US3514972A - Absorption refrigeration apparatus of the inert gas type - Google Patents

Description

June 2, 1970 w. G. KOGEL ABSORPTION REFRIGERATION APPARATUS OF THE INER'I' GAS TYPE Filed Sept. 25, 1968 l INVENIIFOR. BY fixwnw Z; AT TORNEY Patented June 2, 1970 3,514,972 ABSORPTION REFRIGERATION APPARATUS OF THE INERT GAS TYPE Wilhelm Georg Kiigel, Stockholm, Sweden, assignor to Aktiebolaget Electrolux, Stockholm, Sweden, a corporation of Sweden Filed Sept. 25, 1968, Ser. No. 762,426 Claims priority, application Sweden, Sept. 29, 1967, 13,436/ 67 Int. Cl. F25b 15/10 U.S. Cl. 62-490 8 Claims ABSTRACT OF THE DISCLOSURE Absorption refrigeration apparatus of the inert gas type in which refrigerant vapor is expelled from solution at a place of heating and condensed at a place of condensation, a circuit for circulating inert gas which includes an absorber and evaporator structure having a plurality of evaporator sections respectively operable at low and higher temperatures, the circuit having a Weak gas line for flowing inert gas weak in refrigerant from the absorber to the low temperature evaporator section and a rich gas line for flowing inert gas enriched in refrigerant from the evaporator structure to the absorber, conducting liquid refrigerant from the condenser to the evaporator structure in a path of flow which includes a precooler, conducting inert gas in the inert gas ci-rcuit to the precooler and conducting inert gas, after flowing in physical contact with liquid refrigerant in the precooler, to a zone of the evaporator structure at which the inert gas is at least partially enriched in refrigerant.

BACKGROUND OF THE INVENTION Field of the invention In absorption refrigeration apparatus of the inert gas type it has been the practice heretofore to precool liquid refrigerant in its path of flow from a condenser to an evaporator structure by flowing inert gas enriched in refrigerant into the presence of the liquid refrigerant before the latter is introduced into the evaporator structure which may include a first evaporator section operable at a low temperature for freezing purposes and a second evaporator section operable at a higher temperature to promote storing of food and the like at a refrigerating temperature above the freezing temperature.

Description of the prior art It has been proposed heretofore to position above an evaporator structure a gas heat exchanger which is connected in the inert gas circuit and through which inert gas rich in refrigerant vapor flows in heat exchange relation with inert gas weak in refrigerant vapor. Inert gas enriched in refrigerant in the evaporator structure flows through the gas heat exchanger into the presence of liquid refrigerant flowing from the condenser to the evaporator structure. Liquid refrigerant in the gas heat exchanger evaporates and takes up heat from liquid refrigerant and also from enriched inert gas. Further, heat exchange is effected between weak and enriched gas in the gas heat exchanger, thereby cooling the weak inert gas. In this way liquid refrigerant and weak inert gas flowing to the evaporator structure are introduced therein at a lower temperature than a temperature when no precooling of these fluids is effected.

Since the gas heat exchanger in its entirety is employed to promote precooling of liquid refrigerant, the function of the gas heat exchanger to effect optimum heat exchange between weak and rich inert gas is impaired. This is so because the weak inert gas flowing to the evaporator structure is not effectively cooled in the gas heat exchanger by its heat interchange with rich inert gas and hence it is introuced into the evaporator structure at a higher temperature than otherwise would result if the gas heat exchanger could function as originally intended.

Moreover, the rich inert gas cooled by evaporation of liquid refrigerant in the gas heat exchanger flows from the latter at a relatively low temperature without being eflfectively employed to produce refrigeration in the evaporator structure to produce the lowest possible refrigerating temperature, which is objectionable. This is especially true in refrigerators having several thermally segregated compartments in one of which freezing temperatures must be maintained by one evaporator section and satisfactory temperatures must be maintained by another evaporator section to preserve foods and the like at refrigerating temperatures above the freezing temperature.

It also has been proposed to flow weak inert gas from the gas heat exchanger into the presence of liquid refrigerant in a precooler provided in the path of flow of liquid refrigerant from the condenser to the evaporator structure, and, after effecting precooling of liquid refrigerant, flowing the partially enriched inert gas from the precooler to the absorber in the system. However, such a proposal results in loss of useful refrigerating effect. With this arrangement it is necessary to provide two parallel paths of flow for enriched inert gas, one from the precooler to the absorber and the other from the evaporator structure to the absorber. This is objectionable because it is diflicult to control flow of inert gas in parallel paths of flow in the inert gas circuit, especially when disturbances can often occur due to changes and variations in conditions encountered during operation of the refrigeration system.

