US2598035A - Absorption refrigeration - Google Patents

Description

3 Sheets-Sheet 1 w. L. BULKLEYV ABsoRPTIoN REFRIGERATION May 27, 1952 Filed Aug. 2, 1948 3 Sheets-Sheet 2 Filed Aug. 2, 1948 INVENTOR.

May 27, 1952 w. L. BULKLEY 2,598,035

ABsoRPTIoN REFRIGERATION Filed Aug. 2, 1948 `3 sheets-snee*L 3 IN VEN TOR.

Patented May 27, 1952 ABSORPTION REFRIGERATION William L. Bulkley, Munster, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application August 2, 1948, Serial No. 42,014

17 Claims. 1

This invention relates to refrigeration and more particularly to absorption refrigeration systems of the three-fluid type utilizing a refrigerant, an absorbent and a pressure equalizing gas. The present application relates back to my co-pending applications Serial No. 546,635 iiled July 26, 1944, now abandoned; Serial No. 737,032 filed March 25, 1947; and Serial No.'742,317 filed April 18, 1947, now abandoned, for common subject matter.V

In such three-fluid or unipressure absorption refrigeration systems the refrigerant evaporates in the evaporator and diiuses into the pressure equalizing gas to produce refrigeration. The pressure equalizing gas with refrigerant vapor diiused therein falls by gravity, due to its increased density, to cause a circulation in the gas circuit. Because of the arrangement of the elements in certain particular systems it is possible for the gas to flow in either direction in the gas circuit depending upon the direction in which the circulation is rst initiated.

One of the objects of the present invention is to provide an absorption refrigeration system of the type indicated with a check valve in the gas circuit to permit the ilow of gas in one direction and prevent the flow of gas in the opposite direction.

Another object is to provide a check valve in the gas circuit of an absorption refrigeration system of the type indicated for limiting ow of gas to one direction only in said circuit while permitting iiow of liquid from said circuit.

Another object is to provide check valves operable at'the slight difference in pressure prevailing in the gas circuit of an absorption refrigeration system of the type indicated and adapted for installation in systems of usual construction without materially changing the arrangement of its parts.

These and other objects will become more apy parent from the following description and drawings in which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and do not limit the scope of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. 1 is a diagrammatic view of an absorption refrigeration system incorporating a check valve for controlling thefi'low of gasin the gas circuit while permitting the uncontrolled flow of liquid therefrom;

Fig.` 2 is an enlarged 'sectional view Vof the check valve illustrated in Fig. 1 and showing the exible slitted tube adapted to vopen whe expanded and close when contracted;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2 and showing the arrangenent of the slits in the periphery of the flexible ube;

Fig. 4 is a detail view of the inner perforated tube connecting the inlet and drain pipes of the check valve;

Fig. 5 is a diagrammatic View oi a portion of the gas circuit showing the check valve arranged in the return line between the absorber and gas heat exchanger;

Fig. 6 is an elevational view showing the check valve enclosed in the absorber pot which constitutes the outer casing thereof;

Fig. 7 is a side elevational View of the check valve arranged horizontally on the absorber pot;

Fig. 8 is a diagrammatic view showing a pivoted type check valve in the gas' circuit; and

Fig. 9 is a sectional View of a oating type check valve and its arrangement in the gas circuit.

Referring to the drawings, the present invention is shown applied to an absorption refrigeration system of the three-duid uniform pressure type as well known in the art. Such a system includes a generator I9, condenser II, 4evaporator I2 and absorber I3, which are interconnected in a manner to be briey described hereinafter. The system contains a solution of refrigerant in absorption liquid such as, for example, ammonia in water and also an auxiliary pressure equalizing gas such as hydrogen.

