Heat Pump Comprising a Heating Circuit and a Buffer Circuit

Abstract

Heat pump, comprising: —a heating circuit that comprises an evaporator, one or more than one expansion valve, a compressor and a condenser; and—a buffer circuit that comprises or defines a refrigerant accumulator; —wherein the heating circuit and the buffer circuit are arranged in a parallel connection and share a common line passing through the evaporator and the compressor; —wherein the heat pump further comprises a distributor that comprises at least two valves, wherein the distributor is configured to redistribute a refrigerant charge from the heating circuit to the buffer circuit or vice versa; and—wherein the distributor comprises a controller that is configured to selectively redistribute the refrigerant charge from the heating circuit to the buffer circuit or vice versa, to thereby actively optimize the amount of refrigerant in the condenser and in the evaporator for the actual operating conditions.

1 . A heat pump comprising:
 a heating circuit that comprises:
 an evaporator; 
 one or more than one expansion valve that is arranged upstream of the evaporator; 
 a compressor that is arranged downstream of the evaporator; and 
 a condenser that is arranged downstream of the compressor and upstream of the one or more than one expansion valve; and 
   a buffer circuit that comprises or defines a refrigerant accumulator;   wherein the heating circuit and the buffer circuit are arranged in a parallel connection and share a common line passing through the evaporator and the compressor; and   wherein the heat pump further comprises a distributor that comprises at least two valves, wherein the distributor is configured to redistribute a refrigerant charge from the heating circuit to the buffer circuit or vice versa by controlling the at least two valves,   wherein the distributor comprises a controller that is configured to, during normal heating or cooling operation, selectively redistribute the refrigerant charge from the heating circuit to the buffer circuit or vice versa, by controlling the at least two valves of the distributor in dependency of actual operating conditions of the normal heating or cooling operation, to thereby actively optimize the amount of refrigerant in the condenser and in the evaporator for the actual operating conditions.   
     
     
         2 . The heat pump according to  claim 1 , wherein the controller is configured to redistribute the refrigerant charge from the heating circuit to the buffer circuit or vice versa, in dependency of the actual operating conditions that are defined by a level of subcooling of the refrigerant in the heating circuit. 
     
     
         3 . The heat pump according to  claim 2 , wherein the controller is configured to determine a level of subcooling in the heating circuit by calculating a temperature difference between a condensing temperature at the condenser and a temperature of the refrigerant leaving said condenser. 
     
     
         4 . The heat pump according to  claim 3 , wherein the controller is configured to at least one of:
 redistribute refrigerant charge from the heating circuit to the buffer circuit if the subcooling in the heating circuit is above a pre-determined upper threshold temperature difference; or   redistribute refrigerant charge from the buffer circuit to the heating circuit if the subcooling in the heating circuit is below a pre-determined lower threshold temperature difference.   
     
     
         5 . The heat pump according to  claim 4 , wherein the temperature difference between the lower threshold temperature difference and the upper threshold temperature difference is in the range of 0.2 to 3° C. 
     
     
         6 . The heat pump according to  claim 4 , wherein the lower threshold temperature difference is in the range of 0.5 to 1.2° C. 
     
     
         7 . The heat pump according to  claim 4 , wherein the upper threshold temperature difference is in the range of 0.3 to 1.2° C. 
     
     
         8 . The heat pump according to  claim 1 , comprising a branch that is arranged downstream of the compressor and configured to branch the common line off into a first line associated with the first heating circuit and a second line associated with the buffer circuit. 
     
     
         9 . The heat pump according to  claim 8 , comprising a combiner that is arranged upstream of the evaporator and configured to re-combine the first line of the first heating circuit and the second line of the buffer circuit into the common line. 
     
     
         10 . The heat pump according to  claim 9 , wherein the distributor comprises a three-way valve that defines one of the branch and the combiner. 
     
     
         11 . The heat pump according to  claim 10 , wherein the distributor comprises a further three-way valve that defines the other one of the branch and the combiner. 
     
     
         12 . The heat pump according to  claim 8 , wherein the distributor comprises at least two shut-off valves, wherein:
 a first shut-off valve is arranged downstream of the refrigerant accumulator and upstream of the combiner; and   a second shut-off valve is arranged downstream of the condenser and upstream of the combiner.   
     
     
         13 . The heat pump according to  claim 12 , wherein:
 the first shut-off valve is defined by a second expansion valve of the one or more than one expansion valve, wherein this second expansion valve is arranged downstream of the refrigerant accumulator and upstream of the combiner; and   the second shut-off valve is defined by a first expansion valve of the one or more than one expansion valve, wherein this first expansion valve is arranged downstream of the condenser and upstream of the combiner.   
     
     
         14 . The heat pump according to  claim 9 , wherein the distributor comprises at least two shut-off valves, wherein:
 a third shut-off valve is arranged downstream of the branch and upstream of the condenser; and   a fourth shut-off valve is arranged downstream of the branch and upstream of the refrigerant accumulator.   
     
     
         15 . The heat pump according to  claim 14 , wherein the distributor is configured to selectively activate the heating circuit by opening the third shut-off valve and the second shut-off valve and closing the fourth shut-off valve and the first shut-off valve. 
     
     
         16 . The heat pump according to  claim 14 :
 from the heating circuit to the buffer circuit by opening the second shut-off valve and the fourth shut-off valve while the first shut-off valve and the third shut-off valve are closed; or   from the buffer circuit to the heating circuit by opening the first shut-off valve and the third shut-off valve while the second shut-off valve and the fourth shut-off valve are closed.   
     
     
         17 . The heat pump according to  claim 1 , comprising:
 one or more than one further condenser arranged in a further heating circuit, wherein the heating circuit, the buffer circuit and the one or more than one further heating circuit share the common line passing through the evaporator and the compressor,   wherein the distributor is configured to redistribute a refrigerant charge from at least one of the heating circuit, the buffer circuit and the one or more than one further heating circuit to at least one other of the heating circuit, the buffer circuit and the one or more than one further heating circuit.   
     
     
         18 . The heat pump according to  claim 5 , wherein the temperature difference between the lower threshold temperature difference and the upper threshold temperature difference is in the range of 0.5 to 2° C. 
     
     
         19 . The heat pump according to  claim 5 , wherein the temperature difference between the lower threshold temperature difference and the upper threshold temperature difference is in the range of 1 to 1.5° C.