SUMMARY OF THE INVENTION My invention relates to absorbtion refrigeration apparatus of the inert gas type adapted to produce refrigeration at a plurality of temperatures, and it is an object to effect a lower refrigeration temperature in the low temperature section of a plural temperature evaporator structure.

In accord with the invention, a substantial cooling output is effected at an extremely low temperature level without jeopardizing the total cooling output of the refrigeration system. I accomplish this by effecting thelower temperature level in such manner that inert gas in the insert gas circuit flows to a precooler into the presence of liquid refrigerant in its path of flow from a condenser to the evaporator structure. The inert gas, after flowing in physical contact with liquid refrigerant in the precooler, flows to a zone of the evaporator structure at which the inert gas is at least partially enriched in refrigerant.

The zone of the evaporator structure to which inert gas is conducted may be at the region thereof at which the gas outlet of the first evaporator section is connected to the gas inlet of the second evaporator section.

. The low and higher temperature evaporator sections respectively are arranged to abstract heat from thermally segregated compartments of an insulated refrigerator cabinet, the low temperature evaporator section functioning to maintain freezing temperatures in one compartment and the higher temperature evaporator section functioning to maintain refrigerating temperatures above the freezing temperature in another compartment.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, the single figure more or less diagrammatically illustrates an absorption refrigeration apparatus of the inert gas type embodying my invention.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, I have shown my invention in connection with a refrigerator having a thermally insulated space which is divided by a partition 11 into a plurality of compartments 12 and 14 one above the other and arranged to be cooled by evaporator structure comprising first and second evaporator sections 15 and 16 operable at different temperatures. The evaporator sections 15 and 16 are arranged to abstract heat from the interior of the refrigerator 10', the upper compartment 12 being cooled primarily by the evaporator section 15 so as to freeze water and other matter as well as store frozen food packages therein.

The partition 11 functions to prevent circulation of air between the upper and lower compartments 12 and 14 and thermally shields the evaporator sections 15 and 16 from one another. Hence, the upper and lower compartments 12 and 14 are thermally segregated from one another.

The first evaporator section 15, which may be in the form of a horizontally disposed looped coil, is provided with a suitable heat dissipating surface, such as the plurality of heat transfer members 15a, for example. The second evaporator section 16 also may have a suitable heat dissipating surface formed from a plurality of heat dissipating members 16a, for example. The lower refrigerating compartment 14, which may serve as a space in which food and the like is stored at a temperature above the freezing temperature, is cooled primarily by the evaporator section 16.

The evapoartor sections 15 and 16 constitute the evaporator structure of absorption refrigeration apparatus of the inert gas type and are connected by conduits to other parts of the apparatus for circulation of inert gas as well as supply liquid refrigerant to the evaporator structure. In apparatus of this type, refrigerant expelled from a solution in a generator 17 by heating passes upward through an air cooled rectifier 18 into an air cooled condenser 19 in which the expelled refrigerant is condensed and liquefied. Liquid refrigerant flows from condenser 19 through a precooler 20 in which precooling of liquid refrigerant is effected, as will be described presently, and refrigerant flows therefrom through a conduit 21 into the evaporator sections 15 and 16.

In evaporator sections 15 and 16 the refrigerant evaporates and diffuses into an inert gas, such as hydrogen, for example, to produce a refrigerating effect and abstract heat from the surroundings. The resulting gas mixture of refrigerant and inert gas flows from evaporator sections 15 and 16 through a conduit 22 and an outer passageway 23 of a gas heat exchanger 24 and a conduit 25 into an absorber comprising a vessel 26 and a looped coil 27. -In the absorber vessel 26 and looped coil 27 refrigerant vapor is absorbed into a liquid absorbent, such as water, for example, which enters through a conduit 28. The hydrogen or inert gas, which is practically insoluble and weak in refrigerant, is returned to evaporator sections 15 and 16 through a conduit 29 and inner passageway 30 of the gas heat exchanger 24.

Absorption liquid enriched in refrigerant in the absorber flows from vessel 26 through a conduit 31 to generator 17 where it is heated and refrigerant vapor again is expelled out of solution. The weakened absorption liquid from which liquid has been expelled flows from generator 17 through a conduit 32 and conduit 28 to coil 27 to absorb refrigerant vapor again, the conduit 32 desirably being in heat exchange relation with conduit 31.

