US2724245A - Defrosting arrangements for refrigeration systems - Google Patents

Defrosting arrangements for refrigeration systems Download PDF

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US2724245A
US2724245A US312377A US31237752A US2724245A US 2724245 A US2724245 A US 2724245A US 312377 A US312377 A US 312377A US 31237752 A US31237752 A US 31237752A US 2724245 A US2724245 A US 2724245A
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evaporator
line
refrigerant
refrigeration
valve
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US312377A
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Swinburne James
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Carrier Global Corp
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Carrier 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
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT-PUMP SYSTEMS
    • F25B2600/00Control issues
    • F25B2600/02Compressor control
    • F25B2600/026Compressor control by controlling unloaders
    • F25B2600/0261Compressor control by controlling unloaders external to the compressor
    • 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
    • F25B5/00Compression machines, plant, or systems, with several evaporator circuits, e.g. for varying refrigerating capacity

Description

Nov. 22, 1955 J. SWINBURNE 2,724,245

DEFROSTING ARRANGEMENTS FOR REFRIGERATION SYSTEMS Filed Sept. 30, 1952 United States Patent Ofiiice 2,724,245 Patented Nov. 22, 1955 1 2,724,245 DEFROSTIN G ARRANGEMENTS FOR REFRIGERATION SYSTEMS James Swinburne, Syracuse, N. Y., assignor to Carrier Corporation, Syracuse, N. Y., a corporation of Delaware Application September 30, 1952, Serial No. 312,377

Claims. (Cl. 62-415) This invention relates to defrosting arrangements for refrigeration systems and, more particularly, to a refrigeration system for use in transportation such as trailers or trucks for Cooling the storage compartment thereof which is provided with defrosting means for removing frost from the evaporator when it collects thereon.

The chief object of the present invention is to provide a simple and economical defrosting arrangement for the evaporator of a refrigeration system.

An object of the present invention is to provide a refrigeration system in which, during the defrosting cycle, evaporator pressure is increased to a point corresponding to a temperature at least slightly above 32 F. to provide heat for melting frost fromthe exterior surfaces of the evaporator. i i

A further object is to provide a defrosting arrangement for a refrigeration system in which. the cooling arrangement of the prime mover employed to drive the compressor of the system is utilized to reevaporate refrigerant condensed in the evaporator of the system during the defrosting cycle. Other objects of the invention will be readily perceived from the following description.

This invention relates to a refrigeration system which comprises, in combination, a compressor, a condenser, a discharge line connecting the compressor and the condenser, an evaporator, a liquid line connecting the evaporator and the condenser, expansion means in the liquid line, a suction line connecting the evaporator and the compressor, means in said suction line for maintaining evaporator pressure at 'a desired point during a defrosting cycle, a second evaporator, a capillary line connecting the second evaporator with the suction line at a point between said means and the evaporator, a fifth line connecting the second evaporator with the suction line at a point between said means and the compressor, means for evaporating refrigerant in said second evaporator, a sixth line connecting the discharge line and the liquid line at a point between the expansion means and the evaporator and means for closing said sixth line.

The attached drawing illustrates a preferred embodiment of the invention.

Referring to the drawing, there is shown a refrigeration system which includes a compressor 2 connected by discharge line 3 to condenser 4. Preferably compressor 2 is driven by an internal combustion: engine 5 having its own cooling system. Engine 5 may be air cooled as by fan 6 which serves to pass air over the surfaces of the engine. If desired, of course, a water cooling system may be used. Condenser 4 is connected to a receiver 7 by line 8. Receiver 7 is connected to evaporator 9 by. liquid line 10. Expansion means 11 such as an expansion valve is placed in liquid line 10 and regulates flow of refrigerant to evaporator 9. Expansion valve 11 is regulated by means of a bulb 12 placed in contact with the suction line 13 of the refrigeration system. A solenoid valve 14 may be placed in liquid line 10 at a point between expansion valve 11 and receiver 7 for a purpose hereinafter explained. Preferably, a small receiver 15 is placed in liquid line 10 at a point between expansion valve 11 and solenoid valve 14.

Evaporator 9 is placed in the storage compartment 16 of a trailer 17. Evaporator 9 is contained in a casing 18 provided with dampers 19. A fan 2*!) serves to pass air from compartment 16 through evaporator 9 in heat exchange relation with refrigerant therein, thus cooling the storage compartment. The evaporator 9 may be provided with the usual drip pan 21 as hereinafter explained.

