US2691871A

US2691871A - Evaporator structure in refrigeration apparatus

Info

Publication number: US2691871A
Application number: US261443A
Authority: US
Inventors: Jules N Saler
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1951-12-13
Filing date: 1951-12-13
Publication date: 1954-10-19
Anticipated expiration: 1971-10-19

Description

Oct. 19, 1954 Filed Dec. 13. 1951 2 Sheets-Sheet 1 TTz INVENTOR JULES N. SALER ATTORNEY Oct. 19, 1954 J. N. SALER 2,691,371

EVAPORATOR STRUCTURE IN REFRIGERATION APPARATUS Filed Dec. 13, 1951 2 Sheets-Sheet 2 F|G 5 4 INVENTOR JULES N. SALER ATTORNEY Patented Oct. 19, 1954 EVAPORATOR STRUCTURE IN REFRIG- ERATION APPARATUS Jules N. Saler, Springfield, Mass, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 13, 1951, Serial No. 261,443

6 Claims. (Cl. 62-115) This invention relates to refrigeration apparatus and, more particularly to means for rapidly and effectively defrosting such apparatus.

It is an object of this invention to provide an improved refrigerating and defrosting system for selectively refrigerating and defrosting a refrigerant evaporator.

It is another object of this invention to provide a novel evaporator structure for a refrigerating and defrosting system.

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 top plan view of the evaporator structure employed in this invention;

Fig. 2 is a rear elevation view of the evaporator structure;

Fig. 3 is an end elevation view of the evaporator structure;

Fig. 4 is a vertical, enlarged, cross-section view of the evaporator structure taken along the lines IV-IV of Fig. 2; and

Fig. 5 is a diagrammatic view of a refrigerating and defrosting system constructed in accordance with this invention.

Referring to the drawings, the numeral Iii designates generally a refrigerant evaporator structure of box-like configuration having an opening l2 in the front thereof for the reception of ice trays (not shown) and foods to be frozen or cooled to a low temperature. The evaporator structure It is adapted to be mounted within an insulated cabinet structure (not shown) of any suitable construction.

The evaporator structure I0 is of sectional or composite construction and consists of an L- shaped portion I l forming the top and back walls of the evaporator structure and a U-shaped portion [6 forming the bottom and side walls of the evaporator. The L-shaped portion I4 is constructed of superimposed metal sheets [8 and 2H, portions of which sheets are embossed to form refrigerant passages between the sheets. After forming, these sheets are secured together in any suitable manner such as by welding or brazing. Formed within the back wall portions of the L- shaped evaporator portion I4 is an inlet passage 22. Both evaporator sheets l8 and are struck inwardly forming the refrigerant passage 22 to provide a recess on the exterior surface of the evaporator back wall for the reception of an electric heating element 25, the purpose of which will hereinafter be described. The inlet passage 22 extends along the bottom edge of the evaporator back wall, up the side edge thereof and communicates with an upper portion of a storage vessel 26 likewise formed by and between the back wall portions of the L-shaped sheets i8 and 20. A pair of outlet passages 23 and 30 communicate with upper and lower portions, respectively, of the storage vessel 26 and are joined at a point 32 near the upper edge of the storage vessel 26. The upper outlet passage 28 is provided with a restriction 34 which may be formed by crimping the passage 28 or by placing a fixed restriction within the passage 28 before assembling sheets is and 2G. The lower outlet passage 38 continues along the upper edge of the evaporator back wall and communicates with a sinuous refrigerant passage 35 formed by and between the top wall portions of the L-shaped sheets I8 and 20.

The U-shaped portion l6 of the evaporator structure it is likewise formed by two superimposed metal sheets 31 and 38 having refrigerant flow passages formed therebetween, which, for the sake of simplicity, have been shown as parallel passages 39 extending from the upper portion of one side wall downwardly, across the bottom wall, and upwardly to the upper portion of the opposite side wall. The refrigerant passages 39 are connected at one end by an inlet header 4!] and at the other end by a suction or outlet header 42.

The two portions i l and iii of the evaporator structure it are operatively connected to form a continuous refrigerant fiow passage by a conduit Ml connecting the outlet end (it of the sinuous passage 36 with the inlet header 40 on the side wall of the U-shaped evaporator portion [5.

