US2655010A - Absorption refrigeration - Google Patents

Description

Oct. 13, 1953 W G, KOGEL ABSORPTION REFRIGERATION 2 Sheets-Sheet l Filed July 14, 1949 Oct. 13, 1953 W G, KQGEL 2,655,010

ABSORPTION REFRIGERATION Filed July 14, 1949 2 Sheets-Sheet 2 O A 5a.

Patented Oct. 13, 1953 UNITED STATES PATENT GFFICE ABSORPTION REFRIGERATION Application July 14, 1949, Serial No. 104,771 In Sweden July 22, 1948 13 Claims. (Cl. (i2-119.5)

This invention relates to refrigeration and is especially concerned with refrigeration systems of the absorption type and refrigerators embodying such systems or apparatus.

The objects of this invention are to provide an improved refrigeration system of this type having a new arrangement and relationship of parts or members which not only contribute to a compact apparatus or unit but also provide for efficient heat exchange between fluids circulating in the system and insure reliable operation under all operating conditions encountered in practice; to provide in such a system an arrangement in which one component or member forms a unitary or integral part of one or several other members; to combine several components or members in one unitary or integral part whereby eiiicient heat exchange may be effected between fluids circulating in the system; to provide such a unitary or integral part in the circuit for circulation of rerigerant which serves as a pressure vessel for inert gas and is in good thermal relation with the inert gas circuit to promote use of such vessel as an extension of the condenser; to provide such a pressure vessel which is advantageously utilized to conduct refrigerant therefrom to an evaporator; to provide a new relationship of parts in the circuit for absorption liquid in which eiiicient heat exchange between fluids in such circuit is promoted and at the same time loss of heat from such fluids to the surroundings is minimized; to provide an improvement for varying the quantity of refrigerant fluid actively circulating in the system; to provide an improved arrangement for raising liquid refrigerant from a condenser to a higher level, as to the evaporator, for example, whereby reliable lifting or pumping of such refrigerant is always assured; and to provide a unitary and compact condenser and absorber construction whereby eflicient air cooling of such parts by natural draft circulation is effected.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the claims. The invention, both as to organization and method, together with the above and other objects and advantages thereof, will be better understood by reference to the following description taken in conjunction with the accompanying drawings forming a part of this specification, and of which:

Fig. 1 illustrates more or less diagrammatically an absorption refrigeration system of the inert gas type embodying the invention;

Figs. 2 to 5 are fragmentary Views diagrammatically illustrating modiiications of the system shown in Fig. 1; and

Fig. 6 is an elevation View of a refrigeration system like that shown in Fig. l diagrammatically illustrating another embodiment of the invention, the system being fixed to framework adapted to be mounted in a refrigerator cabinet.

In Fig. 1 the invention is shown embodied in an absorption refrigeration system of a type employing an inert gas or pressure equalizing agent. Systems of this type are well known and include a generator or vapor expulsion unit I0, a condenser I I, an evaporator I2 and absorber I 4 which are connected to one another to provide circuits for circulation of refrigerant fluid, inert gas and absorption liquid. By way of example, ammonia may be employed as the refrigerant, hydrogen as the inert gas and water as the liquid absorbent.

The vapor expulsion unit I0, which is enveloped within a body 9 of suitable insulating material, may comprise a boiler I5 in the form of piping to which heat is supplied from a heating tube or iiue I6 thermally connected therewith at Il, as by welding, for example. The heating tube I0 may be heated in any suitable manner, as by an electrical heating element disposed within the lower part of the tube I6 or by a liquid or gaseous fuel burner which is adapted to project its llame into the lower end of the tube.

The heat supplied to the boiler I5 and its contents expels refrigerant vapor out of solution, and the refrigerant vapor passes through a rectifier I8 into the air cooled condenser II in which it is condensed and liqueed. In a manner to be described hereinafter, liquid refrigerant is conducted from condenser I I to evaporator I2 in a path of ow which includes conduits I9 and 20, the evaporator being diagrammatically shown and arranged to eiiect cooling of a thermally insulated space 2l. In evaporator I2 liquid refrigerant evaporates and diffuses into an inert pressure equalizing gas, such as hydrogen, which enters through a conduit 22. Due to evaporation of refrigerant uid into inert gas in evaporator l2, a refrigerating effect is produced with consequent absorption of heat from the surroundings.

The rich gas mixture of refrigerant vapor and inert gas formed in evaporator I2 flows from the lower part thereof through one passage 23 of a gas heat exchanger 24 and conduits 2E and 26 into the lower end of the absorber I4 which is in the form of a looped coil. In the absorber I4 the rich gas mixture ows countercurrent to downwardly iiowing absorption liquid which enters through a conduit 2l. The absorption liquid absorbs refrigerant vapor from inert gas, and inert gas Weak in refrigerant flows from the upper end of absorber I4 through a conduit 28, an-

other passage 29 of gas heat exchanger 24 and conduit 22 into the upper part of evaporator I2. In Fig. 1 the evaporator I2 is connected in the inert gas circuit just described in such manner that parallel flow of inert gas and refrigerant fluid is effected in the evaporator. However, it should be understood that the evaporator I2 may be connected in the gas circuit in any other desired manner so that, for example, inert gas and refrigerant fluid pass in counterflow with respect to one another.