Suction line 13 connects evaporator 9 with compressor 2. A holdback valve 22 is placed in suction line 13 to regulate evaporator pressure. It will be appreciated valve 22 offers little restriction to the flow of gaseous refrigerant through line 13 under normal conditions of operation because normal suction pressure will be below its design setting; thus, there will be only a minor pressure drop across valve 22. p

A small reevaporator 23 is provided which is connected to suction line 13 at a point between evaporator 9 and holdback valve 22 by a capillary tube 24. The exit end of reevaporator 23 is connected to suction line 13 at a point between holdback valve 22 and compressor 2 by a line 25. Reevaporator 23 is so placed in the system that refrigerant therein is placed in heat exchange relation with heated air provided by the engine cooling fan 6. If a water cooling system is employed to cool engine 5' it will be appreciated the heated water may be placed in heat exchange relation with refrigerant in reevaporator 23.

A fan 26 is employed to pass air in heat exchange relation with refrigerant in condenser 4 to condense the refrigerant. Fan 26 and fan 20 may be mounted on the same shaft 27 and may be connected to engine 5 to be driven thereby. A magnetic clutch 28 may be employed, if desired, to permit operation of fans 20, 26 to be discontinued while continuing operation of the engine S.

A hot gas line 30 connects discharge line 3 with liquid line 14 at a point between the entrance end of the evaporator and the expansion valve 11. A second solenoid valve Si is placed in line 30 to close the same. Solenoid valves 14 and 31 may be actuated by any suitable means. Preferably, these valves are actuated by a thermostat (not shown) responsive to the temperature of storage compartment 16, although, if desired, they may be actuated by a manually movable switch (not shown).

Considering the operation of the refrigeration system during its normal cooling cycle, compressor 2 compresses gaseous refrigerant andsupplies the hot gaseous refrigerant to condenser Fan 26 passes air in heat exchange relation with gaseous refrigerant in condenser 4 to condense the same, the condensed refrigerant passing to receiver 7. From receiver 7, the condensed refrigerant passes through liquid line 10 to evaporator 9, expansion valve 11 metering the amount of refrigerant supplied to the evaporator. Fan 2% draws air from storage compartment 15 within casing 18 and passes the air in heat exchange relation with refrigerant in evaporator 9 thereby cooling the air and, evaporating the refrigerant. The evaporated refrigerant returns to compressor 2 through line 13.. it will be appreciated holdback valve 22, as stated above, offers little resistance to passage of gaseous refrigerant through line 13 during normal operation of the system.

Frost collects on the exterior surfaces of evaporator 9 during the normal cooling cycle thus reducing the efliciency of the refrigeration system. It is necessary, therefore, to remove the frost from the exterior surfaces of the evaporator in order to maintain normal cooling operation. When sufficient frost has collected on the evaporator, any suitable means may be employed to place the refrigeration system in its defrosting cycle.

Considering operation of the refrigeration system during the defrosting cycle, solenoid valve 31 is opened and solenoid valve 14 is closed. Closing of valve 14 prevents passage of liquid refrigerant from receiver 7 to evaporator 9. Opening of valve 31 permits hot gaseous refrigerant topass to the evaporator through line 30.

Preferably, operation of fans 20 and 26 is discontinued. If desired, the dampers 19 in casing 18 may be closed to prevent hot air passing into storage compartment 16.

Since the holdback valve 22 is set to a predetermined point, evaporator pressure is increased to a point corresponding to at least 32 F. thus providing heat for thawing the frost collected on the exterior surfaces of the evaporator.

The hot gaseous refrigerant supplied to evaporator 9 under such predetermined pressure is placed in heat exchange relation with the frost collected on the exterior surfaces of the evaporator thawing the frost and condensing the refrigerant. The liquid refrigerant flows through suction line 13 until it arrives at holdback valve 22. Valve 22 may be set to prevent suction pressure from rising above to p. s. i. g. The pressure built up ahead of valve 22 forces the liquid refrigerant through capillary tube 24 into reevaporator 23. The hot air stream from engine 5 passes in heat exchange relation with refrigerant in reevaporator 23 thereby evaporating the refrigerant. Gaseous refrigerant returns to the cornpressor through line 25 and that portion of suction line .13 between holdback valve 22 and compressor 2. Capillary tube 24 and reevaporator 23 provide sufiicient pressure drop and sufiicient evaporator surface so thatthe liquid refrigerant condensed in evaporator 9 is re-evaporated thus preventing liquid pumping by the compressor.