The generator I is in the form of an annular vessel having a central ue I 4 and is heated by any suitable means such as a gas burner I5 connected to a gas supply conduit I6. A vapor conduit II connects the top of the generator I0 to the upper or inlet end of the condenser II. The lower or outlet end of the condenser II is connected by a conduit I 8 to the upper end of a pipe coil constituting the evaporator I 2. Evaporator coil I2 is enclosed in an insulated refrigerator cabinet I9 and comprises a high temperature section I2fa and a low temperature section I2b. The upper end of the evaporator'coil I2 is also connected to the upper end of a descending conduit 20 constituting the inner passage of a gas heat exchanger 2I and the lower end ofv the evaporator coil is connected tov the upper end of a sleeve 22 surrounding the descending conduit 20 and constituting the outer passage of the gas heat exchanger. A drain conduit-35 connects the bottom of the evaporator I2 to the conduit 2l! through which liquid refrigerant overflows from the evaporator and the drain conduit is provided with a depending loop to provide a liquid trap in the conduit.

The absorber I3 comprises a vertically arranged finned coil having its lower end connected to the lower end of descending conduit through a check valve 23, later to be described in detail, and in open communication with an absorber pot 24. The upper end of the absorber coil I3 is connected to the lower end of sleeve 22 of the gas heat exchanger 2l. A pressure vessel is connected between the outlet end of the condenser II and the lower Vend ofv the descending conduit 28 by conduits 23 and 2l', respectively. Thus, the gas circuit comprises gas flows from the upper or outlet end of absorber I3, outer passage 22 of the gas heat exchanger 2I, evaporator coil I2, descending conduit 20 of the gas heat exchanger, and check valve 23 to the lowerfi'nlet end of absorber i3.

The 'absorber vpot 24 is connected tothe generator I0 by means of a conduit 23 constituting the inner passage uof "a liquid heat exchanger 29, heating coil 39 'surrounding the lower end of iiue I4 of the generator F0 and vapor liquid-lift tube 3l connected to the side of the generator le. The lower endof the 'generator vessel I0 is connected to the upper end of the absorber I3 by a conduit 32, jacket 33 constituting the outer vpassage of the liquid heat exchanger 29 and conduit 34. Thus, the liquid circuit comprises and absorbent liquid flows from generator ill through conduit 32, outer passage 33 of the liquid heat exchanger 29, 'conduit 34, absorber I3, absorber pot 24, and 'conduit 28 including the inner passage of the liquid heat exchanger, heating coil 3G 'and lift tube 3l back to the generator.

In accordance with the present invention the flow "of pressure equalizing gas is controlled to insure flow inthe proper direction through the evaporator while permitting the uncontrolled o'w ofliquid from the gas circuit. As illustrated the drawings the gas is permitted to ow in a direction'counter-current to the direction of flow of refrigerant through the evaporator but the gas may be controlled to cause it to iiow in anydirection desired.

In the 4embodiment of the invention illustrated in Figs. l to `4 the fio'w of gas is controlled by the check valve 23 comprising a wall of an impervious flexible material having an aperture therein which 'opens and closes automatically. The flexible wall is illustrated in the form of a tube 36 enclosed in a casing 31, see Fig. 1. 31 is mounted Vin a vsuitable opening in the top of the absorber pot 24 and is sealed therein as by welding the seam therebetween. The lower end of the conduit 20 'extends into the upper end of casing 3T and constitutes an inlet 38 to the check valve 23. The lower end of absorber I3 is connected to arsuitable opening in the side of the casing 31 which constitutes an outlet port 39 from the check valve 23. The bottom of casing 3l is in open communication with the absorber pot 24 Vand has an open frame or spider t@ attached to its sides adjacent the lower end thereof. A drain pipe 4I is supported adjacent its upper end by the spider in alignment with the inlet 38 and has a short section projecting above the spider as illustrated most clearly in Fig. 2.

