US2526379A

US2526379A - Defrosting arrangement for refrigerating systems

Info

Publication number: US2526379A
Application number: US80528A
Authority: US
Inventors: Bernard D Maseritz
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1949-03-09
Filing date: 1949-03-09
Publication date: 1950-10-17
Anticipated expiration: 1967-10-17

Description

Oct. 17, 1950 B. D. MASERITZ 2,526,379

DEFROSTING ARRANGENENT FOR REF'RIGERATING SYSTEMS Filed larch 9. 1949 Inventor": 8 arm ai-d D. Maseritz,

- His Attorney.

Patented Oct. l'l, 1950 v rurgherracilitamdbyp oviding ahaLt p im g,ar,-

" rangement'whichfutillzefijhe heat exchahgerfnormany [provided ,btp'iv'een the liquid ling and, the "suction line and whibh includes} by-bass around thejvaboratorf'betv} the Suction line and 'the "solenoid valj'ligs fidlshlft frbmnormaIQpei'ation to 1' defrosting bperati o n mid simultaneously to ,open

asaasvo in the head pressure of the compressor and also a considerable drop in the suction pressure. For some time, say 10 minutes, after the defrosting operation begins, the gas leaving the compressor is relatively cool because of refrigerant remaining in the evaporator at the end of the normal refrigerating cycle or condensed from the hot gas entering the evaporator before it has warmed up. In order to overcome these difficulties, a heat exchanger 33 is provided in the hot gas line 32. This heat exchanger includes a coil 34 in series with the hot gas line 32. This coil 34 is positioned within a chamber 35 through which refrigerant passing from the evaporator through the suction line 9 is circulated. The heat exchanger 34 causes a transfer of heat from the gas discharged from the compressor to the gaseous or liquid refrigerant returning to the compressor through the suction line 9. This insures a vaporization of any liquid refrigerant in the suction line 9 and prevents its slugging into the compressor. Further, the heating of the refrigerant returning through the suction line 9 by the hot compressed gas achieves a higher back pressure, the head pressure remains near the normal operating head pressure, and the gas leaving the compressor reaches a satisfactory defrosting temperature sooner than it would in the absence of the heat exchanger 33.

If desired, in order to introduce additional heat into the gases passing through the conduit 32, an electric heater 36 may be provided. One side of this heater is connected by a line 31 to the power line I? and the other side is connected to the common line 24. The heater is energized at the same time as the solenoids l8 and I9 by the movement of the contact l into engagement with the contact 25.

During normal operation of the refrigerating system, a heat exchanger 38 is utilized for transferring heat from the liquid refrigerant passing through the line 8 to the refrigerant returning through the suction line 9 to the compressor. This heat exchanger 38 includes a coil 39 arranged in series with the line 8 and a chamber '50 within which the coil 99 is enclosed. Liquid refrigerant passes through the coil 39 on its way to the evaporator and refrigerant passing through the suction line 9 enters the chamber 29 and circulates around the coil 39. I have provided for utilizing the heat exchanger 38 in a heat pump arrangement for introducing additional heat into the system during the defrosting period. This arrangement includes a by-pass 4| extending from the line 3 to the suction line 9. In this by-pass, there is arranged a thermostatic expansion valve 42 which is controlled by a bulb 43 positioned in heat exchange relationship with the suction line 9 at 44. There is also included in the by-pass 4| a normally closed solenoid M45. This valve is controlled by a solenoid 46, one side of which is connected through a line 41 to thepower line l2. The other side of the solenoid 49 is connected by a line 43 to the common line 24 and thence to the stationary contact 25. Thus, the solenoid 46 is arranged to be energized to open the valve 45 by the action of the cam 26 in moving the contact I 5 into engagement with the contact 25. Where this bypass arrangement is employed, therefore, the solenoid 4B is energized at the same time as the solenoids l8 and I9, When the solenoid 49 is energized, the by-pass 4| is opened subiect to the control of the thermostatic expansionvalve 42. Liquid refrigerant may then flow from the condenser-receiver 2 through the line 8 and the by- 4 1 pass 4| into the suction line 9 and thence into the chamber 40 surrounding the coil 39. It then flows back through the suction line 9 to the intake of the compressor. In the chamber 40, some or all of the liquid refrigerant is vaporized, absorbing heat from the air surrounding the chamber 40. This heat is introduced into the system and assists in the defrosting operation. It can be seen that this portion of the system essentially operates as a heat pump absorbing heatavailable in the atmosphere under normal am.- bient conditions.

Reviewing the operation of the system, it can be seen that under normal refrigerating conditions the contacts l4 and I5 are in engagement. This closes a circuit through a fan motor II, and the solenoids l9, l9, and 46 and the electric heater 39 are all de-energized. Under these conditions, the valves l9 and 45 are closed and the valve I1 is open. Compressed gas from the compressor l flows through the oil separator 4 and the check valve 1 to the condenser-receiver 2. Liquid refrigerant passes through the line 3, the coil 39 of the heat exchanger 38 to the evaporator 3 under the control of the thermostatic expansion valve l9. vaporized refrigerant returns to the compressor through the suction line 9, passing en route through the heat exchanger 38 and absorbing heat from the liquid refrigerant passing through coil 39 of this heat exchanger.

