US2563575A

US2563575A - Absorption refrigeration

Info

Publication number: US2563575A
Authority: US
Publication date: 1951-08-07
Anticipated expiration: 1968-08-07

Description

Aug. 7, 1951 N. E. BERRY ABSORPTION REFRIGERATION Filed Jan. 29, 1947 m INVENTOR. BY 6 I 47'7'0i/Vf) the difference in pressures. between the condenser and evaporator the de-= Patented Aug. 7, 1951 2,563,575 ABSORPTION REFRIGERATIGN Norton E. Berry, New'burg, Ind.,.assignor to Servel,

Inc., New York, N. Y., a corporation of Delaware 'A'pplication'January 29, 19 17, Serial'No. 7 25.000

4 Claims. 1

The present invention. relates to refrigeration systems of the type in which refrigerant vapor is condensed at one pressure and temperature and evaporated at a'lower pressure and temperator and more particularly to apparatus for regulating the flow of fluids between the condenser andevaporator in such systems to automatically purge non=condensable gases from the "conde ser. I

v In such refrigeration systems it has heretofore been considered necessary to prevent the flow of any 'uric'ondensed refrigerant vapor from the condenser and devices 'such as valves, orifices, capilafry tubes and'liquidcolumns have been used between the condenser and evaporator to maintain To maintain a seal siiresin the condenser and evaporator can be essentially maintained while permitting passage or some uncondensed vapor. This is due to the fact that the condenser pressure is largely determined by the temperature of the cooling water used to condense refrigerant vapor in the coniinserand is not greatly affected by the amount orvepor condensed.

, Inaccordancewith the present invention uncondensed refrigerant vapor is purposely permitted to continuously flow from the condenser to the. evaporator and the flow is. limited to an amount which is not an appreciable portion of the total refrigerant flow. This may be accomplished by providing a vertically arranged orifice between the condenser and evaporator. Both liquid refrigerant and non-condensabie gases mixed with refrigerant vapor flow concurrently through the orifice from the high pressure to the low pressure side of the system. The orifice is positioned in the path of flow or conduit connecting the condenser and evaporator and may be formed in a vertical .wall in the conduit or in the end of a horizontal tube or in the vertical Wall of a chamber Within a vessel connected to receive liquid refrigerant from the condenser. In either case, the orifice is arranged in a vertical plane and made larger than necessary to pass all of the liquid refrigerant condensed in the condenser but 2 l small enough so as to limit the flow of uncondensed refrigerant vapor to a predetermined small portion of the total amount of refrigerant flowing therethrough. By permitting the flow of all of the liquid refrigerant and a limited flow of uncondensed refrigerant vapor from the condenser to the evaporator, the difference in pressure in the condenser and evaporator can be maintained and any non-condensable gases in the condenser will flow with the uncondensed re frigerant vapor to the evaporator. Thus the present invention comprises continuously flowing non-condensable gases with a limited quantity of refrigerant vapor from the condenser to the evaporator to automaticallypurge the non-condensable gases from the condenser whilelimiting the loss of uncondensed refrigerant vapor to a negligibleportion of the total "amount of refrigerant flowing therebetween. l

The present invention is'particularly adapted for use with absorption refrigeration systems of the type which operate below atmospheric pressure and utilize a liquid such as water as a refrigerant and potash, sulphuric acid, hygroscopic salts, or the like, as absorbents. Such a system utilizing water as a refrigerant and a halide salt as an absorbent is illustrated and described in the United States Letters Patent to AIbertR. Thomas et al. No. 2,30 1,2 32, issued November 10, 1942, and entitled Refrigeration. N on-condensable ases are apt to occur in the condenser of this type of system and the gases have a tremendous volume at the low pressure in theunit and blanket the heat transfer surfaces. Thus, the presence of small amounts of 'non-condensable gases by Weight in the condenser will seriously interfere with the proper operation of the system. A liquid column has heretofore been "provided between the condenser and evaporator and the noncondensable gases have been removed by entraining them in the condensed refrigerant as it flows from the condenser to the evaporator. When non-condensable gases are purged in this manner slugs or bubbles of refrigerant vapor will also be entrained which are apt to collapse in the lid-- uid column causing a knocking sound or noise and under certain operating conditions the intensity of the noise may become so great as to be objectionable. In accordance withthe present invention the non-oonden-sable gases may be continuously purged from such 'a-system without any of the noise caused by collapsing vapor in a liquid column and by properly dimensioning the path of flow the refrigerant loss may be maintained below 1% of the total amount of refrigerant supplied to the condenser.

