US2599562A

US2599562A - Absorption refrigeration apparatus

Info

Publication number: US2599562A
Application number: US788177A
Authority: US
Inventors: Kogel Wilhelm Georg
Original assignee: Electrolux AB
Current assignee: Electrolux AB
Priority date: 1946-11-28
Filing date: 1947-11-26
Publication date: 1952-06-10
Anticipated expiration: 1969-06-10

Description

June 10, 1952 w KQGEL 2,599,562

ABSORPTION REFRIGERATION APPARATUS Filed NOV. 26, 1947 2 SHEETS-SHEET 1 3'0 NVENTOR.

[ah 4770mm? by vapor-liquid lift action through pipe 28 into the upper part of boiler iii. Refrigerant vapor expelled out of solution in boiler it, together with refrigerant vapor entering through pipe 28, flows upwardly from the vapor expulsion unit 3 to the condenser I4, as previously explained. The absorption liquid from which refrigerant vapor has been expelled flows from the boiler [3 through the outer pipe or passage 3% of liquid heat exchanger 2! and conduit 23 into the upper part of absorber coil 22. The circulation of absorption solution in the liquid circuit just described is eifected by raising of liquid through pipe 23.

The outlet end of condenser I4 is connected by an upper extension of conduit l5, vessel 3! and conduit 32 to a part of the gas circuit, as at one end of heat exchanger 19, for example, so that any inert gas which may pass through the condenser M can flow into the gas circuit. Refrigerant vapor not liquified in the condenser flows through the upper part of conduit l5 to displace inert gas in vessel 3| and force such gas into the gas circuit. The effect of forcing gas into the gas circuit in this manner is to raise the total pressure in the entire system whereby an adequate condensing pressure is obtained to insure condensation of refrigerant vapor in condenser Hi.

In accordance with my invention I provide an analyzer 33 which is arranged in a compact manner at the vapor expulsion unit 9 and more or less forms a unitary part thereof. The analyzer 33 is formed by the horizontally extending portion of an L-shaped conduit 3 which is closed at both ends and to one closed end of which is connected the upper end of the inner pipe or passageZG 0f the liquid heat exchanger. Absorption solution from the absorber vessel 2! enters one end of the horizontal portion 33 of conduit 34, and the lower end of the vapor lift tube 28 is connected to the lower closed end of the vertical portion 35 of conduit 34 to receive absorption solution to be raised by vapor lift action into the upper part of the boiler Ill. The boiler I0 is formed by one leg of an inverted U-shaped conduit whose other leg 33 is connected at its lower end to the analyzer 33 at a region removed from the point at which the liquid heat exchanger pipe 26 is connected thereto. .At a region adjacent to the closed end of the horizontally extending portion 33 of conduit 34 is connected a conduit 3'! which forms a part of the vapor supply line leading upwardly from the vapor expulsion unit 9 to the condenser 14.

- The vapor expulsion unit 9 and absorber including the vessel 2| and coil 22 form a circuit for absorption solution in the boiler ii) of which a column of liquid is maintained at a height, such as indicated in Fig. 1, for example, so that absorption liquid will flow by gravity through a connection or tube 33 into the outer pipe or passage 30 of the liquid heat exchanger and conduit 23 into the upper part of the absorber coil 22. The absorption liquid flowing downwardly by gravity through the absorber coil 22 passes into the absorber vessel 2! in which the enriched absorption solution is maintained at a level, such as indicated in Fig. 1, for example. The analyzer or horizontally extending portion 33 of the L-shaped conduit 34 is at or slightly below the liquid level maintained in the absorber vessel 2!, so that the analyzer will be completely filled with absorption solution during operation ofthe refrigeration system. In effect, the liquid contained in the conduit 34 freely communicates with the store of absorption solution in the absorber vessel 2i through a solid and unbroken liquid body. r

In the operation of the refrigeration system of Fig. 1, vapor generated in the vapor lift tube 28 and boiler [0 passes from the upper end of the boiler into the conduit 36. The generated vapor usually is a mixture of refrigerant vapor and absorption liquid vapor; and, when ammonia and water are employed as the refrigerant and absorption liquid, for example, the generated vapor is usually a mixture of ammonia vapor and water vapor. Due to the difference in boiling points of ammonia and water, the water vapor may be removed from ammonia by cooling the mixture to condense out the water. In Fig. 1 this is accomplished by forcing all of the generated vapor from the conduit 35 through the liquid body in the analyzer 33.