As in a conventional refrigerating system, apparatus is provided for supplying refrigerant to and withdrawing refrigerant from the evaporator structure it]. As shown in Fig. 5, this apparatus includes a motor-driven compressor 48, a condenser 50, a hot gas conduit 52 for conveying refrigerant compressed by the compressor 48 to the condenser 50, a capillary tube 54 for conveying refrigerant condensed by the condenser 5E3 to the inlet passage 22 of the evaporator structure l0, and a suction or return conduit 56 for conveying refrigerant from the outlet header 42 on the evaporator structure It] to the compressor 48. As shown in Fig. 5, the return conduit 56 is soldered to or otherwise arranged in heat exchange relationship with portions of the capillary tube 54 and the hot gas line 52.

Power to operate the refrigerating and defrosting system is provided by electric supply lines L1 and L2 under the control of a thermostatic switch 58 connected in series with the leads 6U, 62 and 64 supplying power to the motor compressor 48. Switch 58 is actuated in response to pressure changes within a temperature-sensitive bulb 66 secured to a portion of the evaporator structure It to energize and deenergize the motor compressor 48 to maintain the desired temperature of the evaporator structure I 0, as is well understood. Current toenergizetheelectric heating element 224 is'li-kewise derived fromlines L1 and L2 through lead 60, switch 58,'leads '62, 68 and 10, through switch 12 and lead 14. It will be noted that the thermostatic control switch 58 is also in series with the supply :circuit5for the heater 24 and, therefore, the heater may be energized by the switch 12 only-during those periods when the motor compressor 48 is energized.

Referring to Fig. 5, the operation of .the improved refrigerating and defrosting system is as follows: During a refrigerating operation, :the switch 72 is open and heater 24 is deenerz d- The refrigerant from the compressing and condensing apparatus is conveyed through capillary tube 54 and enters the evaporator structure 19 through inlet passage 22. "This refrigerant, the major portion of which is in a liquid state, flows into and floods or completelyfills storage vessel 26, outlet passages 28 and 3t and flows into passage 36 in the top wall of the evaporator structure l0. Partial evaporation of the liquid refrigerant takes place in passagetfi and the resulting mixture of liquid and gas'fiows through connectingconduit 44 and header 4%! into the refrigerant passages 39 of the U-shape portion it of the evaporator structure. As the refrigerant absorbs further heat from the food stuffs in the evaporator structure It and the surrounding air, it is converted entirely to gas which passes through the outlet header 42 and is conveyed back to the compressing and condensing apparatus by the return conduit 56.

During the refrigerating operation, any gaseous refrigerant which may be conveyed to or gen erated in the storage vessel 25 will escape through the upper outlet passage 28 and will be carried through the remaining refrigerant passages by the liquid refrigerant-flowing .therethrongh. The restriction .34 inthe outlet passage 28 is of sufficient size to permit the escape of all gaseous refrigerant trapped inthe storage vessel during the refrigerating operation.

Due to the fact thattheevaporator structure L0 is maintained at a temperature below 32 F., frost will collect thereon and .must .be removed to ensure efficient operation of the system. The removal of frost is effected by closing switch '12 to energize heater 215 which appliesheat to the refrigerant flowing through .inlet passage .22 .of theevaporator structure iii. Since the. heater. is so located as to apply heat to the refrigerant flowing through the system, it isdesirable that the heater be energized only during ,a running period of the compressor 48. As previouslynoted, this condition of operation iseifected by ,having the thermostatic switch58 in series .withthe supply circuit of the .heater 2.4. .Should the switch .12 .be closed during a shutdown ,period of the compressor 43, defrosting will merely bedelayed until the next running period of the-compressor 48 as controlled by the thermostatic sWitchSB. and its .associated temperature-sensitive bulb .66.