The flexible tube 36 of the check valve 23 extends between the inlet pipe 38 'and drain pipe 4I with its ends surrounding the ends of the Casing f pipes. Tube 3B is provided with one or a plurality of apertures formed as longitudinal slits d2 in its periphery. Preferably, the tube 36 is made of natural or synthetic rubber or a flexible plastic, or may be made of a fabric impregnated with rubber or a flexible plastic. Due to the number and arrangement of the slits 42 the flexible tube 33 is free to expand outwardly upon a slightly greater pressure inside than outside the i tube which opens the slits and permits the flow of gas outwardly therefrom. However, a slightly greater outside pressure will contract the tube 35 and upon contraction the adjacent edges of the slits abut to tform a comparatively rigid structure which closes the tube to prevent the flow of gases inwardly thereto. The pressure drop may vary considerably with the kind of tubing and the length and number of slits. By way of example, a rubber tube vhaving an outside diameter of seven-eighths of an inch and a wall thickness of one-eighth of an inch with fourteen equally spaced slits one 'and seven-'eighths of 'an inch long will produce a pressure drop of Yonly forty-three hundredths of 'an inch of water while passing Vgas at a rate of 1560 liters per hour.

While non-essential to the operation cf the check valve a rigid perforated tube t@ is preferably provided between the 'ends of the inlet pipe 38 and drain pipe il to limit the extent of contraction of the flexible tube 3 6. As illustrated in Fig. 4, the perforated tube 44 has :mout-'side diameter substantially Ythe same as the inside diameter of the inlet and drain pipes 38' and ISI. The ends of perforated tube M extend into 'the ends of the pipes 38 and BI and are fixedlyr-'attached thereto as by welding or the like. `r`The perforations in the tube it are the forin '-'of a series of spiral slots "S5 to permit the flow of gas therethrough. Thus, the pipes 38 and :41 and tube 44 constitute a continuous conduit 'with 'a perforated portion 'intermediate its ends which may be constructed as a single conduit desired. The lower end of the 'drain conduit "4I 'extends into the absorber pot 2'4 below the liquid level therein. One form of 'the invention having now been described in detail lthe inode 'of 'operation is explained as follows.

For purposes of description let it be assumed that the refrigeration system is about to be started initially o'r after an off cycleph'a's'e. To

Ainitiate a refrigeration 'cycle fuel is 'supplied to the gas burner I5 'which Vheats the generator I and expels refrigerant vapor from absorption solution therein. The refrigerant vapor liows from the generator l!! through the conduit I1 to the condenser 5I i where it is condensed to a liquid by the transfer of heat to the surrounding ambient. `Liquid refrigerant -il'o'ws from condenser lI through the conduit I-'8 intowthe'upper part of evaporator I2. As the liquid refrigerant flows by gravity through the evaporator iI2 it evaporates inthe presence of pressure edualizin'g gas. The initial direction 'of fiow-in the-gas circuit is determined by a number of factors which in turn depend upon the particular operating conditions. It may be stated categorically, however, that the relatively 'heavy mixture 4of 'refrigerant vapor and inert gas normally flows from the evaporator I2to Vthe"a'bsorberffI Sthrough the inner passage 29 Aof* the heat exchanger 2I as well understood by those 'skilled in the art. After the now has been initiated in the 'gas vcircuit the flow will continue from the vupper part I2a of the evaporator -into the innerpassage "of conduitZ of the gas heat xchan'ger`2l andwill be displaced by inert gas fiowing into the lower end of the evaporator section I2b from the outer passage 22 of the gas heat exchanger 2 I. Due to the slight diierence in pressure between the mixture of refrigerant vapor andgas in conduit 20 and the inert gas in casing 31 ofthe check valve 23, the exible tube 36 of the check valve will expand to open the slits 42 therein to permit the iiow of the mixture outwardly to the casing. The mixture then ows into the lower end of absorber I3 and upwardly therethrough.