The absorption liquid introduced into the analyzer 33 is relatively rich in refrigerant and at a lower temperature than the generated vapor, and in bubbling through the enriched absorption solution the water vapor is cooled suiiiciently and condenses and in this way is removed from the ammonia vapor. The latent heat of condensation resulting from condensation of water vapor is given up to the enriched absorption solution and forms an internally heated zone in which some ammonia vapor is expelled out of solution. Such expelled refrigerant vapor mixes with refrigerant vapor generated in the vapor lift tube 28 and boiler I3, and the mixture passes from the analyzer 33 through the conduit 37 to the condenser [4.

In the embodiment of Fig. 1 it is desirable to keep the generated vapor in direct contact with the absorption solution in the analyzer 33 for a relatively long interval of time. I accomplish this by making the horizontally extending portion 33 of conduit 34 relatively long in a manner which will not necessitate unduly increasing the overall size of the vapor expulsion unit 9. In a practical form of carrying out the embodiment of Fig. 1, the horizontally extending conduit portion 33 forming the analyzer can be made as a coil which is disposed about the pipes forming the boiler IE3, heating tube II and vapor lift tube 28, in the manner shown in Fig. 3 to be described presently. Such coil can be of any suitable length which may vary from three-quarters to one and one-half turns, for example.

It will be observed that the provision of an analyzer in a vapor expulsion unit 9 like that shown and described lends itself to an extremely compact arrangement of parts. The cluster of vertical pipes forming the vapor expulsion unit occupies a relatively small amount of space in which the individual pipes are in the immediate vicinity of one another. While the pipes in Fig. 1 are shown in spaced apart relation and in the same plane in order to facilitate an understanding of the invention, it is to be understood that in a practical embodiment these pipes may be conveniently spaced apart about the heating tube ll so that they will occupy a minimum amount of space. The liquid heat exchanger 27 can be made in the form of a coil disposed about the lower parts of the heating tube II and the pipes forming the boiler H3 and vapor lift tube 28.

Even when making provision for the analyzer '33 in the vapor expulsion unit 9, there is no greater than that of the liquid heat exchanger,

as seen in Fig. 3. I-Ience, the analyzer 33 in Fig. 1 can beembedded in the same body of insulatingmaterial which thermallyinsulates the... other D rts of the vapor expulsion unit, in the. manner i shown in Fig. 3, thereby providing an efficiently insulated vapor expulsion unit in which provision isumade for analyzing generated vapor. especially important in that the heat recovered in the form-of v latent heat of condensation in the analyzer. 33 can be efiiciently utilized and loss of such recovered heat. from the refrigerationsystern-will be minimized.

Essentially; the absorber coil 22 constitutes an externally cooled zone while the vapor lift tube 28; and boiler lfleach may be referred to as an externally heated zone of the absorption. liquid circuit. In- Fis. 1 it will be seen thattheexternall'y heated zones formed by the vapor lift tube 28gand boiler Ill are vertically extending. and overlap each'other in: a vertical direction; lhe thermal connections of'hoiler Ill and vapor lift tube 28 to the-heating tube H are formed along lines extending-parallel to the axis of the heating tube, such thermal connections extending downwardly from a region above the highest point of the liquid heat exchanger 21. The heat conductive connection of the vapor lift tube as to the heating tube H extends along a vertical distance of which at least one part is fartherfromv the lower heat input end of the heating tube ll than the point of the heat conductive connection of the boiler IE to the heating tube I! which is nearest to the lower end of the heating tube.

In the embodiment just described, the relation of the liquid heat exchanger to the pipes of the vapor. expulsion unit and the conduit forming the analyzer-33 is such that any vapor bubbles which may form in the liquid heat exchanger can freely vent through the connection 38 into the boiler i 0 and from the liquid heat exchanger pipe 26 into the analyzer 33. In this way the absorption solution circulation never can be blocked in the circuit by trapped vapor.

It will also be seen that generated vapor from the conduit 36 passes through liquid in the analyzer 33 with practically no liquid head on the vapor. This has certain advantages in that no appreciable resistance to lifting of liquid in the vapor lift tube 28 is developed. This will be apparent when it is considered that the reaction head for lifting liquid in the vapor lift tube: 28 is contained in the vapor expulsion unit itself.

and extends downwardly from thellquid level in the analyzer 33, which is substantially the same as the liquid level in the absorber vessel 2i,

toa level corresponding to aboutthe pointfi atthe lower end of the vapor lifttube 28. In order to obtain efficient lifting of liquid in the vapor lift tube 28 under theseconditions, the externally heated Zone formedvby the lift tube, is developed as a gas liftpump having a Vapor forming part or which vapor is produced by heating to effect such lightenins'of the fluid columninthe. lift tube that pumping of,

liquid will be promoted under: the. reaction head in, .the Vapor expulsion unit.

