to effect such lifting of liquid. The raised liquid passes from the upper end of tube 31 into theupperpart cfa` standpipe or riser 32, and, as will bedescribed presently, absorption liquid weak in refrigerant` ilows from `the lower part thereof to the absorber 14E-in a path of flbw which includes conduit 27.

TheV standpipeor riser` 32/ may or may not be` heat conductively-` connected to. the heating tube 16. The principalpart of generated vapor produced in the vapor expulsion unit'. 10 is expelled from solution in boiler 15, and liquid of decreasingrefrigerant concentration ows downwardly toward,` the; bott'oinend thereofv into` the vapor-lift tube 31. A liquid column is maintained in theV standpipe` 32r whose liquid surface` is' at such* av level that absorption liquid weak`- yin refrigerant can flow by gravity from the: lower end of the standpipc into the upper part of 'the absorber throughtheconduit 271 The vapor passing from thev upper end of vapor lift in` Fig. l the evaporator 12` tube 3l into the vapor space of standpipe 32 flows therefrom through a downwardly extending conduit 33 into the lower end of a horizontally extending pipe section a formed at the upper part of boiler 15. The pipe section 15a constitutes an analyzer into which passes vapor generated in the boiler 15 and in the vapor lift tube 31. The generated vapor usually is a mixture of refrigerant vapor and absorption liquid vapor. When arnmonia is employed as the refrigerant and water as the absorbent, for example, the generated vapor usually is a mixture of ammonia vapor and water vapor. Due to the diierence in boiling points of ammonia and water, water vapor may be removed from ammonia vapor by cooling the mixture to condense out the water.

In Fig. l vapor generated in the boiler pipe 15 passes upwardly therefrom through the pipe section 15a, and vapor generated in tube 31 also enters such pipe section through conduit 33. The absorption liquid introduced into the pipe section or analyzer 15a is relatively rich in refrigerant and at a lower temperature than the generated vapor, and in bubbling through the enriched absorption solution at least a part of the water vapor is cooled sufficiently and condenses, thus removing water Vapor from ammonia vapor. The latent heat of condensation resulting from condensation of water vapor is given up to the enriched absorption solution and forms an internally heated zone in which some ammonia vapor is expelled out of solution. Such refrigerant vapor mixes with rcfrigerant vapor generated in the vapor lift tube 31 and boiler 15, and the mixture passes from the analyzer 15a to the rectifier 1S.

In the rectifier 13, which may be provided with internal baffles 34, further cooling of generated vapor is effected which is sufcient to cause condensation of Water vapor and thereby effect its removal from ammonia vapor. Such condensate drains downwardly in the rectifier i8 and mixes with enriched absorption solution flowing to the boiler 15. The latent heat of condensation resulting from rectification of generated vapor, that is, condensation of water vapor, is usually referred to as heat of rectification.

Liquid refrigerant formed in condenser 11 is raised therefrom to a higher level in such manner that positive raising or lifting of refrigerant liquid is assured under all operating conditions encountered, particularly when the system is placed in operation following a shut down pcriod. In the embodiment of Fig. l this is accomplished by providing a conduit or vessel 35 to an intermediate portion of which the outlet end 36 of the condenser 11 is connected.

Liquid refrigerant formed in condenser 11 flows therefrom into vessel 35 and accumulates in the lower part thereof. From vessel 35 liquid refrigerant flows through conduit 19 into the lower part of vertically extending conduit which is heat conductively connected with the rectiier 18 at 37, as by Welding, for example. Due to heat of rectification supplied from the rectifier i8, liquid refrigerant is raised by vapor lift action through conduit 2li to an air cooled condenser 38 which may be provided with a plurality of heat dissipating members 39.

The vapor formed in the lower part of conduit 20 for raising liquid therethrough passes from the upper end of such conduit into condenser 38 and is condensed and liquefied therein. The raised liquid refrigerant and refrigerant condensed in condenser 38 ows through a conduit 4h into the upper part of evaporator 12 for gravity flow through the latter, as previously explained.

if desired, the condenser 3d may be omitted and an arrangement provided in which the lifting vapor passing from the upper end of conduit 20 is returned to the vessel which essentially serves as an extension of condenser 11 and in which returned vapor is condensed. Such a modification is shown in Fig. 2 in which the upper end of conduit 2t) is connected to the upper part of the vertical leg 41 of a generally U-shaped liquid trap 42 whose horithereof by a conduit 44 to the upper end of evaporator 12. When liquid refrigerant in liquid trap 42 reaches the level at which conduit 44 is connected thereto, liquid refrigerant overflows through such conduit into evaporator 12 for gravity flow through the latter. The conduit 2i) is connected to leg 41 at a level above the connection of conduit 44 to leg 43, that is, the vapor space of leg 41, and lifting vapor passes from such vapor space through a conduit 45 to the Vessel 35 in which the Vapor is condensed and liquefied.

