US2750763A - Absorption refrigeration - Google Patents

Description

EFRIGERATION 2 Sheets-Sheet l June 19, 1956 w. G. KOGEL ABSORPTION REFRIGERATION Original Filed July 14, 1949 2 Sheets-Sheet 2 States ABSORPTIN REFRIGRATION Wilhelm Georg Kegel, Stockholm, Sweden, assignox;V to

Aktiebolaget Elektroiux, Stockholm, Sweden, a corporation of Sweden Claims priority, application Sweden July 22, 1948 21 Claims. (Cl. 62-119.5)

This invention relates to refrigeration and is especially concerned with refrigeration systems of the absorption type and refrigerators embodying such systems or apparatus. This application is a division of my application Serial No, 104,771, led luly 14, 1949, now Patent No. 2,655,010, granted October 13, 1953.

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 lluids circulating in the system and insure reliable operation undervall 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 etiicient 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 refrigerant 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 eicient heat exchange between iiuids in such circuit is promoted and at the same time loss of heat from such uids to the surroundings is minimized; to provide an improvement for varying the quantity of refrigerant Huid 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 eliicient air cooling of such parts by natural draft circulation is effected. l

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 modifications of the system shown in Fig. l;

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.

arent O A 2,750,763 Patented .lune 19, 1956 ICC In Fig. l the invention is shown embodied in an abso'rption 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 riit 1li, a condenser 11, an evaporator 12 and absorber 14 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 1t), which is enveloped within a body 9 of suitable insulating material, may comprise a boiler 15 in the form of piping to which heat is supplied from a heating tube or flue 16 thermally connected therewith at 17, as by welding, for example. The heating tube 16 may be heated in any suitable manner, as by an electrical heating element disposed within the lower part of the tube 16 o r by a liquid or gaseous fuel burner which is adapted to project its flame into the lower end of the tube.

Flfhe `heat supplied to the boiler 15 and its contents expels refrigerant vapor out of solution, and the refrigerant vapor passes through a rectifier 18 into the air cooled condenser 11 in which it is condensed and liquefied. In a manner to be described hereinafter, liquid refrigerant is conducted from condenser 11 to evaporator 12 in a path of flow which includes conduits 19 and 20, the evaporator being diagrammatically shown and arranged to effect cooling of athermally insulated space 21. In evaporator 12 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 fluid into inert gas in evaporator 12, 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 12 flows from the lower part thereof through one passage 23 of a gas heat exchanger 24 and conduits 2S and 26 into the lower end of the absorber 14 which is in the form of a looped coil. In the absorber 14 the rich gas mixture flows countercurrent to downwardly owing absorption liquid which enters through a conduit 27. The absorption liquid absorbs refrigerant vapor from inert gas, and inert gas weak in refrigerant ilows from the upper end of absorber 14 through a conduit 2S, another passage 29 of gas heat exchanger 24 and conduit 22 into the upper part of evaporator 12. In Fig. 1 the evaporator 12 is connected in the inert gas circuit just described in such manner that parallel flow of inert gas and refrigerant uid is effected in the evaporator. However, it should be understood that the evaporator 12 may be connected in the gas circuit in any other desired manner so that, for example, inert gas 'and refrigerant iiuid pass in counterow with respect to one another.

The circulation of gas in the gas circuit just described is due to the difference in speciiic weight of the columns of gas rich and weak, respectively, in refrigerant vapor. Since the column of gas rich in refrigerant vapor and owing from evaporator 12 to absorber 14 is heavier than the column of gas weak in refrigerant and flowing from absorber 14 to evaporator 12, a force is produced or developed within the system for causing circulation of inert gas in the manner just described. y

In a manner to be described hereinafter, absorption solution enriched in refrigerant flows from the lower part of the absorber 14 through a conduit 30 into the upper part of boiler 15. From the lower closed end of boiler 1-5 absorption solution passes into the lower end of a vertically extending tube 31 in which liquid is raised by vapor-lift action, the tube 31 being heat conductively connected to the heating tube 16, as by welding, to effect such lifting of liquid. The raised liquid passes from the upper end of tube 31 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 14 in a path of fiow which includes conduit 27.