Simultaneously, absorption liquid weak in refrigerant flows from the generatorl through the conduit 32, outer passage 33 of he liquid heat exchanger 29, and conduit 34 to the upper end of the absorber I3 and iiows downwardly through the latter by gravity in a direction countercurrent to the direction of flow of refrigerant vapor and pressure equalizing gas therein. The absorption liquid weak in refrigerant absorbs the refrigerant vapor therein which liberates the pressure equalizing gas. The pressure equalizing gas being lighter than the refrigerant vapor tends to ow upwardly and enters the lower end of the outer passage 22 of the gas heat exchanger 2|, iiows upwardly therethrough and enters the lower end of the evaporator I2 to complete its cycle. The absorption solution enriched with refrigerant flows outwardly from the lower end of the absorber I3 into the casing 31 of the check valve 23 and ows through the spider 40 into the absorber pot 24. The enriched absorption solution in the absorber pot 24 flows through the conduit 28 comprising the inner passage of the liquid heat exchanger 29 and coil 30 surrounding the iiue I4 at the base of the generator I0 which vaporizes part of the refrigerant therein to raise the absorption solution in the vapor lift conduit 3| into the generator I0.

From the above it will be apparent that the re frigerant flows through a circuit including the generator I0, 'condenser II, evaporator I2 and absorber I3; the absorption solution ows through a liquid circuit including the generator I0, liquid heat exchanger 29, absorber I3 and absorber pot 24; and the pressure equalizing gas iiows through the gas circuit including the evaporator I2, inner passage 20 of gas heat exchanger 2|, check valve 23, absorber I3 and outer passage22 of the gas heat exchanger.

Because of the delicate balance in gas columns in gas heat exchanger 2| is sometimes happens that circulation in the gas circuit will be initiated in the wrong direction. The exact reason for such reversal of flow is not fully understood but occasionally occurs in certain installations and may be due to the inert gas being carried along with the absorption solution when the latter is first introduced into the absorber I3 which starts a ow in the wrong direction. -When such a condition exists gas flows downwardly through the outer passage 22 of the heat exchanger 2| to the absorber I3 and upwardly through the inner passage 2G to the evaporator I2.

If for any reason the mixture of refrigerant and inert gas should initially flow downwardly through the outer passage 22 of the gas heat exchanger 2| instead of in the passage 20, a greater pressure will exist in the casing 31 of the check valve than in the conduit 20. Such dierence in pressure will contract theY flexible tube 36 of the check valve 23 to close the slitsl 42 therein and prevent the ilow upwardly through the inner conduit 2t. Such closing of the check valve 23 will prevent the introduction ofinert pressure- 1.

pand to open the slits 42.

ator and Ydrain conduit 35 into, the inner passage 20 ofthe heat exchanger 2|. The liquid refrigerant will :then diiuse in the inert gas inthe conduit 20 .to increase its density until the pressure therein exceeds the pressure in the casing 31, at which time the flexible .tube 36 will ex- The mixture of re.- frigerant vapor and inert gas will then-now. outwardly from the conduit 2|! into the casing 31.-

The flow downwardly through the conduit 20 of the heat exchanger 2| then will cause a iiow from the outer passage 22 ofthe heat exchanger into the ,lower end of the evaporator I2 to displace themixture iiowingtherefrom whereby to causethe flow to be initiated in the proper direction. It will now be apparent fromk the above description that the check valve 23 at all times insures now .of gas in the proper direction in the gas circuit.. v

While the check valve 23 controls the flow of gas in the gas. circuit, it is so constructed and arranged as to permit uncontrolled flow of liquid from the gas circuit at both sides of the check valve. Liquid may enter the gas circuit when handling or tipping the unit during transporta- -tion or may condense in the gasrcircuit during` operation of the unit. In either case liquid in the gas circuit would interfere with the proper operation of the system and also prevent the operation of the check valve 23 at the low difference 1n pressures inthe gas circuit. With the construction of check valve illustrated in Figs. 1 to 4,l

open spider 40 `into the absorber pot. The Vim mersion of the lower end of the drain tube 4| in the liquid in the absorber pot 24 provides aliquid seal which prevents gas from by-passing. the check valve. v

