US1973127A

US1973127A - Cooling element for refrigerating systems

Info

Publication number: US1973127A
Application number: US645431A
Authority: US
Inventors: Robert S Taylor
Original assignee: Electrolux Servel Corp
Current assignee: Electrolux Servel Corp
Priority date: 1932-12-02
Filing date: 1932-12-02
Publication date: 1934-09-11
Anticipated expiration: 1951-09-11

Description

p 1934- R. s; TAYLOR COOLING ELEMENT FOR REFRIGERATING SYSTEMS Filed Dec. 2, 1932 s Sheets-Sheet 1" INVENTOR.

ATTORNEY. I

Jul; 5

Sept. 11, 1934.

R. s. TAYLOR COOLING ELEMENT FOR REFRIGERATING SYSTEMS Filed Dec. 2. 1932 3 Sheets-Sheet 2 a l l I, l I

1N VEN TOR. 5-

ATTORNEY.

Sept. 11, 1934. I R s TAYLOR 1,973,127

COOLING ELEMENT FOR REFRIGERATING SYSTEMS Filed Dec. 2, 1932 Sheets-Sheet 3 C ,in

I ATTORNEY.

a Z5 n i INVENTOR.

Patented Sept. 11, 1934 UNITED STATES COOLING ELEMENT FOR REFRIGERATING SYSTEMS Robert S. Taylor, Evansville, Ind., assignor to Electrolux Servel Corporation, New York, N. Y., a corporation of Delaware Application December 2, 1932, ser al No. 645,431

9 Claims.

My invention relates to refrigeration and more particularly to a new and improved cooling element for a system which produces refrigeration by the evaporation of liquid cooling fluid by diffusion into an inert auxiliary gas.

In household type refrigerators it is usually necessary that the cooling element provide a low temperature chamber for making ice or the like and also a suflicient amount of heat transfer surface for cooling air in the storage compartment to a temperature suitable for the proper preservation of comestibles.

Further, the cooling element should be of the smallest size possible for adequate freezing of ice cubes and cooling the air in the storage compartment in order to allow the greatest possible amount of food storage space.

In refrigerating systems of the pressure equalized absorption type for household service the evaporator heretofore used comprises a closed vessel having a plurality of liquid spreading bafiles. Liquid cooling fiuid such as ammonia introduced into the upper part of the evaporator fiows downwardly over the bafiles evaporating into an inert gas such as hydrogen circulated through the evaporator. In order to provide for freezing ice cubes and cooling the storage compartment, a tray receptacle of thermal conductive material such as cast aluminum, is secured to the evaporator, this receptacle being provided exteriorly with extensive heat transfer Surface such as integrally cast fins.

In accordance with my invention there is provided a cooling element for such a refrigerating system which is compact and provides a thermally isolated freezing compartment for ice trays and adequate heat transfer surface for cooling the air in the storage compartment. My cooling element comprises a pipe coil evaporator generally of the type disclosed in Patent No. 1,729,625 to Carl G. Munters but arranged with loops surrounding an open front freezing area such as disclosed in an application Serial No. 645,422 by Sven W. E. Andersson and W. R. Hainsworth, assigned to the same assignee as the-present invention, and provided with a sheet metal structure forming highly thermal conductive ice tray supports or shelveswithin the freezing area surrounded by a low thermal conductive shield having extensive exterior heat transfer surfaces. My invention will be more readily understood from the following description taken in connection with the accompanying drawings, in which, Fig. 1 is a sideelevation of a cooling element contemplated by my invention;

7 Fig. 2, a front end view of the cooling element shown in Fig. 1; 1 Fig. 3, a plan view of the cooling element shown in Figs. 1 and 2;

refrigerating system for the circulation of an.

inert auxiliary gas such as hydrogen through the coil. A liquid cooling fluid such as ammonia is conducted into the upper end of the coil through conduit, 13 which is shown extending concentrically within the upper end 11 of the coil. As best shown in Fig. 2, the coil 10 has a constantly downward slant such that the liquid cooling fluid introduced at the upper end will have a continuously downward path of flow therethrough. Within the coil I preferably provide means for retaining the liquid in a manner to present an extensive surface, for instance a wick-like lining 23 (see Fig. 5) which distributes the liquid in finely divided form over the'interior surface of the coil by capillarity, as disclosed in the abovementioned application of Andersson et a1. When ammonia is used as the cooling fluid the coil 10 is preferably of steel tubing and the lining of steel mesh or the like. 'As shown in Fig. 2 the turns of the coil may be positioned by spacing bars 14 welded between the front ends of the loops and, as shown in dotted outline in Fig. 1, by spacer bars 15 welded between the rear loops.

Shelves or tray supports 16 are formed by sheets of copper or other good thermal conductive material extending horizontally between substantially opposite leg portions of the U-bends, the outer edges of the sheets being bent over the coil and soldered, brazed, or welded in good thermal contact. The freezing area defined by the coil 10 is enclosed, except at the front, by a side wall formed by a. sheet 1'7 of galvanized iron or other poorer thermal conductive material bent around the outside of the coil 10 and a top cover sheet 18 secured around-its edges to the top edge of the side wall sheet 17.- On the outside of the side wall sheet 17 are mounted grid structures formed by sheets 19 and 20 also of iron or other relatively low thermal conductive material having portions struck outwardly therefrom to form heat transfer fins 21. The side wall 17 and grid structures 19 and 20 are conveniently secured in position around the coil 10 by lugs. or fiaps 22 struck out of the turned-over edges of the shelves 16 extending through slots in the sheet metal wall and over-turned on the outside.