The circulation of gas in the gas circuit just described is due to the difference in specific weight of the columns of gas rich and weak, respectively, in refrigerant vapor. Since the column of gas rich in refrigerant vapor Iand flowing from evaporator I2 to absorber I4 is heavier than the column of gas weak in refrigerant and flowing from absorber I4 to evaporator I2, a force is produced or developed within the system for causing circulation of inert gas in the manner just described.

In a manner to be described hereinafter, absorption solution enriched in refrigerant fiows from the lower part of the absorber I4 through a conduit 30 into the upper part of boiler I5. From the lower closed end of boiler I5 absorption solution passes into the lower end of a vertically extending tube 3I in which liquid is raised by vapor-lift action, the tube 3| being heat conductively connected to the heating tube I6, as by welding, to effect such lifting of liquid. The raised liquid passes from the upper end of tube 3I into the upper part of a standpipe or riser 32, and, as will be described presently, absorption liquid weak in refrigerant flows from the lower part thereof to the absorber I4 in a path of flow which includes conduit 21.

The standpipe or riser 32 may or may not be heat conductively connected to the heating tube I5. The principal part of generated vapor produced in the vapor expulsion unit I is expelled from solution in boiler I5, and liquid of decreasing refrigerant concentration flows downwardly toward the bottom end thereof into the vaporlift tube SI. A liquid column is maintained in the standppe 32 whose liquid surface is at such a level that absorption liquid weak in refrigerant can flow by gravity from the lower end of the standpipe into the upper part of the absorber through the conduit 21.

The vapor passing from the upper end of vapor lift tube 3| into the vapor space of standpipe 32 flows therefrom through a downwardly extending conduit 33 into the lower end of a horizontally extending pipe section I 5a formed at the upper part of boiler I5. The pipe section I5a yconstitutes an analyzer into which passes vapor generated in the boiler I5 and in the vapor lift tube 3I. The generated Vapor usually is a mixture of refrigerant vapor and absorption liquid vapor. When ammonia is employed as the refrigerant and water as the absorbent, for example, the generated vapor usually is a mixture of ammonia vapor and water vapor. Due to the difference in boiling points of ammonia and water, water vapor may be removed from ammonia vapor by cooling the mixture to condense out the water.

In Fig. 1 vapor generated in the boiler pipe I5 passes upwardly therefrom through the pipe section I5a, and vapor generated in tube 3I also enters such pipe section through conduit 33. The absorption liquid introduced into the pipe sec.-

tion or analyzer I5a is relatively rich in refrigerant and at a lower temperature than the generated vapor, and in bubbling through the enriched absorption solution at least a part of the water vapor is cooled suiciently and condenses, thus removing water vapor from 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 refrigeration vapor mixes with refrigerant vapor generated in the vapor lift tube 3l and boiler I5, and the mixture passes from the analyzer I5a to the rectier I8.

In the rectifier I8, which may be provided with internal baflies 34, further cooling of generated vapor is effected which is sufficient to cause condensation of water vapor and thereby effect its removal from ammonia vapor. -Such condensate drains downwardly in the rectifier I8 and mixes with enriched absorption solution flowing to the boiler I5. The latent heat of condensation resulting from rectification of generated vapor, that is, condensation of water vapor, is usually referred to as heat of rectification.

In accordance with this invention liquid refrigerant formed in condenser II is raised therefrom to a higher level in such manner that positive raising or lifting of refrigerant liquid is assured under all operating conditions encountered, particularly when the system is placed in operation following a shut down period. In the embodiment of Fig. 1 this is accomplished by providing a conduit or vessel to an intermeiate portion of which the outlet end 36 of the condenser II is connected.

Liquid refrigerant formed in condenser I I flows therefrom into vessel 35 and accumulates in the lower part thereof. From vessel 35 liquid refrigerant flows through conduit I9 into the lower part of vertically extending conduit 20 which is heat conductively connected with the rectifier I8 at 31, as by welding, for example. Due to heat of rectification supplied from the rectifier I8, liquid refrigerant is raised by vapor lift action through conduit 20 to an air cooled condenser 38 which may be provided with a plurality of heat dissipating members 39.

The vapor formed in the lower part of conduit 20 for raising liquid therethrough passes from the upper end of such conduit into condenser 38 and is condensed and liquefied therein. The raised liquid refrigerant and refrigerant condensed in condenser 38 ilows through a conduit 40 into the upper part of evaporator I2 for gravity flow through the latter, as previously explained.

If desired, the condenser 38 may be omitted and an arrangement provided in which the lifting vapor passing from the upper end 0f conduit 20 is returned to the vessel 35 which essentially serves as an extension of condenser II and in which returned vapor is condensed. Such a modification is shown in Fig. 2 in which the upper end of conduit 20 is connected to the upper part of the vertical leg 4I of a generally U- shaped liquid trap 42 whose horizontally extending leg 43 is connected at the outer end thereof by a conduit 44 to the upper end of evaporator I2. When liquid refrigerant in liquid trap 42 reaches the level at which conduit 44 is connected thereto, liquid refrigerant overflows through such conduit into evaporator I2 for gravity flow through the latter. The conduit 20 is connected to leg 4I at a level above the connection of conduit 44 to leg 43, that is, the Vapor space of leg 4I, and lifting vapor passes from such vapor space through a conduit t5 to the vessel 3'5 in which the vapor is condensed and liquefied.