In Fig. 5 an arrangement is illustrated in which the check valve 23 is connected between the upper end of absorber I3 and thev outer passage 22 of the gas heat exchanger 2 I. The lower end of the conduit 20 of the gas heat exchanger 2| is connected to the top of the absorber pot 24 and the side of the absorber pot is connected to the lower or inlet end of absorber |3. Absorption solution weak in refrigerant is suppliedto Vthe upper end of the absorber` I3 through the conduit 34 in the same manner as explained with respect to the construction illustrated in Fig. 1. The upper end of absorber I3 constitutes the inlet to the check valve 23 to adapt the latter to its new location. The rigid perforated tube 44 has its lower end extending into the upper end of of the pipe from absorber I3 and its vopposite end is sealed by a cap 41. The iiexible tube 36 surrounds the perforated tube 44 with its ends overlying the upper end of the absorber pipe and the cap 41. Flexible tube 36 has longitudinal slits 42 in its periphery as previously described and surrounding the flexible tube is a casing 48 mounted on the upper end of th'ef .The check valve 23 inthe; arrangement` illustrated in r'ig. 5 operates msubstantially :thesarae -way-.fas previouslyaexplained to permit i'low in the gas circuit rinicneidirection and prevent .flow vln's-the cpposite'direction. The pressure equal- -izing rgas liberated .in the absorber 13 flows upwardly into the interior of the `fiexible tube 36 and :expands the latter to open the slits 42 thererin through which .the gas flows outwardly into the casing 48. The gas then iiows from the casing 48 through the conduit 4S to `the gas heat exchange 2l, However, if the pressure in the casing 48 is greater than the pressureat the in- .ter'icr of the exible vtube 36, rthelatter will contract to close the .slits 42 and `prevent the flow of v4gas Yinwardly thereto. The iiow Vof liquid re- .frigerant into conduit 2B then will reverse the `direction Yof kflow vas previously explained. Any :liquid at the interior of the check valve 23 will ffiow'by .fgravityjinto the upper .end of the absorber .I3 .and :any :liquid 'in the casing 48 will lflow by gravity through the drain nconduit 5l! which, together with the conduit 34, provides a liquidtrap Vbetween* the two sides of the check `valve. Thus, the check valve operates to insure theurlow of gas `in the proper direction inthe gas circuit while permitting liquid 'to flow :from the Fig v.6 illustrates anrarrangement in which the absorber Ipot 24 `Vconstitutes 'the outer casing of the. check valve. 'Thel inlet vconduit 20 ,of the `vgas heat :exchanger 2i `Vexten-ds downwardly into `the ltop-of the'absorber potz24 `toaprovfide an inlet SL38. VThe rigid perforated tube 44 is connected be- --tween .the .end 33zofthe conduit 20 and drain pipe "Marranged'nithe 'manner illustrated in Fig. 2.

'fIhe flexible islitted tube A316 Asurrounds the per- `vcrafted:tube l rand the .ends of the inlet pipe 3-8 fanddrai-n 'pipe 4 l. The sident the labsorber pot '21 is iconnectedto :the Flower zend'of the absorbe-r i3 above. the liquid leve-lin the potfas 'in Fig. 1. *The .checktvalveillustratedin Fig. 6 operates in `exaizztly .the same lway as the check valve illus- `trated in Fig. '1. The construction in Fig. 6, .how'even requires a comparatively larger absorber pot 24, while the construction illustrated -i-n Fig. l 'permits the use of Van 4alosorbergpot of .ordinary-size but .requires the fabrication .of the special casingiil and its attachment thereto..

In Fig. 7 an arrangement is illustrated in which thec'heck Naive 23 isf .mounted in va:substantially horizontal position-onlanabsorber pot 24 -in :the vvfior-m rof;a horizontal cylinder. Jthe .check valve,.:2.3 -is supportedeby a conduit v.2 `extending .upwardly from 'the :absorber Apot 24 and the casing vis inclined slightly from 4 the horizontal 'to insure tproper :drainage therefrom. vTheinlet v.conduit 120 .extends :into one endof the .casing .51 -anda drain conduit 53 extends .from thebpposite end ofthe casing with its lower Vend connected to :the absorberfpot 24 .below the liquid level ".therein. Aperforated tube 44 isprovidedbetween :the tinletand drain conduits 2li `and .53 and a exiblefsltted tube 3S surrounds the perforated tube :and ends of :the inlet and .drain conduits .in `Pathe same lway pas explained Awith .respect to .the check valve in Fig. -l. "Although .not shown in -detail .only/the upper half got-the ztube44 is per- -fora'ted so .that liquid will drainbygravity along 'ftiie lower imperforated half fof :the tube and `through. conduit :53 .into theiabsorber. pot-24. Any fliquidin 'the casingSl Aof the .check valve .'23wwill `:drainv through the conduit- 52 ,into :the absorber rpot. The-constructionlillustratedin :Eigx ioperla'tesdmthe lsame vmanner .as previously .described butibeoauseiff-its mounting inza .generallyhoriaantal-"position Sit 4infiay be .used fwhere' there is `insucient height for the vertical type check valve villustrated in the other views.

