Device and method for operating a refrigeration cycle with noncondensable gas addition.

Abstract

The present invention relates to a device and method for operating a refrigeration cycle with the addition of noncondensable gas.

1 . A device comprising a compressor ( 1 ) comprising an inlet ( 2 ) and an outlet ( 3 ); a condenser ( 9 ), comprising an inlet ( 10 ) and an outlet ( 11 ), wherein the condenser inlet is operatively coupled to the outlet of the compressor; a metering means ( 12 ), comprising an inlet ( 13 ) and an outlet ( 14 ), wherein the inlet of the metering means is operatively coupled to the outlet of the condenser; an evaporator ( 17 ), comprising an inlet ( 18 ), an outlet ( 19 ) and an evaporative surface, wherein the evaporator inlet is operatively coupled to the outlet of the metering means and the outlet of the evaporator is operatively coupled to the inlet of the compressor; a refrigerant fluid that circulates from said compressor to said condenser to said metering means to said evaporator and back to said compressor in a refrigeration cycle; wherein at least 90% of the molar concentration of said refrigerant fluid is condensed inside said condenser during the refrigeration cycle; wherein at least 90% of the molar concentration of said refrigerant fluid consists of one or more pure fluids having critical temperatures higher than 310 kelvins and normal boiling point over 220 kelvins; characterized in that said device comprises an addition of at least one pure non condensable gas; wherein said noncondensable gas is mixed with or contained in at least one phase of said refrigerant fluid; wherein the noncondensable gases mixed with or contained in said refrigerant fluid have the average value of the overall molar concentration comprised between 0.4% and 1% of said refrigerant fluid, wherein said average concentration takes into account both the liquid and vapor phases of said refrigerant; wherein the molar concentration of molecular oxygen mixed with or contained in said refrigerant fluid does not exceed 0.02% of said refrigerant fluid; wherein said noncondensable gases do circulate in the refrigeration cycle along with both the refrigerant liquid phase and refrigerant vapor phase, not being said gases confined nor segregated nor collected in a dedicated part of the device. 
     
     
         2 . Device as in  claim 1 , wherein said noncondensable gases—in their own molar composition—are composed for at least 40% by molecular nitrogen. 
     
     
         3 . Device as in  claim 1 , wherein molecular nitrogen mixed with or contained in at least one phase of said refrigerant fluid has a molar concentration of at least 0.16% of said refrigerant fluid, wherein said concentration is an average taking into account both the liquid and vapor phases of said refrigerant. 
     
     
         4 . Device as in  claim 1 , wherein said noncondensable gases—in their own molar composition—are composed for at least 40% by atomic helium. 
     
     
         5 . Device as in  claim 1 , wherein atomic helium mixed with or contained in at least one phase of said refrigerant fluid has a molar concentration of at least 0.16% of said refrigerant fluid, wherein said concentration is an average taking into account both the liquid and vapor phases of said refrigerant. 
     
     
         6 . Device as in  claim 1 , where said metering means comprises a solenoid valve having solenoid actuator that, when is activated (energized), moves a valve member in its open position while when said actuator is de-activated (de-energized) it allows the valve member to return in its closed position. 
     
     
         7 . Device as in previous claim, wherein said solenoid valve is operatively coupled to a suitable controller ( 21 ) and said controller does anticipate immediately the opening of said solenoid valve in case at the same time the latter is in closed configuration and the refrigerant overheating is increased over a preset value of “maximum overheating”, wherein said overheating is measured in a position comprised between the evaporator inlet and the compressor outlet. 
     
     
         8 . Device as in  claim 6 , wherein said solenoid actuator is periodically activated/de-activated by a suitable controller ( 21 ) in order to regulate the refrigerant flow as a function of the desired refrigerant overheating, wherein said overheating is measured in a position comprised between the evaporator inlet and the compressor outlet. 
     
     
         9 . Refrigeration plant according to the preceding claim, characterized by the fact that said electronic controller receives a signal from a pressure probe ( 4 ) and from a temperature probe ( 5 ), wherein both probes are positioned between the inlet of the evaporator and the outlet of the compressor. 
     
     
         10 . Refrigeration plant according to  claim 6 , characterized by the fact that said metering means do not comprise any metering orifice. 
     
     
         11 . Device as in  claim 1 , characterized by the fact that said device comprises a hot gas bypass means ( 8 ), comprising an inlet, an outlet, an open position and a closed position; wherein the hot gas bypass means is operatively coupled to a controller ( 21 ) in order to carry out the defrosting and the heating of the evaporator; wherein the hot gas bypass means inlet is operatively coupled to the outlet of the compressor and the hot gas bypass means outlet is operatively coupled to the inlet of the evaporator or to an inlet of a manifold, wherein: the manifold comprises an inlet and a plurality of outlets, each outlet being operatively coupled to a different one of a plurality of inlets at different locations on the evaporative surface. 
     
     
         12 . Refrigeration plant according to the preceding claim, characterized by the fact that the hot gas bypass means comprises a solenoid valve and the latter is maintained closed (off) during the refrigeration cycle. 
     