The heat conductive connection 37 between conduit 20 and rectifier 18 extends for a sufficient distance lengthwise of these members to insure such transfer of heat of rectification to conduit 2t) that vaporization of liquid refrigerant will occur in the latter to insure lifting of refrigerant by vapor lift action. The conduit or lift tube 20 is thus heated to a definite temperature, depending upon the boiling point of substantially pure refrigerant under conditions prevailing in the system, to cause vaporization of such refrigerant or refrigerant having a relatively small concentration of liquid absorbent. The diameter of conduit 20 is sufficiently small so that the vapor bubbles formed due to heat transfer in this manner cannot freely pass liquid in conduit 2t), thereby effecting lifting of liquid by vapor lift action. Such lifting of liquid is accomplished under the influence of the column of liquid in vessel 35 whose liquid surface level may be at the level indicated at i6 in Fig. l, for example, such liquid column usually being referred to as a reaction head which overbalances the column of vapor bubbles and liquid slugs therebetween being raised in conduit 2).

Vaporization of liquid refrigerant in conduit 20 by heat of rectification takes place at a relatively low temperaturc. When the concentration of or quantity of absorption liquid present in liquid cooling agent or refrigerant in conduit 20 becomes too high, vaporization of such Aliquid by heat of rectification often cannot take place at such relatively low temperature because the presence of liquid absorbent increases the boiling temperature, that is, the temperature at which vaporization occurs. This is especially true when the conduit or vessel 35 contains liquid which is essentially liquid absorbent and which may occur, for example, when the system is turned or canted during transportation or being moved from one place to another.

In order to insure positive and reliable raising or lifting of liquid refrigerant under the most adverse operating conditions encountered, particularly when the refrigeration system is being started, provision is made for removing liquid absorbent from the liquid lifting system formed by Vessel 35 and conduits i9 and 20. In the embodiment of Fig. 1 this is accomplished by providing a conduit 47 whose lower end communicates with the conduit 19 and lower end of conduit 2d and whose upper end is preferably connected to rectifier 18 at a level which is substantially at or slightly above the liquid surface level of the liquid column maintained in vessel 35 during operation of the system, such liquid column constituting the reaction head for pumping or raising liquid refrigerant, as previously explained.

lf it is assumed the liquid lifting system contains liquid which is essentially or for the most part liquid absorbent when the refrigeration system is started following a shut down period, the vessel 35 will contain such liquid absorbent. Under these conditions liquid refrigerant having a ralatively small concentration of liquid absorbent will be formed in condenser 11 and flow therefrom into vessel 35 and gradually settle over the body of liquid absorbent. In this way liquid absorbent in vessel 35 will be displaced from the latter and pass through conduits 19 and d'7 into the rectifier 18. Eventually all of the liquid absorbent in vessel 35 and conduit 19, as well as the liquid absorbent in conduit 20, will be replaced by liquid refrigerant having a relatively small concentration of asaltar liquid absorbent,"l thereby enabling conduit-: tJfu'nction' and cause lifting of liquid refrigeranttherethrough'by vapor lift action b'y heat of" rectification; asip'r'evious'ly explained. The liquid 'absorbent entering rectifier 18 from the upper end of conduit 47 flows downwardly by` gravity and finds its way to the absorption liquidcircuit.

In view of the foregoing, it will nowbeunderstood that" positive and reliable lifting or pumping of liquidre`f`rig` erant from condenser 11 to la higher level can always be effected, even underlie@V most adverse operating conditions encountered, by removing liquid absorbent from the liquid lift or pumplsystem. In Fig. 3 is illustrated another manner of removing liquid absorbent from the liquid lifting system which is especially effective in promoting rapid lifting of liquid refrigerant from condenser 11 to a higher level. The embodiment of Fig. 3 differs from that of Fig. l in that conduit 47 is replaced by a conduit 48 which is more or less U-shaped to form a liquid trap having one leg 49 communicating withv the conduit 20 at approximately the liquid level 46 in vessel 35 andthe other leg 50 communicating with the'rectier 18 at. the same level or possibly slightly higher level.