In Fig. 8 a check valve' of modified construction is shown and in the embodiment illustrated is located betweenthe upper end of the absorber' i3 Vand the outer passage 22 of the gas heat exchanger 2 I .v The check valve 60 comprises a housing 6I, a valve seat 62 in the housing and a movable valve element 63 adapted to engage the valve seat. The valve seat 62 is formed at the end of a pipe section Ge extending upwardly from the .absorber I3 which projects horizontally into the housing 6l. The valve element 63 is formed by a slightly cupped sheet metal disk pivotally mounted upon the horizontal end portion 64 of the absorber pipe adjacent the valve seat 62. The arrangement is such that when the refrigeration system is level the weight of the valve element 63 just closes the valve. In other words, the `valve element G3 is pivoted in a Vmanner so that the slightpressure of the inert gas flowing vupwardly from the absorber i3 toward the heat exchanger 2l will hold the valve open whereas a slight pressure in the opposite direction irnmediately closes the valve.

6| and the pipe section 6d from the absorber I3.

The check valve 6B permits the ow of gas from theupper end of the absorber i3 to the evaporator l2 by swinging the pivoted valve element 63 away from the valve seat 62 and prevents the flow of `gas in the opposite direction b y engaging the valveelementwith the valve seat. Liquid drains from the gas circuit through conduits 64 and 55 at opposite sides of the movable valve velement 83 and liquid in trap 61 prevents the gas from bypassing the check valve.

In Fig.9 a check valve 'l0 of .still further modilied construction is illustrated. The check valve 'FD illustrated in Fig. 9 comprises a valve housing i l inwhich is located what maybe termed .a floating-valve. This floating valve includesa movable valve element 'I2 adapted to engage a valve seat '13 formed at the upper end .of a vertical conduit 'i4 connected to the upper end of .the absorber i3. A conduit 15 connects the lower .end of the housing 'H -to the upright .conduit i4 below the housing and is 4provided with a depending liquid .trap 'it therein. A conduit V connects housing ll wwith .the outer passage 22 of the gas heat exchanger -2vl. As shown, a plurality of guide members Hlare provided at the upper or outlet en d of `conduit -i for guiding and llimiting upward movement of the floating valve element 12.

Valveelement 'l2 is-made of a light material .suchzas aluminum alloy and is free to move -up- -wardly vand downwardly between .the guides 78.

Themovable valve element 1.2 is ypreferably of vinverted dish shape and merely rests upon the valve Seat 'i3 so that a slight pressure exerted by the inert gas flowing upwardly from the absorber theevaporator coil i2. A greater pressure ofgas inhousing ll than in conduit '1.4 will hold the valve element fi 2 against the valve seat i3 at the .upperend of .conduit 14.

-lEt will.-now be observed from the foregoing description that the present 'invention provides a check valve in the gas circuit o f an absorption refrigeration system which controls the flow` of gas therein while permitting the uncontrolled flow of liquid from the gas circuit. It will also be observed that the present invention provides several different forms of check valves adapted for operation by the slight difference in pressure occurring in a three-fluid type absorption refrigeration system.

While several forms of the invention are herein illustrated and described, it will be understood by those skilled in the art that further changes may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. For example, the check valve illustrated in any particular figure of the drawings may be used at any of the locations in the inert gas circuit illustrated in other figures of the drawings, Therefore, without limitation in this respect, the invention is dened by the following claims.

