US2492648A - Two temperature refrigeration apparatus - Google Patents

Description

'Dec. 27, 1949 (5.5. M CLOY TWO-TEMPERATURE REFRIGERATION APPARATUS 2 Sheets-Sheet 1 Filed NOV. 10, 1945 -7 INVENTOR ERA/IAN 5. N :11)

WIT gssEs: 9446/ ATTORN EY De c. 21, 1949 G. s. McCLOY 9 6 TWO-TEMPERATURE REFRIGERATION APPARATUS Filed NOV. 10, 1945- 2 Sheets-Sheet 2 WITNESSES: v INVENTOR n5 4 ERAH EZN JIY BWW A'ITAORNEY Patented Dec. 27, 1949 TWO TEMPERATURE REFRIGERATION APPARATUS Graham 8. McCloy, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 10, 1945, Serial No. 627,890 Claims. (Cl. 62-2) This invention relates to refrigeration apparatus, more particularly to two-temperature means of a secondary refrigeration circuit which is operated by the primary circuit. 4

The present invention is primarily concerned with means for varying or modifying the heat exchange rate between the primary and secondary refrigeration circuits in accordance with the temperature of the second zone or with the ambient temperature of the refrigerator in order to maintain the temperature of the second zone more nearly constant. This is accompanied by spacing .the'condensing portion of the secondary circuit from the cooling portion of the primary circuit and locating a liquid chamber therebetween. This liquid chamber communicates with a liquid container placed either in the ambient air of the refrigerator or in the high temperature compartment. The liquid in the container is displaced as the temperature of the container increases and is forced into the chamber, thereby increasing the liquid contact area between the primary and secondary circuits to increase the heat transfer therebetween. Likewise, as the temperature of the container decreases, the liquid is returned to the container, thus reducing the liquid contact area'between the primary and secondary circuits to effect a reduction in refrigeration of the secondary circuit.

It is, therefore, another object of the invention to provide improved means for varying the heat exchange rate between the primary and and secondary circuits will be relatively simple in construction and dependable in operation.

These and other objects are effected by the invention as will be apparent from the following description and claims taken -in connection with the accompanying drawings forming a part of this application, in which:

Fig. 1 is a diagrammatic vertical sectional view of a two-temperature refrigerator taken substantially on the line I-I of Fig. 2 and showing a primary and secondary refrigeration circuit with the invention applied thereto;

Fig. 2 is a horizontal sectional view taken substantially along the line II-II of Fig. 1;

Fig 3 is an enlarged longitudinal sectional view taken along the line IIIIII of Fig. 2, and showing the heat exchanger between the primary and secondary refrigeration circuits and'the expansible means for varying the heat transfer rate;

Figsui and 5 are vertical sectional views of modified forms of the expansible means shown in Fig. 3; and,

secondary refrigeration circuits, in accordance Fig. 6 is a modification of the heat exchanger shown in Fig. 3.

Referring now to the drawings, Figs. 1 and 2 show a household refrigerator having an insulated cabinet In provided with a door II. The interior of the cabinet in is divided by a baflle l2 into a first zone or low temperature compartment I4 in which ice may be frozen and frozen foods stored, and into a second zone or compartment I6, having a relatively high temperature and humidity wherein food is cooled. A machinery compartment H), which preferably houses the mechanical portion of the primary refrigeration circuit [5 is located below the insulated cabinet ID.

The primary refrigerating circuit 15 is -of wellknown construction and operation and, briefly, comprises a motor 2|, energized from an electrical source 22 for driving a compressor 23, which compresses refrigerant vapor. A condenser 24 cools and liquefies the compressed refrigerant vapor discharged by the compressor 23 and conducts it to .a capillary tube 25. This capillary tube 25 impedes the flow of liquid refrigerant therethrough and delivers it at a low pressure to a primary evaporator 26 disposed in or about the first zone or low temperature compartment I 4 to cool the same. The refrigerant vapor generated in the primary evaporator 26 is withdrawn therefrom through a conduit 21 by the suction of the compressor 23 after which the refrigeration cycle is repeated. The cyclic operation of the primary refrigeration .circuit zone H at a substantially uniform low temperature.

The secondary refrigeration circuit I3 is a separated closed circuit containing a volatile refrigerant and comprises a secondary evaporator 23 disposed in or about the second zone It to absorb heat therefrom, and a secondary condenser 3| which is disposed in heat exchange relation to a tubular portion 32 of the primary evaporator 26 to provide a heat exchanger 33.

In order to minimize outside influence on the heat exchanger 33, it is preferably embedded, as

shown in Figs. 1 and 2, in the insulation of the cabinet Ill. However, it may be desirable under some conditions to place the heat exchanger 33 at any other suitable location, for example, in the food storage compartment IE or have it insulatedly mounted on the back of the cabinet.