1 tially horizontal tubes For purposes of illustration, the invention is shown applied to an absorption refrigeration systern of the type operable below atmospheric pressure. It is to be understood, however, that the drawings are for the purpose of illustration only and not a definition of the limits of the invention, reference being had for this purpose to the appended claims. I

In the drawings:

Fig. 1 is a diagrammatic view of an absorption refrigeration system showing an'orifice between the condenser and evaporator for permitting simultaneous flow of liquid refrigerant and uncondensed refrigerant vapor and restricting the flow of vapor;

Fig. 2 is an enlarged part sectional plan View of a portion of conduit between the condenser and evaporator to more clearly show the orifice;

Fig. 3 is a sectional view of a modified construction for permitting the simultaneous flow of liquid refrigerant and vaporfrom the condenser 'to the evaporator .and restricting the flow of vapor, and Fig. 4 is'a still further modified construction incorporating the novel features of the present invention. 7 r

Fig. 1 of the drawings shows the present invention applied to an absorption'refrigeration system forconditioning air of the type illustrated and described in the Thomas patent, referred to above. The system operates below atmospheric pressure and utilizes water as a refrigerant and a halide salt solution such as lithium chloride or lithium bromide as an absorbent. The refrigeration system comprises a generator 5, condenser 6, evaporator Labsorber 8, and heat exchanger 9 interconnected to provide paths of flow for the circulation of refrigerant and absorbent through the system. Generator 5 has a series of upright tubes I connected at their lower end to'an inlet chamber II for absorption solution and connected at their upper ends to a separating chamber I2. Surrounding the tubes I0 is a shell I3 providing a heating chamber I4 I2 is the condenser, in turn, is connected to the evaporator I by a conduit I I having branches IBa and I Ely-see Fig. 2, constituting a path of flow for liquid refrigerant while permitting a limited flow of refrigerant vapor from the condenser 6 to the evaporator I, as will later be described in detail.

The evaporator 1 comprises a series of substan- IS extending between headers 20 and 2I. Liquid refrigerant supplied 7 by the branches Ifia and I6b of the conduit I6 to one end of the uppermost tubes I 9 in the header 20 flows therethrough by gravity and is collected in a-trough 22 in the header 2| for I directing it into the end of the next lowermost tube. Each tube I9 has a trough 22 for collecta conduit 23 to a concentration vessel 24 which,

I in turn, is connected by a conduit 25 to the inlet 1 chamber II at the bottom of the generator 5. A pressure equalizing conduit 26 connects the top of the concentration vessel 24 to the header 20 of the evaporator I. The concentration vessel 24 is illustrated and described in detail in an application for United States Letters Patent of Lowell McNeely, Serial No. 539,620, filed June 10, 1944, now Patent No. 2,465,904, and operates in response to variations in the difference in pressures in the high and low pressure sides of the system to either store or deliver liquid refrigerant for varying the concentration of the absorption so1u= tion in accordance with varying conditions of operation such as the cooling water temperature. Evaporator 'I communicates with the absorber 8 through the passages or headers 20 and 2| which open directly into the top of the absorber. The headers 20 and 2I together with the top of the absorber B constitute a passageway for directing a stream of air to be conditioned over the tubes I9 and between a series of fins 21 in thermal contact with the tubes to transfer heat from the air to the refrigerant in the tubes.

Absorption solution weak in refrigerant or, in other Words, a concentrated salt solution flows from the separating chamber I2 to the top of the absorber 8 in a path of fiow including a conduit 28, heat exchanger 9, and conduit 29. Absorption solution strong in refrigerant or, in other Words, dilute solution flows from the bottom of the absorber to the inlet chamber II of the generator 5 I in a path of flow including the conduit 30, heat exchanger 9, conduit 3|, leveling vessel 32 and conduit 33. Liquid columns in the conduits 29 .and 30 maintain the difference in pressures in I cated by a reference character 1 and the liquid level in the conduit it is indicated by the refer= ence character 2.