The heat conductive connection 3'! between conduit 20 and rectifier I3 extends for a sulficient distance lengthwise of these members to insure such transfer of heat of rectification to conduit 20 that vaporization of liquid refrigerant will occur in the latter to insure lifting of refrigerant by vapor lift action. The conduit or lift tube 20 is thus heated to a definite temperature, depending upon the boiling point of substantially pure refrigerant under conditions prevailing in the system, to cause vaporization of such refrigerant or refrigerant having a relatively small concentration of liquid absorbent.

The diameter of conduit 20 is sufficiently small so that the vapor bubbles formed due to heat transfer in this manner cannot freely pass liquid in conduit 20, thereby effecting lifting of liquid by vapor lift action. Such lifting of liquid is accomplished under the influence of the column of liquid in vessel 35 whose liquid surface level may be at the level indicated at t6 in Fig. 1, for example, such liquid column usually being referred to as a reaction head which over-balances the column of vapor bubbles and liquid slugs therebetween being raised in conduit 20.

Vaporization of liquid refrigerant in conduit 20 by heat of rectication takes place at a relatively loW temperature. tion of or quantity of absorption liquid present in liquid cooling agent or refrigerant in conduit 20 becomes too high, vaporization of such liquid by heat of rectification often cannot take place at such relatively low temperature 'oecause the presence of liquid absorbent increases the boiling temperature, that is, the temperature at which vaporization occurs. This is especially true when the conduit or vessel 35 contains liquid which is essentially liquid absorbent and which may occur, for example, when the i most adverse operating conditions encountered, n

particularly when the refrigeration system is being started, provision is made for removing liquid absorbent from the liquid lifting system formed by vessel 35 and conduits i9 and 25. In the embodiment of Fig. l this is accomplished by providing a conduit 41 whose lower end communicates with the conduit I9 and lower end of conduit 2!! and whose upper end is preferably connected to rectifier I8 at a level which is substantially at or slightly above the liquid surface level of the liquid column maintained in vessel 35 during operation of the system, such liquid column constituting the reaction head for pumping or raising liquid refrigerant, as previously explained.

If it is assumed the liquid lifting system contains liquid which is essentially or for the most part liquid absorbent when the refrigeration system is started following a shut down period, the vessel 35 will contain such liquid absorbent. Under these conditions liquid refrigerant having a relatively small concentration of liquid absorbent will be formed in condenser Il and flow therefrom into vessel 35 and gradually set- When the concentrag;

tle over the body of liquid absorbent. In this way liquid absorbent in vessel 35 will be displaced from the latter and pass through conduits I9 and 4'! into the rectifier I8. Eventually all of the liquid absorbent in vessel 35 and conduit I9, as well as the liquid absorbent in conduit 20, will be replaced by liquid refrigerant having a relatively small concentration of liquid absorbent, thereby enabling conduit 20 to function and cause lifting of liquid refrigerant therethrough by vapor lift action by heat of rectication, as previously explained. The liquid absorbent entering rectifier I8 from the upper end of conduit 41 flows downwardly by gravity and finds its Way to the absorption liquid circuit.

In view of the foregoing, it will now be understood that positive and reliable lifting or pumping of liquid refrigerant from condenser I I to a higher level can always be effected, even under the most adverse operating conditions encountered, by removing liquid absorbent from the liquid lift or pump system. In Fig. 3 as illustrated another manner of removing liquid absorbent from the liquid lifting system which is especially effective in promoting rapid lifting of liquid refrigerant from condenser II to a higher level. The embodiment of Fig. 3 differs from that of Fig. 1 in that conduit 41 is replaced by a conduit i3 which is more or less U- shaped to form a liquid trap having one leg 49 communicating with the conduit 20 at approximately the liquid level 46 in vessel 35 and the other leg 50 communicating with the rectifier I8 at the same level or possibly slightly higher level.

The connections of conduit 48 to the conduit 2Q and rcctier I5 may be accomplished by forming small openings 5I and 52 in the latter, and securing the upper open ends of legs 49 and 5@ to the conduit 25 and rectifier I8, respectively, at regions surrounding such openings. In addition, conduit i3 is formed of relatively small or narrow tubing to develop a definite resistance to passage of liquid even before the U- shaped trap formed by this conduit is completely filled with liquid. In the event the liquid lifting system of Fig. 3 contains liquid absorbent, such absorbent is replaced by liquid refrigerant having a relatively small concentration of absorbent substantially in the saine manner as in the embodiment of Fig. l and described above. However, in Fig. 3 liquid absorbent is displaced from vessel l35 and forced through conduit I9 and lower part of lift tube or conduit 20 into the U-shaped conduit 48. From conduit 48 such liquid absorbent passes into rectifier IB, and ultimately conduit 2i) will contain liquid refrigerant having a relatively small concentration of absorbent, so that lift tube 25 will effectively function to raise such liquid therethrough.

In accord with the invention the embodiment of Fig. 1 embodies provisions for varying the quantity of refrigerant fluid circulating in the refrigeration system for producing useful refrigeration. This is accomplished by providing a vessel 53 in which refrigerant fluid is held in an inactive portion of the refrigeration system under certain operating conditions. The vessel 53, which may be referred to as a concentration vessel, is connected to receive liquid refrigerant in the lower part thereof through a conduit 54 whose upper end is connected at 55 to the conduit 25 immediately ahead of a barrier or dam 56 with respect to the direction of flow of liquid from the evaporator I2.