The" connections of conduit 48I to the conduit 20 and rectifier' 18 may be accomplished by forming small open-l ings 51 and 52 in the latter, and securing the upper open ends of legs 49 and Stlto the conduit 20 andrectiter 18, respectively, at regions surrounding such openings. In addition, conduit It is formed of relatively small or narrowtubing to develop a definite resistance to passage of liquid even before the U-shaped trap formed by this con` duit is completely filled` withV liquid. In the event the' liquid lifting system of Fig. 3 containsliquid absorbent, such absorbent is replaced by liquid refrigerant having a relatively small concentration of absorbent substantially in the' same manner as in the embodiment of Fig. l and described above. However, in Fig. 3 liquid absorbentis displaced from vessel35 and forced throughpconduit 19 and lower part of lift tube or conduit 20 into the U-shaped conduit 4b. Fromconduit 48 such liquid absorbent passes into rectifier i8, and ultimately conduit 2S willv contain liquid refrigerant having a relatively small concentration of absorbent, so that lift tube 2t) will effectively function to raise such liquid therethrough.

The embodiment of Fig. l embodies provisions for varying the quantity of refrigerant fluid circulating in the refrigeration system for producing useful refrigeration. rfhisis accomplished by providing a vessel 53 inwl'lich refrigerant iiuid is held in an inactive portion of therefrigeration system under certain operating conditions.' The vessel 53, which may be referred to as a concentration vessel, is connected to receive liquid refrigerant in the lower part thereof through a conduit 54 whose upper end is connected at 55 to the conduit 25" immediately ahead of a barrier or dani 56 with respect to the direction of iiow of liquid from the evaporator 12;

In this manner unevaporated liquid refrigerant .passingv from the lower end of evaporator i2 and" iiowing'th'ro'ugh the inner passage 23 of gas heat exchanger 24' is diverted by the `dam or barrier 56 into conduit Sthrongh which it is conducted to vessel 53' and collectstherein. The vessel 53" is heat conductively connected to rectifier" 18 in any suitable' manner, as by welding, so that heatl of rectification is transferred by rectifier 1S to vessel 53 and its contents. Vaporization of liquid refrigerant continuously takes place in vessel 53 due to suchlieating, and' such vapor passes upwardly from the. vessel through a connection 57 into the extreme upper. part of rectifier 13 and flows into the condenser 1I along with vapor flowing. from the rectifier into the condenser.

When the' load on evaporator 12 increases less unevaporated refrigerant passes from the lower end` thereof; and, when `the evaporator load increases sufficiently, allof` the refrigerant supplied to theevaporator 12 evaporates and' diffuses intro inert gas therein' to" produce useful refrigeration. Under such operating conditionstheflow y forms` a jacket about the latter.

6. or `liquidA refrigerant-t6 vessel 5st through conduit 54 ceases; and, withcontinu'edfevaporation `of liquidrefrig`v erantinvesselh53` by' heat transfer thereth from rectifier 18, refrigerantva'por flows therefrom to condenser 1l. until the vessel'is depleted of liquid.

Hence, when the load o'n evaporator 12 increases, as when ice-trays containing water tobe frozen are posi-` tionedin an. ic'e'ffreezin'g? compartment of the thermally insulated" space 21, for example, a greater quantity of refrigerant ilhid actively' circulates in the refrigeration system to promote usefulv refrigeration and take care of increase `in load. Conversely, when the load on the evaporator` 12p decreases and unevaporated refrigerant passesffrom the lower end thereof, such refrigerant fluid collectsin vessel-53"whenitiows thereto ata faster rate than that-at which-it evaporates duef to heating from the rectifier 18`; While unevaporatedrefrigerant may be allowedto drain through'aliquid trap in conduit 54 directly intolth'el'bottom partof vessel 35 and mix with refrigerant therein, it will be' understood from the foregoing that certain? advantages' are realizedby providing the concentratibn` vessel 53' which functions in the manner just described'.

