US2237302A - Absorption refrigeration system - Google Patents

Description

Mm W A. mums ABSDRPTION REFRIGERATION SYSTEM iled 001:. 23, 1937 MMNMMMW www wk mmwodo jay-"JM Patented Apr. 8, 1941 asonr'rioN S PATE 2,237,302 Y I nEFmGEaATroN SYSTEM Nra ` ori-ics Andrew Flakes, Chicago, lll.. assigner to Mills `Novclitsy Company, Chicago, Ill., a corporation ol' Illino Application October 23, 1937, Serial N0. 170,571

19 Claims.

This invention relates to absorption refrigeration apparatus of the type disclosed in my pending application Serial No. 6,899, filed February 16, 1935, now matured into Patent No. 2,150,369 of which the present application forms a continua' tion "in part. The object oi the invention is toI provide a continuously operative,-fully automatic absorption refrigeration system of improved efflclency, adapted for embodiment in large-capacity installations, wherein the eiilciency factor is an important consideration, more so than in the small unit employed in the conventional household refrigerator.-

Other objects of the invention will become apparent from the vfollowing detailed description,"

taken in connection with the accompanying drawing, in which:

The figure is a diagram of a refrigeration system embodying the invention.

In the preferred form of the invention, shown in the ligure, there is provided a generator I in which a body II4 of refrigerant in solution, such as ammonia in water, is heated by a constantly burning gas burner I2. The ammonia vapor driven out of solution, passes upwardly, as indicated by the arrow I3, through a rectifier I4 in the form of a stack secured in the top of the generator I0 and projecting upwardly. The ammonia vapor is initially cooled in the rectier I4 by the heat absorbing action of the coils I5 and I6 surrounding the rectifier. From the upper end of the rectier,4 I4, the ammonia vapor passes through a tube I1 into the coil l5, which constitutes the ammonia vapor condenser of the system.

The ammonia vapor is liquefied in the condenser I5 by the combinedeffectof pressure which exists in the system and the temperature drop caused by the ilowing of cold water through a water tube I8 passing through the coil I5 from one end to the other. After being thus condensed, the liquid ammonia flows from the condenser I5 through a tube I S into a receiver 20, which is of conventional construction. From vthe receiver the ammonia vapor flows through a tube 2l `and an expansion valve 22 to an evaporator 23, wherein the refrigerant vaporizes and cools Whatever refrigerating enclosure ls provided in connection with the system.

From the evaporator 23 the ammonia vapor goes through. a conduit 24 and a check valve 25 to an absorber 26, in which it bubbles up through a body of weak solution 2l.`

The weak solution is taken from the lower region of the, generator I0 through the lower end of a tube 28, by means of a tube 29 extending out of the generator. It thence passes to a heat exchanger 30, which comprises an inner tube 3| and a jacket 32, the inner tube 3| forming a continuation of the tube 29. From the heat exchanger 30,

1 the weak liquor passes through a tube 33 tothe weak-liquor cooler I6. The latter comprises an outer jacket forming a continuation of the tube 33, and a water tube extending inside of said Jacket, said water tube forming a continuation of the tube I8, passing throughv the condenser I5,

. and leaving the condenser and entering the weakliquor cooler at 34.

` Fromthe weak-liquor cooler I6, the weak liquor passes through a tube 35 to the absorber 26, where it absorbs the ammonia vapor entering the absorber through the tube 24. The arrangement thus far described is largely a conventional one Vof the type in which Weak liquor and ammonia vapor are driven at relatively high temperature and pressure from a generator through separate channels in which they are cooled, to an absorber in which they reunite at lower temperature and lower pressure caused by such reunion.

The present invention is concerned primarily with the problem of returning the solution thus formed, back to the generator, against the higher pressure of the generator. In the arrangement disclosed in my prior application above identied, this ls accomplished by periodically equalizing the pressures between the generator and the absorber, allowing the liquor to drain by gravity into the generator from the absorber, which is located at a higher level than the generator, and allowing sufflcient vapor to enter the absorber to displace the liquor drained from the absorber.

