US2737030A - Refrigerating system having defrosting arrangement - Google Patents

Refrigerating system having defrosting arrangement Download PDF

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US2737030A
US2737030A US262809A US26280951A US2737030A US 2737030 A US2737030 A US 2737030A US 262809 A US262809 A US 262809A US 26280951 A US26280951 A US 26280951A US 2737030 A US2737030 A US 2737030A
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evaporator
refrigerant
motor
liquid
accumulator
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Lawrence A Philipp
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Nash Kelvinator Corp
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT-PUMP SYSTEMS
    • F25B47/00Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02Defrosting cycles
    • F25B47/022Defrosting cycles hot gas defrosting
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25DREFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT COVERED BY ANY OTHER SUBCLASS
    • F25D11/00Self-contained movable devices, e.g. domestic refrigerators
    • F25D11/02Self-contained movable devices, e.g. domestic refrigerators with cooling compartments at different temperatures

Description

March 6, 1956 L. A, PH|| |PP 2,737,030

REFRIGERATING SYSTEM HAVING DEFROSTING ARRANGEMENT Filed Deo. 21', 1951 2 sheets-sheet 2 INVENToR. [nuff/vr: ,4 Fly/mv Arran/vn REFRIGERATING SYSTEM HAVING DEFROSTING ARRANGEMENT Lawrence A. Philipp, Detroit, Mich., assigner to Naslb Kelvinator Corporation, Detroit, Mich., a corporation of Maryland Application December 21, 1951, Serial No. 262,809

1 Claim. (Cl. 62-116) This invention relates to refrigerating apparatus and more particularly to the arrangement for defrosting the refrigerant evaporator of the cooling system thereof.

One of the objects of my invention is to provide a new and improved methodV for the self defrosting of a refrigerator.

Another object of my invention is to provide a new and improved method for defrosting the evaporator of a refrigerating system by increasing the pressure therein, causing liquid refrigerant during the period of said increased pressure to flow to and through said evaporator to the motor-compressor unit, utilizing the motor-compressor unit to evaporate said liquid refrigerant, andthen conduct the latent heat of such evaporation by conducting the evaporated refrigerant to said evaporator.

Another object of my invention is to provide a new and improved arrangement for automatically defrosting a refrigerating system for a refrigerator which includes utilizing inherent characteristics of the system without the aid of additional or extraneous heating elements.

Another object of my invention is to provide a refrigerating system including a motor-compressor unit and a refrigerant evaporator with an unrestricted flow between the outlet of the evaporator and the motor-compressor unit and a by-pass conduit around the liquid supply means to the evaporator and to periodically operate the by-pass means either by a timer or counting mechanism to cause the motor-compressor unit to increase the pressure in the evaporator to drive some of the liquid therethrough and conduct same to the motor-compressor unit to evaporate said liquid refrigerant and conduct such evaporated refrigerant to said evaporator to rapidly defrost same.

Another object of my invention is to provide a refrigerating system wherein the evaporator is constructed to retain some liquid refrigerant therein during normal operation of the refrigerating system and to make provisions for increasing the pressure in the evaporator and equalizing the pressure throughout said system during periods when it is desired to defrost the evaporator so that the increased pressure and velocity of the refrigerant entering the evaporator will cause some liquid to flow from the outlet of the evaporator into the motor-compressor unit housing where it is evaporated to further increase the pressure and temperature in the system by the latent heat of evaporation to rapidly defrost the evaporator.

Another object of my invention is to provide a refrigerating system wherein liquid refrigerant during normal operation is stored in a refrigerant receiver or accumulator and during defrosting time such liquid refrigerant is delivered to the evaporator at an increased pressure so that some liquid overflows the evaporator and is driven into the condensing element to be evaporated and the latent heat of evaporation is conducted to the evaporator to rapidly defrost same.

It is another object of my invention to provide an improved arrangement for controlling the automatic defrosting period for defrosting the refrigerating system and 2,737,030 Patented Mar. 6, 1956 ICC the restoration of normal operation upon completion of such defrosting period.

Another object of my invention is to provide an improved refrigerant evaporator wherein liquid refrigerant is stored in both an inlet accumulator and an outlet accumulator during the cooling operation of the evaporator to aid in the cooling function of the evaporator.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred forms of the present invention are clearly shown.