The absorber 8 and. condenser 6 are cooled by cooling water from any suitable source, such as a city main, cooling tower, or the like. The cooling water is supplied from a conduit 34 to a header 35 which supplies the cooling Water to a bank of pipe coils 3% in the absorber 8. Cooling water from the coils 56 is delivered to a header 3'1 and from the header it flows through the conduit 38 to the inlet chamber 39 of the condenser 6. Cooling water from the condenser is discharged from the chamber 40 to a waste pipe, not shown. Concentrated salt solution delivered to the absorber 8 through the conduit 29 is divided into drops by a liquid distributor 4| and the drops trickle by gravity over the bank of pipe coils 36.

The generator 5 is heated by steam supplied through a conduit 43 from any suitable source the heating chamber I4 of the generator 5 is such as a boiler, not shown. It will be understood that a boiler controlled heating system, such as illustrated in the Thomas et a1. Patent No. 2,282,504, issued May 12, 1942, entitled Refrigeration may be used for supplying steam to the chamber I4 of the generator. The upper end of vented to the atmosphere by. a vent pipe 44 and condensate drains from the lower end of the heating chamber through a drain pipe 45. Thus,

steam is supplied to the heating chamber I4 of the generator '5 at atmospheric pressure and at a predetermined constant temperature corresponding to atmospheric pressure and its heat is transferred through the tubes IE to heat the absorption solution therein and expel refrigerant therefrom. The rate at which refrigerant is expelled from the absorption solution in the generator 5 is dependent upon the amount of steam supplied to the heating chamber I4.

In accordance with the present invention the conduit I6 between the condenser 6 and evaporater I is so constru ted and arran ed as to permit the flow of liquid refrigerant as it is con densed in the condenser and a limited flow of noncondensable gases with refrigerant vapor in separate continuous streams. In the embodiment of the invention illustrated in Figs. 1 and Z the conduit It has a restriction in the form of a vertically septum 4% extendin across the conduit 16 with an orifice fill therein. The orifice M is larger than that necessary to pass all of the liquid refrigerant condensed in the condenser E but is small enough to restrict the flow of vapor therethrough to an amount such that no appreciable loss of refrigerant is incurred. For example, with an absorption refrigeration system of the type described for w producing refrigeration at the rate of five tons ice melting effect in twenty-four hours, liquid refrigerant will be condensed in the condenser at the rate of about 1.0 lb./min., the condenser will have a pressure of .049 lb./sq. in. corresponding to a condensing temperature of 106 and the .evaporator will have a pressure of .1474 lb./sq.

in. corresponding to a temperature of 45 F. With ,a difference of pressure of .8016 lbs/sq. in., an orifice of .085 inch in diameter will pass liquid re frigerant at the rate of 1.0 lb./min. The orifice l'ihas a diameter of .110 inch and, therefore, is

Any non condensable gases occurrin in the condenser 6 will flow through the conduit it and orifice ll to the evaporator l with the refrigerant vapor. Due to the fact that the non-condensable gases merely flow through a conduit, they will not produce any objectionable noise such as may occur when vapor is trapped in a liquid column, as

previously explained. The non-condensable gases flowing through the first tubes l 9 of the evaporator I will enter the header 2| and be swept with the refrigerant vapor into the absorber 8. As the non-condensable gases will not be absorbed they will accumulate at the bottom and center of the absorber where there is the least turbulence.

Non-condensable gases in the absorber will also blanketthat portion of the heat transfer surfaces which they cover and a purging device, claimed in a separate application filed concurrently herewith, is provided for constantly withdrawing the non-condensable gases from the absorber B. I As illustrated in Fig. l of the drawings the purging device comprises an auxiliary absorber vessel 50 having a suction tube 5i extending into the absorber 8. A coil 52 in the auxiliary absorber vessel 50 is connected between the

conduits

34 and 38 to flow cooling water therethrough and a conduit 53 connects the top of auxiliary absorber vessel to the conduit 29 to trickle a limited quantity of absorption solution weal; in refrigerant over the cooling coil. A vertical tube 54 is connected between a sump at the bottom of the auxiliary absorber vessel tt and a riser tube 55 and the latter is connected to the conduit 30 at its lower end and to a storage vessel 5%": at its upper end. The auxiliary absorber vessel 50 draws refrigerant vapor and non-condensable gases from the main absorber 8 and the refrigerant vapor is absorbed in solution flowing therethrough. The tube 54 exhausts the solution and non-condensable gases in alternate slugs and the solution news into the conduit 30 while the non-condensable gases ascend through the riser tube 55 and are collected and stored in the storage vessel 55. One embodiment of the invention having now been described in detail the mode of operation is explained as follows:

When steam is supplied to the chamber is of the generator 5 heat is transmitted through the tubes i0 of the generator to expel refrigerant, water, from the salt solution therein and the solution is lifted in the tubes by vapor lift action. The refrigerant vapor then flow through the separating chamber 12 and conduit it into the condenser 5 where it is condensed to a liquid. The absorption solution in the chamber [2 flows by gravity through the conduit 28, heat exchanger 9, and conduit as into the distributor ll at the top of the absorber ii where it is divided into drops and trickles over the bank of cooling coil 36.

Liquid refrigerant and refrigerant vapor flow concurrently through the conduit l6 and orifice d! from the condenser E to the evaporator l. As the stream of liquid refrigerant requires a cross sectional area constituting 0:113. a part of the area of the orifice ll to freely flow therethrough, the refrigerant vapor will flow through the remaining part of the orifice due to the difference in pressure in the condenser 6 and evaporator I. As the volume of refrigerant vapor at the low pressure in the condenser 6 has a ratio to the volume of liquid of 20,000 to 1, the flow of uncondensed refrigerant vapor at low density will be limited to a negligible quantity by the orifice 47 while permitting the flow of liquid refrigerant as fast as it i condensed in the condenser 5. Thus, any non condensable gases in the condenser s will flow with refrigerant vapor through the conduit It and orifice ll to the evaporator T.

The liquid refrigerant entering the uppermost tubes id of the evaporator l flows by gravity through the tubes successively and is evaporated by the transfer of heat from the stream of air flowing over the tubes. Refrigerant vapor caused by the evaporation of liquid refrigerant in the tubes 19 of the evaporator l flows through the headers 20 and 2! into the absorber B where it is absorbed in. the absorption solution trickling over the bank of cooling coils 36 in the absorber. Absorption solutionaccumulating in the bottom of the absorber 8 then flows through the conduit 39, heat exchanger 9, conduit 3i, leveling pot 32, and conduit 33 to the inlet chamber ii at the bottom of the generator 5. Simultaneously, absorption solution flows from the conduit through the auxiliary absorber bill to absorb refrigerant vapor and draw non-condensable gases from the absorber 8. The absorption solution and non-condensable gases in the auxiliary ab=- sorber then flows in alternate slugs through the siphon tube 54 into the riser tube 55 where the gases rise into the storage chamber 5t and the absorption liquid flows into the conduit 39.

In Fig. 3 a modified construction is illustrated for permitting a concurrent flow of liquid refrigerant and non-condensable ases with uncondensed refrigerant vapor from the condenser E to the evaporator 1 comprising a storage vessel 58, claimed in my application for Letters Patent Serial No. 724,821 filed concurrently herewith, for receiving refrigerant condensed in the condenser E. The vessel 58 has a cylindrical wall 59 there- "at the bottom of the generator 5.

of the chamber. The wall 59 has an orifice fil -.to' deliver liquid refrigerant to the sump at a slower rate than it is condensed until the annular chamber 6! is filled and after which the refrigerant overflows the top of the wall 59 to enter the sump. A conduit 53 has a horizontally arranged end projecting into the sump 6i andits opposite branched end connected to the uppermost tubes it of the evaporator I. The horizontal end of the conduit 63 in the sump 6| is reduced and shaped to form an orifice B4 in a vertical plane through which liquid. refrigerant and refrigerant vapor may flow concurrently in separate streams.