The heat applied to the refrigerant flowing through inlet passage 2.2 vaporizes a major portion of this refrigerant and increases thequantity of gas in the storage vessel. 26. Because .of the restriction 3B in the upper .outletpassage28, only a portion of this gas is permitted to escape from the storage vessel 26, whereupon the pressure in the storage'vessel :25 rises sufficiently to force the liquid refrigerant contained therein outthrough the-lower outlet passage 3-0-and=int0 the remaining refrigerant flow passages 35 and 39 in the evaporator structure It. The storage vessel 25 contains sufficient liquid refrigerant to flood the

remaining refrigerant fiowipassages

36 and 39 as well as the headers 40 and *42 of the evaporator Hi and cause some liquid refrigerant to be spilled over into the return conduit 56. A :portion of 'the'liquid refrigerant in return conduit'zfi'fi-is vaporized by the heat derived through the heatexchanger between the return conduit '56 and the capillary tube 54 and the remaining liquid is vaporized 'by heat derived through the heat exchanger between the return conduit 56 and the hot gas line 52. This vaporization of liquid refrigerant returning to the compressor causes an increase in the overall pressure in the lower pressure side ofthe refrigerating system and materially aides in the defrosting operation. The major defrosting action is attained, however, bythecondensation of the'hot gaseous refrigerant issuing from the heated portion-of the inlet passage 22. This hot gas is "forced through the Various refrigerant passages'in the evaporator structure It and, in condensinggives up heat to the wall portions of the evaporator!!! to melt the frost which has collected thereon. The refrigerant thus condensed is revaporized in "the'return'conduit 56'by the "heat exchangers between the return conduit 56 and thecapillary tube 54 and the hot gas line-52.

When defrosting is complete, the switch 12 is opened to deenergizethe heaterffl'andpermit the system to'return'to refrigerating operation.

If desired, automatic control means may be provided for closing and opening switch .12 in response to the various conditions indicating the collection of frost and the absence of frost on the evaporator. Such a.control is describedand claimed in U. S. Patent "No. 2,595,967, granted May 6, 1952 to Graham's. 'McQloy and assigned to the assignee of the present invention.

"It will be apparent from the foregoing that this invention contemplates the construction of a refrigerating and defrosting system in which a storage vessel is formed by and between the superimposed sheets of the evaporator structure for "the purpose of collecting and discharging liquid refrigerant. This construction is economical andpermits of ease of assembly as compared to prior refrigerating and defrosting systems wherein the :storage vessel was formed independently of the other elements ofthe system. It will further be noted that the novel arrangement of outlet passages from the storage vessel insures positive discharge of the liquid contents of the vessel during defrosting and yet allows the vessel to collect a maximumamountof liquid refrigerant during the refrigerating operation.

While I have shown my invention inbutone i-Qrm, it will be obvious to those skilledintheart that it .not .so limited, butis susceptible of various changes and modifications without departing from the. spirit thereof.

What I claim is:

1. In a refrigerating and defrosting system, the combination of a refrigerant evaporatorcomprising superimposed sheets, first and second refrigerant passages each having inlet and outlet ends and'formed by and between said evaporatorsheets, a compresson-a condensenfirst conduit means for conveying compressed refrigerant frqm-saidcompressor to said "condenser, second conduit means including-afiow impeding'device forconveying refrigerant-condensed by said condenser to the'inlet end of-said first refrigerant passage, third conduit .-means for conveying,

refrigerant from the outlet end of said second refrigerant passage to said compressor, said third conduit means having a portion thereof arranged in heat exchange relationship with the refrigerant compressed by said compressor, a storage vessel formed by and between said evaporator sheets, said first refrigerant passage having the outlet end thereof communicating with said storage vessel, a first outlet passage communicating at one end with a lower portion of said storage vessel and at its other end with the inlet of said second refrigerant passage, a second outlet passage communicating at one end with an upper portion of said storage vessel and at its other end with said first outlet passage, said second outlet passage having a restriction therein, the construction and arrangement being such that liquid refrigerant accumulates in said storage vessel during refrigerating operation of said system, and means for appiying heat to the refrigerant flowing through said first refrigerant passage to vaporize at least a portion of said refrigerant to increase the pressure in said storage vessel whereby the refrigerant liquid contained therein is forced out of said vessel through said lower outlet passage, said storage vessel containing sufficient refrigerant liquid to flood said second refrigerant passage and spill over into said third conduit means.