In the drawings:

Fig. 1 is a front view of a refrigerator embodying features of my invention and showing a portion thereof broken away;

Fig. 2 is a side view of the refrigerator shown in Fig. 1 and showing a portion thereof broken away;

Fig. 3 is a layout View of a portion of a refrigerant evaporator embodying features of my invention and showing the evaporator in the flat before same is bent to form a box-like structure;

Fig. 4 is a diagrammatic illustration of the refrigerating system embodying features of my invention with an isometric illustration of the evaporator;

Fig. 5 is a rear view of a portion of the evaporator shown in Fig. 4 and showing a modified system of control elements attached to the evaporator and embodying features of my invention;

Fig. 6 is a rear view of an evaporator showing a modified form of refrigerant receiving and storage passages and showing the latter in cross section;

Fig. 7 is a further modified form of a refrigerant evaporator showing the refrigerant storage passage in cross section;

Fig. 8 is a modified form of a refrigerant motor-compressor unit embodying features of my invention; and

Fig. 9 is a still further modified form of motor-compressor unit embodying features of my invention.

In accordance with my invention I provide an improved arrangement in a refrigerating system for rapidly defrosting the refrigerant evaporator thereof. My improved arrangement includes utilizing inherent characteristics of a refrigerating system to rapidly defrost the refrigerant evaporator thereof. The inherent characteristics of the system include utilizing the heat of the motor-compressor unit to evaporate liquid refrigerant which is conducted from the refrigerant evaporator into the motor-compressor casing where the liquid is conducted into thermal or actual contact with the motor-compressor unit and the casing which encloses said unit. This liquid refrigerant is conducted from the evaporator which is so designed as to retain all liquid refrigerant within the refrigerant flow passages including the accumulator thereof during normal operation of the refrigerating system and to conduit liquid refrigerant from the evaporator to the motor-compressor unit when the pressure in the evaporator is increased. Thus a change in velocity and pressure causes liquid refrigerant to be driven from the evaporator into the vapor return conduit which is connected to the interior of the motor-compressor casing. The increase in pressure and the increase in velocity takes place automatically by a timing or counting device which opens a by-pass around the refrigerant condenser and supply conduit to permit compressed gas to flow into the evaporator thus increasing the pressure and temperature therein and increasing the velocity of the refrigerant passing therethrough. My invention also includes the provision of a receiver or accumulator at the outlet of the liquid supply means so that some liquid is retained in the receiver during normal operation and when the system is automatically placed in condition for defrost, this liquid retained in the receiver is circulated through the evaporator into the unrestricted avancee supply conduit 26. The conduit 26 is a capillary or small diameter tube which controls the ilow of liquid refrigerant from the condenser to the accumulator 98 to allow -the proper amount of liquid to be delivered to the evaporator 22 and in so doing establishes a pressure differential between the outlet of' the compressor and the interior of the evaporator. Liquid refrigerant entering the accumulator 98 at substantially lower pressure than that in the condenser will tend to ll the accumulator before passing into and through the conduit 80 of the evaporator 22. As will be noted, the accumulator 98 is placed so that the inlet end thereof is much lower than the outlet end :thereof so that some liquid will be retained therein during normal operation of the refrigerating system. When the system is originally charged, the amount of liquid is computed so that during normal operation a small amount of liquid rerefrigerant will be retained in the accumulator 100 but below the inlet end of the vapor return conduit 28. Thus during normal operation only gaseous refrigerant ows from the outlet of accumulator 180 of the evaporator 22. This gaseous refrigerant ows through the conduit 28 as previously described herein, which conduit is unrestricted so that the refrigerant is free to flow without any reduction of pressure throughout the flow from the evaporator to the motor-compressor unit.

In View of the fact that the two accumulators 98 and i) are in good thermal contact with the member 96, the sarne tend to aid in cooling food stored within the evaporator 22 in the same manner as the conduit 80. These two accumulators have some liquid therein and act to absorb heat through the member 96 to provide refrigeration at the rear portion of the evaporator 22.