Inthe; embodiment of Fig. 1 the heating tube:

electrical; heating element; In thisway; the uppenxfiarts. ofcthe :boiler; l 0 I WhiOh': do-notcon- This is By forming such a slit til the flow of heat till taln' liquid are not heated to such .a higlr: tenrperature that generated vapor. therein: willdoe;

come-superheated4 By. preventing superheating; of generated vapor, the normalccondensatiorr of: vapor' in: other parts: of. the; refrigeration system.

willlnot'be disturbed.

In the embodimentlofl lisr l thENfi pDI'LIifilETMbBJ 28 receives;abSOrptiorrsoliltion which iszrelatively; rich. in refrigerant and which: thereforcmayxbareferred to" as. a; rich liquidv pumpi lin; Fig.1. .25 I have [ShOWll an embodiment of:the,inventions which differs from thatof Fig, ly in that, the, vapor lift ,tube therein receives absorptionssolue" tion which is relatively weakflin refrigerant-and:

which, may be referred 3 to. asza, WEfitklliQlli-d pulllp those shownin Fla, l'are; referred to::by the samereference numerals, absorption solution; enriched, in refrigerant and flowing from the absorber-:21 l to the vapor expulsion unit 9a passes from the" the same manner as the boiler pipe IB-in Fig. 1 and the lower partorsection Illa. thereof isin.

good thermal contact with theheatinggtube Ila, as by Welding, for example, as indicatedat- I211..-

To the lower end'of pipe M is connectedthe.

lower end of vapor lift tube 28a which is in; thermal contact with the exterior of the heating.

tube along a line extending upwardly to. the slitv 49a, such thermal contact in this instance ex?- tending upwardly a greater distancewthan the.

thermal contact of section I90, of the pipe 4!.

Liquid is raised through vapor lift tube 28a. to the upper part of a standpipe or riser 43- whoselower end is connected to the outer passage .01- pipe Bil of the liquid. heat exchanger 21.- The: heating tube Ha in. normal operation heats ;en-= riched absorption solution in the pipe section lila to cause expulsion of refrigerant vapor from solution. The principal part of generated vapor produced in the. vapor expulsion unit of Fis.,. 2 is expelled from solution in pipe section Ilia, and liquid of decreasing, concentration flows downwardlyin, the section Illa to the bottom closedend thereof. In certain. instances it is desirable; to provide a thermal gap or air space. between the lower portion of the pipe section villa and. the. heating tube Ila. In this way excessivenexpulsion of refrigerant vapor from solution in the lower part of pipe section. lila is. prevented. thereby avoiding undesirable decrease in con centrationof the absorption solution and consequent increase in its temperature.

A liquid column is maintained in the riser 33 which is at a level corresponding" t th liquid level in boiler Iii of Fig. 1, so that absorption: solution weak in refrigerant canufiow by gravity. from the lower end of the riser to the upper part. of the absorber coil throughthe outer. passageill of liquid heat exchangers! and conduit 23.. The. plpe ll at a region above the bottom section llla is formed to provide a. horizontally extending section 33w which is utilized as the analyzer of the vapor expulsion unit. From the pipe section. silathe pipe ll extends upwardly to the. condenser and communicates therewith, such upper: pipe section (tla forming the vapor supply lead-. ingito the condenser and corresponding; tothe. conduit 37 in Fis. 1.

Vapor expelled from solution in pipe setig In Fig. 2; in; which. parts similar; ,to;

in which it is analyzed and refrigerant vapor flows through the pipe section 31a to the condenser in which it is liquefied, as explained above in connection with Fig. l. The vapor which passes from the upper end of vapor lift tube 28a into the vapor space of riser 43 flows therefrom through a conduit 45 into the lower part of the horizontally extending pipe section or analyzer 33a. The vapor entering the analyzer 33a from the conduit 45 bubbles through enriched absorption solution and is analyzed, whereby absorption liquid vapor will be removed from refrigerant vapor, as explained above in connection with the embodiment of Fig. 1.