In this manner unevaporated liquid refrigerant passing from the lower end of evaporator I2 and flowing through the inner passage 23 of gas heat exchanger 24 is diverted by the dam or barrier 55 into conduit 54 through which it is conducted to vessel 53 and collects therein. The vessel 53 is heat conductively connected to rectifier I8 in any suitable manner, as by welding, so that heat of rectification is transferred by rectifier I8 to vessel 53 and its contents. Vaporization of liquid refrigerant continuously takes place in vessel 53 due to such heatingy and such vapor passes upwardly from the vessel through a connection 51 into the extreme upper part of rectifier I8 and flows into the condenser I I along with vapor flowing from the rectifier into the condenser.

When the load on evaporator I2 increases less unevaporated refrigerant passes from the lower end thereof; and, when the evaporator load increases sufficiently, all of the refrigerant supplied to the evaporator I2 evaporates and diffuses into inert gas therein to produce useful refrigeration. Under such operating conditions the flow of liquid refrigerant to vessel 53 through conduit 54 ceases; and, with continued evaporation of liquid refrigerant in vessel 53 by heat transfer thereto from rectifier I8, refrigerant vapor flows therefrom to condenser I I until the vessel is depleted of liquid.

Hence, when the load on evaporator I2 increases, as when ice trays containing water to be frozen are positioned in an ice freezing compartment of the thermally insulated space 2 I, for

example, a greater quantity of refrigerant fiuid actively circulates in the refrigeration system to promote useful refrigeration and take care of increase in load. Conversely, when the load on the evaporator I2 decreases and unevaporated refrigerant passes from the lower end thereof, such refrigerant fluid collects in vessel 53 when it ows thereto at a faster rate than that at which it evaporates due to heating from the rectifier I8. While unevaporated refrigerant may be allowed to drain through a liquid trap in conduit 54 directly into the bottom part of vessel I and mix with refrigerant the-rein, it will be understood from the foregoing that certain advantages are realized by providing the concentration vessel 53 which functions in the manner just described.

The vessel 53 is connected in the system in such manner that removal of liquid therefrom, even a mixture of liquid refrigerant and absorbent, is readily effected without any additional provisions. Liquid absorbent present in vessel 53 is vaporized therein and the vapor thus formed, which is not required to lift liquid by vapor lift action, passes into condenser Il from which it is drained into the absorption liquid circuit, as previously described. Also, the refrigeration system may be such that there is inadequate space in the system for storing and holding a large quantity of excess refrigerant. By providing the vessel 53, such excess refrigerant is effectively withheld from circulation and returned to the active portion of the system to produce useful refrigeration without the necessity of draining such refrigerant into the absorption liquid circuit.

In absorption refrigeration systems of the inert gas type being described, it is usually the practice to provide a separate vessel which is connected to the outlet end of the condenser and to the gas circuit, respectively, so that any inert gas which may pass through the condenser can fiow into the gas circuit. Refrgerant vapor not liquefied in the CLI condenser flows into such separate vessel to displace inert gas therefrom 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 the condenser. For this reason the separate vessel connected in the refrigeration system in the manner just described is usually referred to as a pressure vessel.

In further accord with the invention, in order to simplify the refrigeration system and provide a compact arrangement of components or parts, the vessel or conduit 35 is arranged to serve as a pressure vessel which surrounds or envelops the conduit 26 and forms a jacket about the latter. The outlet end of condenser I I is connected to an intermediate part of pressure vessel 35, so that the lower part thereof serves as a place for holding liquid refrigerant flowing thereto from the condenser. Further, the upper part of conduit 26 is formed with an opening 58 to connect the pressure vessel 35 to a part of the gas circuit so that the latter will function in the manner described above. Therefore, as illustrated in Fig. l and just described, the vessel 35 serving as the pressure vessel of the refrigeration system forms a unitary or integral part of at least one other member or component of the system. In the embodiment of Fig. 1 the vessel 35 and the manner in which it envelops conduit 26 actually makes the pressure vessel an integral part of several members of the refrigeration system and eliminates connections previously necessary, especially the conduit connections to such a pressure vessel when a separate vessel is employed for such purpose.

By employing vessel 35 as a pressure vessel which envelops conduit 26, desirable heat exchange between fiuids in the system is effected, particularly to effect cooling and condensation of refrigerant in vessel 35 which passes therein from condenser II. Since gas enriched in refrigerant, which is relatively cold, ows through conduit 2G, it is desirable to shield the latter thermally from atmospheric air to avoid condensation of moisture at the outer surfaces thereof. In Fig. 1 this is effectively accomplished by employing vessel 35 as a jacket about conduit 26. In order to shield all parts of the path of flow for relatively cool enriched gas, the conduit 25 and adjacent ends of gas heat exchanger 24 and vessel 35 may be enveloped in a body 5819 of suitable insulating materlal, as shown in Fig. 4. Alternatively, the gas heat exchanger 24 and vessel 35 may be so formed and connected in the refrigeration system that adjacent ends of these members or components are in abutting relation at 59, as shown in Fig. 5, thereby completely enveloping conduit 26 for the relatively cool rich gas. In the arrangement of Fig. '5, the conduit 28 through which gas Weak in refrigerant flows from absorber I4 desirably is shifted to the outer extreme end of the gas heat exchanger 24.