A thermostat 130 of the usual type may be used to control normal cycling of the refrigerating system. This thermostat includes bellows 132 which has connected thereto a thermal bulb 134 which is placed in contact with the member 82 of evaporator 22. When the evaporator reaches a certain high temperature the pressure within the bellows 132 causes the snap acting thermostat 130 to close contacts 136 to initiate operation of the motor-compressor unit 47. When the temperature of the evaporator reaches a certain low point the bellows 132 will contract and cause the snap acting thermostat to open contacts 136 and interrupt the circuit to the motor-compressor unit to cause the motor to stop operating. The circuit to the motorcompressor unit is through line 140 which has contacts 136 therein.

In order to maintain operation of the refrigerating system herein described, I have arranged so that defrosting takes place so rapidly that frozen foods stored within the interior of the evaporator are not permitted to thaw before the defrosting cycle has been completed and the system has been restored to normal operation. This defrosting condition takes place strictly automatically by the provision of a clock or timer which when once set for the hour of the day desired for operating it will cause the system to go on defrost automatically at the same hour each day so that the user of the refrigerator need not do anything in order to have automatic defrosting as the timing device takes care of initiating such defrosting cycle and a thermostat control is arranged to restore the system to normal operation when the temperature of the evaporator reaches a predetermined high value. The timing device as herein diagrammatically disclosed is a conventional type of clock 144 having an actuating arm 146 which at a certain time of the day engages contact carrying arm 148 to cause movable contact 150 to engage contact 154. This contact carrying arm 148 is frictionally carried in a housing 156 so that when the actuating or striking arm 146 engages the contact carrying arm 148 the contact carrying arm 148 will move the contact 150 in engagement with contact 154 to complete the circuit l6 through wires 160, 162 and 163 which are connected across the line 140. The member 144 is connected across the line 140 by wires 165.

Included in the circuit of wires 162 and 163 is a winding 168 which is part of a solenoid valve 170. The solenoid valve is connected in a by-pass supply conduit 174 which is connected to the inlet of the accumulator 98. This by-pass conduit 174 is vof considerably larger diameter than the small diameter capillary supply conduit 26 and when the solenoid valve is moved to open position the refrigerant leaving the compressor will move directly into the inlet of accumulator 98 to by-pass the condenser conduit 52 and the capillary tube 26.

Preferably the solenoid valve 170 is placed within the insulation 34 of the refrigerator and the valve proper thereof is located above the inlet to the accumulator 98 so that in the event the valve should move to open position during a period when the motor-compressor unit is not in operation, no liquid refrigerant from the accumulator 98 will drain into the by-pass conduit 174.

When the timer 144 causes contact 150 to engage contact 154 a circuit is completed through the solenoid valve to cause such valve to open and when the motor-compressor unit is operating, gaseous refrigerant leaving the compressor flows through the by-pass conduit 174 into the liquid containing accumulator 98. Since this refrigerant enters the evaporator at an increased pressure over that which normally enters the evaporator through the small diameter tube 26 such increased pressure and change of velocity causes liquid refrigerant from the accumulator 98 to be forced through the evaporator conduit into the accumulator 100 and causes liquid to overflow said accumulator and to enter the vapor return conduit 28 which conducts said liquid refrigerant to the outlet end 126 of conduit 28 into the cup-shaped portion of the motor rotor 114. When this takes place the liquid refrigerant comes in thermal contact with the motor-compressor unit and is evaporated by the heat of said unit and the heat of the casing since some of the liquid entering the cup-shaped portion of the rotor is caused to move upwardly by flash-off and by rotation of the motor to move into contact with the heated casing 110. This causes the liquid refrigerant to evaporate before it enters the inlet 128 of the compressor 116. This evaporated refrigerant is then conducted to the evaporator where it is utilized to rapidly defrost the evaporator by giving up this latent heat of evaporation and due to this latent heat and the heat of condensation in the evaporator said evaporator is rapidly defrosted. This refrigerant which condenses by coming in contact with the cold walls of the evaporator is again caused to overllow the accumulator 100 and continue in its cycle back to the motor-compressor unit where it is again evaporated and this cycle is com-y pleted until the evaporator is defrosted and the temperature of the evaporator reaches a predetermined high value. At this time a thermostatic control element 180 which includes a thermal bulb 182, bellows 184 'and push-rod 186 interrupts the defrost cycle and restores the refrigerating system to normal operation. When the temperature in the evaporator reaches a predetermined high value the bellows 184 expands causing the push-rod 186 to move into engagement with the contact carrying arm 148 to move the movable contact away from the contact 154 to interrupt the circuit through the winding 168 of solenoid valve 176 to thus close the by-pass conduit 174 and restore the refrigerating system to normal operation.