     
         13 . Refrigeration plant according to the preceding claim, characterized by the fact that, to carry out the defrosting and the heating of the evaporator, the metering means is maintained closed, the hot gas valve is maintained open, the compressor is maintained on, thereby supplying hot gas to the evaporator without bypassing the evaporator inlet. 
     
     
         14 . Refrigeration plant according to the preceding claim characterized by the fact that, in order to prevent the liquid from returning to the inlet of the compressor, during the defrosting and the heating said controller monitors the value of the refrigerant overheating and, when such overheating goes down, below of a preset value, said controller closes the hot gas valve; wherein said overheating is measured in a position comprised between the evaporator inlet and the compressor outlet. 
     
     
         15 . Device as in  claim 1 , wherein a four-way inversion valve ( 22 ) is operatively coupled to the compressor inlet, the compressor outlet, the condenser inlet and the evaporator outlet; wherein said metering means performs the metering action even when the four-way valve does invert the cycle said in  claim 1 ; wherein the refrigerant fluid flows through the metering means, when the four-way valve does invert the cycle, in the opposite direction of the flow of the refrigerant that occurs in the direct cycle said in  claim 1 . 
     
     
         16 . A method for performing a refrigeration cycle, comprising: providing a compressor ( 1 ) comprising an inlet ( 2 ) and an outlet ( 3 ); providing a condenser ( 9 ), comprising an inlet ( 10 ) and an outlet ( 11 ), wherein the condenser inlet is operatively coupled to the outlet of the compressor; providing a metering means ( 12 ), comprising an inlet ( 13 ) and an outlet ( 14 ), wherein the inlet of the metering means is operatively coupled to the outlet of the condenser; providing an evaporator ( 17 ), comprising an inlet ( 18 ), an outlet ( 19 ) and an evaporative surface, wherein the evaporator inlet is operatively coupled to the outlet of the metering means and the outlet of the evaporator is operatively coupled to the inlet of the compressor; providing a refrigerant fluid that circulates from said compressor to said condenser to said metering means to said evaporator and back to said compressor in a refrigeration cycle; wherein at least 90% of the molar concentration of said refrigerant fluid is condensed inside said condenser during the refrigeration cycle; wherein at least 90% of the molar concentration of said refrigerant fluid is composed by pure fluids having critical temperatures higher than 310 kelvins and normal boiling point over 220 kelvins; providing an addition of at least one pure non condensable gas; wherein said noncondensable gas is mixed with or contained in at least one phase of said refrigerant fluid; wherein the noncondensable gases mixed with or contained in said refrigerant fluid have overall molar concentration comprised between 0.4% and 1% of said refrigerant fluid, wherein said average concentration takes into account both the liquid and vapor phases of said refrigerant; wherein the molar concentration of molecular oxygen mixed with or contained in said refrigerant fluid does not exceed 0.02% of said refrigerant fluid; wherein said noncondensable gases do circulate in the refrigeration cycle along with both the refrigerant liquid phase and refrigerant vapor phase, not being said gases confined nor segregated nor collected in a dedicated part of the device. 
     
     
         17 . Method as in  claim 16 , wherein the refrigerant charge is determined as to get a preset value of the refrigerant overheating as measured in a position comprised between the evaporator inlet and the compressor outlet. 
     
     
         18 . Method as in  claim 16 , wherein molecular nitrogen mixed with or contained in at least one phase of said refrigerant fluid has a molar concentration of at least 0.16% of said refrigerant fluid, wherein said concentration is an average taking into account both the liquid and vapor phases of said refrigerant. 
     
     
         19 . Method as in  claim 16 , wherein atomic helium mixed with or contained in at least one phase of said refrigerant fluid has a molar concentration of at least 0.16% of said refrigerant fluid, wherein said concentration is an average taking into account both the liquid and vapor phases of said refrigerant. 
     
     
         20 . Method as in  claim 16 , providing a hot gas bypass means ( 8 ), comprising an inlet, an outlet, an open position and a closed position, wherein the hot gas bypass means inlet is operatively coupled to the outlet of the compressor and the hot gas bypass means outlet is operatively coupled to the inlet of the evaporator or to an inlet of a manifold, wherein: the manifold comprises an inlet and a plurality of outlets, each outlet being operatively coupled to a different one of a plurality of inlets at different locations on the evaporative surface. 
     
     
         21 . Method as in  claim 16 , wherein said metering means comprises a solenoid valve having solenoid actuator that, when is activated (energized), moves a valve member in its open position while when said actuator is de-activated (de-energized) it allows the valve member to return in its closed position; wherein said solenoid valve is operatively coupled to a suitable controller ( 21 ) and said controller does anticipate immediately the opening of said solenoid valve in case at the same time the latter is in closed configuration and the refrigerant overheating is increased over a preset value of “maximum overheating”; wherein said overheating is measured in a position comprised between the evaporator inlet and the compressor outlet.