In the embodiment of Fig. 2, it will be seen that vapor passing through conduit 45 is introduced into the analyzer 330; below the liquid surface level of the column of enriched absorption solution therein. While the vapor in conduit 45 and the vapor space of the riser 43 must overcome the liquid head extending upwardly from the point that conduit 45 is connected to the analyzer 33a and the resistance to lifting of liquid in the vapor lift tube 23a is increased, this has not been found objectionable and refrigeration systems which have been constructed and embody vapor expulsion units generally like the one illustrated in Fig. 2 have been satisfactory in operation.

The embodiment of Fig. 2 possesses certain advantages in that the boiler section iila, analyzer section 33a and vapor supply line can be formed from a single continuous length of piping, thereby providing an extremely simple and inexpensive construction. A practical form of vapor expulsion unit like the one shown in Fig. 2 and just described is illustrated in Fig. 3, in which similar parts are referred to by the same reference numerals. It will be seen in Fig. 3 that the liquid heat exchanger 2? is in the form of a coil disposed about the pipes extending downwardly to the lower part of the vapor expulsion unit, and that the analyzer 330; is developed as a turn or coil which envelops the vapor expulsion unit piping. While the pipes are shown as being alongside one another, it will be understood that the component parts are distributed as symmetrically as possible about the heating tube i la.

It will be seen that in Figs. 2 and 3 the pipe providing the boiler section Ilia and vapor lift tube 28a and heating tube I la are disposed alongside one another and extend together as a group or cluster in an upward direction to a region at least as high as the upper end of the vapor lift tube 28a. Likewise, in Fig. l the boiler pipe l0, vapor conducting connection 35, vapor lift tube 28 and heating tube H form a similar group or cluster of pipes and conduits. Further, in both embodiments of Fig. 1 and of Figs. 2 and 3 the analyzing portions 33 and 33a and liquid heat exchangers 21, which are disposed about the heating tubes I I, essentially form a part of such group or cluster of pipes and conduits serving as component parts of the vapor expulsion unit.

The vapor expulsion unit in its entirety, together with the liquid heat exchanger 27 and analyzer- 33a, are embedded in a single body 45 of insulating material retained in a metal shell or casing 41 having openings at the top and bottom through which the ends of the heating tube Ila project.

In vapor expulsion units of the kind shown in Figs. 2 and 3, it is desirable to develop the units in such manner that they can be tilted to a considerable extent and yet avoid the liquid level in pipe 4| falling below the point 42 at which the l q id

exch eer pipe

26,15 connected thereto. This result is obtained'by arranging the absorber vessel 2| at a relatively high level. However, the absorber vessel 2| should not be arranged at such a high level that the liquid surface level therein is such a distance above the connecting point of conduit 45 to the analyzer 33a to render the vapor lift tube 28a ineffective to lift liquid. Hence, in carrying out the embodiment of Fig. 2 in practice, it will be understood that a proper relation of the levels indicated at I, II and III in Fig. 2 is essential for satisfactory operation.

In view of the foregoing, it will now be understood that a new arrangement for circulating fluids in an absorption refrigeration system has been provided which is efiicient in operation, simple in construction and inexpensive to manufacture. In the embodiments described above, generated vapor is analyzed by bubbling such vapor through and in counter-flow to enriched absorption solution passing from the absorber to the vapor expulsion unit. Hence, generated vapor is analyzed by passing directly in contact with absorption solution circulating in an active part of the solution circuit. By way of example and without limitation, the point 42 at which the liquid heat exchanger pipe 26 is connected to pipe 4| may be approximately midway between the liquid level in the absorber vessel 2| and the point at which the vapor conduit 45 is connected to the analyzer or pipe section 33a.

While several embodiments of the invention have been shown and described, it will be apparent that modifications and changes may be made without departing from the spirit and scope of the invention as pointed out in the following claims.

What is claimed is: r

1. In absorption refrigeration apparatus having a refrigerant vapor supply line, a circuit for circulation of absorption solution including an absorber and a vapor expulsion unit comprising an upright heating tube having a lower heat input end, a vertically extending pipe which serves as a boiler vessel and is in communication with said vapor supply line, conduit means for conducting solution from said vapor expulsion unit to the inlet of said absorber including a lift tube having the lower end thereof communicating with the lower part of said pipe, said pipe and lift tube and heating tube being disposed alongside one another and extending together as a group or cluster in an upward direction to a region at least as high as the upper end of said lift tube, said pipe and lift tube being in thermal relation with the exterior of said heating tube, conduit means connecting the outlet end of said absorber and said pipe at one level which is intermediate the ends of the latter for flowing solution by gravity in an unbroken stream from the absorber outlet through said pipe into the lower end of said lift tube and forming a liquid column in said pipe having a liquid surface above said one level,