The-vessel 5.3i isconnected inthe system in such manner that removal of liquid therefrom, even a mixture of liquidi refrigerant and absorbent, is readily effected without anyI additional provisions. Liquid absorbent present in'ves'sel 53 is vaporized therein and the vapor thus formed, which is notV required to lift liquid by vapor lift action, passesinto condenser 11 from which it is drained intothe absorptioniliquid circuit, as previously described. Also, thel refrigeration system may be such that there is inadequate spacein the system for storingv and holding a large quantity" of excess refrigerant. By providing the vessel 53; such excess' refrigerant is effectively Withheld from' circulation and returnedto the active portion of the system to produce useful refrigeration without the necessit'y of draining such refrigerant into the absorption liquid circuit.

In absorption refrigeration; systems of the inert gas type being described, it is usually the practice to provide a separate vesselwhich is connected to the outlet end of the condenser andto the gas circuit, respectively, so thatany inert gas which may pass through the condenser can flow into the gas circuit. Refrigerant vapor not liquefied in the condenser flows into such separate vessel to displace inert gas therefrom and force such gas into thegas circuit. The effect of Vforcinggas into the gas circuit in this manner is to raise the total pressure in the entiresystern whereby an adequate condensingpressure is obtained to insure condensation'of refrigerant vapor in the. condenser. For this reasonv the separate vessel connected in the refrigeration system in the manner just described is usually referred to as a pressure vessel.

In order to simplify` the refrigeration system and pro vide a compact" arrangement of components or parts, the vessel or conduit 354 is arranged to serve as a pressure vesselv which surrounds or envelops the conduit 26 and l The outlet end of corn. denser 11 is connected to an intermediate part ofpressure-vessel 351 so that the lower part thereofservesras a place for holding liquid refrigerant flowing thereto from the condenser. Further, theupper part of conduit 26 is y formedwith an opening 58 `to connect the pressure vessei 35 to `a part ofthe gas circuit so that the latter will fun`c.. tion in the manner described above. Therefore, as illustrated in Fig; l' and just described, the vessel 3S serving as the `.pressure vessel of the refrigeration system forms a' unitary' or integral part of at least one otherv member or component o'fthe system; In Athe embodiment of Fig. l thevessel 35 and the manner in` which it envelope con`` duit actually malt'es theV pressure vessel an integral partY of' several Vmembers of; the refrigeration system. and eliminates connections previously necessary, especially/'the conduit connections to such a pressure vessel when a separate vessel is employed for such purpose.

By employing vessel 35 as a pressure vessel which envelops conduit 26, desirable heat exchange between uids in the system is effected, particularly to eff-ect cooling and condensation of refrigerant in vessel 35 which passes therein from condenser l1. Since gas enriched in refrigerant, which is relatively cold, flows through conduit 26, it is desirable to shield the latter thermally from atmospheric air to avoid condensation of moisture at the outer surfaces thereof. In IFig. `l this is effectively accomplished by employing vessel 3S as a jacket about conduit 26. In order to shield all parts of the path of flow for relatively cool enriched gas, the conduit 25 and ladjacent ends of gas heat exchanger 24 and vessel 35 may be enveloped in a body Sb of suitable insulating'material, as shown in Fig. 4. Alternatively, the gas heat exchanger 24 and vessel 35 may be so formed `and connected in the refrigeration system that adjacent ends of these members or components arc in abutting relation at 59, as shown in Fig. 5, thereby completely enveloping conduit 26 for the relatively cool rich gas. In the arrangement of Fig. 5, the conduit 28 through which gas weak in refrigerant iiows from absorber 14 desirably is shifted to the outer extreme end lof the gas .heat exchanger 24.

.in accordance with the invention special consideration is given -to the storing of enriched absorption liquid in` the absorption liquid circuit. It is usually the practice to iiow enriched absorption liquid from the absorber coil to a vessel and collect liquid therein, such collected liquid forming the upper part of la liquid column under the iniiuence of which liquid is raised to `a higher level in the vapor expulsion unit. Since heat of absorption is liberated i-n the absorber coil, such enriched absorption liquid collecting in the storage vessel is relatively warm. It is customary to iiow such warm absorption liquid in thermal vrelation `with weak absorption liquid passing from the vapor expulsion unit to the absorber coil in a liquid heat exchanger which constitutes a separate part or component of the refrigeration apparatus.