Any suitable type of timing device or counting device may be utilized for controlling the operation of the solenoid valve 170. Any suitable device which will periodically close the circuit to the solenoid valve may be utilized for placing the system in condition for automatic defrosting. Any of the well-known timing devices now in use may be suitable for such purpose. Also, any suitable device which wouldV break the circuit through the solenoid valve upon a predetermined high temperature in the evaporator would be satisfactory for restoring the system to normal operation. It' dcsired, a counting device as disclosed in my co-pending application SerialNo. 254,466 filed November 2, 1951, now Patent No. 2,708,348, granted May 17, 1955', may be used for such purpose. As to the thermostat 130, any of the well-l nown types now in use may be used for the normal control of the refrigerating. system.

In Fig. 8 l have shown a modiiedv form of motorcompressor unit 2li@ which includes a casing 202. having an inlet 204. Within the casing is a motor 206 having a rotor 2tl8 which carries a cup-shaped memberV 21u. Below the motor is positioned a compressor 212' having an inlet 214. Refrigerant entering the casing 292 moves in the direction of the cup-shaped mein ber 210 and any liquid refrigerant so entering drops into said cup-shaped member and due to the rotation of the rotor such liquid is thrown upwardly into contact with the dome portion of casing 202 which causes evaporation of said liquid due to the heat of the motor-cornpressor unit including the heat of its casing. Thus only gaseous refrigerant enters the inlet 214.

In Fig. 9 there is shown a motor-compressor unit 220 having a casing 222 provided with an inlet 224 which receives refrigerant from the evaporator of the refrigerating system. In the casing is shown a motor 226 in the upper portion thereof and a compressor 227 is positioned in the lower part of the casing and provided with an inlet 22S and an outlet 23). Refrigerant entering casing 222 comes in Contact' with baffle 232 which causes any liquid refrigerant to il'ow into Contact with the motor 226, compressor 227 and the inside casing walls to evaporate said liquid due to the heat of the motor and casing which receives heat from both the motor and the compressor. Thus only refrigerant gas enters the inlet 228. Under some conditions of operation the motor-compressor units of the type disclosed in Figs. 8 and 9 may be used to certain advantages.

In Fig. 5 I have shown a rear portion of the evaporator 22 and a modiiied form of control system. This modied form of control system includes the timer 144 and the thermostat lZ-il. ln this particular instance both thermostat and timer bellows are connected to the same thermal bulb 134 by conduit 240 and conduit 24 which is joined to conduit 240. This eliminates the thermal bulb 182 of thermostat 180.

In Fig. 6 l have shown a rear view of the evaporator 22 with both modified form of accumulators shown in cross section. In this particular arrangement the outlet accumulator 2553 may be provided with a perforated baffle 252 so that liquid refrigerant entering the acl cumulator 250 would not tend to splash into the inlet of vapor return conduit 28. In this modication an inlet accumulator 254 is provided with an inlet con nection 256 adjacent the upper portion of the accumulator. ln this embodiment liquid refrigerant entering the accumulator 254 during normal operation will tend to move towards the lower part of, the accumulator254 until the accumulator is substantially lled. In this accumulator it will be noted that there is provided a conduit 269 which extends downwardly into the accumulator to a point adjacent the lowermost portion thereof. At the uppermost portion of the conduit 26! is a small orice 262 through which liquid refrigerant normally ilows into the inlet of conduit 3 of the evaporator 22. This small orifice 262 is somewhat larger than the small diameter tube 26 so that at all times liquid refrigerant lnay passthrough that orice to properly permit the ilow of liquid into evaporator 22. vThe orifice 262, however, is smaller than the internal diameter of the tube 260 so that when the solenoid valve Cil 1:70 is open anygaseous refrigerant' which enters, the accumulator 254 from the compressor unit will tend to increase the pressure within the accumulator 254 and force liquid from the Ylower portion of the accumulator into the inlet of the conduit 260 and force thev liquid refrigerant out of the accumulator 254' during such defrost cycle. This takes place due to the increase in pressure entering the accumulator 254 at that time.

