US2279059A - Refrigeration - Google Patents

Description

April 7,1942. B. REISTAD ,2 5

- v REFRIGERATION Filed Dec. 19, 1%39 I 2 Sheets-Sheet; l

I INVENTOR.

' arm A ATTORNEY.

April 7, 1942. B. RElSfAD 2,279,059

- 1 REFRIGERATION File d Dem-19,1959 V 2 Sheets-Sheet 2 Patented Apr. 1. 1942 anr'ar EnArroN Bengt Beistad, Stockholm, Sweden, assignor, by

mesne assignments, to Servel, Inc., New York, 7 N. Y., a corporation'of Delaware I Application Decemberlll, 1939, Serial No, 309,943 g In Germany December 20, 1938 r QCIalms.

My invention relates to refrigerating apparatus and more especially to an improved evaporator which is particularly well adapted for use in connection with an absorption refrigerating-a1) paratus of the continuously operating uniform pressure type.

Among the objects of my invention is to promunicates with'a space 24 formed within a gas heat exchanger 25.. The opposite end of space 24 is connected by a conduit 26 with the upper part of a vessel 21;.

vide an evaporator constructed essentially of sheet metal parts in which an excellent transfer of heat is obtained between the tubes carrying the refrigerant and the sheet metal parts which support the ice trays. Another object of my invention is to reduce the size of the opening required in the wallof the refrigerator cabinet for the insertion of the evaporator.

Further objects and advantagesof my invention will be apparent from the following description, considered in connection with the accom panying drawings, which form part of this specification and of which;

Fig. 1 is a more or less diagrammatic view, partially in cross-section, of a preferred embodiment of my invention; Y

Fig. 2 is a view partially in cross-section, and on an enlarged scale of a portion of the evaporator shown in Fig. 1;

Fig. 3 is a top view, partially in cross-section,

The lower end ofan absorber 001128 is likewise connected to the upper part of vessel 21-. The

upper end of absorber coil 28 is connected by a conduit 29 with a space 3|! formed in one end of. gas heat exchanger 25 and separated fromspace 24 therein by a partition 3 I. A plurality of tubes 32 connects space 30 with a similar space 33 formed in the opposite end of the heat exchanger and separated from space 24 by a; partition 34. A conduit 35 connects space 33 with the end of leg |9 adjacent to the point where conduit ll communicates with the leg l9. A baflle 38 la locatedat the juncture of legv I9 and conduit 38 to prevent the flow of liquid from thelower part of the leg into the conduit.

of a portion of the evaporator shown in Fig. 1;

Fig. 4 is a side view, chiefly in cross-section, of the complete evaporator;

Fig. 5 is a top view of a portion of the evaporator illustrated in Fig. 4;

Fig. 6 is a cross-sectional view taken on-the line 6+6 of Fig. 4; and 7 r Fig. 7 is a perspective view of'the evaporator shown in the preceding figures. r 7 Referring more particularly to Fig. 1, reference character l0 designates a generator which includes a flue ll surrounded by a jacket I2. A conduit l3 connects the. upper part of the jacket with the upper end of a condenser l4. Heat transfer fins l5 are secured along a portion of the conduit l3, thus providing a rectifier. The flue is arranged 'to be heated by any suitable means, such as the gas burner l8.

The lower end of the condenser is connec The U-shaped evaporator conduit 20 is-formed with a non-circular cross-section, such as an ellipse, with the major axis extending-in a vertical direction. The legs l9 and 2| are preferably .lined with a tubular wire screen 31. Evaporator conduit 23 may be constructed of ordinarytubing having a circular cross-section. Indentations 38 are preferably provided along its lower edge for the purpose of damming up pools of liquid.

A member 40 0f sheet metal extends-around the legs 9 and 2| of evaporator coil" 20, as is most clearly shown in Fig. 6. Adjoining edges of the member 40 are secured together in anysuitable manner which will place the member under tension around the legs l3 and 2|.

AS is shown, in Figs. 6 and 7 the edges in the member are formed as tongues 4| which are inserted through openings formed in a plate 42 and then bent back so as to draw the edges together, thus shelf is enclosed by means of the upper shelf and to a 'vessel H, from the bottom'of which extends of a second generally U-shaped evaporator conduit 23. The opposite end of conduit 33 comby rear and side plates 45 which extend'between the upper and lower shelves and preferably in contact with the conduit 20. These plates may be formed with flanges 48 which are welded or otherwise secured to the member 49. These plates serve to protect the evaporator conduit from possible injury.

