US2256519A - Refrigeration - Google Patents

Description

4septzs, 1941. @.GUBB .2,256,519

v REFRIGERATION Filed sept. 17, 1938 zsheetS- sheet 1.

INVENTOR.

v ATTORNEY.

sept. 2 3, 1941.

G. GRUBB 2,256,519 REFRIGERATION Filed sept. 17, 19:58 `2 sheets-sheet 2 1NvENToR v BY Y @3E/MMM ATTORNEY. l

- ly modified or changed at intervals.

listened sept. v23, 1941 i nEFnIGEnA'rIoN Gunnar Grubb, Stockholm, Sweden, assignor, by mesne assignments, to Servei, Inc., New York, N. Y., a corporation of Delaware Application September 17, 1938, `Serial No. 230,402

Germany September 30, 1937 6 Claims.

This invention relates to refrigeration, and

more particularly to an absorption refrigeration system of` the kind containing an inert gas or auxiliary agent.

It. is an object of the invention to provide an improvement in refrigeration systems of this type whereby a condition in the system is automatical- A condition in the system may be modied or changed in accordance with the invention, for example, by bringing about a change of `composition of an agent or a iiuid in the system.

This is accomplished by accumulating successive bodies of uid in liquid phase at a place of accumulation in the system, and automatically dumping elachbody of liquid from time to time from such place of accumulation. 'IIhe liquid dispersed from the place of accumulation, as pointed out above, is utilized to bring about a desired action or change in a part of the system.

The liquid accumulated may be refrigerant, for example, and the successive bodies of accumulated liquid may be automatically dumped from time to time into the weak gas portion of the gas circuit to bring vabout a reduction in` the gas circulation and cause rise of .evaporator temperature to eiect defrosting. v

Instead of dumping successive bodies of accumulated refrigerant into the gas circuit to reduce gas circulation, the liquid may be automatically dumped from time to time into lthe evaporator and collected therein, ywhereby av greater quantity of refrigerant will be available.

for the production of cold to take care ofV an increase inload. A

The successive bodies of refrigerant which are accumulated may be utilized in different ,ways to bring about a change in a condition in the system.

Y For example, the bodies of liquidrefrigerant may be dispersed from the'place of accumulation to -a place of vaporization, andthe refrigerantvapors' ilow at desired intervals of time to renew or force liquid from one part o'f the system to another part of the System, or bring about a change in a condition or of an agent in the system.

The above and other objects and advantages of the invention will be more fully understood upon reference to the following description and the accompanying drawings forming a part of this specication, and in which;

Fig. 1 illustrates more or less diagrammatically a refrigeration system embodying the invention;

and

Fig. 2 is a modiiication of the invention shown in Fig. l. l

In Fig. 1 the invention is embodied in an ab sorption refrigeration system of a uniform pressure type containing a pressure equalizing gas or auxiliary agent. A system of this type includes a generator III, condenser I I, evaporator I2, and an absorber I3- which are interconnected in a manner well-known in the' art and which will briefly be described hereinafter. The system contanis a solution of refrigerant in absorption liquid,

such as ammonia in water, for example, and also an auxiliary agent or inert gas, such as hydrogen,

The generator III is heated in any suitable manner, as by a gas burner I4, for example, whereby refrigerant is expelled from solution in generator III. Refrigerant vapor ilows upwardly through`conduit I5 and an air-cooled rectiiierI I6 into first condenser section I I a of air-cooled condenser I I.

Refrigerant liquefied in condenser section IIa flows into= a trap formed by pipe I'I and conduit Iii. When sufficient liquid accumulates in the liquid trap, liquid iiows through conduit I8 into upper evaporator section `I2a and thence through conduit I9 into lower evaporator section I2b. Evaporator sections I2a and I2b are disposed in a thermally insulated space 20. f,

Refrigerant uid in evaporator section I2b evaporates and diffuses into inert gas which enters through conduit 2|, thereby producing a refrigerating eiect. 'I'he rich gas mixture of refrigerant vapor and inert gas formed in evaporator section I2b flows through a vessel 22and conduit 23 into an outer passage 24 of a gas heat exchanger 25.

Evaporator section I2a is connected by conduits 26 and 21 to outer passage 24 of the gas heat exchanger. Refrigerant fluid in evaporator section I2a evaporates and diiuses into rich gas #which circulates therethrough, thereby producing a refrigerating effect and precooling liquid flowing to evaporator section I2b.

Refrigerant vapor not liqueed in first condenser section IIa ows from the upper end oi' pipe I1 into a second condenser section IIb. Refrigerant liqueed in condenser section IIb shown in the form of a looped coil having a plurality of cooling ns xed thereto.