The standpipe or riser 32 may or may not be heat conductively connected to the heating tube 16. The principal part of generated vapor produced in the vapor expulsion unit is expelled from solution in boiler 15, and liquid of decreasing refrigerant concentration flows downwardly toward the bottom end thereof into the vapor-lift tube 31. A liquid column is maintained in the standpipe 32 whose liquid surface is at such a level that absorption liquid weak in refrigerant can ow by gravity from the lower end of the standpipe into the upper part of the absorber through the conduit 27.

The vapor passing from the upper end of vapor lift tube 31 into the vapor space of standpipe 32 ows therefrom through a downwardly extending conduit 33 into the lower end of a horizontally extending pipe section 15a formed at the upper part of boiler 15. The pipe section 15a constitutes an analyzer into which passes vapor generated in the boiler 15 and in the vapor lift tube 31. 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. l vapor generated in the boiler pipe 15 passes upwardly therefrom through the pipe section 15a, and vapor generated in tube 31 also enters such pipe section through conduit 33. The absorption liquid introduced into the pipe section or analyzer 15a 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 sufficiently and condenses, thus removing water vapor from ammonia vapor. rIhe 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 refrigerant vapor mixes with refrigerant vapor generated in the vapor lift tube 31 and boiler 15, and the mixture passes from the analyzer 15a to the rectifier 18.v

In the rectifier 18, which may be provided with internal baies 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 18 and mixes with enriched absorption solution flowing to the boiler 15. 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 11 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 3S to an intermediate portion of which the outlet end 36 of the condenser 11 is connected.

Liquid refrigerant formed in condenser 11 flows therefrom into vessel and accumulates in the lower part thereof. From vessel 35 liquid refrigerant flows through conduit 19 into the lower part of vertically extending conduit 20 which is heat conductively connected with the rectifier 18 at 37, as by welding, for example. Due to heat of rectification supplied from the rectier 18, 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 2t) 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 flows through a conduit 40 into the upper part of evaporator 12 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 of conduit 20 is returned to the vessel 35 which essentially serves as an extension of condenser 11 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 41 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 12. 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 12 for gravity fiow through the latter. The conduit 2t? is connected to leg 41 at a level above the connection of conduit 44 to leg 43, that is, the vapor space of leg 41, and lifting vapor passes from such vapor space through a conduit 45 to the vessel 35 in which the vapor is condensed and liquefied.

The heat conductive connection 37 between conduit 20 and rectifier 18 extends for a sufficient 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 2() 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 46 in Fig. l, for example, such liquid column usually being referred to as a reaction head which overbalances the column of vapor bubbles and liquid slugs therebetween being raised in conduit 20.

Vaporization of liquid refrigerant in conduit 2f) by heat of rectification takes place at a relatively low temperature. When the concentration 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 because 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 system is turned or canted during transportation or being moved from one place to another.

In order to insure positive and reliable raising or lifting vof liquid refrigerant under the most adverse operating conditions encountered, 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 19 and 2t). In the embodiment of Fig. l this is accomplished by providing a conduit 47 whose lower end communicates with the conduit 19 and lower end of conduit 20 and whose upper end is preferably connected to rectifier 18 at a level which is substantially at or slightly above the liquid surface level of the ensures liquid column maintained in vessel 35 during operation of the system, such liquid column constituting the reaction head for pumping or raising xiquid refrigerant, as previously explained.

lf 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 ll and flow therefrom into vessel 35 and gradually settle over the body of liquid absorbent. In this way liquid absorbent in vessel l35 will be displaced from the latter and pass through conduits 19 and 47 into the rectifier 18. Eventually all of the liquid absorbent in vessel 35 and conduit 19, as well as the liquid absorbent in conduit 2d, will be replaced by liquid refrigerant having a relatively small concentration of liquid absorbent, thereby enabling conduit to function and cause lifting of liquid refrigerant therethrough by vapor lift action by heat of rectification, as previously explained. The liquid absorbent entering rectifier 1S from the upper end of conduit 47 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 or liquid refrigerant from condenser 11 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 is 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 11 to a higher level. The embodiment of Fig. 3 differs from that of Fig. 1 in that conduit 47 is replaced by a conduit 48 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 18 at the same level or possibly slightly higher level.