.When the frosthas been removed from the exterior surfaces of evaporator 9 the defrosting cycle is discontinued and normal cooling operation of the refrigeration system is resumed.

Receiver 15 contains a minor quantity of liquid refrigerant. When solenoid valve 14 is closed at the beginning of the defrosting cycle, liquid in receiver 15 flows through expansion valve 11 intothe evaporator 9 thus providing sufiicient refrigerant to begin the defrosting cycle. In addition, such receiver 15 assures that sufficient refrigerant is present in the system during the defrosting cycle to insure removal of frost from the evaporator.

. If desired, solenoid valve 14 may be omitted, expansionvalve 11 closing liquid line 10 during the defrosting operation. However, it is generally desirable to employ valve 14 as a safety measure to assure that line 10 is closed to passage of refrigerant from condenser 4 to evapto equalize the high and low side of the compressor at suction pressure. I

It will be understood the defrosting arrangement of the present invention may be employed to heat storage compartment 16 as well as to remove frost from the evaporator 9 when it is desired. For example, to prevent the temperature of the compartment falling below 32 F.

While the present invention has been described in connection with a refrigeration system employed in transportation, it will be understood the defrosting arrangement may be employed, if desired, in stationary applications.

The present invention provides a simple and inexpensive defrosting arrangement for the evaporator of a re frigeration system. It is adapted for use with refrigeration systems employed in transportation. The arrangement may be actuated automatically or manually as desired. The defrosting arrangement assures that only gaseous refrigerant returns to the compressor during the 4 defrosting cycle thereby eliminating wear on the valves of the compressor and reducing greatly the noise of compression. The provision of a small receiver or reservoir in the liquid line assures sufiicient refrigerant present in the low side of the system during defrosting.

While I have described a preferred embodiment of the invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In a refrigeration system, the combination of a compressor, a condenser, a discharge line connecting the compressor and the condenser, an evaporator, a liquid line connecting the evaporator and the condenser, expansron means in said liquid line, a suction line connecting the evaporator and the compressor, a holdback valve in said suction line for maintaining evaporator pressure at a desired point during a defrosting cycle, a second evaporator, a capillary line connecting the second evaporator with the suction line at a point between said holdback valve and the evaporator, a fifth line connecting the second evaporator with the suction line at a point between said holdback valve and the compressor, means for evaporating refrigerant in said second evaporator, a sixth line connecting the discharge line and the liquid line at a point between the expansion means and the evaporator, and a solenoid valve closing said sixth line during the normal cooling cycle of the refrigeration system.

2. A refrigeration system according to claim 1 in which a second solenoid valve is provided in the liquid line at a point between the expansion valve and the condenser to prevent passage of liquid refrigerant from the condenser to the expansion means during the defrosting cycle of the refrigeration system.

3. A refrigeration system according to claim 2 in which a reservoir is provided in the liquid line between the expansion means and the second solenoid valve.

4. In a defrosting arrangement for a refrigeration system, the combination of a holdback valve'in the suction line to increase evaporator pressure to a point at least corresponding to an evaporator temperature of 32 F., a reevaporator, a capillary line connecting the reevaporator to the suction line of the system at a point between the valve and the evaporator, means for evaporating liquid refrigerant collected in the suction line during the defrosting operation in the re-evaporator, and a line to return gaseous refrigerant from said re-evaporator to the compressor.

5. In a defrosting arrangement for a compressor-condenser-expander refrigeration system, the combination of a holdback valve in the suction line to increase evaporator pressure to a point at least corresponding to an evaporator temperature of 32 F., a re-evaporator, a capillary line connecting the re-evaporator to the suction line of the system at a point between the valve and the evaporator, a line connecting the re-evaporator to the suction line at a point between the valve and the compressor to return gaseous refrigerant from the reevaporator to the compressor, means for passing a heating medium in heat exchange relation with liquid refrigerant in the re-evaporator to evaporate the liquid refrigerant, a line connecting the discharge line of the refrigeration system with the entrance end of the evaporator of the refrigeration system, and a solenoid valve placed in said line to close the same during the normal cooling cycle of the refrigeration system.