The gas heat exchanger 24 comprises outer and inner conduits 33 and 34 which form the outer and inner passageways 23 and 30, respectively, of the heat exchanger. The conduit 29 for conducting weak inert gas from the upper end of absorber coil 27 to the gas heat exchanger 24 extends downward from the upper end of the coil to a region 35 at the lower end of the gas heat exchanger 24 which is near the absorber vessel 26. The lower end of conduit 29, at the region 35, is connected to the lower end of the conduit 34 which forms the inner passageway 30 of the gas heat exchanger 24. At the region 35 the conduit 34 includes a downward extending portion 34a which extends below the liquid surface level 26a of the body 26b of absorption liquid in the absorber vessel 26. The conduit 25 through which inert gas enriched in refrigerant flows into the absorber vessel 26, on the other hand, discharges the rich gas mixture into the absorber vessel 26 into the vapor space therein above the liquid surface level 26a.

In accordance with my invention, in order to introduce liquid refrigerant to the first evaporator section 15 at a lower temperature than the temperature at which it flows from the condenser 19, the refrigerant is cooled in the precooler 20 by flowing thereto inert gas in the inert gas circuit. Weak inert gas flowing from the upper end of the inner passage 30 of the horizontal portion of the gas heat exchanger 24 flows into the conduit 21 in its path of flow to the evaporator section 15. In the conduit 21, at the region 36 thereof, a portion of the weak inert gas is diverted into the lower end of conduit 20. The diverted weak gas flows upward in the precooler 20, as indicated by the arrow A, such upward flow of Weak inert gas being countercurrent to downward flow of liquid refrigerant. Liquid refrigerant in the precooler 20 evaporates and diffuses into the weak inert gas and takes up heat from liquid refrigerant flowing to the evaporator section 15 through conduit 21.

The weak gas, which becomes partially enriched in refrigerant vapor in the precooler 20, flows downward from the upper part thereof through a conduit 37, as indicated by the arrows B, to a zone 38 of the evaporator structure at which the inert gas is at least partially enriched in refrigerant. The zone 38 of the evaporator structure is at a conduit 39 which connects the gas outlet end of the first evaporator section 15 and the gas inlet end of the second evaporator section 16.

Since inert gas weak in refrigerant vapor initially flows through the first evaporator section 15 and partially enriched gas then flows through the second evaporator section 16, the inert gas in the evaporator section 15 contains a lesser amount of regrigerant vapor than the inert gas in the evaporator section 16. The partial vapor pressure of the refrigerant is a gradient, so that the temperature in the evaporator section 15 and 16 also is a gradient, the evaporating temperature of liquid refrigerant being lower in evaporator section 15 which constitutes the freezing portion of the evaporator structure.

An important aspect of the invention is that diverted weak inert gas, which is capable of producing a low temperature refrigerating elfect, is effectively employed in the precooler 20 to reduce the temperature of the liquid refrigerant flowing to the evaporator section 15; and such diverted gas thereafter is employed in the evaporator section 16 to produce a sufliciently low temperature in the compartment 14 in which foods and the like are maintained at a refrigerating temperature above freezing temperature. The inert gas flowing through the conduit 37 desirably enters the zone 38 of the evaporator structure at the same partial pressure of refrigerant vapor as that of the inert gas reaching the zone 38 at the gas outlet of the first evaporator section 15.

In view of the foregoing, it will now be undestood that the conduit 34 of the gas heat exchanger 24, which forms the inner passageway 30 and may be referred to as a weak gas line, extends from the region 35 adjacent to the absorber vessel 26 to the region 40 at which the conduit 21 is connected thereto. The outer conduit 33 of the gas heat exchanger, which envelops the inner conduit 34 to pro vide the outer passageway 23 and may be referred to as a rich gas line, extends to the absorber vessel 26 from the region 41 at which the conduit 22 is connected thereto. The lower end of the precooler 20 is connected to the weak gas line at the region 36 thereof which is before inert gas reaches the gas inlet of the first evaporator section 15 and after heat interchange has been effected between Weak gas and rich gas in the gas heat exchanger 24.

Inert gas partially enriched in refrigerant in the first evaporator section 15 flows from the gas outlet end thereof through the conduit 39 to the gas inlet end of the second evaporator section 16. Unevaporated liquid refrigerant also flows from the first evaporator section 15 through the conduit 39 into the second evaporator section 16. Inert gas enriched in refrigerant flows from the gas outlet end of the second evaporator section 16 through conduit 22 to the region 41 of the outer passageway 23 of the gas heat exchanger 24, and unevaporated refrigerant flows from the lower end of the second evaporator section 16 through a conduit 42 to the outer passageway 23 of the gas heat exchanger. The conduit 42 is formed to pro- Vide a liquid trap and is connected at the region 43 to the gas heat exchanger 24.