In Fig. 7 l have shown a modified form of evaporator wherein a single accumulator 27u is utilized. In this embodiment the coil of the evaporator 22 may be wound about its side walls theA same as previously described, however, the rear wall is provided with but a single accumulator 27%. ln this embodiment the liquid enters the laccumulator 270 through conduit 276 and leaves by outlet conduit 280 which is connected with the intake of the motor-compressor unit. ln this particular embodiment of the invention Vthe particular coils on the walls of the evaporator' 22 are proportioned as to size so that during normal operation some liquid is contained in the accumulator 270 and a substantial amount of liquid is retained in the walls of the evaporator during normal operation. Thus when the solenoid valve is open the gaseous refrigerant leaving the -v motor-compressor unit ows directly into the evaporator and the increase in pressure therein and change of velocity tends to force the liquid through the evaporator into the accumulator thereof where it overflows and goes to the motor-compressor unit where it is evap- @rated and returned tothe evaporator to rapidly defrost the same as is done in connection with the evaporators shown in Figs. 4 and 6.

From the foregoing it will be noted that I have provided a new arrangement for defrosting a refrigerant evaporator of a refrigerating system by conducting liquid refrigerant from the evaporator during the defrost period to the motor-compressor unit wherein it is evaporated and this latent heat of evaporation is utilized to increase the vapor pressure and temperature in the evaporator. This is caused by the sensible heat stored in the motor-compressor unit and casing, which heat is generated by mechanical friction and additional heat by electrical losses which are effective to evaporate the liquid which is returned to the motor-compressor unit and returned to the evaporator in the form of hot gases which are condensed in the evaporator and the latent heat of condensation provides for rapid defrosting of the evaporating element. This is accomplished by a single solenoid valve and an automatic control therefor to initiate automatic or self defrosting and return the system to normal operation upon completion of the `defrost cycle. It will further be noted that. the flow of refrigerant from the outlet of the evaporator to the interior of the motor-compressor casing is unrestricted, thus denoting that the system is operated without any restrictions or other form of controls on the return flow portion of the refrigerating system and that a single solenoid valve controls the inlet flow to the evaporator during defrosting and that an inlet accumulator is provided to provide for additional liquid to ilow to the evaporator to aid in causing the overflow of liquid refrigerant from the evaporator so that same is conducted to the motor-compressor unit to increase the pressure and temperature in the evaporator to aid in effectively'and rapidly defrosting the refrigerant evaporator. It will also be noted that a modified form of my invention consists in proportioning the size of the refrigerant conduit forming the major portion of the refrigerant evaporator so that same is slightly larger than the conventional conduit to aid in storing liquid refrigerant in the evaporator during the normal operation of the refrigerating system so that when the system is on` defrost cycle `such stored liquid is driven from the evaporator conduit into and out of the accumulator to the motorcompressor unit for evaporation to increase the pressure 9 and temperature in the refrigerant evaporator for effecting rapid defrosting thereof.

Although preferred and modied forms have been i1- lustrated, and described in detail, it will be apparent to those skilled in the art that various other modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claim.

I claim:

Refrigerating apparatus comprising a cabinet having a chamber, a motor-compressor unit, an evaporator in said chamber, a condenser, a restrictor, conduit means connecting said unit, evaporator, condenser and restrictor in series circuit relation, said conduit means including an enlarged portion the inlet of which is connected to the outlet of the restrictor and the outlet thereof to the inlet of the evaporator, said enlarged portion being in heat exchange relation with said evaporator in said chamber, and a valve-controlled line by-passing said restrictor and communicating with the inlet end of said enlarged portion and being operable to interrupt normal ow of liquid through the restrictor and thence to the evaporator,

and to establish modified ow of vaporous refrigerant through said line to the inlet of said enlarged portion so that the stated ow of vaporous refrigerant through said line causes refrigerant liquid accumulated in said enlarged portion during normal operation to ow therefrom through said evaporator and toward said motor-compressor unit.