One objectionable feature of introducing arnmonia vapor directly into the absorber from the generator, is thata portion ofthe vapor will be absorbed by the weak liquor ln the absorber. Obviously, any absorption of this vapor will impair the efficiency of a system of this kind since it will be necessary to by-pass enough additional vapor to replace that which has been absorbed. Also, it will reduce the capacity of the absorber to absorb vapor coming from the evaporator. The present invention eliminates the direct contact between the by-passed vapor and the liquor in the absorber, while retaining the feature of returning the liquor to the generator by gravity under pressure equalization produced by by-passed vapor.

This is accomplished by providing an accumulator which is associated with the absorber in such a. manner as to periodically withdraw a por-- erator. The liquor is allowed to now by gravity from the accumulator to the generator, and a by-pass conduit adaptedto by-pass vapor from the generator to the accumulator, is provided with a pressure controlled balancing valve adapted to periodically open so as to allow vapor to by-pass into the accumulator from the generator to displace the liquor which flows by gravity from the accumulator back to the generator. According to this arrangement, the bypassed vapor, instead of being allowed to contact the weak liquor in the absorber as was formerly done, is directed to the accumulator in which the liquor has already reached a state of maximum ammonia absorption.

In attaining the foregoing result, it has been necessary to deal with the problem of transferring the liquor from the absorber, which is ordinarily the region of lowest pressure owing to the absorption process going on therein, to the accumulator. in which the pressure would normally be higher owing toits forming a link in the passage back to the region of maximum pressure-the generator. To accomplish this, an arrangement is provided whereby the pressure in the accumulator is reduced for a short period of time during each cycle of operation, suiiiciently to allow excess liquor to flow from the absorber to the accumulator.

Referring again to the drawing, the accumulator 36 is connected to the absorber 26 by a tube 31 through which excess liquor may ilow from the absorber to the accumulator when the pressure in the latter is equal to or slightly lower than. that in the absorber. The accumulator communicates with the generator l through a tube 38 and the jacket 32 of the heat exchangerY 30, whereby liquor may return to the generator when the pressures between the accumulator and generator are equalized.

In order to allow the solution to ow by gravity from the accumulator 36 to the generator, I provide a by-pass conduit 39 leading from the upper end offfthe tube 28 in the generator to the top of the accumulator 36. In the tube 39 is a pressure controlled balancing valve 40, which is norman! Denve' 40 comprises a casing 4l having at fend a valve seat 42, a valve element in crm or a cylindrical skirt 43 having at its j vda. valve head 44 adapted to seat against alve seat 42,- and a. cap 46 which closes the tabove the valve head 44.

of the conduit 39 which is attached toatliefg'enerator, communicates with -the upper regionfof the' valve casing through the valve cap 45 as'shown. That portion of the conduit 39 which attaches to the accumulator, communicates with the bottom of the valve casing 4I. Inside oi the skirt 43 of the valve element is a coil spring 46 which bears against the bottom of the valve casing 4| and the underside of the valve head 44. 'I'he spring 46 normally supports the valve element in an open position in which vapor flowing through the tube 39 in the direction indicated by the arrow 41, may pass through openings 43 in the skirt 43 and thence through the valve. The spring 46 is so balanced against the weight of the valve element 43, 44 and the openings 48 are restricted to such a total area that vapor may flow through the valve with sufiicient rapidity to displace the strong liquor flowing by gravity from the accumulator 36 to the generator l0, and so that a sudden reduction in y valve element to close.

A secondary lay-pass conduit 49 extends from the weak-liquor conduit II to the by-pass conduit 36, communicating with the latter through a restricted orince connection IU, the latter being suillciently small in diameter to allow a sudden reduction of pressure to occur in the accumulator without substantial reduction of pressure in the generator or absorber.