The connections of conduit 43 to the conduit 20 and rectifier 18 may be accomplished by forming small openings 51 and 52 in the latter, and securing the upper open ends of legs 49 and 50 to the conduit 20 and rectifier 18, respectively, at regions surrounding such openings. In addition, conduit 48 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 same manner as in the embodiment of Fig. l and described above. However, in Fig. 3 liquid absorbent is displaced from vessel and forced through conduit 19 and lower part of lift tube or conduit 20 into the U.,shaped conduit 48. From conduit 48 such liquid absorbent passes into rectifier 1S, and ultimately conduit 20 will contain liquid refrigerant having a relatively small concentration of absorbent, so that lift tube 20 will effectively function to raise such liquid therethrough.

In accord with the invention the embodiment of Fig. l 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 toreceive liquid refrigerant in the lower part thereof through a conduit S4 whose upper end is connected at 55 to the conduit 25 immediately ahead of a barrier or darn 56 with respect to the direction of flow of liquid from the Vevaporator 12.

In this manner unevaporated liquid refrigerant passing from the lower end of evaporator 12 and flowing through the inner passage 23 of gas heat exchanger 24 is diverted by the dam or barrier S6 into conduit 54 through which it is conducted to vessel 53 and collects therein. The vessel 53 is heat conductively connected to rectifier 18 in any suitable manner, as by welding, so that heat of rectification is transferred by rectifier 18 to vessel 53 and its contents. Vaporization of liquid refrigerant continuously takes place in vessel 53 due to such heating, and such vapor passes upwardly from the vessel through a connection S7 into the extreme upper part of rectifier 18 and flows into the condenser 11 along with vapor flowing from the rectifier into the condenser.

When the load on evaporator 12 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 12 evaporates and. diffuses into inert gas therein to produce useful refrigeration. Under such operating conditions the ow 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 18, refrigerant vapor flows therefrom to condenser 11 until the vessel is depleted of liquid.

Hence, when the load on evaporator 12 increases, as when ice trays containing water to be frozen are positioned in an ice freezing compartment of the thermally insulated space 21, for example, a greater quantity of refrigerant iiuid actively circulates in the refrigeration system to promote useful refrigeration and take care of increase in load. Conversely, when the load on the evaporator 12 decreases and unevaporated refrigerant passes from the lower end thereof, such refrigerant fluid collects in vessel 53 when it flows thereto at a faster rate than that at which it evaporates due to heating from the rectifier 18. While unevaporated refrigerant may be allowed to drain through a liquid trap in conduit 54 directly into the bottom part of vessel 35 and mix with refrigerant therein, 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 S3 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 provisio-ns. 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 11 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 flow into the gas circuit. Refrigerant vapor not liquefied in the 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 systemand 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 il. 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. l the vessel 35 and the manner in which it envelops conduit 2d 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 fluids in the system is effected, particularly to effect cooling and Condensation of refrigerant in vessel 35 which passes therein from condenser 11. Since gas enriched in refrigerant, which is relatively cold, flows through conduit 26, it is desirable to shield the latter thermally from atmospheric air to avoid condensation of moisture at the outer surfaces thereof. In Fig. l 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 58b of suitable insulating material, 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 14 desirably is shifted to the outer extreme end ofthe 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 open or closed or partly closed by a wall member. ln any event the vertically extending space, 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. l lends itself to efficient air cooling because the absorber 14, condenser il and pressure vessel 3S 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` 11 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 ll. 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. l may be omitted, if desired, and t'ne arrangement of Fig. 2 employed in which vapor for lifting liquid can be returned from the upper end of lift tube or conduit 8 20 to the pressure vessel 35, as shown in Fig. 2 and described above.