The defrosting period is initiated by the engagement of the portion 30 of the cam 26 with the arm ti. This shifts the contact l5 out of engagement with the contact l4 and into engagement with the contact 25. The solenoids I8, 59, and 4B and'the electric heater 36 are thereby energized, the motor ll of'the fan ll being simultaneously de-energized. Under these conditions, the valves is and 45 are open and the valve I1 is closed. The flow of liquid refrigerant to the evaporator 3 is blocked by the valve 11. A path is simultaneously opened through the valve I6 and hot compressed gas from the compressor passes through the valve IS, the coil 34 of the heat exchanger 33, and conduit 32 to the evaporator 3. The refrigerant returns to the compressor through the suction line 9 passing en route through the chamber 40 of the heat exchanger 88 and the chamber 35 of the heat exchanger 33. The heat exchanger 33 in particular effects vaporization of any liquid refrigerant in the suction line before it can pass to the compressor. This liquid refrigerant might be that remaining in the evaporator at the time defrosting is initiated or it might result from condensing of compressed gas in passing through the evaporator. Additional heat is supplied to the hot gas before reaching the evaporator by the electric heater 36 if such heater is employed. If desired, further heat is introduced into the system through the utilization of the by-pass 4| whereby liquid refrigerant is circulated through the heat exchanger 38 to absorb heat from the atmosphere and introduce it into the system.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described, and I intend, by the appended claims, to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a refrigerating system including a compressor, a condenser and an evaporator connected in a closed refrigerant circuit, a hot gas line, means for selectively directing compressed refrigerant from the compressor through the condenser to the evaporator during normal operation and from the compressor through said hot as line directly to the evaporator during defrosting operation, a suction line for returning refrigerant from said evaporator to said compressor, and a heat exchanger for transferring heat from said hot gas line to said suction line only during the defrosting operation.

2. In combination with a refrigerating system including a compressor, a condenser and an evaporator connected in a closed refrigerant circuit, a defrosting arrangement comprising a hot gas line for conducting hot compressed gaseous refrigerant from the compressor to the evaporator to remove frost therefrom, a valve for controlling flow of hot compressed gaseous refrigerant, a solenoid for operating said valve, a heater adjacent said hot gas line for imparting additional heat to said hot compressed gaseous refrigerant before passage to said evaporator, and a timer for simultaneously energizing said heater and said solenoid, a suction line for returning re-' frigerant from said evaporator to said compressor, and a heat exchanger for transferring heat from said hot gas line to said suction line.

3. In a refrigerating system including a compressor, a condenser, and an evaporator connected in a closed refrigerant circuit, conduitstfor providing parallel paths for refrigerant flow from the compressor to the evaporator, one of said paths providing for flow of refrigerant from said I compressor through the condenser to said evaporator for refrigerating said evaporator, the other of said paths providing for flow of hot compressed gas from said compressor to said evaporator for defrosting said evaporator, a valve in each of said paths for controlling the flow therethrough, means for simultaneously opening one of said valves and closing the other, and a suction line for returning refrigerant from said evaporator to said compressor, said suction line being arranged in heat exchange relationship with said other of said paths.

4. In a refrigerating system including a compressor, a condenser, and an evaporator connected in a closed refrigerant circuit, conduits forother of said paths providing for flow of hot compressed gas from said compressor to said evaporator for defrosting said evaporator, a suction line for returning refrigerant from said evaporator to said compressor, a heat exchanger b tween said one of said paths and said suction line, said heat exchanger including a chamber through which refrigerant passing through said suction line flows, said chamber being exposed to the atmosphere, and a by-pass about said evaporator for conducting refrigerant from said one of said paths to said suction line, said refrigerant returning to said compressor through said heat exchanger whereby he at absorbed from the atmosphere in passing through said heat exchanger is introduced into the system for facilitating defrosting of said evaporator.

6. In a refrigerating system including a compressor, a condenser, and an evaporator connected in a closed refrigerant circuit, conduits for providing parallel paths for refrigerant flow from the compressor to the evaporator, one of said paths providing for flow of refrigerant from said compressor through the condenser to said evaporator for refrigerating said evaporator, a first valve for controlling flow of refrigerant through said one of said paths, the other of said paths providing for flow of hot compressed gas from said compressor to said evaporator for defrosting said evaporator, a second valve for controlling fiow of hot compressed gas through said other of said paths, a suction line for returning refrigerant from said evaporator "to said compressor, a first heat exchanger between said one of said paths and said suction line, said first heat exchanger including a chamber through which refrigerant passing through said suction line flows, said chamber being exposed to the atmosphere, a by-pass about said evaporator for conducting refrigerant from said one of said paths to said suction line, a third valve for controlling fiow of refrigerant through said by-pass,

said refrigerant returning to said compressor other of said paths and said suction line, an

of said valves and closing the other, a solenoid for operating each of said valves, means for simultaneously energizing said solenoids to open one of said valves and to close the other of said valves, said means simultaneously de-energizing said solenoids to open said other of said valves and to close said one of said valves, and a suction line for returning refrigerant from said evaporator to said compressor, said suction line being arranged in heat exchange relationship with said other of said paths.

5. In a refrigerating system including a compressor, a condenser and an evaporator connected in a closed refrigerant circuit, conduits for providing parallel paths for refrigerant flow from the compressor to the evaporator, one of said paths providing for flow of refrigerant from said compressor through the condenser to said evaporator for refrigerating said evaporator, the

electric heater for supplying additional heat to said other of said paths, a solenoid for controlling each of said valves, and means for simultaneously energizing each of said solenoids and said electric heater, energization of one of said solenoids effecting closing of said first valve to block flow of refrigerant through said one of said paths, the energization of the second of said solenoids effecting opening of said second valve to permit flow of hot compressed gas through said other of said paths, the energization of the third of said solenoids effecting opening of said third UNITED STATES PATENTS Number Name Date 2,281,770 Hoesel May 5, 1942 2,440,146 Kramer Apr. 20, 1948 2,459,173 McCloy Jan. 18, 1949