As shown in Fig. 3, the heat exchanger includes the tubular portion 32 of the primary evaporator 26 wherein liquid refrigerant is vaporized; an intermediate annular member 34 surrounding and spaced from the tubular portion 32 to provide an intermediate liquid chamber 35; and an outer annular member 36 surrounding and spaced from the intermediate member 34 to provide a condensing chamber 31 for the vaporized refrigerant in the secondary refrigerating circuit II.

The condensing chamber '31 is preferably located so that the vapor passing from the secondary evaporator 29 enters the upper portion of the condensing chamber 31 and 38. As the vapor enters the condensing chamber 31, it will contact the outer surface of the intermediate member 34 and be cooled by the refrigerant in the primary evaporator portion 32 in a manner to be hereinafter described. When the vapor is cooled and condensed, the liquid refrigerant will flow out of the chamber 31 at 39 to be returned to the secondary evaporator 29 for revaporization. This action in the secondary circuitll continues as long as there .is a temperature difference in the heat exchanger 33.

Under conditions wherein the refrigerator cabi-- net is placed in an atmosphere having a substantially constant temperature, the heat leakage into the cabinet will be relatively constant, and the refrigeration rate of the secondary circuit may be designed to maintain a relatively uniform temperature in the second zone. However, as is well known, the ambient temperature of a refrigerator cabinet may vary over a substantially wide range, and these wide variations in ambient air will cause changes in the temperature of the second zone. Thus, with a high ambient temperaturethe heat leakage into the cabinet will be high and the temperature in the second zone may tend to rise above the desired normal safe operating range. Likewise, a low ambient temperature will result in decreased losses, with the result that the second zone may be cooled-below the desired temperature for proper food storage.

Accordingly, to overcome the'above-mentioned disadvantages, the intermediate liquid chamber 35 communicates with-a container 4| through a connecting tube 42.

Th container 4| is filled with a heat exchange liquid 43 and an adsorbent material 44 which has been charged with a gas. The materials utilized inthe container 4| may be of any suitable combination, for example, activated charcoal may be used as the adsorbent material, glycerine as the heat exchange fluid, and dichlorodifluoromethane vapor, commonly called F-12 as the gas adsorbed by the charcoal. As shown in Figs. 1 and 2, the container 4| is preferably located on the outside of the refrigerator cabinet so as to be influenced directly by the ambient air temperature of the refrigerator. When the container 4| is located on the outside of the cabinet it may be made relatively small, because it will be subjected to wide temperature variations. However, the container I the compartment Ii if 4| also may be placed in the size of the container 4| and the quantity of actuating material is increased so that the liquid level in the chamber 35 manner.

Assuming a liquid level 45 in the intermediate liquid chamber 35 corresponding to a relatively low ambient temperature, it can be seen that the chamber has a relatively small quantity of liquid therein and that the liquid is contacting only a small portion of the adjacent surfaces of the primary evaporator portion 32 and the intermediate member 34. Due to the fact that the space in the chamber above the liquid level 45 contains only a gas which is a relatively POOr heat conductor, the eflective heat transfer area is small, and therefore, the heat transfer rate between the refrigerant vapor in the condensing chamber 31 and the primary evaporator portion 32 is necessarily small. This operating condition will, therefore, provide a low refrigeration rate in the secondary circuit I8. If the ambient temperature decreases still further, the liquid may be entirely removed from the chamber 35 by the adsorption of the gas into the adsorption material 44, thereby reducing the refrigeration in the secondary circuit to a minimum.

Now, assuming that the ambient temperature increases, the gas adsorbed in the adsorption material 44 will be released and will force a portion of the liquid into the chamber 35. As the liquid level increases, more and more of the primary evaporator portion 32 and intermediate member 34 will be contacted by the liquid 43, thereby increasing the effective heat transfer area therebetween. When the liquid 43 reaches the level indicated at 46, it can be seen that the heat transfer rate will be approaching its maximum and that the gas in the chamber has been displaced and is confined in a relatively inactive portion of the heat exchanger.

Thus, it will be observed that a heat exchanger is provided which is simple in construction and in eflect provides a variable heat exchange surface, and that the heat transfer rate between the primary and secondary refrigeration circuits will be varied so as to compensate for changes in the ambient temperature of the refrigerator cabinet l0.

Referring to Fig. 4, there is disclosed a modified form of container 41 which has the same function as the previously-mentioned container 4|. A bellows 48 is located in the container 41 and is filled with any suitable expansible gas which will displace liquid from and draw liquid into the container, in accordance with the ambient temperature to which it is subjected.

In Fig. 5 there is disclosed still another form of container 49. This container 49 eliminates the use of the gas for varying the liquid level in the chamber 35 and uses the expansion of the liquid directly. If the spacing of the primary evaporator 26 and intermediate member 34 is suificiently close and the container 49 is sufliciently large, the volume of the liquid and hence its level in the chamber 35 will vary sufiicientiy in varies in the proper response to the thermal expansion of the liquid ,in the container to effect the desired change of the heat transferring capacity of the heat exchanger.