As shown in Fig. l, a vessel 6l, which is connected to receive enriched absorption liquid from the absorber 14 through conduit 36, is enveloped in the `same body 9 of insu-lation enveloping the vapor expulsion unit 10 and constructed and connected in the .refrigeration system so that the Warm enriched liquid is advantageously utilized to elect hea-t transfer with weak absorption liquid and generated vapor or either of these fluids.

As seen in Fig. l, the vessel 61 for storing enriched absorption liquid is enveloped in 4the single body 9 of insulating material `and such enriched absorbent rises upwardly therein 'from the connection `of conduit 30 to the upper part thereof within which the horizontally extending pipe section or analyzer a projects. Below the pipe section 15a is positioned a vertically extending coil 62 whose upper end is connected to receive weak absorption liquid from the lower part of standpipe 32 through a conduit 63. Hence, weak absorption liquid is conducted downward-ly through coil 62 and heat transfer is effected between such weak liquid and rich absorption liquid rising in vessel 61. In addition, conduits 27 and 3l may be arranged -in heat exchange relation at 64, as by welding, so that further counteriiow heat exchange can be effected between these iluids.

By way of example and without limitation, the vessel 6i. may be of such size that it can hold from 0.75 to 2 liters of absorption solution which may constitute 6) percent or more of the `enti-re `quantity of liquid absorbent held in the refrigeration system. `In other words, the upright vessel 61 in the immediate vicinity of the generator 1) is arranged to hold a major portion of the absorption solution circulating in the system. Since the enriched liquid absorbent passing from absorber 14 is relatively warm, it will be understood that an arrangement has been provided Iwhereby heat is effectively conserved within the system, the liquid in the insulated liquid body within vessel 61 being in eiiicient heat transfer relation with weak liquid absorbent in coil 62. Further, by projecting the `analyzer 15a into the upper part of vessel 61 below the liquid level therein, a compact arrangement is `also provided to effect heat transfer bet-Ween enriched absorption liquid and generated vapor in the manner previously described.

Modifications of the embodiment of the invention which have been described and illustrated will occur to those skilled in the art, so that it is desired not to be limited to the particular arrangements set forth. Therefore, it is intended in the claims to cover all those modilications and features which do not depart from the spirit and scope of the invention.

What is claimed is:

l. In an absorption refrigeration system, a circuit for circulation of absorption liquid comprising an absorber7 generator and liquid heat exchanger therebetween having passages for flowing in thermal exchange relation absorption liquid rich and weak, respectively, in refrigerant, a cluster of vertically extending conduits grouped together 'in the immediate vicinity of one another, common insulating means for thermally insulating said conduits from the surroundings, one of said conduits forming an upright 4heating tube, said generator comprising several of said vvertically extending conduits which are connected in said circuit and at least two of which contain absorption liquid arranged t@ receive heat from said heating tube, said two conduits being essentially upright and substantial-ly parallel to said heating tube and forming a boiler and vapor-liquid lift tube, respectively, the principal part of the vapor produced in said generator being expelled from solution in said conduit forming said boiler, one of said generator conduits in the cluster forming a stand pipe connected at its upper end to receive liquid raised by `said vapor-liquid lift tube from said generator conduit forming said boiler, and another pair of said vertically extending conduits forming the passages of `said liquid heat exchange-r which is `of tubular form and disposed substantially parallel to said heating tube, one of said conduits in the cluster forming one of said liquid heat exchanger passages including a section communicating with the lower end lof said `standpipc and extending vertically downward therefrom at the immediate vicinity of said heating tube, at least said two generator conduits forming said boiler and said lift tube and pair of conduits forming said liquid heat exchanger being located within said common insulating means in vertical positions ec- -centrically disposed with respect to said heating tube.

2. An absorption refrigeration Vsystem as set forth in claim 1 in which said circuit contains a column ef liquid forming a reaction head under the inlluence of which liquid is raised in said lift tube by vapor-liquid litt action, said liquid heat exchanger extending through a major portion of the vertical range between horizontal planes intersecting the top and bottom end Vregions of such reaction head.