absorber and a vapor expulsion unit comprising an upright heating tube, a first vertically extending conduit which serves as a boiler vessel and is in communication with said vapor supply line, conduit means for conducting solution from said vapor expulsion unit to said absorber including a second vertically extending conduit and a lift tube having the lower end thereof communicating with the lower part of said first conduit and the upper end thereof communicating with the upper part of said second conduit, said first and second conduits and lift tube and heating tube being disposed alongside one another and extending together as a group or cluster in an upward direction to a region at least as high as the upper end of said lift tube, said first conduit and lift tube being in thermal relation with the exterior of said heating tube, conduit means connecting the outlet end of said absorber and said first conduit at one level which is intermediate the ends of the latter for flowing solution by gravity in an unbroken stream from the absorber outlet through said first conduit into the lower end of said lift tube and forming a liquid column in said first conduit having a liquid surface above said one level, and vapor conducting means to conduct vapor from the upper part of said second conduit to a region of said first conduit below said one level and above the connection of said lift tube thereto for flowing vapor in intimate contact and in counterflow to absorption solution in a part of said first conduit which serves as an analyzer, said last-mentioned analyzer part of said first conduit essentially forming a part of said group or cluster.

3. In absorption refrigeration apparatus having a refrigerant vapor supply line, a circuit for circulation of absorption solution including an absorber and vapor expulsion unit and a vertically extending liquid heat exchanger connected therebetween, said vapor expulsion unit comprising an upright heating tube having a lower heat input end and piping in the immediate vicinity of such heating tube comprising a plurality of sections including a first vertical section which serves as a gas lift pump and a second section which is in communication with said refrigerant vapor supply line and. to the lower part of which said gas lift pump section is connected, conduit means including said liquid heat exchanger which is disposed about said heating tube and connects the outlet end of said absorber and said other piping section for flowing solution in an unbroken stream from the absorber outlet through said liquid heat exchanger and second piping section into the lower end of said first gas lift pump section and forming a liquid column in said second piping section freely communicating with liquid in the absorber, said first gas lift pump section having a part in which vapor is formed which is thermally connected to the exterior of said heating tube in a zone extending downwardly below the highest point of said liquid heat exchanger, means including a third piping section for conducting vapor generated in said vapor expulsion unit to said second piping section for flowing vapor in intimate contact with enriched absorption solution in an analyzing portion of the second piping section and thereafter to said refrigerant vapor supply line and said first and third piping sections and heating tube being disposed alongside one another and extending as a group or cluster in an upward direction to a region at least as high as the upper end of said first gas lift section, the analyzing portion of said second piping section and said liquid heat exchanger essentially forming a part of said group or cluster.

4. In absorption refrigeration apparatus having a refrigerant vapor supply line, a circuit for circulation of absorption solution including an absorber and vapor expulsion unit and a vertically extending liquid heat exchanger connected therebetween, said vapor expulsion unit comprising an upright heating tube having a lower heat input end, a vertically extending pipe in thermal relation with said heating tube which serves as a boiler vessel and is in communication with said vapor supply line, conduit means for conducting absorption solution from said vapor expulsion unit to the inlet of said absorber including said heat exchanger and a vapor lift tube having the lower end thereof communicating with the lower part of said pipe, conduit means including said heat exchanger which is disposed about said heating tube and connects the outlet end of said absorber and said pipe at one level which is intermediate the ends of the latter for flowing solution by gravity in an unbroken stream through said heat exchanger and pipe into the lower end of said vapor lift tube and forming a liquid column in said pipe having a liquid surface above said one level, said vapor lift tube having a part thermally connected to the exterior of said heating tube in a zone extending downwardly below the highest point of said heat exchanger, vapor conducting means including a connection to conduct vapor generated in said vapor expulsion unit to a region of said pipe below said one level and above the connection of said vapor lift tube thereto for flowing vapor in intimate contact with absorption solution in a part of said pipe which serves as an analyzer, and said pipe and lift tube and vapor conducting connection and heating tube being disposed alongside one another and extending together as a group or cluster in an upward direction to a region at least as high as the upper end of said lift tube, the analyzing part of said pipe and said liquid heat exchanger essentially forming a part of said group or cluster.

WILHELM GEORG KoGEL.

REFERENCES CITED The following references are of record in the