' There are two stages in the return of the liquor to the generator, one in which the accumulated liquor in the accumulator is being drained back into the generator and the other in which the excess liquor is being drained from the absorber into the accumulator. The separation of liquor and vapor in the generator and their reunion in the absorber proceeds continuously during both of these stages, although the rate of absorption will iiuctuate to some extent as a result of variations in several factors including .tne rate of heat absorption in the evaporator and the concentration of the liquor in'the absorber. such fluctuation is under the control or a control valve 11, pressure operated, which closes when vthe pressure in the absorber drops below a predetermined minimum, and opens when the pressure in the absorber rises sufficiently above said minimum to take up the diiierential in pressure which is necessary to cause the valve to operate. The control valve 'l1 thus acts as a governor, holding the operation of the system sumciently below its normal capacity under light load so that the temperature will not drop below the desired-minimum in the space to be refrigerated.

The return of liquor from the accumulator. to the generator occurs while Ithe pressures are equalized between the generator and the accumulator-i. e., while the valve 40 remains open. The stage of transfer of excess liquor from the absorber to the accumulator occurs during a period o! reduced pressure in the accumulator, which reduced pressure is brought about by injection of weak liquor into the accumulator to absorb the ammonia vapor therein, and the closing of the valve 46 to shut olf the communication between the generator and -the accumulator through tube 39, so that the reduction of pressure in the accumulator may be maintained until the accumulator has become lled with liquor.

In detail, the operation proceeds as follows:

Starting with the stage of liquor return to the generator, illustrated in the gure, thevalve4li will be open, and the pressures in generator and accumulator will be substantially equal. While the liquor iiows by gravity from the accumulator to the generator, liquor will simultaneously be iiowing from the generator to Ithe absorber, as long as valve il is open,l but the return iiow from the accumulator to the generator will be suiliciently faster than the iiow fto the absorber so that by the time the accumulator is emptied, the level of the liquid in the generator will have risen above port P connecting the tube 28 to the tube 39.

As soon as the level in lthe generator rises above the port P, the pressure in the generator will force weak liquor from the bottom of the generator through the tube 28 and the tube 39 and valve 40 into the accumulator.

'I'he emptying of the accumulator has caused lt to be filled with ammonia vapor which has ilowed to it through the open valve 40. This vapor will be absorbed by the weak liquor entering the accumulator, which has been cooled by a water jacket 18 so as to have-absorbing capacity.

casacca As a result, the pressure in the accumulator will be sharply reduced and the valve 40, which is sensitive to the consequent drop in pressure at its lower end, will close.

When the valve 40 closes, the reduced pressure in the accumulator will cause weak liquor to be drawn from the tube 3l through the auxiliary by-pass 49 and the restricted orifice 50 into the tube 39 and thence into the accumulator, and\ this flow will continue until all of the vapor in the accumulator has been absorbed and the accumulator is full of liquor.

The reduction of pressure in the accumulator causes the excess liquor in the absorber, standing above the level of the port Si, to be drawn into the lower region of the accumulator while the weak liquor is entering the upper region of the accumulator.

When the accumulator has become lled, the pressures between the accumulator and the generator will be equalized through the oriilce oonnectonjll, sumciently to allow the valve l to open. This equalization of pressure causes the pressure in the accumulator to rise above that in the absorber owing to the continued absorptive action in the absorber, and the ow of solution thence commence to flow by gravity through the tube 38 and jacket 32 of the heat exchanger 3U into the generator, until the point has been reached where the port P is covered by the rising level in the generator, whereupon another cycle of operation, identical with that just described, will take place.

A oat 52 is provided, which covers most of the area of the body of liquor 53 in the accumulator. The purpose of this oat is to prevent absorption by the body of liquor 53 in the accumulator of the vapor 'which is by-passed to the accumulator through the balancing valve I0. It also tends to maintain in the upper region of the accumulator the weak liquor which is delivered thereto through the tube 49 during the stage of that the weak liquor is delivered into the upper region of the accumulator in direct communication with the vapor that it is to absorb while the strong liquor drawn from the absorber is delivered to the lower region of the accumulator.