The space above the upper shelf 43 is enclosed The space above the lower to the rear of shelf 43 and tongues 42 are provided on the structure 41 in such a location as to be received by the brackets, thus holding the members together at this point.

A front plate 50 is formed with an opening in alignment with the spacesfor receiving the ice trays. Member ill is preferably formed with inturned flanges which are removably secured to structure .41 by means of bolts I2. The lower 50 serves to secure the front end of structure 41 to the remainder of the evaporator.

Projections 54 and ii are arranged within the .ice tray compartments. Projection 54 may be riveted to the sides of structure 41, while projection 55 may be welded directly to the side plates 45. These projections cooperate with means carried by the ice trays for prying the latter loose if they become frozen to the shelves.

A conduit 60 communicates with the lower part of the vessel 21 and extends within the outer tube of a liquid heat exchanger 6|. The opposite end of conduit 50 is connected to the lower end of a coil 62 wound around flue II. A conduit 63 connects the upper end of this coil with the upper part of the generator. A conduit 64 connects the lower part of the generator with one end of the outer chamber ofheat exchanger while a conduit 65 connects the other end of this chamber with the upper part of absorber coil 28.

A conduit 66 connects the upper part of vessel I! with one end of a pressure vessel 61, while the other end of this vessel is connected by means of a conduit 68 with the conduit 26.

conduit amount of water vapor is also formed which I! to the condenser M. A certain passes along with the ammonia. However, the cooling produced by the fins II is sufficient to condense most of the water vapor, but not the ammonia. The ammonia gas-deprived of accompanying water vapor is cooled in the condenser and;-liquefled therein. The liquid ammonia flows from the lower end of the condenser through the vessel l1 and conduit I. to evaporator coil 2|. Due to the baiiie 26 this liquid is The evaporator and a portion of ,the gas heat exchanger 25 is disposed within a refrigerator cabinet 69. One wall of this cabinet is formed with an opening Ill through which the evaporator.

and heat exchanger are inserted during assernbly. 'Upon assembly, this opening is closed by means of an insulating block H. In order to maintain at a minimum the heat leakage about the opening I0 it is' desirable to have the opening as small as possible. 'By reason of having the structure 41 removable from the remainder of the evaporator, it is possible to have the opening solved in a liquid absorption medium, such as water. After this solution has been placed in the apparatus an inert gas such-as hydrogen is prevented from flowing into the conduit and forms a pool in the conduit 2|. A similar baflle is provided at the juncture of leg 2| and conduit 22, in order to prevent flow of liquid refrigerantinto the conduit 22 until the depth of the pool is sufficient to cause it v to spill over this baflle. Through capillary attraction the liquid refrigerant creeps upwardly in the. wire screens 21,- thus increasing -the area of the liquid available for evaporation.

Hydrogen is introduced into the evaporator.

coil 22 through the conduit 25. In accordance with Daltons law the presence of this hydrogen reduces the partial pressure of the ammonia, thus causing the latter to evaporate and absorb heat from the surroundings. This heat flows into the coil 22 chiefly from the member which is in good heat transfer relation therewith. If trays containing water are placed on either of the shelves 42 or 44, heat is rapidly extracted therefrom, thus causing the water to freeze.

Liquid ammonia which spills over the baffle between leg 2| and conduit 22 flows into the evaporator conduit 23 ,where it continues to evaporate in the presence of the hydrogen. The gaseous mixture of ammonia and hydrogen thus formed flows from conduit 22, into the space 24 in the heat exchanger 25 and thence through the conduit 26 and upper part of the vessel 21 to the absorber coil 28. In the absorber the mixture comes'into intimate contact with weak absorption liquid introduced through the conduit 5 with the result that the ammonia gas is absorbed. The hydrogen, which is now weak in ammonia, flows from the absorber through the conduit 29. space 20, tubes 22. space 33, and conduit 3! to the upper part of the evaporator. The heat absorbed by the evaporation of ammonia in the evaporator conduit 23 is taken from the space within therefrigerator" cabinet 69} and hence serves to cool this space.