Referring now to the embodiment shown in Fig. 6, there is disclosed a heat exchanger preferably disposed in the cabinet insulation, which differs from that disclosed in Fig. 3 in that the annular intermediate member 52 and the portion 53 of the primary evaporator 26 are bent to provide a vertical section 54 and an upwardly-inclined section 55 and the outer annular member 56, forming the secondary refrigerant condensin chamber 51 is only disposed around the inclined section 55 of the intermediate member 52.

In this modification, the liquid container 58 is charged with a volatile fluid, such as, for example, trichlorotrifiuoroethane (commonly known as Freon-113) and is preferably disposed in the second or high temperature zone It at a point below the lower end of the vertical section 54. A conduit 59 connects the container 58 to a liquid chamber 60 at the lower end of the vertical section 54 so as to provide for direct communication therebetween.

The relative positioning of the liquid container 58 with respect to the heat exchanger 5| and the lengths of the vertical and inclined sections 54 and 55 are proportioned to operate in the following manner: Assume that the ambient'temperature of the container 58 is 40 F. and that the primary refrigeration circuit is inactive. The charge of volatile fluid placed in the container 58 will be such that the liquid chamber 80 will be filled with vapor and the pressures developed in the chamber 68 and the container 58 will balance, with a resultant static head of liquid that will fill the conduit 58.

Now, if the primary refrigeration circuit I5 is operated to cool the low temperature zone l4 and if the temperature of the second zone Hiremains constant, the primary evaporator will cool and thereby reduce the vapor pressure in the liquid chamber 60. This reduction in vapor pressure will upset the static balance in the system, and the liquid will be forced to flow into the chamber 60 by the pressure prevailing in the container 58. The liquid will continue to rise until the vertical section 54 is filled with liquid, and at thispoint the static head is again balanced. With this head, there will be very little, if any, change in the heat transfer rate between the primary and secondary refrigeration circuits.

However,when the temperature of the second zone l6 increases above 40 F., the temperature difference between the container 58 and the chamber 60 is increased and the vaporization of the volatile fluid in the container 58 generates a pressure therein, which will cause the static head of liquid in the chamber 68 to rise proportionately. With this increase in static head, liquid will flow into the inclined section 55 and contact both portions of the primary evaporator and the intermediate member 52, to provide means for rapidly transferring heat therethrough from the condensing chamber 51 to the portion 53 of the primary evaporator 26. The higher the ambient temperature of the container 58, the higher will become the static head of liquid in the chamber 60, which will result in a greater effective heat transfer area therebetween with a resultant increase in secondary refrigeration.

The upper portion of the heat exchanger 5| is inclined at an angle, so as to provide means for making available a larger heat exchange surface for small changes in temperature in the container 58. In other words, smaller changes in static head will result in an increased heatexchange rate per unit of head. It is to be understood that, under some conditions, the container 58 for the heat exchanger 5| may be modified and placed so as to be subjected to the ambient air temperature of the refrigerator cabinet.-

It will be observed that a two-temperature refrigerator has been provided in which the rate of secondary refrigeration is responsive to an intermediate liquid disposed between the primary and secondary refrigeration circuits, and that the quantity of liquid available for transferring heat therebetween is varied in response to the temperature in the second or high temperature zone Hi. This fluid is varied so that with a high temperature the heat transfer rate is high and with a low temperature the heat transfer rate is low.

Also, there has been provided heat exchange apparatus which is relatively simple in construction and durable in operation.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What I claim is:

1. In a refrigerator, the combination of an insulated cabinet having a low temperature compartment and a higher temperature compartment, a primary refrigerant circuit including a primary evaporator having a first portion and a second portion, said first portion being adapted to cool the lower temperature compartment, a secondary volatile refrigerant circuit having an evaporative portion adapted to cool said higher temperature compartment and a condensive portion disposed adjacent said second portion of the primary evaporator, and a variable device for conducting heat from said condensive portion to said second portion of the primary evaporator, said device comprising an intermediate chamber interposed between said condensive portion and said second portion, a container communicating with said intermediate chamber, and means responsive to temperature for transferring a liquid from said container to said intermediate chamber when said temperature increases and for transferring said liquid from said intermediate chamber to said container when said temperature decreases.

2. The refrigerator defined in claim 1 wherein said container is subjected to ambient temperature of the insulated cabinet.

3. The refrigerator defined in' claim 1 wherein said container is subjected to the temperature of said higher temperature compartment.

4. The refrigerator defined in claim 3 wherein said means comprises a volatile liquid located in said container and wherein said intermediate chamber communicates with a lower portion of said container.

5. The refrigerator defined in claim 4, wherein at least a portion of the intermediate chamber is inclined.

GRAHAM S. McCLOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Certificate of Correction Patent N 0. 2,492,648 December 27, 1949 GRAHAM S. McCLOY It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 25, for the word accompanied read accomplished; column 3, line 6, for separated read separate; line 34, for and read at;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 11th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

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