3. In an absorption refrigeration system, a circuit for circulation of absorption liquid comprising an absorber, generator and liquid heat exchanger therebetween having passages for ilowing in thermal exchange relation absorption liquid rich and weak, respectively, in refrigerant, a cluster of vertically extending conduits grouped together in the immediate vicinity of one another, one of said conduits forming a vertical heating tube, said generator comprising several of said conduits which are connected in said circuit and at least two of which contain absorption liquid arranged to receive heat from said heating tube, said two conduits comprising lengths of essentially stra-ight piping which are substantially parallel to said heating tube and form a boiler and vaporliquid lift tube, respectively, one of said generator conduits in the cluster forming a standpipe connected at its upper end to receive liquid raised by said vapor-liquid lift tube from said generator conduit forming said boiler, the principal part of the vapor produced in said generator being expelled from solution in said conduit forming said boiler, and another pair of said vertically extending conduits forming the passages of said liquid heat exchanger in which one such conduit extends lengthwise within the other, the outer liquid heat exchanger conduit comprising a section of essentially straight piping at the vicinity of said heating tube, one of said conduits in the cluster forming one of said liquid heat exchanger passages including a section communicating with the lower end of said standpipe and extending vertically downward therefrom at the immediate vicinity of said heating tube, said conduits forming said heating tube, boiler, vapor-liquid lift tube and liquid heat exchanger being positioned near one another to provide a compact bundle of pipes in which all of said fluid conveying conduits connected in said circuit are eccentrically disposed with respect to said heating tube, and insulating means extending lengthwise of said bundle of pipes for thermally insulating said generator and liquid heat exchanger from the surroundings.

4. In an absorption type refrigeration apparatus having a plurality of parts interconnected for circulation of uids including a generator, an air-cooled condenser connected to receive vapor generated in said generator, an air-cooled absorber, connections between said absorber and said generator to provide a circuit for circulation of absorption solution whereby solution weak in refrigerant flows from said generator to said labsorber and solution enriched in refrigerant flows from said absorber to said generator, and a body of insulation enveloping said generator; said generator comprising a cluster of upright pipes which are essentially straight and grouped together in the immediate vicinity of one another, one of said pipes being a heating tube, a second pipe serving as a vapor-lift pump which is `heat conductively connected to the exterior of said heating tube, a third pipe serving as a boiler which is heat conductively connected at the exterior thereof to the exterior of said heating tube along a vertically extending zone, and a fourth pipe serving as a standpipe connected at its upper end to receive liquid raised by said vapor-lift pump from said third pipe serving as said boiler, the principal part of the vapor produced in said generator being expelled from solution in said third pipe serving as said boiler; and an upright casing or shell which is enveloped in said body of insulation and forms a part of said absorption solution connections, said casing being in the vicinity of and separated from said heating tube and having a vertically extending portion thereof essentially at the same elevation as the zone at which the exterior of said boiler pipe is heat conductively connected to the exterior of said heating tube, the cross-sectional area of said casing being greater than `that of said boiler, and said casing providing a vessel 'capable of holding a relatively large portion of the absorption solution in said circuit and embodying provisions to promote heat exchange between `absorption solution therein and another fluid.

5. Apparatus as set forth in claim 4 including a vertically extending coil within said vessel through which weak absorption solution flows from said generator to said absorber, said coil having the upper end thereof communicating with the lower end of said standpipe and extending downwardly therefrom.

6. Apparatus as set forth in claim 4 in which the lower part of said vessel is connected to receive enriched absorption solution discharged from said absorber, conduit means in heat exchange relation with the body of absorption solution in said vessel through which weak absorption solution flows from said generator to said absorber, the upper end of said last-mentioned conduit means communicating with the lower end of said standpipe and extending vertically downward therefrom, and said structure being formed and arranged so that generated Vapor received by said condenser bubbles through liquid in the upper part of said vessel.

References Cited in the tile of this patent UNITED STATES PATENTS 1,802,537 Roos Apr. 28, 1931 1,905,727 Maiuri Apr. 25, 1933 2,096,093 Drevet Oct. 19, 1937 2,134,149 Schellens Oct. 25, 1938 2,269,099 Grubb Jan. 6, 1942 2,287,281 Thomas a June 23, 1942 2,354,982 Bikkers Aug. 1, 1944 2,368,493 Reistad Jan. 30, 1945 2,399,922 Grossman May 7, 1946 2,504,784 Ashby Apr. 18, 1950

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