In absorber I3. the rich gas mixture flows counter-current to downwardly flowing weak absorption liquid which enters through conduit 3I.

The absorption liquid absorbs refrigerant vapor from the inert gas, and inert gas weak in refrigerant flows from absorber I3 through conduit 32, a plurality of .tubes 33 forming an inner passage of the gas heat exchanger, and conduit 2| into the upper part-of evaporator section I2b.

Absorption liquid enriched in refrigerant flows from the lower part of absorber I3 into a vessel 34. From vessel 34 enriched absorption liquid ows through conduit 35 .and an inner passage of liquid heat exchanger 36 to a coil 31-which is disposed about the lower end of generator flue 38. Liquid' is raised by vapor-lift action from coil 31 through tube 39 into the upper part of generator I 0. Refrigerant vapor expelled outl of solution in generator I0, together with refrigerant vapor entering through tube 39, flows upwardly through conduit I5 into condenser section IIa, as explained above.

Absorption liquid from which refrigerant has been expelled iiows from generator I0 through conduit 40, outer passage of liquid heat exchanger 36, and conduit 3| into the upper part of absorber I3. This circulation of absorption liquid is eected by raising of liquid in tube 39 by vapor-lift action.

The lower end of condenser section IIb is connected by conduit 28, vessel 4I, and conduit 42 tothe gas circuit, as at gas heat exchanger 25, for example, so that any inert gaswhich may pass through the condenser can iiow into the gas circuit. Refrigerant vapor not liquefied in condenser II ows through conduit 28 to displace inert gas in vessel 4I and force such gas through conduit 42 into thev gas circuit. By forcing gas into the gas circuit in this manner, the total pressure in the system is raised whereby an adequate condensing pressure is obtained to insure condensation of refrigerant vapor in the condenser. I

Since rich gas ows through evaporator section I2a while gas weak in refrigerant enters evaporator section I2b through conduit 2l, the

gas in-evaporator section I2a contains a greater amount of refrigerant vapor than the gas in evaporator section I2b. The partial pressure of culates continuously in the gas circuit including evaporator I2 and absorber I3. This circulation of inert gas is due to the difference in specific weight of the rich gas mixture in evaporator section I2b, outer passage 24 of gas heat exchanger 25, and conduit 30; and the weak gas mixture in absorber I3, conduit 32, inner passage 33 of the gas heat'exchanger, and conduit 2I.

Since the rich gas is heavier than the weak gas, a force is produced or developed in the gas circuit for causing flow of rich gas toward absorber I3 and flow of weak gas toward evaporator section I2b. Likewise, due to the difference in specific weight of rich gas in conduit 2S and richer gas in evaporator section I2a and conduit 21, a force is developed for causing ow of gas in the local circuit including evaporator section I2a.

In accordance with this invention successive bodies of fluid in liquid phase are accumulated at a place of accumulation and automatically dumped intermittently from such place of accumulation. The successive bodies of liquid automatically dumped intermittently from` the place of accumulation are utilized to bring about a the refrigeration system. Stated another way,

refrigerant vapor is therefore higher in evap orator section I2a than in evaporator section I2b,'and evaporation of liquid takes place at a Ahigher `temperature in evaporator section I2a During normal operation of the system, ey,

frigrant fluid, inert gas, and absorption liqid circulate in the manner described above, whereby evaporator sections I2a and I2bvproduce a refrigerating eiect. Inert gas or hydrogen cirof condenser section bodies of liquid are accumulated and withdrawn from circulation at one place in the system and automatically introduced at intervals of time in another portion of the system to modify or change a condition in the system.

In the particularA embodiment of the invention shown in Fig. l refrigerant fluid in liquid phase is accumulated at a place of accumulation, and successive bodies Vof accumulated refrigerant are automatically dumped at intervals of time into the weak gas column ofthe gas circuit to change the composition of the weak gas and bring about a reduction in the refrigerating effect producedby evaporator section I2b.

-This may be accomplished by connecting a vertically extendng conduit 43 to an upper part of condenser section IIa at 44. The conduit 43 is formed with a U-shaped portion to provide a liquid trap or placeof accumulation 45. Liquid flows from trap 45 at the overflow 46. The internal diameter of conduit 43 is suiiiciently small so that liquid and gas cannot freely pass each other therein.

The lower end of conduit 43 is connected at 41 to a larger conduit or pipe section 48 having an internal diameter sufficiently large whereby gas and liquid canfreely pass each other. The lower end of pipe section 48 is connected at 49 to conduit 32 through which gas weak in refrigerant normally flows from absorber I3 to evaporator section I2b.