I claim:

1. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure-equalizing gas, a circuit for the pressureequalizing gas having a construction for producing circulation therein by a differential force of gas strong in refrigerant, a gas weak in refrigerant in said circuit, and a check valve lin the gas circuit so constructedand arranged as to be operated to open and closed positions by the flow of gas in said circuit to permit flow of gas in one direction and prevent flow of gas in the opposite direction, and depending passages at opposite sides of the check valve for draining liquid therefrom.

2. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, a liquid absorbent and a pressure-equalizing gas, a circuit for the pressureequalizing gas having separate paths forming a column of gas strong in refrigerant and a column of gas weak in refrigerant, the gas circulating in said circuit by a differential force of said columns of gas strong in refrigerant and gas weak inrefri'gerant, a check valve in the gas circuit operated to open and closed positions by the flow of gas in said circuit to permit flow of gas in one direction and prevent the flow of gas in the opposite direction, a circuit for absorbent liquid, and means connecting the gas and liquid circuits to drain liquid from opposite sides of the check valve and providing a liquid seal to. prevent the flow of gas therefrom.

3. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for.the 'pressure equalizing gas, a check valve in the gas circuit having a movable element operated by the flow of gas in one direction to open the circuit and operated by the flow of gas in the opposite direction to close the circuit, and a construction and arrangement of parts in the gas circuit to provide passages below the movable element of the check valve for draining liquid therefrom.

4. In an absorption refrigeration system hav-A ing a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas including an evaporator and absorber arranged at different levels with conduits connected therebetween, said gas circulating in said circuit by the differential force of gas strong in refrigerant and gas weak in refrigerant in said conduits, a circuit for absorption liquid interconnected with the gas circuit, a check valve in the gas circuit having a movable element closing the circuit and operated by the flow of gas in one direction to open the circuit for permitting the flow of gas in one direction and preventing the iiow of gas in the opposite direction, and said connections between the gas and liquid circuits being so constructed and arranged as to provide passages below the movable valve element -at each side thereof to drain liquid from the gas circuit.

5. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas, a circuit for absorption liquid interconnected with the gas circuit, a check valve in the gas circuit having a movable element for closing the circuit and operated to open position by the flow of gas in one direction in said circuit for permitting the flow of gas in one direction and preventing the ow of gas in the opposite direction, connections between the gas and liquid circuits for ldraining liquid from the gas circuit at opposite sides of the valve, and a liquid trap in at least one of the connections to prevent gas from by-passing the check valve.

6. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas, and a check valve in the gascircuit comprising a tube of an impervious and exible material having longitudinal slits in its periphery, a conduit connected to one end of the flexible tube to supply gas to the interior thereof, means for sealing the opposite end of the tube While permitting liquid to drain therefrom, a casing surrounding the tube, said exible tube expanding to open the slits to permit the gas to flow outwardly from the tube into the casing and contracting to close the slits to prevent the ow of gas from the casing to the interior of the tube, an outlet conduit connected to the casing, and means for draining liquid from the casing.

'7. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas, and a check valve in the gas circuit` comprising a tube having perforations intermediate its ends, ak casing surrounding the tube, a tube of an impervious and flexible material surrounding the perforated tube and having longitudinal slits in its periphery, a conduit for supplying gas to the interior of the perforated tuba-said flexible tube expanding to open the slits to permit the gas to ow outwardly from the conduit to the casing and contracting to close the slits to prevent the flow of gas from thev casing' to the conduit, and an voutlet conduit connected to the casing.

8. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas including an evaporator and an absorber, a circuit for absorption liquid including the absorber and a generator, a conduit through which gas flows from the evaporator to the absorber, a check valve in said conduit and having a movable element operated by the flow 11 of gas toward the absorber to open the conduit and operated by the flow of gas in the opposite direction to close the conduit, and means connecting the gas and liquid circuits to provide passages at each side of the check valve below the movable element to drain liquid therefrom.

