Refrigeration circuit

Abstract

A refrigeration circuit ( 1 a ) comprises in the direction of flow of a circulating refrigerant a compressor unit ( 2 ) for compressing the refrigerant, a condenser ( 4 ), and at least one evaporator ( 10 ) having an expansion device ( 6 ) connected upstream thereof. The refrigeration circuit ( 1 a ) further comprises a subcooling temperature sensor ( 6 ) located at an outlet of the condenser ( 4 ) for measuring the temperature of refrigerant leaving the condenser ( 4 ), a control unit ( 12 ) functionally connected to the subcooling temperature sensor ( 6 ) and configured for detecting a leak in the refrigeration circuit ( 1 a ) based on the refrigerant temperature measured by the subcooling temperature sensor ( 6 ). The condenser ( 4 ) comprises a liquefying portion ( 4 a ) configured for at least partially liquefying the refrigerant and a subsequent subcooling portion ( 4 b ) configured for subcooling and storing liquefied refrigerant, and the outlet of the condenser ( 4 ), particularly the outlet of the subcooling portion ( 4 b ), is connected to the expansion device ( 8 ) of the at least one evaporator ( 10 ) through a receiver-free connection line ( 7 ).

1 . A refrigeration circuit comprising in the direction of flow of a circulating refrigerant:
 a compressor unit for compressing the refrigerant;   a condenser; and   at least one evaporator having an expansion device connected upstream thereof;   the refrigeration circuit further comprising:   a subcooling temperature sensor located at an outlet of the condenser for measuring the temperature of refrigerant leaving the condenser;   a control unit functionally connected to the subcooling temperature sensor and configured for detecting a leak in the refrigeration circuit based on the refrigerant temperature measured by the subcooling temperature sensor compared to a predetermined temperature calculated based on (i) at least one temperature measured outside the condenser or (ii) an external value input by an operator;   wherein the condenser comprises a liquefying portion configured for at least partially liquefying the refrigerant and a subsequent subcooling portion configured for subcooling and storing liquefied refrigerant; and   wherein the outlet of the condenser, particularly the outlet of the subcooling portion, is connected to the expansion device of the at least one evaporator through a receiver-free connection line.   
     
     
         2 . The refrigeration circuit of  claim 1 , wherein, the subcooling portion is connected to the liquefying portion without a further device arranged in between, or only by means of a gas-liquid-separator. 
     
     
         3 . The refrigeration circuit of  claim 1 , wherein the control unit comprises a comparison unit which is configured for comparing the temperature measured by the subcooling temperature sensor to a predetermined value. 
     
     
         4 . The refrigeration circuit of  claim 3 , wherein the control unit further comprises a calculation unit which is configured for calculating the predetermined value. 
     
     
         5 . The refrigeration circuit of  claim 3 , wherein the control unit further comprises a storing unit which is configured for storing at least one predetermined value. 
     
     
         6 . The refrigeration circuit of  claim 4 , further comprising at least one additional temperature sensor functionally connected to the control unit, wherein the control unit is configured for calculating and/or selecting the predetermined value using the temperature value measured by the at least one of the additional temperature sensors. 
     
     
         7 . The refrigeration circuit of  claim 6 , wherein the at least one additional temperature sensor is at least one of an ambient air temperature sensor and a temperature sensor configured for measuring the temperature of the refrigerant circulating within the refrigeration circuit. 
     
     
         8 . The refrigeration circuit of  claim 4 , wherein the control unit is configured to reduce or even stop the operation of the at least one compressor and/or to set off an alarm signal after detecting a leakage of the refrigeration circuit. 
     
     
         9 . The refrigeration circuit of  claim 1 , wherein a gas-liquid-separator is arranged between the liquefying portion and the subcooling portion of the condenser, an inlet of the gas-liquid-separator being fluidly connected to an outlet of the liquefying portion of the condenser. 
     
     
         10 . The refrigeration circuit of  claim 9 , wherein a gas outlet of the gas-liquid-separator is fluidly connected to an inlet of the condenser, and wherein a liquid outlet of the gas-liquid-separator is fluidly connected to an inlet of the subcooling portion of the condenser. 
     
     
         11 . The refrigeration circuit of  claim 1 , wherein two or more evaporators having a respective expansion device connected upstream thereof are provided, and wherein the outlet of the condenser, particularly the outlet of the subcooling portion, is connected to the respective expansion devices of the two or more evaporators by a receiver-free connection line branching into receiver-free branch lines connecting to the respective expansion devices. 
     
     
         12 . A method for detecting a leak in a refrigeration circuit comprising:
 compressing the refrigerant;   at least partially liquefying the refrigerant in a liquefying portion of a condenser;   flowing the at least partially liquefied refrigerant from the liquefying portion to a subsequent subcooling portion of the condenser;   subcooling the refrigerant in the subcooling portion of the condenser;   leading the refrigerant from the outlet of the condenser, particularly the outlet of the subcooling portion, to an expansion device of at least one evaporator in a receiver-free manner, and evaporating the refrigerant;   the method further comprising:   measuring the temperature of the liquid refrigerant leaving the subcooling portion of the condenser; and   detecting a leak in the refrigeration circuit based on the liquid refrigerant temperature measured by the subcooling temperature sensor compared to a predetermined temperature calculated based on (i) at least one temperature measured outside the condenser or (ii) an external value input by an operator.   
     
     
         13 . The method of  claim 12 , wherein the at least partially liquefied refrigerant is led from the liquefying portion to the subcooling portion without passing a further device except for an optional gas-liquid-separator. 
     
     
         14 . The method of  claim 12 , wherein the refrigerant is led from the outlet of the condenser, particularly the outlet of the subcooling portion, to two or more evaporators having a respective expansion device connected upstream thereof, through a direct, receiver-free connection line branching into receiver-free branch lines connecting to the respective expansion devices. 
     
     
         15 . The method of  claim 12 , further comprising separating the gas phase from the liquid phase of at least partially liquefied refrigerant, delivering the liquid phase to the subcooling portion of the condenser and delivering the gas phase to the liquefying portion of the condenser.