The construction illustrated in Fig. 3 operates in the same way as the conduit 16 and orifice 4'1 illustrated in Fig. 1 but provides for the storage of liquid refrigerant during operation of the system and the delivery of stored refrigerant through the orifice 82 after the completion of a period of operation to dilute the absorption solution in the generator 5. To this end the refrigerant flows through the conduit 63, tubes IQ of the evaporator I, conduit 23, concentration vessel 24 and conduit 25 to the inlet chamber 1 Only a small amount of refrigerant will evaporate in the tubes '19 of the evaporator I after the completion .of a cycle of operation as no absorption solution is supplied to the absorber i3 and forced circulation of air over the tubes is stopped.

In Fig. 4 an arrangement of still further modifled construction is illustrated comprising a vessel It connected to receive liquidL refrigerant directly from the condenser E. A closed chamber II is provided in the vessel iii which is illustrated in the form of a cylinder having a vertically 'arranged-side wall. The closed chamber H depends below the vessel to provide a sump E2. The vertical wall of. the chamber ll is provided with an orifice 13 of such dimensions as to permit the simultaneous flow of liquid refrigerant and re frigerant vapor therethrough in separate streams while restricting the fiow of refrigerant vapor to limit the loss of refrigerant. A conduit M connects the sump 12 to the uppermost tubes 19 of the evaporator l. The construction illustrated inFig. 3 operates in the same manner as the conduit I6 illustrated in Fig. 1.

It will now be observed that the present invention provides a method of and apparatus for permitting the continuous flow of liquid refrigerant and non-condensable gases with refrigerant vapor in separate streams from the condenser to the evaporator while maintaining the difference in pressures in the elements. It will further be observed that the present invention provides for automatically purging non-condensable gases from the condenser to the evaporator without the use of special pumping equipment or without noise.

While several embodiments of the invention are illustrated and described it will be understood that further modifications may be made in the construction and arrangement of elements without departing from the spirit and scope of the invention. Therefore, without limiting myself in this respect the invention is defined by the following claims.

I claim:

1. In a vacuum type absorption refrigeration system which utilizes water as a refrigerant and a-salt solution as; an absorbent, aplurality oflements including a condenser operable at one pressure and an evaporator operable at a lower pressure, conduits interconnecting the elements to provide paths of flow for refrigerant and absorbent, said conduit between the condenser'a'n'd evaporator comprising a vessel for receiving liquid refrigerant from the condenser, a closed chamber having a portion in the vessel and a portion below the vessel, said'cha'mber having a substantially vertical wall, an orifice in-the-vertical wall of such dimensions as to permit. the concurrent flow of liquid refrigerant and noncondensable gases with refrigerant vapor and limit the flow of vapor to a predetermined small portion of the total amount of refrigerant flowing therethrough, and a pipe connecting the portion of the chamber below the vessel to the evaporator.

2. In an absorption refrigeration system having a plurality of elements interconnected for the circulation of refrigerant and absorption solution including a generator and condenser operable at a pressure below atmospheric and an evaporator and absorber operable at a still lower pressure, a combination for noiselessly purging non-condensable gases from the system comprising a fall tube so connected to the low pressure side of the system as to utilize flow of said absorption solution to Withdraw gases, a conduit connecting the condenser and evaporator, and a restricting orifree so positioned in said conduit and of a size to maintain the difference in pressure whilepassing liquid refrigerant and simultaneously passing non-condensable gases from the higher pressure side to the fall tube in the lower pressure side without noise.

3. An absorption refrigeration system in accordance with claim 2 having a chamber between the condenser and evaporator connected to receive liquid refrigerant from the condenser, a standpipe in the chamber having an orifice in the side wall thereof for retarding the flow of liquid refrigerant until it accumulates and overflows the top of the standpipe, and. a tube connecting the standpipe to the evaporator and in which said orifice connecting the condenser and evaporator is arranged in an upright position to continuously pass non-condensable gases from the condenser tothe evaporator without noise.

4. An absorption refrigeration system in ac cordance with claim 2 having a vessel between the condenser and evaporator and connectedto re- .ceive liquid refrigerant from the condenser, a

closed chamber in the vessel having a substantiallyvertical wall with said orifice therein, and a tube connected at one end to the chamber below the orifice and at its opposite end to the evaporator.

NORTON E. BERRY. 7

REFERENCES CITED 7 The following references are of record in the file of this patent:

Thomas Apr. 20, 1943