The lifting of liquor from the generator to the valve 40 can be accomplished either by "arranging the sys-tem so that the closing of the port P will cause the pressure in the generator to increase suiiciently to lift the liquor to the height of the accumulator, or by arrangngthe valve 40 on a level with or below the levelv of the accumulator and arranging for the port P to close while the column of liquor remains in the pipe 38 so that this column of liquor will balance the column of liquor being forced upwardly to the valve I0, or by a combination of both.

In the operation of the valve 40, the sudden reduction of pressure in the accumulator accelerates the flow of vapor through the openings 48 in the valve skirt 4-3. The openings 48 are -tween the absorber and the accumulator.

.lust large enough to allow the normal iiow of vapor suiiicient to displace the liquor ilowing from the accumulator by ,gravity and, consequently, the acceleration of vapor ilow is insumcient to maintain the equalization of pressure through the valve necessary to allow the valve to remain open, and as a result, the valve will close.

A feature of improvement in the present in vention, is the 'arrangement whereby the relatively cold liquor leaving the accumulator is heated during its passage through the heat exchanger so that the amount of heat that it takes from the generator upon returning thereto, will be kept at a minimum. At the same time, the weak liquor delivered from the generator to the absorber is cooled as it passes through the heat eX- changer 3|! so that the amount of cooling water required to operate the cooler IB, is kept at a minimum. Stated in another manner, a substantial portion oi the heat which is taken from the weak liquor during its passage from the generator to the absorber, is returned to the generator through the 'medium of the strong liquor returning from the accumulator to the generator.

The check valve 25 allows flow between the evaporator and the absorber only in the direction or the absorber. Should the absorber pressure at any time exceed that of the evaporator, the check valve 25l will close. A check valve 15 is located in the return line 38 between the accumulator and the generator. This valve allows ,nowhetweenthe accumulator and the generatorionly toward the generator during the stage of equalization between the generator and accumulator, while liquor is being returned. During the stage when the accumulator is at a lower pressure than the generator, the check valve 'I5 closes to allow the lower pressure to be maintained in the accumulator for the purpose hereinbefore set forth.

A check valve 1B is located in the line 31 be- This valve allows flow between the absorber and accumulator only in the direction of the accumulator, and is open during the stage when the accumulator pressure is equalized with or lowered below that of the absorber, so as to allow the drawing olf of liquor from the absorber to the accumulator as hereinbefore described. During the stage when the pressure in the accumula-tor L: above that in the absorber, the valve 16 is closed, so as to -all-ow 4the lower pressure in the absorber to be maintained.

Among the advantages of the present invention are the following:

Constant low pressure is maintained in the absorber. As a result, the absorbing cycle, instead of occupying only a fraction of the complete cycle of operation of the system, extendsuto practically continuous operation. The fluctuation in pressures takes place in the accumulator instead of in the absorber. The absorber may be maintained at a lower tempera-ture owing to the fact that the by-passing of hot liquor from .the generator directly to the absorber, is eliminated. The accumulator is maintained at an intermediate temperature and consequently there is less heat loss from this by-passing step.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limita-tions should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

I claim as my invention:

1. Ina continuous absorption refrigeration system, the combination of a generator, an absor an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively from the generator to the absorber. a draw-off connection for conveying strong liquor from the absorber to the accumulator. a return line for returning liquor from the accumulator to the generator, a by-pass connection for by-passing vapor from the generator to .the accumulator -to displace such returning liquor, and a pressure controlled valvein said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged to Dass a quantity of liquor from the generator to the accumulator when the liquor in .the generator has reached a high level and the accumulator is largely illled with vapor, whereby to produce a reduction in pressure in the accumulator by absorption of the vapor therein, and to cause said Yvalve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction.