2. In a refrigerating and defrosting system, the combination of a refrigerant evaporator comprising superimposed sheets, first and second refrigerant passages each having inletand outlet ends and formed by and between said evaporator sheets, a compressor, a condenser, first conduit means for conveying compressed refrigerant from said compressor to said condenser, second conduit means including a flow-impeding device for conveying refrigerant condensed by said condenser to the inlet end of said first refrigerant passage, third conduit means for conveying refrigerant from the outlet end of said second refrigerant passage to said compressor, a storage vessel formed by and between said evaporator sheets, said first refrigerant passage having the outlet end thereof communicating with said storage vessel, said second refrigerant passage having the inlet end thereof communicating with said storage vessel, the construction and arrangement being such that liquid refrigerant accumulates in said storage vessel during a refrigerating operation of said system, and means including a heater arranged in heat exchange relationship with said first refrigerant passage for heating and discharging the contents of said storage vessel into said second refrigerant passage to effect defrosting of said evaporator.

3. In a refrigerating and defrosting system, the combination of a refrigerant evaporator comprising superimposed sheets, first and second refrigerant passages each having inlet and outlet ends and formed by and between said evaporator sheets, a compressor, a condenser, first conduit means for conveying compressed refrigerant from said compressor to said condenser, second conduit means including a flow-impeding device for conveying refrigerant condensed by said condenser to the inlet of said first refrigerant passage, third conduit means for conveying refrigerant from the outlet end of said second refrigerant passage to said compressor, a storage vessel formed by and between said evaporator sheets, said first refrigerant passage having the outlet end thereof communicating with said storage vessel, a pair of outlet passages communicating respectively with upper and lower portions Of said vessel, said upper outlet passage having a restriction therein, said second refrigerant passage having the inlet end thereof communicating with said vessel outlet passages, the construction and arrangement being such that liquid refrigerant accumulates in said storage vessel during refrigerating operation of said system, means including a heater arranged in heat exchange relationship with said first refrigerant passage for heating and discharging the contents of said storage vessel into said second refrigerant passage to effect defrosting of said evaporator, said storage vessel containing sufficient refrigerant liquid to flood said second refrigerant passage and spill over into said third conduit means, and means for vaporizing the refrigerant liquid spilled into said third concluit means.

4. A defrostable refrigerant evaporator unit comprising a pair of superimposed L-shaped sheets adapted to form the top and back walls of a storage compartment, a refrigerant storage vessel formed by and between the back wall portions of said sheets, an inlet passage and a pair of outlet passages for said vessel, said passages being formed by and between said sheets, said outlet passages communicating respectively with upper and lower portions of said vessel, a sinuous passage formed by and between said L -shaped sheets, at least the major yortion of said sinuous passage lying in the top wall portion of said sheet, said sinuous passage having the inlet end thereof connected to said storage vessel outlet passages, and an electric heating element arranged in heat transfer relation with said inlet passage.

5. A defrostable refrigerant evaporator unit comprising superimposed sheets, at least a portion of said sheets lying in a substantially vertical plane, a storage vessel formed by and between the vertical portions of said sheets, a refrigerant inlet passage and a pair of outlet passages for said vessel, said passages being formed by and between said sheets, said outlet passages communicating respectively with upper and lower portions of said storage vessel, a fourth refrigerant passage formed by and between said sheets, said fourth passage having the inlet end thereof connected to said pair of outlet passages, and an electric heater arranged in heat transfer relation with said storage vessel inlet passage.

6. A defrostable refrigerant evaporator unit comprising superimposed sheets, at least a portion of said sheets lying in a substantially vertical plane, a storage vessel formed by and between the vertical portions of said sheets, a refrigerant inlet for said vessel, a pair of outlet passages for said vessel, said passages being formed by and between saicl sheets, said outlet passages communieatin respectively with upper and lower portions of said storage vessel, said upper outlet passage being formed with a restriction therein, and a third refrigerant passage formed by and between said sheets, said third passage having the inlet end thereof connected to said pair of outlet passages.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,459,173 McCloy Jan. 18, 1949 2,544,938 Phillip Mar. 13, 1951