As stated above, the condenser may envelop the presl sure vessel 35 in which case the straight sections of the condenser 11 are disposed in spaced apart vertical planes. Similarly, the absorber coil 14 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 dissipating members are provided on the absorber coil 14 which also may be utilized as heat transfer members for the condenser 11. Such a construction is shown in Fig. 1 in which the length of the tins 60 is approximately the same as the overall height of the condenser l1 and absorber 14. It is to be understood that a separate group of such fins 60 may be provided for the straight sections of the condenser 11 and absorber 14 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 eifect by the natural draft circulation of air induced in the manner described above.

This arrangement of condenser 11, absorber 14 and pressure vessel 35 is especially important in a refrigeration system of the type shown in Fig. l 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 level 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 of 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 of 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 ow 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 inuence 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 61, which is connected to receive enriched absorption liquid from the absorber 14 through conduit 30, is enveloped in the same body 9 of insulation enveloping the vapor expulsion unit 10 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. 1, the vessel 61 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 15a projects. Below the pipe section 15a is positioned a vertically extending coil 62 whose upper end is connected to receive Weak absorption enseres 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 61. In addition, conduits 27 and 31 may be arranged in heat exchange relation at 64, as by welding, so that further counteriiow heat exchange can be effected between these fluids.

By way of example and without limitation, the vessel 61 may be of such size that it can hold from- ().75 to 2 liters of absorption solution which may constitute 60 per cent or more of the entire quantity of liquid absorbent held in the refrigeration system. ln other words, the upright vessel 61 in the immediate vicinity of the generator is arranged to hold a major portion of the absorption solution circulating in the system. Since the enriched liquid absorbent passing from absorber 14 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 61 being in efficient heat transfer relation with weak liquid absorbent in coil 62. Further, by projecting the analyzer 15a into the upper part of vessel 61 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 similar parts are designated by the same reference numerals. The vapor expulsion unit 10a of Fig. 6 is enveloped in a body 9a of suitable insulation and comprises a boiler 15b in the form of a Vertical p-ipe having an upper extension which constitutes the rectifier 18a having baffles 34a therein. Heat is supplied to boiler 15b from a heating tube 16a thermally connected therewith at 17a, 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 14a in a path of flow which includes a conduit 65 and an inner passage of liquid heat exchanger 66 whose upper end is connected at 67 to boiler 15b at a region below the liquid surface level maintained in the latter. To the lower end of boiler 15b is connected the lower end of vapor lift tube 31a thermally connected at 68 to the heating tube 16a. Liquid of decreasing `refrigerant concentration flows downwardly in boiler 15b, and liquid is raised by vapor lift action in tube 31a 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 27a into the upper part of absorber 14a.

Vapor for lifting absorption liquid through lift tube 31a passes from the upper end of standpipe 32a through a conduit 33a into the upper inclined section 15e of boiler 15b and bubbles through liquid therein, such inclined section constituting an analyzer similar to the analyzer 15a in Fig. 1'. The vapor generated in boiler 15b andv lifting vapor entering through conduit 31a passes from analyzer 15C into rectifier 18a and into condenser 11a in which refrigerant vapor is condensed and liquefied.

The lower end of condenser 11a is connected at 68a to vessel 35a which is disposed about conduit 26a through which relatively cool enriched gas fiows from evaporator 12a to absorber 14a. Liquid refrigerant flows from vessel 35athrough conduits 19a and 20a and is raised in the latter to a condenser 38a provided with cooling fins 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 12 in Fig. 1.