In operation, vapors flowing through conduit I5 from generator I0 first flow into air-cooled rectier I6 in which absorption liquid for the most part is condensed and returned through conduit I5 to generator I0. Refrigerant vapor begins to condense and liquefy in the upper part IIa. Liquid refrigerant formedin the extreme upper part of condenser section IIa and ahead of connection 44 of liquid trap'45 can flow into thelatter and accumulate therein. l

The interval of time requiredto fill trap 45 with liquid will depend upon the rate at which heat is supplied to generator I0, the extent of cooling effected in the portion of condenser section IIa between rectifier I6 and connection 44 of liquid trap 45, and the size of the liquid trap. The size of liquid trap 45 and the point where it is connected to condenser section IIa can be selected so that, even when heat is supplied to gen-f erator I at a maximum rate, it will take a desired interval of time for liquid to fill trap 45 to the overow 46. This interval of time may be chosen sothat itv will take several hours or days for liquid to accumulate in trap 45 to the overow 46. y

When sumcient liquid accumulates in trap 45 to reach overow 46,' liquid will automatically flow by siphon action from the trap through conduit 43 into pipe section 46. Flow of liquid by siphon action is eiected inasmuch as the internal diameter of trap 45 and conduit 43 is sufllciently small so that liquid and gas cannot freely pass each other therein. When the liquid column in the left-hand leg of trap 45 becomes sufciently high to start siphoning past overflow 46, the liquid column ilows uninterruptedly from the liquid trap. In effect the body of accumulated liquid is automatically dumped into pipe section I4I! when a predetermined amount of liquid has accumulated in trap 45. When-liquid reaches the connection 41 the liquid column is broken up and the liquid ows downwardly along the walls of pipe section .48 and thence into conduit 32.

The liquid flowing into conduit 32 from pipe section 48 evaporates and diffuses into weak gas flowing from absorber I3 to evaporator section I2b. This increases the specic weight ofthe column of weak gas in the gas circuit and reduces uid refrigerant may therefore continue to iiow from condenser II into evaporator I2. To prevent unevaporated refrigerant fromiiowing out of thelower part of evaporator section I2b when circulation of gas in the gas circuit is reduced, vessel 22 is connected vto the lower part of evaporator section I2b to collect unevaporated refrigerant. In addition to providing vessel 22 thecoil forming evaporator section I2b may be provided with inserts 56 so that shallow pools of liquid ca form therein.

The vessel 22 is provided with spaced baliles 5I having upper openings 52 and other spaced balles 53 having lower openings 54. Further, the lefthand.. end of vessel 22 is provided with an overflow conduit 55 connecting the lower part of the vessel and conduit 23 at approximately the height of upper openings 52. The bailles 5I and 53 and conduit 55 are provided so that vessel 22 can be purged of absorption solution. In the larger pockets liquid refrigerant presses down absorption solution whereby the latter flows through openings 54. In the alternate small pockets absorption solution is raised by mechanical lifting effected by liquid. The vessel 22 can therefore be purged of absorption solution which flows the diierence in specific weight ofthe columnsv of rich and weak gas, whereby the force normally developed for circulation of gas in the gas circuit is reduced. At the termination of a liquid dumping period from trap and before suicient liquid has again accumulated inthe trap to seal the latter, condenser section IIa is in open communication with the gas circuit. In addition to liquid refrigerant evaporating and diffusing into weak gas, therefore, relatively warm refrigerant vapor can also iiow from condenser section I Ia into conduit 32.'

During the period when gas circulation is r'educed, less cold is produced by evaporator section I2b and the temperature of the` evaporator secl tion rises. By properly selecting the size of trap suflicient liquid .has accumulated'in trap 45 to reach overflow 46, another body of accumulated liquid will be dumped into conduit 32. Thus successive bodies of liquidare accumulated in trap 45 and each body of liquid is automatically dumped after an interval of time .to modify or change a condition in the refrigeration system. When liquid refrigerant is dumped 'in the weak gascolumn, the composition of the weak gas is changed to bring about a reduction in gas circulation in the gas circuit.

The heating of generator I0 may continue during the periods when circulation of gas in the gas circuit is reduced or completely stopped and liqtherefrom through conduit 55.

When normal gas circulation in the gas circuit is resumed after liquid has been dumped from trap 45, liquid refrigerant in vessel 22 is immediately available to produce a refrigerating efl and the accumulated liquid in vessel 22 is emmediately available in, the freezing unit to take care of the temporary Iincrease in load.