2. In a continuous absorption refrigeration system, the combination of a generator, an absorber,

an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively from the generator to the absorber, a draw-of! connection for conveying strong liquor from the absorber to the accumulator, a return line for returning liquor from the accumulator to the generator, a by-pass connection for by-passing vapor from the generator to the accumulator to displace such returning liquor, a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged to pass a quantity of liquor from the generator to the accumulator when the liquor in the generator has reached a high level and the accumulator is largely lled with vapor, whereby .to produce a reduction in pressure in the accumulator by absorption of the vapor therein. and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction, and an auxiliary by-Dass connection between the weak liquor line and the accumulator, adapted to pass an additional quantity of liquor into accumulator after the closing of said valve, to continue the absorption of the vapor therein and thereby continue the ow of strong liquor i'rom the absorber to the accumulator.

3. In acontlnuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weaknliquor and vapor respectively from the generator to the absorber, a draw-011' connection for conveying strong liquor from the absorber to the accumulator, a return line for returning liquor from 4the accumulator -to the gen.. erator, a by-pass connection for by-passing vapor from the generator to the accumulator to displace such returning liquor, a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged to pass a quantity of liquor from the generator Ito the accumulator when the liquor in the generator has reached a high level and the accumulator is largely filled with vapor, whereby to produce a reduction in pressure in the accumulator by absorption of the vapor therein, and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result oi' such pressure reduction, and an auxiliary bit-Pass connection. between the weak liquor line and the'aocumulator, adapted-to pass an additional quantity or liquor into accumulator alter lthe closing 'or said valve, to continue the absorption oithe vapor therein and thereby continue :the now of strong liquor from the absorber to the accumulator, said auxiliary by-pass connection including a restricted orifice for preventing rapid equalization of pressures between the absorber and .the accumulator while allowing passage of liquor.

4. In a continuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively Irom the generator to the absorber, a draw-of! connection for conveying strong liquor .from the absorber to the accumulator, a return line for returning liquor from the accumulator to the generator, a by-pass connection for by-passing vapor from the generator to the accumulator to displace such returning liquor, and a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged to pass a quantity of weak liquor from the lower region of the generator to 'the accumulator when the liquor in the generator has reached a high level and the accumulator is largely illled with vapor, whereby to produce a reduction in pressure in the accumulator by absorption of the vapor therein, and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction.

5. In a continuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor an'd vapor respectively from the generator to the absorber, a draw-oil connection for conveying strong liquor`trom the absorber to the accumulator, a return line for returning llquor from the accumulator to the generator, a by-pass connection for by-passing vapor from the generator to the accumulator to displace such returning liquor, and a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged to pass a quantity of liquor from the generator to the accumulator when the liquor in the generator has reached a high level and the accumulator is largely lled with vapor, whereby to produce a reduction in pressure in the accumulator by absorption of the vapor therein, and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction, said draw-olf and by-pass connections communieating respectively with the lower and upper regions of the accumulator, whereby to concentrate the weaker liquor at the top of the body of liquor in the accumulator during the absorption of the vapor therein.

6. In a continuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively from the generator to the absorber, a draw-oil.' connection for conveying strong liquor from the absorber to the accumulator, a return line for returning liquor from the accumulator to the generator, a by-pass connection lor by-passing vapor from the generator to the accumulator to displace such returning liquor, a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-'pass connection being arranged to pass a quantity of liquor from the generator to the accumulator when the liquor in the generator has reached a high level and the accumulator is largely nlled with vapor, whereby to produce a reduction in pressure in the accumulator' by absorption of the vapor therein. and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction, and a iloat in the accumulator, adapted to minimize contact of bypassed vapor with liquor therein, said draw-off and by-pass connections being so arranged that the weaker liquor will be delivered above the strong liquor, in contact with the vapor in the accumulator.