Evaporator 12a isconnected in a gas circuitwhich. 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 12a 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 35a in Fig. 6 differs from theV corresponding vessel 35 in Fig. 1 in that it is divided by a partition 69- to form an upper space 70 and a lower space 71. The part of vessel 35a serving as` the pressure vessel forms a jacket about conduit 26a, the lower end of which terminatesv at an opening in partition 69. The lower space 71 constitutes the absorber vessel of the refrigeration system toan intermediate region of which the absorber coil 14a is connected at 72.

The operation of the system shown in Fig.. 6 is generally like that described above in connection with Fig. l.y In Fig. 6 gas enriched in refrigerant ows from evaporator 12a through the inner passage of gas heat exchanger 24a and conduits 25a and 26a into the space 71' of vessel 35a. From the upper part of such` space 71 the enriched gas fiows upwardly through absorber coil 14a countercurrent to weak absorption liquid which enters the upper part of absorber 14a through conduit 27a. lnert gas weak in refrigerant flows from the upper part of absorber 14a through conduit 28a and outer passage of gas heat exchanger 24a to the evaporator 12a. As previously stated, liquid refrigerant is supplied to the evaporator from condenser 38a through conduit 40a.

Liquid refrigerant formed in condenser 11a flows therefrom into the upper space 7u of vessel 35a and collects in the bottom part thereof. As in the embodiment of Fig. l, the space 7i) communicates with the gas circuit through an opening 58a formed in conduit 26a. One end of conduit 19a is connected at 73 to vessel 35a to withdraw liquid refrigerant from the bottom of space 79. From conduit 19a liquid refrigerant passes into conduit or lift tube 20ct which is heat conductively connected at 37a to rectifier 18a. A conduit 47a similar to conduit 47 in Fig. l is provided for removing liquid absorbent from space '71) and conduits 19a and 20a. Such conduit 47a at its upper end is connected to rectifier 13a for conducting liquid absorbent to the latter which then ows by gravity in the rectifier into the absorption liquid circuit.

The conduits 1.911,2@ and 47a in Fig. 6 correspond to the conduits 19, 2t) and 47 in Fig. l and the part of the description of Fig. l directed to the function and opera` tion of these members is equally applicable to the corresponding members in Fig. 6. Although not shown, it is be understood that Fig. 6 may also embody a concentration vessel like the vessel 53 in Fig. l and conduit connections S4 and S7 associated therewith.

From the absorber 14a enriched absorption liquid flows into the lower space 71 of vessel 35a which constitutes` the absorber vessel. From this vessel enriched liquid flows through conduit 65 to the boiler 15b as previously explained.

ln Fig. 6 the condenser 11a and absorber 14a may be formed of iiattened looped piping each having straight sections in spaced apart vertical planes, and separate groups of cooling fins 60a may be provided for the straight coil sections in each vertical plane, each fin 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 isl disposed. Hence, the advantages described above in connection with Fig. l concerning the compact arrangement and cooling of vessel 3S, condenser 11 and absorber 14 are equally applicable to the similar compact arrangement of vessel 35h condenser 11a and absorber 14a of Fig. 6. it should be further understood that the modified constructions iliustrated in Figs. 2 to 5 in connection with the embodiment of Fig. l are also equally applicable to the embodiment of Fig. 6.

In Fig. 6 the refrigeration apparatus is fixed at a number of places 74, as by welding, to a frame 75 formed of angle members 76, 77, 78 and 79. Such frame 7S 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 defined by the rear insulated wall and rearwardly extending parts of the lateral side walls of the outer metal shell of the cabinet. When the frame 75 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 niember, Hence, the advantages described above, in connection with the embodiment in Fig. l 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:

l. In the art of refrigeration with the aid of an absorption refrigeration system having a circuit in which inert gas normally circulates in a path of flow including a place of cooling in which refrigerant normally evaporates in the presence of the inert gas circulating between first and second regions thereof, the improvement which comprises flowing liquid refrigerant by gravity between the first and second regions in the place of cooling and conducting unevaporated refrigerant passing from the place of cooling to another place at a lower level which is outside the normal path of flow of circulating inert gas and in which the liquid surface normally is always out of physical contact with inert gas when liquid refrigerant is present in said other place, flowing refrigerant from the other place in a path of flow which includes raising such refrigerant in liquid phase against gravity by vapor lift action, effecting such raising of refrigerant against gravity while out of the presence of the inert gas, and conducting the raised refrigerant back to the place of cooling for gravity flow between the first and second regions thereof.