9. In an absorption refrigeration system of the type utilizing a refrigerant, an absorbent and a pressure equalizing gas, a generator, a condenser, an evaporator, an absorber, an absorber pot, conduits interconnecting the elements to provide cilcuits for the refrigerant and absorbent, a circuit for the pressure equalizing gas including the evaporator and absorber, a check valve in the gas circuit between the outlet from the evaporator and the inlet to the absorber comprising a casing mounted on the absorber pot, a tube of an impervious and flexible material in the casing and having slits in its periphery, a conduit vconnecting the evaporator and the interior of the flexible tube, a tube extending from thev opposite end of the iiexible tube into the absorber pot below the liquid level therein, a conduit ccnnecting the casing to one end of the absorber, and a conduit connecting the opposite end of the absorber tothe evaporator to complete the gas circuit, said tube of flexible material expanding to open the slits to permit the flow of gas outwardly to the casing and contracting to prevent the iiow of gas from the casing to the interior of the exible tube.

10. In an absorption refrigeration system having a plurality of interconnected elements and utilizing a refrigerant, an absorbent and a pressure equalizing gas, a circuit for the pressure equalizing gas including an evaporator and absorber, a circuit for absorption liquid including the absorber and a generator, said gas circuit including a conduit through which gas iiows from the absorber to the evaporator, a check` valve in said conduit and having a movable element operated by the flow of gas toward the evaporator to open the conduit and operated by flow in the opposite direction to close the conduit, and connections between the gas and liquid circuits to provide passages below the movable element of the check valve at opposite sides thereof to drain liquid therefrom.

11. In an absorption refrigeration system of the type utilizing a refrigerant, an absorbent and a pressure equalizing gas, a generator, a condenser, an evaporator, an absorber, a gas heat exchanger having inner and outer conduits with the inner conduit connecting the outlet-from the evaporator to the inlet to the absorber, a check valve between the outlet from the absorber and the outer conduit of the heat exchanger, said check valve having a movable element operated to open position by the flow of gas in one direction and operated to closed position by the flow of gas in the opposite direction, a conduit connecting the outer conduit of the heat exchanger to the inlet of the evaporator, and drain connections at opposite sides of the check valve below the movable element for draining liquid from the check valve.

12. An absorption refrigeration system of the uniform pressure type including a generator, a condenser, an evaporator, an absorber, structure interconnecting said elements providing circuits for new of a refrigerating medium, an absorption liquid and an inert pressure-equalizing gas, and a W control in the inert gas circuit, said flow control including a housing, a first conduit having an outlet end thereof opening into said housing and connected `at the opposite end thereof to said inert gas circuit, a check valve in said housing having a movable valve head adapted to seat'upon the outlet end of said first conduit, said check valve being arranged to be opened by'inert gas flowing in one dierction only through said inert gas circuit and t0 be closed by gravity, and a second'conduit connected between the iiow control housing and the rst conduit for flow of liquid from the former to the latter in a direction opposite to the ow of inert gas through said inert gas circuit, said second conduit having a liquid trap therein.

l13. An absorption refrigerating system as set forth in claim 12 wherein the head of said check valve comprises a cupped sheet metal disk that seats upon the outlet end of said first conduit.

14. An absorption refrigerating system as set forthin claim 12 wherein the head of said check valve is mounted for pivotal movement upon the outlet end o f said first conduit.

15. An absorption refrigerating system as set forth in claim 12 wherein the outlet end of said iirst conduit projects horizontally into said housing, and the head of said check valve is pivotally mounted upon the top of said iirst conduit at the outlet end thereof.

16. An absorption refrigerating system as set forth vin claim l2 wherein a plurality of guides is formed upon the outlet end of said iirst conduit for guiding and limiting movement of the head of said check valve.

17. An absorption refrigerating system as set forth in claim 12 wherein the outlet end of said first conduit projects vertically into said housing, and the head of said check valve rests freely upon the outlet end of said first conduit.

VVILLIALI L. BULKLEY.

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

UNITED STATES PATENTS Brace Dec. 30, 1941

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