7. In a continuous absorption refrigeration system, the combination of a generator, an absorber. an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively from the generator to the absorber, a draw-oil connection for conveying strong liquor from the absorber to the accumulator, a return line for returning liquor from the accumulator to the generator, a by-pass connection for by-passing vapor from the generator to the accumulator to displace such returning liquor, a pressure controlled valve in said by-pass connection adapted to close upon a reduction in pressure in the accumulator, said by-pass connection being arranged -to pass a quantity of liquor from the generator to the accumulator when the liquor in the generator has reached a high level and the accumulator is largely filled with vapor. whereby to produce a reduction in pressure in the accumulator by absorption of the vapor therein, and to cause said valve to close, whereby strong liquor will be passed from the absorber into the accumulator as a result of such pressure reduction, said valve comprising a casing having an upwardly facing valve seat, a valve elementvertically movable therein, said element comprising a skirt portion provided with a restricted orifice, means resiliently supporting said valve in a position in which said orifice allows a normal flow of iluid therethrough, the resistance of the orifice being so correlated to that of the resilient supporting means that a sharp increase in the pressure drop across said valve will cause it to close -and to seat against said valve seat.

8. In a continuous absorption refrigeration system, the combination of a generator, an absorber. an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively to the absorber, a drawofi' connection for conveying strong liquor from the absorber to the accumulator, and a return line for returning strong liquor from the accumulator to the generator, said accumulator being arranged to at times have a pressure substantially equal to that in the generator and greater than that in the absorber, and means adapted by the introduction of weak liquor into the accumulator following the admission of vapor thereto, to periodically reduce the pressure in the accumulator sumciently to -ca'use liquor to pass from the absorber to the accumulator through said draw-of! connection.

9. In a. continuous absorption refrigeration sys tem, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively to the absorber, a draw-off connection for conveying strong liquor from the absorber to the accumulator, said accumulator being arranged to at times have a pressure substantially equal to that in the generator and greater than that in the absorber, and means adapted to periodically reduce the pressure in the accumulator sufficiently to cause liquor to pass from the absorber to the accumulator through said draw-oil connection', said means being automatically made eiective for said purpose by rise of the liquor in 'the generator ,to a high level.

10. In a continuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively to the absorber, a draw-oil connection for conveying strong liquor from the absorber to the accumulator, and a return line for returning strong liquor from the accumulator to the generator, said accumulator'being arranged to at times have a pressure substantially equal to that in the generator and greater than that in the absystem, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectively to the absorber, a draw-oit connection for conveying strong liquor from the absorber to the accumulator, said accumulator being arranged to at times have a pressure substantially equal to that in the, generator and greater than that in the absorber, means adapted to period.

ically reduce the pressure in the accumulator sufficiently to cause liquor to pass from the absorber to the accumulator through said draw-oil connection, and to thereafter allow the pressure in the accumulator toreturn to substantially that of the generator and to cause by-passing of vapor from the generator tothe accumulator to allow the liquor to return from the accumulator to the generator, there being a by-pass connection between the generator and the accumulator and said means including a pressure responsive valve in said by-pass connection adapted to remain open as long as the pressures in generator and accumulator are substantially equal and to close under the reduction of pressure in` the accumulator, a restricted orice connection between the weak liquor line and the accumulator, and a return line for returning strong liquor from the accumulator to the generator.

12. In a 'continuous absorption refrigeration system, the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor respectiyely to the absorber, a draw-olf connection for conveying strong liquor from the absorber to the accumulator, a return line for returning strong liquor from the accumulator to the generator, means to periodically cause liquor to flow from the absorber to the accumulator and to thereafter allow the liquor in the accumulator to return by gravity to the generator, a counter-flow heat exchanger forming part of said return line and part of the weak liquor conduit, and a weak liquor cooler through which` the weak liquorows after passing through said heat exchanger, said cooler comprising a counter-flow water conduit disposed in heat exchange relation to said weak liquor conduit.