It is usually the practice to mount the refrigeration system or apparatus on a wall of a household refrigerator cabinet, particularly the rear Wall of such a cabinet, for example. In such case the lateral side Walls of the outer shell of the cabinet project rearwardly from the rear insulated wall to form a vertically extending space for housing parts of the refrigeration apparatus. Such vertically extending space may be completely operi or closed or partly closed by a Wall member. In any event the vertically extending similar parts are designated by the same reference numerals. The vapor expulsion unit Illa of Fig. 6 is enveloped in a body 9a of suitable insulation and comprises a boiler Ib in the form of a vertical pipe having an upper extension which constitutes the rectier Ia having baffles 34a therein. Heat is supplied to boiler lh from a heating tube I6a thermally connected therewith at Ila, such heating tube being of a type adapted to be heated by an electrical heating element therein. However, the heating tube may be arranged to extend entirely through the insulation body 9a and adapted to be heated by a gaseous or liquid fuel burner at the lower end thereof.

As will be described presently, enriched absorption liquid flows from absorber Ilia in a path of flow which includes a conduit 65 andan inner passage of liquid heat exchanger 66 whose upper end is connected at 61 to boiler I5b at a region below the liquid surface level maintained in the latter. To the lower end of boiler b is connected the lower end of vapor lift tube 31a thermally connected at 66 to the heating tube Ia. Liquid of decreasing refrigerant concentration flows downwardly in boiler 15a, and liquid is raised by vapor lift action in tube 3io to the upper part of standpipe or riser 32a. Absorption liquid weak in refrigerant passes from the lower end of standpipe 32a into the outer passage of liquid heat exchanger 66 and thence through conduit 21a into the upper part of absorber Ida.

Vapor for lifting absorption liquid through lift tube Sla passes from the upper end of standpipe 32a through a conduit 33a into the upper inclined section I5c of boiler I5b and bubbles through liquid therein, such inclined section constituting an analyzer similar to the analyzer I 5a in Fig. l. The vapor generated in boiler Ib and lifting vapor entering through conduit 3 I a passes from analyzer I5c into rectier Ia and into condenser Ila in which refrigerant vapor is condensed and liquefied.

The lower end of condenser IIa is connected at 68a to vessel 35a which is disposed about conduit 26a through which relatively cool enriched gas flows from evaporator IZc to absorber Ida. Liquid refrigerant flows from vessel 35a through conduits lea and a and is raised in the latter to a condenser 38u,` provided with cooling ns 39a. The lifting vapor is condensed in condenser 38a and such condensate, together with raised liquid, is `conducted to the evaporator 12a in the same manner that liquid is conducted from condenser 38 to evaporator I2 in Fig. l. Evaporator I2a is connected in a gas circuit which includes a gas heat exchanger 24a, only the outer end of which is seen in Fig. 6. In order to simplify Fig. 6, the connections between evaporator I2a and gas heat exchanger 24a are not shown, it being understood that such connections are similar to those illustrated in Fig. 1 and described above.

The vessel a in Fig. 6 differs from the corresponding vessel 35 in Fig. 1 in that it is divided by a partition 69 to form an upper space 10 and a lower space 1I. The part of vessel 35a serving as the pressure vessel forms a jacket about conduit 26a, the lower end of which terminates at an opening in partition 69. The lower space 1I constitutes the absorber vessel of the refrigeration system to an intermediate region of which the absorber coil Ilia is connected at 12.

The operation of the system shown in Fig. 6 is generally like that described above in connection with Fig. 1. In Fig. 6 gas enriched in refrigerant flows from evaporator 12a through the inner passage of gas heat exchanger 24a and conduits 25a and 26a into the space 1I of vessel 35a. From the upper part of such space 1I the enriched gas iiows upwardly through absorber coil Ida countercurrent to weak absorption liquid which enters the upper part of absorber Ida through conduit 21a. Inert gas weak in refrigerant flows from the upper part of absorber Ha through conduit 28a and outer passage of gas heat exchanger 24a to the evaporator I2a. As previously stated, liquid refrigerant is supplied to the evaporator from condenser 38a through conduit 40a.

Liquid refrigerant formed in condenser IIa iiows therefrom into the upper space 10 of vessel 35a and collects in the bottom part thereof. As in the embodiment of Fig. 1, the space 10 communicates with the gas circuit through an opening 58a formed in conduit 26a.. One end of conduit lila is connected at 13 to vessel 35a to withdraw liquid refrigerant from the bottom of space 10. From conduit ISa liquid refrigerant passes into conduit or lift tube 20a which is heat conductively connected at 31a to rectifier I8a. A conduit 41a similar to conduit 41 in Fig. 1 is provided for removing liquid absorbent from space 10 and conduits [9a and 20a'. Such conduit 41a at its upper end is connected to rectifier Ia for conducting liquid absorbent to the latter which then flows by gravity in the rectier into the absorption liquid circuit.

The conduits Isa, 20a and 41a. in Fig. 6 correspond to the conduits I5, 20 and 41 in Fig. 1 and the part of the description of Fig. 1 directed to the function and operation of these members is equally applicable to the corresponding members in Fig. 6. Although not shown, it is to be understood that Fig. 6 may also embody a concentration vessel like the vessel 53 in Fig. 1 and conduit connections 54 and 51 associated therewith.