I claim:

1. In a refrigerator,

(a) a cabinet comprising thermally insulated walls defining an insulated interior having a plurality of spaces thermally segregated from one another, one of said spaces functioning as a freezing compartment and the other of said spaces functioning as a compartment for refrigerating foods at a temperature above freezing temperature,

(b) absorption refrigeration apparatus of the inert gas type comprising avapor expulsion unit for expelling refrigerant vapor from solution,

() refrigerant liquefying means in which liquefaction of expelled vapor is effected,

(d) a gas circuit including an absorber having an inlet for inert gas enriched in refrigerant vapor and an outlet for inert gas weak in refrigerant vapor and evaporator structure including first and second evaporator sections each respectively having an inlet and outlet for inert gas,

(e) said first evaporator section being arranged to abstract heat from the freezing compartment and said second evaporator section being arranged to extract heat from the food storage compartment,

(f) said gas circuit including a weak gas line for fiowing inert gas weak in refrigerant vapor from the outlet of said absorber to the inlet of said first evaporator section and a rich gas line for flowing inert gas enriched in refrigerant vapor from said evaporator structure to the inlet of said absorber,

(g) first conduit means including a precooler for flowing liquid refrigerant from said refrigerant liquefying means to said evaporator structure,

(h) means connecting said precooler in said inert gas circuit for flowing inert gas thereto in the presence of liquid refrigerant, and

(i) second conduit means for conducting inert gas, after flowing in physical contact with liquid refrigerant in said precooler, to a zone of said evaporator structure at which the inert gas is at least partially enriched in refrigerant.

2. Apparatus as set forth in claim 1 which includes third conduit means connecting the gas outlet of said first evaporator section and the gas inlet of said second evaporator section, said zone of said evaporator structure to which inert gas is conducted from said precooler by said second conduit means comprising said third conduit means.

3. Apparatus as set forth in claim 1 which includes a gas heat exchanger having first and second passageways, said first passageway forming a part of said weak gas line and said second passageway forming a part of said rich gas line, and said connecting means for flowing inert gas to said precooler communicating with said weak gas line at a region thereof which is before inert gas reaches the gas inlet of said first evaporator section and after heat interchange has been effected between weak gas and rich gas in said gas heat exchanger.

4. Apparatus as set forth in claim 1 in which the partial pressure of refrigerant vapor of the inert gas reaching said zone in said evaporator structure is substantially the same as that of the inert gas flowing to said zone through said second conduit means.

5. Absorption refrigeration apparatus of the inert gas type comprising (a) a vapor expulsion unit for expelling refrigerant vapor from solution,

(b) refrigerant liquefying means in which liquefaction of expelled vapor is effected,

(c) a gas circuit including an absorber having an inlet for inert gas enriched in refrigerant vapor and an outlet for inert gas weak in refrigerant vapor and evaporator structure including first and second evaporator sections each respectively having an inlet and outlet for inert gas,

(d) said first evaporator section being operable at one temperature and said second evaporator section being operable at a higher temperature,

(e) said gas circuit including a weak gas line for flowing inert gas weak in refrigerant vapor from the outlet of said absorber to the inlet of said first evaporator section and a rich gas line for flowing inert gas enriched in refrigerant vapor from said evaporator structure to the inlet of said absorber,

(f) first conduit means including a precooler for flowing liquid refrigerant from said refrigerant liquefying means to said evaporator structure,

(g) means connecting said precooler in said inert gas circuit for flowing inert gas thereto in the presence of liquid refrigerant, and

(h) second conduit means for conducting inert gas after flowing in physical contact with liquid refrigerant in said precooler, to a zone of said evaporator structure at which the inert gas is at least partially enriched in refrigerant.

6. Apparatus as set forth in claim 5 which includes third conduit means connecting the gas outlet of said first evaporator section and the gas inlet of said second evaporator section, said zone of said evaportor structure to which inert gas is conducted from said precooler by said second conduit means comprising said third conduit means.

7. Apparatus as set forth in claim 6 which includes a gas heat exchanger having first and second passageways, said first passageway forming a part of said weak gas line and said second passageway forming a part of said rich gas line, and said connecting means for flowing inert gas to said precooler communicating with said weak gas line at a region thereof which is before inert gas reaches the gas inlet of said first evaporator section and after heat interchange has been effected between weak gas and rich gas in said gas heat exchanger.

8. Apparatus as set forth in claim 7 in which the partial pressure of refrigerant vapor of the inert gas reaching said zone in said evaporator structure is substantially the same as that of the inert gas flowing to said zone through said second conduit means.

References Cited UNITED STATES PATENTS 3,177,675 4/1965 Kogel 62490 X LLOYD L. KING, Primary Examiner US. Cl. X.R. 62492

Images