US2063292A - Refrigeration - Google Patents

Description

Dec. 8, 1936. K BERGHOLM I 2,063,292

REFRIGERATION Filed April 16 1935 2 Sheets-Sheet 2 I 2. BY

MATTORNEY.

Patented Dec. 8, 1936 UNITED STATES REFRIGERATION Harry K. Bergholm, St

ockholm, Sweden, assignor, by mesne assignments, to Servel, Inc., Dover, I Del., a cor oration of Delaware Application Ap In Germany 3 Claims.

My invention relates to refrigeration and more particularly to a refrigeration system of the absorption type in which refrigerant evaporates and diffuses into an auxiliary fluid.

It is an object of the invention to provide an improved system of this type which produces refrigerat'ion at a plurality of temperatures and at increased efficiency.

My invention, together with the objects and advantages thereof, will become apparent upon consideration of the following description and the accompanying drawings forming a part of this specification, and of which: 7

Fig. 1 shows in vertical section a refrigerator embodying my invention; and

Fig. 2 is a rear view of the refrigerating unit appearing in side elevation in Fig. 1.

Referring to the drawings, a refrigeration system comprises a generator Ill interconnected through a liquid heat exchanger II with an air cooled absorber comprising an air cooled coil I2 and a tank l2 for circulation therebetween of absorption liquid. The upper part of the generator III is connected by a. conduit I3 to' a first part I4 of an air cooled condenser. Conduit I3 extends upwardly through a rectifier vessel I5 to the upper part of which is connected the lower end of the first part I4 of the condenser; The upper part of the rectifier vessel I5 is also connected to the upper end of a second part I6 of the air cooled condenser.

Within a thermally insulated storage compartment ll of a refrigerator cabinet is a cooling element including a high temperature section I8 and a low temperature section I9. The high temperature section v I8 is located uppermost and comprises a closed tube provided with external heat transfer fins 20. Within the high temperature section I8 is a plurality of baffles 2I comprising disc partitions having relatively large central openings. The lower part of the baffles 2| forms weirs alongthe bottom of the high temperature evaporator section I8 in the path of flow of liquid therein, as will hereinafter appear.

The low temperature evaporator section I9 is formed by a pipe coil arranged for continuously downward fiow of liquid therein. This coil may be imbedded in or otherwise arranged in thermal transfer relation with a suitable ice tray receptacle or the like 22 which may be an aluminum casting.

The rear end of the high temperature evaporator I8, which is slightly lower than the forward end, is connected by means of a conduit.23

to the upper end of the pipe coil I9. The pipe coil 1935, Serial No. 16,555 April 19, 1934 I9 is interconnected through a gas heat exchanger 24 with the absorber I2 for circulation therebe tween of an auxiliary fluid. The lower end of the pipe coil I9 may be connected directly to the gas heat exchanger 24 and the upper end of the pipe coil is connected to the heat exchanger by means of a conduit 25. I I

The gas heat exchanger 24 is of a known type comprising an outer tubular shell divided into a lohg central chamberand relatively small end chambers by partitions 26. The two end chambers 21 and 2B are connected by a plurality of tubes 29 which extend through the middle cham-, ber 30., The forward end of thehigh temperature evaporator section' I8 is connected to the central chamber 30 of the'gas heat exchanger 24 by means of a conduit 3I. This conduit extends centrally through the'high temperature section I8 and terminates in the forward end thereof 5 preferably with a slightly upturned end 32. The rear end of the high temperature evaporator section I8 is also connected to the central chamber 30 of the gas heat exchanger by means of a conduit 33. v

The rectifier vessel I 5 is connected by means of a conduit 34 to an intermediate point 35 of the low temperature evaporator coil I9. A vent conduit 36, including a pressure vessel 3", is connected between the lower end of the condenser section I6 and the gas heat exchanger 24.

The refrigeration system is charged with a solution of refrigerant in an absorption liquid, such as a30% water solution of ammonia. This may be introduced into the system through a charging plug (not shown) in the absorber I2. An auxiliary fluid, as, for instance, hydrogen, is introduced into the system under apressure corresponding to that at which ammonia will condense, for instance, a fairly high room temperature. The generator I0 is heated in any desired manner as, for instance, by a gas burner 38.

In operation, ammonia vapor is expelled from solution by heat in the generator Ill. The ammonia vapor flows through conduit I3 to the first part I4 of the condenser. Liquid ammonia formed in the part I4 of the condenser fiows into the rectifier vessel I5 and thence through conduit 34 into the lowerportion of the evaporator coil I9. Ammonia vapor fiows from the upper part of the rectifier I5 to the second part to the rear end of this section and thence through conduit 23 into the upper end of the low temperature evaporator coil l9. I

Hydrogen enters the upper end of the evaporator coil I 9 through conduit 25. In the coil l9, liquid ammonia evaporates and diffuses into the hydrogen producing a refrigerating effect. The resulting gas mixture, being heavier than the hydrogen, fiows downwardly in coil l9 and thence through the chamber 30 of the gas heat exchanger 24 and conduit 39 to the absorber tank l2f,.. .In the absorber, ammonia is absorbed out of the gas mixture by ,weak absorption solution and the hydrogen or weak gas flows through conduit 40, internal tubes 29 of the gas heat exchanger 24 and conduit 25 back to the upper end of the evaporator coil l9.