2. In the art of refrigeration with the aid of an absorption refrigeration system in which refrigerant evaporates in the presence of an inert gas at a place of cooling and absorbed into absorption liquid from the inert gas at a place of absorption, the improvement which comprises flowing unevaporated refrigerant from the place of cooling to another place at a lower level out of contact with inert gas and absorption liquid, vaporizing refrigerant at such other place, flowing the vaporized refrigerant to a place of condensation, and, while out of the presence of the inert gas, conducting condensed refrigerant back to the place of cooling in a path of flow which includes raising such condensed refrigerant by vapor lift action.

3. In the art of refrigeration with the aid of an absorption refrigeration system having a circuit for circulation of inert gas and in which refrigerant normally evaporates in the presence of the inert gas at a place of cooling and absorbed into absorption liquid from the inert gas at a place of absorption, the improvement which comprises flowing unevaporated refrigerant passing from the place of cooling to another place at a lower level out of contact with inert gas and absorption liquid, continuously supplying heat to the other place during operation of the system to vaporize liquid therein, flowing vaporized refrigerant from said other place to a place of condensation, conducting condensed refrigerant in a path of flow from the place of condensation to the place of cooling,

'l2 and, while out of the presence of the inert gas, raising condensed refrigerant in such path of flow by vapor lift action.

4. The improvement set forth in claim 3 in which the other place is continuously heated by heat dissipated from a place in the system.

5. The improvement set forth in claim 4 in which heat of rectification is supplied to said other place.

6. In the art of refrigeration employing a system irrcluding a circuit for circulation of absorption liquid and an evaporator in which refrigerant evaporates in the presence of an inert gas, the improvement which coniprises adjusting the quantity of refrigerant actively circulatin'g in the system by withdrawing excess liquid refrigerant from the evaporator upon decrease in load, heating such withdrawn liquid at a place outside the absorption liquid circuit to effect vaporization thereof, condensing such vaporized refrigerant at a place below the evaporator, and, while out of the presence of the inert gas, raising such condensate to a higher level for recirculation through the evaporator, so as to reeirculate continuously through the evaporator excess liquid refrigerant withdrawn therefrom.

7. In an absorption refrigeration system containing an inert gas, a circuit for circulation of such inert gas including an evaporator, a condenser below said evaporator in which refrigerant vapor is liquefied, means for conducting liquid formed in said condenser to said evaporator including a vapor lift tube, a vessel connected to receive excess liquid leaving said evaporator, and means to heat said vessel to vaporize liquid therein, said condenser bcing connected to receive vapor from said vessel.

8. in an absorption refrigeration system as set forth in claim 7, conduit means including a rectifier for con ducting vapor to said condenser, said vessel being arranged to receive heat of rectification from said rectifier.

9. ln an absorption refrigeration system containing an inert gas, a circuit for circulation of such inert gas including an evaporator, a condenser in which refrigerant vapor is condensed and liquefied at a level below said evaporator, conduit means for conducting liquid refrigerant formed in said condenser to a part of said evaporator from which such liquid flows therethrough by gravity, said conduit means including a vapor lift tube through which liquid refrigerant is raised against gravity, a vessel in a part of the system which is outside said inert gas circuit and connected to receive excess liquid leaving said evaporator, and means for removing such liquid from said vessel to said conduit means.

l0. ln 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 flowing unevaporated refrigerant from the place of cooling to another place at a lower level which is out of contact with inert gas and in thermal exchange relation with a place of rectification, and flowing refrigerant from said other place at a lower level to said place of cooling, substantially all of such refrigerant reaching said place of cooling from said other place in steps which include vaporizing liquid in said other place by heat of rectification, flowing vaporized refrigerant from said other place to a place of condensation and conducting condensed refrigerant from the place of condensation to said place of cooling.