In Fig v2 is illustrated a modification of the invention in which parts similar to those shown in Fig. l are designatedl by the same reference numerals. Fig. 2 differs from Fig. 1in that the lowerend of pipe I1 is' connectedto a conduit 56 having a horizontal portion and an upwardly extending vertical portion. The pipe I1 and conduit 56 forma U-shaped liquid trap in which liquid refrigerant from condenser section IIa accumulates before it ows through conduit I8 into evaporator section I2a. The lower vertical portion of conduit 56 is arranged in heat exchange relation with conduit I5 by. means of'a metal member 51. Y

The upper end of conduit 56 is connected to an end of a downwardly inclined or slanting conduit 58 to which the cooling fins 59 of condenser II are fixed. The lower end of conduit 58 is bent upwardly to provide a liquidtrap 60. The upwardly bent portion is then bent downwardly to form an overflow 6I. From overiiow 6I liquid can viiow downwardly in conduit 62 which is connected at 63 to a pipe section 64.

' conduit 56' is slowly vaporized by heated' metal member 51 which in turn is heated bythe rel- ,f

atively -warm vapors flowing through conduit I5 from generator I0.' The vapor in conduit 56 flows upwardly into conduit 58 where itlis liqueiied and condensed. TheA liquid accumulates in trap 60, and, when liquid reaches overflow A6r I, the liquid in the trap is automatically dumped by siphon action *into conduit 64 and thence into conduit 32. As in the embodiment of Fig. Y

51 may be formed of metal or other suitable material may be employed `having less heat conductivity. The conduit 56 and member 51 may be spaced apart and the air gap therebetween bridged with different metal members permitting moreor less heat to be transmitted to conduit 56. lThe internal diameter of liquid trap 50 and conduit 62 is suiiciently small whereby liquid and gas cannot freely pass each other therein. On the other hand, pipe section 64 may be of larger diameter so that liquid and gas can freely pass each other.

Although several embodiments of the invention have been shown and described, it will be apparent to those-skilled in the art that various modifications and changes may be made without departing from the spirit and scope of the invention. In Fig. 1, for example, liquid trap 45 may be connected to a separate small auxiliary condenser adapted to receive vapors expelled from solution in generator I0. It is therefore contemplated to cover all modifications and changes which come within the true spirit of the invention, fas pointed out in the following claims.

What isclaimed is:

accumulation to provide a liquid seal in a path connecting the place of evaporation and said path of ow of vaporous refrigerant, and opening the seal by intermittently dumping liquid from the place of accumulation responsive to liquid level.

3. In the art of refrigeration in which ow of auxiliary agent takes place in a circuit having a place in which refrigerant evaporates in the presence of the agent to producea refrigerat-r ing effect, the improvement which consists in collecting liquid in a place of accumulation, intermittently dumping liquid from the place of accumulation when a predetermined quantity of liquid has collected therein, and utilizing the dunped liquid to disturb the flow of auxiliary agent in said circuit to lessen said refrigerating effect.

mulation, intermittently dumping liquid into said y circuit lfrom the place of accumulation when a predetermined quantity of liquid refrigerant has collected in the latter, and utilizing the liquid y `:dumped into said circuit to disturb the ow of 1. In the art of refrigeration in which evaporation to produce a refrigerating eiect,.inert A gas enriched with refrigerant vapor ws from the place of evaporation to a place of absorption, and inert gas weak in refrigerant vapor flows from the piace of absorption to the place of evaporation,` the flow of gas being due to the difference in specific weight of the enriched and weak gas columns, the improvement which consists in collecting refrigerant fluid in liquid phase at a place of accumulation, and intermittently flowing accumulated liquid into the weak gas column when a predetermined quantity of liquid has collected in the place of accumulation, whereby the flow of gas between the place of evaporation and place of absorption-is reduced to lessen said refrigerating effect.

2. In the art of refrigeration with a system in which vaporous refrigerant flows to Va place of condensation and condensed refrigerant flows from the latter to a place of evaporation, the improvement which consists invaccumulating refrigerant fluid 4in liquid phase in a place f of auxiliary agent therein to lessen said refrigerating effect.

5. An absorption refrigeration system of an inert gas type comprising interconnected parts including a gas circuit having a cooling element into which liquid refrigerant is conducted for evaporation in the presence of inert gas to produce a refrigerating effect, means providing a place for accumulating liquid, and said last-mentioned means being embodied in the system in such a manner and being so constructed andarranged thatit is self-acting to cause intermittent removal of liquid therefrom to another pant of the system to disturb the flow of inert gas in said gas circuit to reduce said refrigerating ef- Y fect.

, 6. An absorption refrigerating system of an inert gas type comprising interconnected parts including a gasvcircuit having a cooling element into which liquid refrigerant is conducted for evaporation in the presence of the inert gas to y produce a refrigerating effect, means providing a place for collecting liquid refrigerant and a connection therefrom to said gas circuit, and saidy

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