References Cited in the le of this patent UNITED STATES PATENTS 530,494 Chuch et al Dec. 4, 1894 2,069,201 Allison Feb. 2, 1937 2,221,212 Wussow et al Nov. 12, 1940 2,281,770 Hoesel May 5, 1942 2,430,960 Soling Nov. 18, 1947 2,440,146 Kramer Apr. 20, 1948 2,452,102 Cocanour Oct. 26, 1948 2,455,421 Kirkpatrick Dec. 7, 1948 2,555,161 Smith May 29, 1951 2,564,310 Nussbaum et al. Aug. 14, 1951 2,635,433 Schordine Apr. 21, 1953

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2962871A (en) * 1957-12-09 1960-12-06 Revco Inc Defrosting and head pressure releasing refrigerating apparatus
US3024625A (en) * 1956-06-08 1962-03-13 Jenaer Glaswerk Schott & Gen Cooling device for vacuum apparatus
US3763659A (en) * 1972-02-02 1973-10-09 Tecumseh Products Co Refrigeration process, apparatus and method

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US530494A (en) * 1894-12-04 of newton
US2069201A (en) * 1932-09-16 1937-02-02 Arthur L Hardin Defrosting apparatus
US2221212A (en) * 1934-08-13 1940-11-12 Wussow Reinhard Refrigerating apparatus
US2281770A (en) * 1941-01-17 1942-05-05 Peerless Of America Defrosting system
US2430960A (en) * 1945-05-29 1947-11-18 York Corp Refrigeration system including evaporator defrosting means
US2440146A (en) * 1944-11-07 1948-04-20 Kramer Trenton Co Defrosting mechanism in refrigerating apparatus
US2452102A (en) * 1944-11-06 1948-10-26 Colvin Templeton Inc Refrigerating system defrosted by hot liquid refrigerants
US2455421A (en) * 1946-06-03 1948-12-07 Advance Mfg Inc Control means for air conditioning apparatus
US2555161A (en) * 1947-06-03 1951-05-29 C V Hill & Company Inc Refrigerating system with defrosting arrangement
US2564310A (en) * 1950-10-05 1951-08-14 Kramer Trenton Co Means for controlling the head pressure in refrigerating systems
US2635433A (en) * 1949-03-16 1953-04-21 Fred J Schordine Liquid defrosting unit

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US530494A (en) * 1894-12-04 of newton
US2069201A (en) * 1932-09-16 1937-02-02 Arthur L Hardin Defrosting apparatus
US2221212A (en) * 1934-08-13 1940-11-12 Wussow Reinhard Refrigerating apparatus
US2281770A (en) * 1941-01-17 1942-05-05 Peerless Of America Defrosting system
US2452102A (en) * 1944-11-06 1948-10-26 Colvin Templeton Inc Refrigerating system defrosted by hot liquid refrigerants
US2440146A (en) * 1944-11-07 1948-04-20 Kramer Trenton Co Defrosting mechanism in refrigerating apparatus
US2430960A (en) * 1945-05-29 1947-11-18 York Corp Refrigeration system including evaporator defrosting means
US2455421A (en) * 1946-06-03 1948-12-07 Advance Mfg Inc Control means for air conditioning apparatus
US2555161A (en) * 1947-06-03 1951-05-29 C V Hill & Company Inc Refrigerating system with defrosting arrangement
US2635433A (en) * 1949-03-16 1953-04-21 Fred J Schordine Liquid defrosting unit
US2564310A (en) * 1950-10-05 1951-08-14 Kramer Trenton Co Means for controlling the head pressure in refrigerating systems

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3024625A (en) * 1956-06-08 1962-03-13 Jenaer Glaswerk Schott & Gen Cooling device for vacuum apparatus
US2962871A (en) * 1957-12-09 1960-12-06 Revco Inc Defrosting and head pressure releasing refrigerating apparatus
US3763659A (en) * 1972-02-02 1973-10-09 Tecumseh Products Co Refrigeration process, apparatus and method

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