Circulation of absorption liquid between the generator I!) and absorber is accomplished by means of a thermosyphon conduit 4| arranged to be heated by the gas burner '38. By means of the thennosyphon conduit 4|, liquid is raised to such a level in the generator III that it may flow by gravity from the lower part thereof through conduit 42, the liquid heat exchanger ll and conduit 43 into the upper part of the absorber. Enriched absorption liquid formed in the absorber flows, from the lower part of the absorber tank l2 through conduit 44, the liquid heat exchanger ll and'the thermosyphon conduit 4| back to'the upper part of the generator l0.

Since conduits 3| and 33 are connected to the chamber 30 of the gas heat exchanger 24, hydro-- gen is conducted into the high temperature evaporator section l8. Liquid ammonia in this evaporator section evaporates and diffuses into the hydrogen producing a refrigerating effect. The resulting gas mixture, thus becomgig heavier, descends through conduit 33 back into the central gas heat exchanger chamber 30 and fiows therefrom through conduit '39 to the absorber 12. Since the gas heat exchanger chamber 30 contains rich gas from the evaporator coil ill, some of this rich gas is conducted upwardly through conduit 3| into the high temperature evaporator section l8 .to replace that which leaves' through conduit 33. Thus is created a local circulation of rich gas from the evaporator coil I!) through the high temperature evaporator section I8. 'In the evaporator sec-' tion l8, the partial pressure of ammonia in the gas which enters this section through conduit 3| determines the temperature at which ammonia evaporates in this section. Since the partial pressure of ammonia in the hydrogen in the evaporator section 18 is higher than the partial pressure of ammonia in the hydrogen entering the evaporator'coil I9, the temperature of the evaporator section l8 will be higher than the temperatureof the evaporator coil IS. The liquid ammonia which flows through conduit 23 from the evaporator section l8 to the evaporator coil I9 has become cooled, due to evaporation in the section l8, to a temperature lower than that at which it comes from the condenser portion l6. Therefore, the evaporator coil 19 maybe maintained at a lower temperature than that if liquid ammonia were conducted directly there to from the condenser.

Air in the refrigerator compartment I! may be cooled by flowing first in thermal exchange relation with the high temperature section l8 and then with the low temperature section formed by the coil l9 and tray receptacle 22.

' temperature is low.

The latter or low temperature section has a relatively limited surface for contact with the air, this surface merely being sufficient for maintaining the air at the desired temperature when heat leakage into the refrigerator com partment as determined by the outside or room Under these conditions, that is, low air temperature, the surface of the Y first condenser section [4 will be sufiicient to produce condensation" of all the ammonia so that liquid ammonia will be delivered only to the evaporator coil 1 9 through conduit 34. However, upon increase inair temperature, unevaporated ammonia is supplied to the second condenser section It and liquid ammonia from this condenser section flows through conduit 9 into the high temperature evaporator section l8, thus bringing the more extensive surface of this evaporator section into effect for cooling the air It will be understood that various changes and modifications may be made within the scope of refrigerator.

What is claimed is:

1. In 'a refrigerator, a thermally insulated refrigerating compartment, and a refrigeration apparatus including a first evaporator section having extensive heat transfer surface, a second evaporator section having a relatively limited heat transfer surface, a generator, an absorber, means for circulating absorption liquid between said generator and absorber, a first condenser, a second condenser, means for conducting refrigerant vaporfrom said generator to said first condenser, means for conducting liquid from said first condenser to said second evaporator section, means forconducting vapor from said first condenser to said second condenser, means for conducting liquid from said second condenser to said first evaporator section, means for conducting unevaporated liquid from said first evaporator section to said second evaporator section, and means to conduct auxiliary gas in a circuit including said absorber and said second evaporator section and includingmeans for conducting a portion of the gas flowing from said second evaporator section to said absorber through said first evaporator section;

2. In a refrigerator having a thermally insulated compartment, absorption refrigeration apparatus including a plurality of evaporation mem-' my invention embodied in the herein described upper evaporation member, said evaporation members being located in the upper part of said insulated compartment so that air therein is cooled by natural flow downwardly over first said upper evaporation member and then said lower evaporation member, and means for conducting part of the inert gas from said lower evaporation member to said absorber in a path of flow' including said upper evaporation member, whereby said upper evaporation member operates at a temperature higher than that of said lower evaporation when liquid flows only from the first part of said condenser to said lower evaporation member, said upper evaporation member having relatively extensive heat transfer surface for adequate procooling of the air when the condenser temperature is high enough so that liquid flows from the further part of the condenser to the upper evaporation member. 1 v

3. In a refrigerator having a thermally insulated compartment, absorption refrigeration apparatus including a first evaporation member comprising a pipe coil in the upper part of said compartment, a second evaporation member comprising a conduit having relatively extensive heat coil so that air in said compartment is cooled by natural flow downwardly over first said upper evaporation member and then said lower evaporation member, an absorber interconnected with said pipe coil for circulation of inert auxiliary gas therebetween, an air cooled condenser havin connections for deliveryof liquid to both'said evaporation members, and means for conducting part of the inert gas from said pipe coil to said absorber in a path of flow including said upper evaporation member, whereby said upper evaporation member operates at a temperature higher than that of said pipe coil, and air in said compartment is.cooled in two stages.

HARRY K. BERGHOLM.

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