From the absorber Ma enriched labsorption liquid ows into the lower space 1I of vessel 35a. which constitutes the absorber vessel. From this vessel enriched liquid flows through conduit B5 to the boiler |51) as previously explained.

In Fig. 6 the condenser Ila and absorber Ma may be formed of flattened looped piping each having straight sections in spaced apart vertical planes, and separate groups of cooling ns 60a may be provided for 'the straight coil sections in each vertical plane, each n being utilized both for the condenser and absorber. In this manner an air shaft is formed between the spaced apart straight coil sections within which the vessel 35a is disposed. Hence, the advantages described above in connection with Fig. 1 concerning the compact arrangement and cooling of vessel 35, condenser II and absorber I4 are equally applicable to the similar compact arrangement of vessel 35h, condenser Ila and absorber Illa of Fig. 6. It should be further understood that the modied constructions illustrated in Figs. 2 to 5 in connection with the embodiment of Fig. 1 are also equally applicable to the embodiment of Fig. 6.

In Fig. 6 the refrigeration apparatus is fixed at a number of places 14, as by welding, to a frame 15 formed of angle members 16, 11, 18 and 19. Such frame 15 may be removably secured to a household refrigerator cabinet at the rear insulated wall thereof so as to position the apparatus in a vertically extending space dened by the rear insulated wall and rearwardly extendspace, due to the positioning of heat dissipating parts of the refrigeration apparatus therein, promotes upward natural draft circulation of air for cooling such heat dissipating parts which include the condenser, absorber and pressure vessel.

The embodiment of Fig. 1 lends itself to enicient air cooling because the absorber I4, condenser II and pressure vessel 35 provide a compact unitary construction in which the pressure vessel is contacted by upwardly flowing cooling air at substantially the same time such cooling air sweeps over the surfaces of the condenser. Further, the straight portion of the piping forming the condenser I I may form an elongated coil which encircles and is more or less wrapped about the pressure vessel 35, thereby tending to localize the regions at which heat is given up to cooling air and making more effective the induced natural draft circulation of air over these parts. Since the pressure vessel 35 is effectively cooled, it serves as an extension of the condenser II in which effective condensation of refrigerant vapor takes place, thereby contributing to a compact condenser and pressure vessel construction. It is for this reason that the condenser 38 of Fig. 1 may be omitted, if desired, and the arrangement of Fig, 2 employed in which vapor for lifting liquid can be returned from the upper end of lift tube or conduit to the pressure vessel 35. as shown in Fig. 2 and described above.

As stated above, the condenser may envelop the pressure vessel in which case the 'straight sections of the condenser I I are disposed in spaced apart vertical planes. Similarly, the absorber coil I4 may be formed in -a similar manner, and. by virtue of the compact arrangement of these parts, they can be treated or considered as a single component in the fabrication of the refrigeration apparatus. This is especially important when heat -dissinating members are provided on the absorber coil I4 which also may be utilized as heat transfer members for the,` condenser II. Such a construction is shown in Fig. 1 in which the length of the fins 60 is approximately the same as the overall height of the condenser II and absorber I4. It is to be understood that a separate group of such ns 50 may be provided for the straight sections of the condenser II and absorber I4 in each vertical plane of such straight sections, thereby providing a vertically extending air shaft therebetween in which the pressure vessel 35 is disposed and subjected to vigorous cooling effect by the natural draft circulation of air induced in the manner described above.

This arrangement of condenser II, absorber I4 and pressure vessel 35 is especially important in a refrigeration system of the type shown in Fig. 1 in which the condenser is located below the evaporator. This is so because the compact condenser, absorber and pressure vessel structure is located at a relatively low leve1 compared to the overall height of the apparatus. With such construction heat is dissipated from all of the heat emitting parts or components near the lower part lof the apparatus space which tends to promote a driving upward force to cooling air being circulated by natural draft circulation. Such driving upward force imparted to cooling air can be accentuated by closing off the open side fof the vertically extending apparatus space previously described from the upper end of the cabinet down to the condenser or, if desired, to a point immediately below the absorber. In this way a good chimney effect can be provided to cause upward movement of air by natural draft circulation over the heat emitting parts of the apparatus to take up heat dissipated therefrom.

In another phase of the invention special consideration is given to the storing of enriched absorption liquid in the absorption liquid circuit. It is usually the practice to flow enriched absorption liquid from the absorber coil to a vessel and collect liquid therein, such collected liquid forming the upper part of a liquid column under the influence of which liquid is raised to a higher level in the vapor expulsion unit. Since heat of absorption is liberated in the absorber coil, such enriched absorption liquid collecting in the storage vessel is relatively warm. It is customary to flow such warm absorption liquid in thermal relation with Weak absorption liquid passing from the vapor expulsion unit to the absorber coil in a liquid heat exchanger which constitutes a separate part or component of the refrigeration apparatus.

In further accord with the invention a vessel E I, which is connected to receive enriched absorption liquid from the absorber I 4 through conduit 30, is enveloped in the same body 9 of insulation enveloping the vapor expulsion unit I0 and constructed and connected in the refrigeration system so that the warm enriched liquid is advantageously utilized to effect heat transfer with weak absorption liquid and generated vapor or either of these fluids.