13. In a continuous absorption refrigeration system, the combination of a generator, a absorber, weak liquor and vapor conduits forl conveying weak liquor and vapor, respectively, from the generator to the absorber, connections for returning strong liquor from the absorber to the generator, a by-pass for passing a quantity oi vapor fromvthe generator to displace the liquor returning to the accumulator, and a pressure-controlled valve in said by-pass, adapted to close upon a reduction in pressure in said connections,

said valve comprising a casing having an upwardly facing valve seat, a valve element vertically movable therein, said element comprising a skirt portion provided with a restricted oriilce, means resiliently supporting said valve in a position in which said orifice allows a normal flow of iluid 4 therethrough, the resistance of the orice being lso correlated to that of the resilient supporting means that a sharp increase in the pressure drop across said valve will cause it to close and to seat against said valve seat.

14. The method oi operating an' absorption refrigeration system having a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor, re-

spectively, from the generator to theabsorber, a-

draw-o' connection for conveying strong liquor from the absorber to the accumulator, and a return line for returning liquor from the accumulator .to the generator, comprising the following steps: injecting cooled `weak liquor into the accumulator to absorb vapor therein and reduce the pressure therein to a level substantially equal -to that of the absorber so as to allow the excess liquor in the absorber to flow into the accumulator. allowing the pressure in the accumulator to raise to that in the generator as it fllls with liquor, and then opening a by-pass from the generator to the accumulator as a result of such pressure increase, to displace the liquor from the accumulator back into the generator.

15. The method of operating an absorption reirigeration system having a generator, an absorber. an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor, respectively, from the generator to the absorber, a draw-off connection for conveying strong liquor from the absorber to the accumulator, and a return line for returning liquor from the accumulator to the generator, comprising the following steps: injecting cooled weak liquor into the ac- -cumulator to absorb vapor therein and reduce the pressure therein to a level substantially equal to that of the absorberso as to allow the excessliquor in the absorber to tiow into the accumulator, a1- lowing the pressure in the accumulator to raise to that in the generator as it illls with liquor, and

causing said return line and by-pass to close as a result of the reduction of pressure during the stage of transfer from the absorber to the accumulator, so as 'ro temporarily maintain the reduction of pressure in the accumulator. 18. In a continuous absorption refrigeratio system the combination of a generator. an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor, respectively, to the absorber, means controlled by a rise of liquid level in the generator for transferring strong liquor from the absorber to the accumulator, and means for transferring the strong liquor from the accumulator to the generator.

17. In a continuous absorption refrigeration system the combination of a generator, an absorber, an accumulati, weak liquor and vapor conduits for conveying weak liquor and vapor, respectively, to the absorber, means for transferring strong liquor from the absorber to the accumulator while the operation of the absorber continues uninterrupted, the pressure in the accumulator being normally higher than that in the absorber and said means including devices for periodically lowering the accumulator pressure to not more than that of the absorber,

lwhereby to effect such transfer, and means for transferring said strong liquor from the accumulator to the generator likewise while the operation of vthe absorber continues uninterrupted.

18. The method of operating an absorption reirigerationv system having a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor, respectively, from the generator to the absorber, a draw-oil' connection for conveying strong liquor from the absorber to the accumulator, and a conduit for returning liquor from the accumulator to the generator, which comprises maintaining constantly a lower pressure in the absorber than in theenerator, the pressure in the absorber being such that absorption may take place therein practically continuously, maintaining at times a higher pressure in said accumulator than in the absorber, periodically reducing the/ pressure in said accumulatorsumciently to cause transfer oi liquor from the absorber to the accumulator, and at other periods increasing the pressure in the accumulator sufilciently to cause transfer of the accumulated liquor therein to the generator.

19. In a continuous absorption refrigeration system the combination of a generator, an absorber, an accumulator, weak liquor and vapor conduits for conveying weak liquor and vapor, respectively, to the absorber, means for transferring strong liquor from the absorber to the accumulator, and means for transferring the strong liquor from the accumulator to the generator, said ilrst mentioned means being controlled by action of the strong liquor after the return thereof from the accumulator to the generator.

ANDREW FLUKES.

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