The strong solution formed in the absorber flows therefrom into the vessel 21 from where it introduced under pressure and the apparatus is sealed. When the hydrogen under pressure is introduced it tends to change the cross-section of the evaporator conduit 20 to a circular form.

- This tendency causes the member 40 to be placed erator causes the ammonia. to be driven off 'in the form of a gas, which passes through the passes through the conduit to the coil 62. Here the application of heat vaporizes a portion of the solution and the resulting bubbles serve to lift the unvaporized portion through the conduit C3 to the upper part of the generator. In

thegenerator the ammonia is driven out of solution, as previously described, and by the time the absorption liquid reaches the lower part of the generator it is comparatively weak. This weak solution flows through the conduit 64, heat exchanger ii and conduit to the upper part oi the absorber.

The pressure vessel 6'! is provided for the purpose of storing uncondensed ammonia vapors under conditions of high temperature of the cooling mediumavailable for the condenser. This serves to increase the pressure within the system, thus enabling condensation to take place at the higher temperature, as is well known.

In order that the member 40 of the evaporator may be wrapped around the evaporator conduit 2,279,059 1 20 in the manner described, it is necessary that the vertical dimension of thisconduit be sumcient so that enough space is provided between the shelves 43 and M to accommodate an ice tray. If this conduit were of circular cross-section, the width of the evaporator would be materially increased. This would mean that the evaporator would not only occupy more space in the refrigerator cabinet, but the opening 70 would have to be wider.

While I have shown one more or less specific embodiment of my invention it is to be understood that this has been done for the purpose of illustration only and is not to be considered as limiting the scope of my invention, which is to be determined by the appended claims.

What is claimed:

1. In an evaporator, a pair of spaced conduits,

and a sheet of metal extending around both of said conduits and maintained under tension in contact therewith by the application of internal fluid pressure to the interior of said conduits.

2. In an evaporator, a pair of spaced conduits, and a sheet of metal extending around both of said conduitsand having its opposite ends Joined together, said conduits being of non-circular cross-section whereby the application of internal fluid pressure thereto deforms the conduits and subjects said sheet to tension.

3.'In an evaporator, a pair of spaced conduits,

therewith, said sheet providing upper and lower shelves for ice trays, the space above the lower shell being closed in part by the upper shelf, a hollow member on the upper shelf for enclosing in part the space above said upper shelf, and a front plate removabiy secured to said hollow member for removabiy securing said member in place on said upper shelf.

6. In a refrigerator, refrigerating apparatus shelf for partially enclosing the space there-.

above, a refrigerator cabinet having an opening in a wall thereof, said refrigerating apparatus being secured to said cabinet with said evaporator within the cabinet and with said condenser and said means outside the cabinet, said opening being only of sufficient size to permit the introduction therethrough of said evaporator a sheet of metal extending around both of said conduits with the opposite ends of the sheet ad- I jacent to each other, said ends being formed with tongues, and a bar formed with apertures in alignment with said tongues, said tongues extending through said apertures and being bent back for drawing said ends together to thereby maintain said sheet under tension in contact with said conduits.

4. In an evaporator, a pair of horizontally spaced conduits, a sheet, of metal extending around both of said conduits and in contact therewith, said sheet providing upper and lower shelves for ice trays, the spaceabove the lower shelf being closed in part by the upper shelf,

and a hollow member secured to the upper shelf for enclosing in part the spaceabove said upper shelf. I .5. In an evaporator, a pair of horizontally spaced conduits, a sheet of metal extending around both of said conduits and in contact with said hollow member removed.

7. For use in a refrigeration system, an evaporator including a pair of spaced conduits, a metal wall member having parts disposed about and in thermal exchange relation with both of said conduits, said wall memberbeing urged into good thermal exchange relation with said conduits by the application of internal fluid pressure to the interior of said conduits.

8. For use in a refrigeration system, an evaporator including a conduit and a metal part having a portion disposed about said conduit, said conduit being non-circular in cross section and urged in good thermal transfer relation with said portion by the application of internal fluid pressure to said conduit.

9. In an evaporator, a conduit, a metal part having a portion disposed about and hugging said conduit, said portion and said conduit being so constructed and arranged that they are maintained in good thermal exchange relation by continual pressure from within said conduit.

BENG'I' REISTAD.

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