Integrated Refrigerating/Freezing System and Defrost Method

Abstract

A medium and low-temperature integrated refrigeration/freezing system ( 100 ) has the function of discharge gas defrosting. It comprises medium and low-temperature compressors sets ( 120, 122 ) and medium and low-temperature evaporators, as well as control valves ( 141, 142, 143, 144 ), adjusting valves ( 145, 146 ), one-way valves ( 147, 148 ) and expansion valves ( 150, 152, 154 ), and the switching between a refrigerating cycle and the discharge gas defrosting cycle is performed by the combination of actions between multiple control valves. When a first control valve is opened, a second valve is closed and a fourth valve is closed to the refrigerant pipeline to said reservoir, the refrigerating cycle operation is performed; and when the first control valve is closed, the second valve is opened and the fourth valve is closed to the refrigerant pipeline of an intercooler ( 128 ), the discharge gas defrosting operation is performed.

1 . A medium and low-temperature integrated refrigeration/freezing system ( 100 ), comprising: a medium-temperature compressor ( 120 ), a low-temperature compressor ( 122 ), a condenser ( 124 ), a reservoir ( 126 ), an intermediate heat exchanger ( 128 ), a medium-temperature evaporator ( 130 ), and a low-temperature evaporator ( 132 ), characterized in that said system further comprises:
 a first control valve ( 141 );   a second control valve ( 142 );   a third control valve ( 143 );   a fourth control valve ( 144 );   a first adjusting valve ( 145 );   a second adjusting valve ( 146 );   a first one-way valve ( 147 );   a second one-way valve ( 148 );   a first expansion valve ( 150 );   a second expansion valve ( 152 ); and   a third expansion valve ( 154 ),   which are for switching between a refrigerating cycle operation and a discharge gas defrosting cycle operation by controlling the combination of actions between said first, second, third and fourth control valves.   
   
   
       2 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 1 , characterized in that when said first control valve ( 141 ) is opened, said second control valve ( 142 ) is closed, and said fourth control valve ( 144 ) is closed to the refrigerant pipeline of the reservoir, said system performs the refrigerating cycle operation. 
   
   
       3 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 2 , characterized in that when said system performs the refrigerating cycle operation, the suction temperature of the low-temperature compressor is adjusted by said first adjusting valve ( 145 ) to lower the discharge temperature of said low-temperature compressor. 
   
   
       4 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 1 , characterized in that when said first control valve ( 141 ) and said second control valve ( 142 ) are opened, and said fourth control valve ( 144 ) is closed to the refrigerant pipeline of the intercooler, said system performs the discharge gas defrosting operation. 
   
   
       5 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 4 , characterized in that when said system performs the discharge gas defrosting operation, the suction temperature of said low-temperature compressor is adjusted by said second adjusting valve ( 146 ), so as to lower said discharge temperature of the low-temperature compressor. 
   
   
       6 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 1 , characterized in that when said system performs the refrigerating cycle operation or the discharge gas defrosting operation, said medium-temperature compressor and the low-temperature compressor are both in operation. 
   
   
       7 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 4 , characterized in that said low-temperature evaporator is provided with a temperature sensor, and relevant parameters of said temperature sensor are preset to determine the starting time and ending time of the discharge gas defrosting operation. 
   
   
       8 . The medium and low-temperature integrated refrigeration/freezing system as claimed in  claim 1 , characterized in that said medium-temperature compressor can be a medium-temperature compressor set, said low-temperature compressor can be a low-temperature compressor set; said medium-temperature evaporator can be a group of medium-temperature evaporators, and said low-temperature evaporator can be a group of low-temperature evaporators. 
   
   
       9 . A method for switching between a refrigerating cycle operation and a discharge gas defrosting operation in a medium and low-temperature integrated refrigeration/freezing system, said medium and low-temperature integrated refrigeration/freezing system comprising at least a medium-temperature compressor, a low-temperature compressor, a condenser, a reservoir, an intercooler, a medium-temperature evaporator, a low-temperature evaporator, and a first control valve, a second control valve, a third control valve, a fourth control valve, a first adjusting valve, a second adjusting valve, a first one-way valve, a second one-way valve, a first expansion valve, a second expansion valve and a third expansion valve, characterized in that:
 when said first control valve is opened and said second valve is closed, and said fourth valve is closed to the refrigerant pipeline of said reservoir, the system performs the discharge gas defrosting operation; and   when said first control valve is closed and said second valve is opened, and said fourth valve is closed to the refrigerant pipeline of the intercooler, said system performs the discharge gas defrosting operation.   
   
   
       10 . A switching method as claimed in  claim 9 , characterized in that when said system performs the refrigerating cycle operation, the suction temperature of the low-temperature compressor is adjusted by said first adjusting valve, so as to lower the discharge temperature of said low-temperature compressor. 
   
   
       11 . The switching method as claimed in  claim 9 , characterized in that when said system performs the discharge gas defrosting operation, the suction temperature of the low-temperature compressor is adjusted by said second adjusting valve, so as to lower the discharge temperature of said low-temperature compressor. 
   
   
       12 . The switching method as claimed in  claim 9 , characterized in that said low-temperature evaporator is provided with a temperature sensor, and the relevant parameters of said temperature sensor are preset to determine the starting time and ending time of the discharge gas defrosting operation. 
   
   
       13 . The switching method as claimed in  claim 9 , characterized in that said medium-temperature compressor can be a medium-temperature compressor set, said low-temperature compressor can be a low-temperature compressor set; said medium-temperature evaporator can be a medium-temperature evaporator set, and said low-temperature evaporator can be a low-temperature evaporator set. 
   
   
       14 . A refrigeration system ( 100 ) comprising:
 a first compartment ( 200 );   a second compartment ( 202 );   at least one compressor ( 120 , 122 ) for compressing refrigerant;   a heat rejection heat exchanger ( 124 ) for cooling compressed refrigerant from the at least one compressor;   a reservoir ( 126 ) for storing condensed refrigerant;   a first expansion device ( 150 ) and a first evaporator( 130 ) in a flow path associated with the first compartment ( 200 ) for expanding refrigerant and cooling the first compartment; and   a second expansion device ( 152 ) and second evaporator ( 132 ) in a flow path associated with the second compartment for expanding the cooled refrigerant and cooling the second compartment,   
     further characterized by:
 means for providing:
 a normal refrigerating condition in which refrigerant from the compressors is cooled by the heat rejection heat exchanger, passed to the evaporators to absorb heat from the compartments, and returns to the at least one compressor; and 
 a defrost mode wherein:
 the heat rejection heat exchanger is bypassed so that compressed refrigerant is passed to the second evaporator in a reverse direction to the refrigerating mode to heat to deliver heat to the second compartment; 
 after heating the second compartment, the refrigerant passes to the first expansion device and first evaporator. 
 
 
 
   
   
       15 . The system of  claim 14  wherein:
 the heat rejection heat exchanger and the reservoir are common to the flow path associated with the first compartment and the flow path associated with the second compartment.   
   
   
       16 . A method for operating the system of  claim 14 , comprising:
 operating in the refrigeration mode; and   switching to operation in the defrost mode.   
   
   
       17 . The method of  claim 16 , wherein:
 in the defrost mode, the first evaporator continues to cool the first compartment.