Refrigeration System and Method with Controllable Heat Recovery

Abstract

A method for providing controllable amounts of heat recovery from a refrigerant circuit includes the steps of providing a cooling circuit comprising a compressor, a condenser, an expansion device and an evaporator connected in series by refrigerant flow lines; providing a heat recovery circuit comprising a heat recovery heat exchanger, the heat recovery circuit being connected to the cooling circuit so that the heat recovery heat exchanger is in parallel with the condenser, and the heat recovery heat exchanger being in heat exchange relationship with a fluid to be heated based upon an end-user demand for heat; and selectively flowing refrigerant through the condenser of the cooling circuit and the heat recovery heat exchanger of the heat recovery circuit so as to maintain temperature of the fluid within a temperature hand around a set point provided by the end user.

1 . A method for providing controllable amounts of heat recovery from a refrigerant circuit, comprising the steps of:
 providing a cooling circuit comprising a compressor, a condenser, an expansion device and an evaporator connected in series by refrigerant flow lines;   providing a heat recovery circuit comprising a heat recovery heat exchanger, the heat recovery circuit being connected to the cooling circuit so that the heat recovery heat exchanger is in parallel with the condenser, and the heat recovery heat exchanger being in heat exchange relationship with a fluid to be heated based upon an end-user demand for heat; and   selectively flowing refrigerant through the condenser of the cooling circuit and the heat recovery heat exchanger of the heat recovery circuit so as to maintain temperature of the fluid within a temperature band around a set point provided by the end user.   
   
   
       2 . The method of  claim 1 , further comprising a plurality of cooling circuits and a plurality of heat recovery circuits, and wherein the selectively flowing step comprises comparing a temperature of the fluid with a fluid temperature setpoint and increasing a number of heat recovery circuits which are active when the temperature is below the fluid temperature setpoint. 
   
   
       3 . The method of  claim 2 , further comprising the step of decreasing the number of heat recovery circuits which are active when the temperature is greater than the fluid temperature setpoint. 
   
   
       4 . The method of  claim 1 , further comprising the step of cycling the heat recovery circuit between an active mode wherein a substantial portion of refrigerant passes through the heat recovery heat exchanger and transfers heat to the fluid in heat exchange relationship with the heat recovery heat exchanger; and an inactive mode wherein a substantial portion of refrigerant flows to the condenser. 
   
   
       5 . The method of  claim 1 , further comprising selectively operating in a cooling mode wherein the heat recovery heat exchanger is not active, and a heat recovery mode wherein the condenser is not active, and selectively recovering charge from whichever of the condenser and the heat recovery heat exchanger is not active. 
   
   
       6 . A refrigeration system with controllable heat recovery, comprising:
 a cooling circuit having a compressor, a condenser, an expansion device and an evaporator connected in series by refrigerant flow lines;   a heat recovery circuit having a heat recovery heat exchanger, the heat recovery circuit being connected to the cooling circuit so that the heat recovery heat exchanger is in parallel with the condenser, and wherein the heat recovery heat exchanger is in heat exchange relationship with a fluid to be heated based upon an end-user demand for heat; and   a control unit programmed to selectively flow refrigerant through the condenser of the cooling circuit and the heat recovery heat exchanger of the heat recovery circuit so as to maintain temperature of the fluid within a temperature band around a set point provided by the end user.   
   
   
       7 . The system of  claim 1 , further comprising at least one charge recovery flow line connected from at least one of the condenser and the heat recovery heat exchanger to the evaporator. 
   
   
       8 . The system of  claim 7 , wherein the control unit is further programmed to selectively flow refrigerant through one of the condenser and the heat recovery heat exchanger, and to recover charge from the other of the condenser and the heat recovery heat exchanger through the at least one charge recovery flow line.