As seen in Fig. l, the vessel 5I for storing enriched absorption liquid is enveloped in the single body 9 of insulating material and such enriched absorbent rises upwardly therein from the connection of conduit 30 to the upper part thereof within which the horizontally extending pipe section or analyzer I5a projects. Below the pipe section I5a is positioned a vertically extending coil 62 whose upper end is connected to receive weak absorption liquid from the lower part of standpipe 32 through a conduit 63. Hence, weak absorption liquid is conducted downwardly through coil 62 and heat transfer is effected between such weak liquid and rich absorption liquid rising in vessel 6I. In addition, conduits 21 and 3I may be arranged in heat exchange 'relation at 64, as by welding, so that further counterflow heat exchange can be effected between these fluids.

By way of example and without limitation, the vessel 6I may be of such size that it can hold from 0.75 to 2 liters of absorption solution which may constitute per cent or more of the entire quantity of liquid absorbent held in the refrigeration system. In other words, the upright vessel 6I in the immediate vicinity of the generator I0 is arranged to hold a major portion of the absorption solution circulating in the system. Since the enriched liquid absorbent passing from absorber I4 is relatively warm, it will be understood that an arrangement has been provided whereby heat is effectively conserved within the system, the liquid in the insulated liquid body within vessel 6I being in efficient heat transfer relation with weak liquid absorbent in coil 62. Further, by projecting the analyzer ISG, into the upper part of vessel 6I below the liquid level therein, a compact arrangement is also provided to effect heat transfer between enriched absorption liquid and generated vapor in the manner previously described.

In Fig. 6 is shown a refrigeration system generally like that illustrated in Fig. 1 in which ing parts of the lateral side walls of the outer metal shell of the cabinet. When the frame 15 and apparatus fixed thereto are mounted in position, the evaporator 12a is adapted to be positioned within the thermally insulated interior of the cabinet through an opening in the rear insulated wall which may be closed by an insulated closure member. Hence, the advantages described above, in connection with the embodiment in Fig. 1 when such system is mounted in a vertically extending apparatus space like that just described, are also realized in the embodiment of Fig. 6.

Modifications of the embodiments of the invention which have been -described and illustrated will occur to those skilled in the art, so that it is desired not to be limited to the particular arrangements set forth. Moreover, certain features of the invention can be advantageously employed independently of other features. Therefore, it is intended in the claims to cover all those modifications and features which do not depart from the spirit and scope of the invention.

What is claimed is:

1. In absorption refrigeration apparatus having a plurality of parts including an evaporator and absorber and connections therebetween for circulation of inert gas therethrough, one of said parts functioning to transform refrigerant vapor to liquid, a pump system providing means for conducting liquid refrigerant from said one part to said evaporator by vapor lif't action under the iniiuence of a column of liquid serving as a reaction head, another of said parts providing a vessel for holding liquid in said column which is connected to receive liquid from said one part and in thermal exchange relation with the connection through which relatively -ccol inert gas flows from said evaporator to said absorber, the vapor space of said vessel being in communication with said last-mentioned connection, and means for draining objectionable liquid from said pump system comprising a connection communicating with said pump system and with one of said parts outside said pump system.

2. Apparatus as set forth in claim 1 in which another of said parts constitutes a rectifier, said pump system being arranged to make use of the heat of rectific-ation produced by said rectifier to form vapor to conduct liquid by vapor lift action, a concentration vessel in thermal exchange relation with said rectier, and connections for owing unevaporated liquid from said evaporator to said concentration vessel and for fiowing vapor from the latter to said one part to transform such vapor to liquid.

3. Apparatus as set forth in claim 1 in which said vessel comprises part of an upright tubular member having a partition intermediate the ends thereof, the space above said partition serving as said vessel, the space below said partition being connected to receive absorption solution from said absorber and serving as a part of the latter.

4. Apparatus as set forth in claim 1 in which said part functioning to transform refrigerant vapor to liquid comprises a ycondenser and said vessel extends vertically downward below the outlet end of said condenser, said condenser comprising a looped coil having vertically extending portions which are disposed alongside of and spaced from one another, and a separate group of fins fixed to each of said coil po-rtions to form an air shaft within which said vessel is disposed.

5. In the art of absorption refrigeration, the

improvement ywhich `comprises heating at a first place liquid cooling agent or such agent substantially free of another liquid to form vapor for normally raising liquid from said first place to a second place at a higher level by vapor lift action under the iniiuence of a column of liquid at a third place which is removed from said rst place and serves as a reaction head and from which liquid iiows by gravity toy said first place, and, when said other liquid having a higher boiling point than said cooling agent passes to said first place, employing liquid cooling agent or such agent substantially free of said other liquid to push out and displace said other liquid from said first and third places to a place other than said second place.

6. In the art of absorption refrigeration with the aid of a system having a place lat which heat is dissipated, the improvement which comprises making use of such dissipated heat to heat at a first place liquid refrigerant or such liquid refrigerant substantially free of another higher boiling point liquid so as to form vapor for normally raising liquid from said first place to a second place at a higher level by vapor lift action under the influence of a column of liquid at a third place which is removed from said first place and serves as a reaction head and from which liquid flows by gravity to said first place, and, when said other liquid passes to said first place, employing liquid refrigerant or such refrigerant substantially free of said other liquid to push out and displace said other liquid from said first and third places to a place other than said second place.

7. That improvement set forth in claim 6' in which heat yof rectification is employed to effect heating of liquid at -said first place.