References Cited in the file of this patent UNITED STATES PATENTS 2,455,421 Kirkpatrick Dec. 7, 1948 2,459,173 McCloy Jan. 18, 1949 2,526,379 Maserit z' Oct. 17, 1950 2,573,684 Binder Nov. 6, 1951

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2916893A (en) * 1954-02-01 1959-12-15 Mercer Engineering Co Refrigerating system with hot gas defrosting means and adapted for use with a low temperature compressor
US3088291A (en) * 1961-10-10 1963-05-07 Gen Motors Corp Refrigerating apparatus for vehicles
US3256708A (en) * 1964-05-28 1966-06-21 Howard W Redfern Refrigerator unit defroster with auxiliary heater
EP0123554A2 (en) * 1983-04-23 1984-10-31 Daikin Industries, Limited Refrigeration unit
US5787717A (en) * 1996-08-03 1998-08-04 Samsung Electronics Co., Ltd. Suction inlet/discharge outlet opening and closing apparatus for an air conditioner and method therefor
US20090113914A1 (en) * 2006-05-19 2009-05-07 Shigeichi Kitano Refrigeration unit for trailer
US20130061608A1 (en) * 2010-05-14 2013-03-14 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the Refrigerated Transportation of a Stock in a Vehicle Implementing a Liquid Combustible Gas Tank and a Liquid Nitrogen Tank

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455421A (en) * 1946-06-03 1948-12-07 Advance Mfg Inc Control means for air conditioning apparatus
US2459173A (en) * 1946-02-05 1949-01-18 Westinghouse Electric Corp Defrosting means for refrigeration apparatus
US2526379A (en) * 1949-03-09 1950-10-17 Gen Electric Defrosting arrangement for refrigerating systems
US2573684A (en) * 1946-07-13 1951-11-06 Thomas W Binder Refrigeration apparatus, including defrosting means

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2459173A (en) * 1946-02-05 1949-01-18 Westinghouse Electric Corp Defrosting means for refrigeration apparatus
US2455421A (en) * 1946-06-03 1948-12-07 Advance Mfg Inc Control means for air conditioning apparatus
US2573684A (en) * 1946-07-13 1951-11-06 Thomas W Binder Refrigeration apparatus, including defrosting means
US2526379A (en) * 1949-03-09 1950-10-17 Gen Electric Defrosting arrangement for refrigerating systems

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2916893A (en) * 1954-02-01 1959-12-15 Mercer Engineering Co Refrigerating system with hot gas defrosting means and adapted for use with a low temperature compressor
US3088291A (en) * 1961-10-10 1963-05-07 Gen Motors Corp Refrigerating apparatus for vehicles
US3256708A (en) * 1964-05-28 1966-06-21 Howard W Redfern Refrigerator unit defroster with auxiliary heater
EP0123554A2 (en) * 1983-04-23 1984-10-31 Daikin Industries, Limited Refrigeration unit
EP0123554A3 (en) * 1983-04-23 1985-05-22 Daikin Industries, Limited Refrigeration unit
US4602485A (en) * 1983-04-23 1986-07-29 Daikin Industries, Ltd. Refrigeration unit including a hot gas defrosting system
US4688392A (en) * 1983-04-23 1987-08-25 Daikin Industries, Ltd. Refrigeration unit including a hot gas defrosting system
US5787717A (en) * 1996-08-03 1998-08-04 Samsung Electronics Co., Ltd. Suction inlet/discharge outlet opening and closing apparatus for an air conditioner and method therefor
US20090113914A1 (en) * 2006-05-19 2009-05-07 Shigeichi Kitano Refrigeration unit for trailer
US8701430B2 (en) * 2006-05-19 2014-04-22 Daikin Industries, Ltd. Compact refrigeration unit for trailer
US20130061608A1 (en) * 2010-05-14 2013-03-14 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for the Refrigerated Transportation of a Stock in a Vehicle Implementing a Liquid Combustible Gas Tank and a Liquid Nitrogen Tank
US9186958B2 (en) * 2010-05-14 2015-11-17 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Method for the refrigerated transportation of a stock in a vehicle implementing a liquid combustible gas tank and a liquid nitrogen tank

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