A cooling element constructed as described above is characterized by high heat conductivity and relatively small surface for freezing water in the ice trays, and by a large surface of relatively low heat conductivity for cooling air in the box. In cooling the air in the storage compartment, a large surface for heat transfer is necessary because the greatest temperature drop is between the air and this surface. However, the conductivity between the transfer surface and the evaporator coils need not be very great because the amount of heat transfer per unit of surface is. relatively small wherefore the enclosing wall and grid structure described above is made of low conductivity metal such as galvanized iron or some similar material which will not rust. The

low conductivity metal enclosure also acts as ashield and prevents conduction of heat fromthe cabinet to the ice trays, thus decreasing the'freezing time. .The shield also prevents circulation of air in the freezing chamben'thus reducing the condensation and freezing of moisture around the tinuously downward flow of liquid therethrough,

said coil comprising a plurality of substantially horizontal superposed U-shaped turns, means within said coil for retaining liquid in finely divided form over an extensive surface, a connection for liquid cooling fluid to the upper end of said coil, highly thermal conductive supports for containers of substance to be frozen within the space outlined by said coil and attached thereto, and a shield of low thermal conductive material around said coil.

2. A cooling element comprising a pipe coil adapted for circulation of inert gas and continuously downward flow of liquid therethrough, said coil comprising a plurality of substantially horizontal superposed U-shaped turns, means within said coil for retaining liquid in finely divided form over an extensive surface, a connection for liquid cooling fluid to the upper end of said coil, highly thermal conductive sheet metal plates extending between and mounted on opposite legs of said turns, and a shield of low thermal conductive sheet material around said coil.

3. A cooling element comprising a pipe coil adapted for circulation of inert gas and continuously downward flow of liquid therethrough, said coil comprising a plurality of substantially horizontal superposed U-shaped turns defining a freezing space open at one end, means within said -coil for retaining liquid in finely divided form overan extensive surface, a connection for liquid cooling fluid to the upper end of said coil, and a casing of low heat conductivity around said coil, said casing having an aperture at the open end of said freezing space and an extensive heat transconduit comprising a plurality of substantially,

horizontal superposed U-s haped turns, means within said coil for retaining liquid in a manner to present extensive surface area of the liquid to the gas, a connection for liquid cooling fluid to the upper end of said coil, supports formed by sheets of highly thermal conductive metal extending between and attached to opposite legs of said turns, a metal casing of low thermal conductivity around said coil forming a freezing chamber open at the open ends of said turns, and a plurality of heat transfer fins on the outside of said casing.

5. A cooling element comprising a steel pipe coil adapted for circulation of inert gas and continuously downward flow of liquid therethrough, said coil comprising a plurality of substantially horizontal superposed U-shaped turns, means within said coil for. retaining-liquid in a manner to present extensive surface area of the'liquid' to the gas', a= connection for-liquid cooling fluid to the upper end of said coil, horizontal-shelves formed by sheets of copper extending between i and attached to opposite legs of said turns, and a casing of galvanized sheet iron around said coil forming a freezing'chamber open at the open ends of said turns, said casing having extensive exterior heat'transfer surfaces. i

6. A cooling element comprising a steel pipe coil adapted for circulation of inert gas and continuously downward flow of liquid therethrough,

said coil comprising a plurality of substantially horizontal superposed U-shaped turns, means within said coil for retaining liquid in a manner to present extensive surface area of the liquid to the gas, a connection'for liquid cooling fluid to the upper end ofsaid coil, shelves formed by sheets of copper extending between and bent downwardly over the outside of opposite legs of said turns, said sheets having tabs struck outwardly from the down-turned portions, and a casing of galvanized sheet iron around said coil forming a freezing chamber open at the open end of said turns, said casing being provided with heat transfer flns and having slots through which said tabs extend for securing said casing.

'7. A cooling element comprising a pipe coil adapted for circulation of inert gas and continuously downward flow of liquid therethrough, said coil having vertical rows of substantially parallel horizontal portions, supports formed by sheets of highly thermal conductive metal extending between and attached to horizontally opposite, portions of said coil, and a metal casing around said coil and secured to said support-forming sheets.

8. A cooling element comprising a pipe coil having a plurality of superposed U-shape turns, supports formed by sheets of thermal conductive metal extending between and attached to opposite legs of said turns, and a metal casing around said coil forming a freezing chamber open at the front ends of said turns and secured in place by tabs struck out from said support-forming sheets.

, 9. A cooling element comprising a pipe coil having a plurality of substantially horizontal superthermal conductive metal extending between and bent downwardly over opposite legs of said turns, said sheets having tabs struck outwardly from the down-turned portions, and a casing of low thermal conductive material around said coil provided with heat transfer fins and having slots through which said tabs extend for securing the casing.

ROBERT S; TAYLOR;