8. In the art of refrigeration with the aid of an absorption refrigeration system in which refrigerant evaporates in the presence of inert gas at a place of cooling, the improvement which comprises owing unevaporated refrigerant from the place `of cooling to another place at a lower level which is out of Contact with inert gas, continuously supplying heat to said other place during operation of the system to vaporize liquid therein, iiowing vaporized refrigerant from said other place to a place of condensation, flowing condensed refrigerant formed at the place of condensation to the place of cooling in a path of flow from a first place at one level to a second place at a higher level by vapor lift action under the influence of a column of liquid condensate at a third place which serves as a reaction head and from which such liquid fiows to said first place, and removing absorption solution from the first and third places and flowing such removed solution to a place other than said place of cooling.

9. In the art of refrigeration in which liquid cooling agent or such agent substantially free of absorption solution is normally raised from a rst place at one level to a second place at a higher level by vapor lift action under the iniiuence of a column of liquid cooling agent at a third place which is removed from said first place and serves as a reaction head and from which such liquid fiows in a path of ow to said first place, the improvement which comprises removing absorption solution from the iirst and third places of such path of fiow at a region thereof located substantially at or in the Vicinity of the liquid surface level of the reaction head produced during normal lifting of liquid cooling agent to said second place, and flowing said removed absorption solution from said region in a path of flow to a place other than said second place.

l0. In the art of refrigeration with the aid of a system in which liquid is raised by vapor lift action, the improvement which comprises heating liquid refrigerant at a first place to form vapor therein for raising said liquid by vapor lift action from said rst place at one level to a second place at a higher level with the aid of said vapor under the influence of a column of liquid serving as a reaction head, and, when liquid having an appreciable concentration of liquid absorbent flows to the rst place, producing a positive force within the system to push out such last-mentioned liquid therefrom to a place vother than said second place.

l1. In refrigeration apparatus having a plurality of parts, a pump system providing means for normally raising liquid cooling agent from one level to a higher level by vapor lift action under the influence of a column of liquid cooling agent serving as a reaction head, said pump system comprising a riser conduit which provides a passage in which vapor cannot freely pass liquid therein and includes a heat receiving and vapor forming part at said one level, and means for draining objectionable liquid from said pump system comprising a connection communicating with said pump system and with one of said parts outside said pump system at a level which is approximately at `or in the vicinity of the liquid .Y

12. In the art of refrigeration with the aid ofY an absorption refrigeration system in which refrigerant evaporates in the presence of an inert gas at a place of cooling, the improvement which comprises ilowing unevaporated refrigerant fluid from said place of cooling to another place at a lower level which is out of contact with inert gas, conducting in a path of ow to said place of cooling liquid refrigerant having a small concentration of liquid absorbent and including refrigerant fluid from said other place, and diverting from said path of now to a place other than said place of cooling liquid absorbent collecting therein and having a substantially higher boiling point than liquid refrigerant.

13. In an air cooled absorption refrigeration apparatus having a plurality of interconnected parts providing a gas circuit including an evaporator into the upper part of which liquid refrigerant is introduced and an absorber, and a condenser having an inlet which is connected to receive refrigerant vapor, pumping means for conducting liquid refrigerant from said condenser upwardly against gravity to the upper part of said evaporator which is at a higher level than the refrigerant vapor inlet of said condenser, said pumping means including a vapor lift tube for normally raising liquid refrigerant by Vapor lift action to said evaporator during `operation of the apparatus, structure providing a pressure vessel which is in communication with said gas circuit and connected to said condenser and said lift tube to hold a column of liquid therein which serves as a reaction head for lifting liquid in said lift tube, said pressure vessel extending vertically downward below the outlet end of said condenser, said pressure vessel and lift tube forming a liquid lifting system to raise liquid refrigerant to said evaporator, conduit means for withdrawing absorption liquid from said system by displacement of such liquid by liquid refrigerant flowing from said condenser, said conduit means communicating with said system in a manner to drain liquid therefrom to a lower part of the apparatus from a region at a level approximately the same or slightly above the liquid surface level of the reaction head formed in said pressure vessel when liquid refrigerant is normally being raised to said evaporator, said condenser comprising a looped coil having vertically extending portions which are disposed alongside of and spaced from one another, and a separate group of fins fixed to cach of said coil portions to form an air shaft. said pressure vessel being disposed within such shaft.

WILHELM GEORG KOGEL.

References Cited in the ille of this patent UNITED STATES PATENTS -lumber Name Date 2,069,865 Ullstrand Feb. 9, 1937 2,129,982 Ashby Sept. 13, 1938 2,194,505 Kogel et al Mar. 26, 194() 2,252,791 Ullstrand Aug. 19, 1941 2,256,584 Bergholm Dec. 16, 1941 2,295,064 Ullstrand Sept. 8, 1942 2,303,816 Brace Dec. 1, 1942 2,317,519 Coons Apr. 27, 1943 2,321,113 Taylor June 8, 1943 2,329,863 Thomas Sept. 21, 1943 2,336,085 Gaugler Dec. 7, 1943 2,338,265 Sherwood Jan. 4, 1944 2,345,454 Brace Mar. 28, 1944 2,363,434 Osborn Nov. 21, 1944 2,490,401 Bergholm Dec. 6, 1949 2,529,113 Stierlin Nov. 7, 1950

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