ll. In an absorption type refrigeration apparatus having a plurality of interconnected parts providing fluid circuits for active circulation of absorption liquid, refrigerant fluid and inert gas during normal operation of the apparatus to produce a refrigerating effect and including a condenser connected to receive refrigerant vapor and an evaporator connected to receive liquid refrigerant formed in said condenser, a unitary structure which is connected in an active portion of said refrigerant fluid circuit and also provides a pressure vessel having the vapor space thereof in communication with said gas circuit, and said refrigerant fluid circuit including connecting means pro viding a path of flow for gas between said condenser and pressure vessel and for also conducting to said pressure vessel liquid refrigerant initially formed in said condenser.

12. Apparatus as set forth in claim 1l in which said structure also embodies provisions for holding a body of liquid in an active portion of the absorption liquid circuit.

13. Apparatus as set forth in claim 11 in which said condenser is at a lower level than said evaporator and the latter is connected to receive liquid from said condenser by a vapor lift tube, said structure being connected in an active portion of said refrigerant circuit to hold a body of liquid therein which serves as a reaction head for raising liquid in said vapor lift tube.

14. In absorption type refrigeration apparatus as set forth in claim 11 in which said absorption liquid circuit includes a vapor lift pump for causing circulation of liquid in such circuit and in which said structure includes an integral part for holding a body of absorption liquid which serves as a reaction head under the inuence of which absorption liquid is raised by vapor lift action in said pump.

15. Apparatus as set forth in claim 1l in which said structure comprises a vertically extending tubular member having a partition intermediate the ends thereof to provide upper and lower chambers, said upper chamber serving as the pressure vessel and the lower chamber being connected in an active portion of said absorption liquid circuit.

16. Apparatus as set forth in claim 11 in which said structure forms a jacket enveloping conduit means forming a part of said gas circuit through which relatively cool gas ows from said evaporator, said conduit means having an opening in the wall thereof to establish communication between the gas circuit and the interior of said jacket which serves as said pressure Vessel.

17. Apparatus as set forth in claim 11 in which said structure providing said pressure vessel envelops a portion of said gas circuit through which relatively cool gas passes from said evaporator for thermally shielding said portion to prevent condensation of atmospheric moisture on the outer surfaces thereof.

18. In an air cooled absorption refrigeration apparatus having a plurality of interconnected parts providing a gas 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, structure providing a pressure vessel which is connected to said condenser and in communication with said gas circuit, said pressure vessel extending 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 xed to each of said coil portions to form an air shaft, said pressure vessel being disposed within such air shaft.

19. Apparatus as set forth in claim 18 in which said pumping means includes a vapor lift tube for normally raising liquid refrigerant by vapor lift action to said evaporator during operation of the apparatus, and said pressure vessel being 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.

20. Apparatus as set forth in claim 18 in which said absorber comprises a looped coil below said condenser having spaced apart portions substantially in vertical alignment with the spaced apart portions of said condenser coil, the portions of the condenser and absorber coils substantially in alignment having the same cooling iins fixed thereto.

21. Apparatus as set forth in claim 20 in which said structure providing said pressure vessel also provides a vessel in the lower part thereof connected to receive absorption solution from said absorber coil.

References Cited in the le of this patent UNITED STATES PATENTS 2,194,505 Kogel Mar. 26, 1940 2,210,613 Anderson Aug. 6, 1940 2,252,791 Ullstrand Aug. 19, 1941 2,264,292 Brace Dec. 2, 1941 2,285,884 Ashby lune 9, 1942 2,295,064 Ullstrand Sept. 8, 1942 2,303,816 Brace Dec. 1, 1942 2,401,300 Gross June 4, 1946 2,402,416 Kogel June 18, 1946 2,468,104 Phillips Apr. 26, 1949 2,490,401 Bergholm Dec. 6, 1949

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