Heat Pump Water Heating System Using Variable Speed Compressor

Abstract

A transcritical refrigeration system includes a compressor, a gas cooler, an expansion device, and an evaporator. Refrigerant is circulated though the closed circuit system. Preferably, carbon dioxide is used as the refrigerant. A variable speed drive controls the speed of the refrigerant flowing through the compressor. Varying the speed of the refrigerant flowing through the compressor changes the mass flow rate of the refrigerant in the system to optimize the coefficient of performance.

1 - 15 . (canceled) 
   
   
       16 . A transcritical refrigeration system comprising:
 a compression device to compress a refrigerant to a high pressure;   a variable speed device that moves said refrigerant through said compression device at a variable speed to optimize a coefficient of performance of the system;   a sensor that monitors the coefficient of performance of the system; and   a control that controls the variable speed device, wherein the control adjusts a mass flow rate of the refrigerant using the variable speed device when the control determines that the coefficient of performance detected by the sensor is not an optimal coefficient of performance.   
   
   
       17 . The system as recited in  claim 16  wherein the refrigerant is carbon dioxide. 
   
   
       18 . The system as recited in  claim 27  further including a fan that blows a fluid over said heat accepting heat exchanger. 
   
   
       19 . The system as recited in  claim 18  wherein the coefficient of performance is relative to a heating capacity of the system and an amount of work of the compression device plus an amount of work of the fan, wherein the heating capacity of the system is an amount of heat transfer in the heat rejecting heat exchanger. 
   
   
       20 . The system as recited in  claim 27  further including a fan that blows the airflow, wherein decreasing the mass flow rate of the refrigerant increases a power of the fan per unit mass flow of the refrigerant. 
   
   
       21 . A transcritical refrigeration system comprising:
 a compression device to compress a refrigerant to a high pressure;   a heat rejecting heat exchanger for cooling said refrigerant;   an expansion device for reducing said refrigerant to a low pressure;   a heat accepting heat exchanger for evaporating said refrigerant, wherein a fluid exchanges heat with said refrigerant in said heat accepting heat exchanger;   a fan that blows the fluid over said heat accepting heat exchanger;   a variable speed device that moves said refrigerant through said compressor at a variable speed to optimize a coefficient of performance of the system;   a sensor that monitors the coefficient of performance of the system; and   a control that controls the variable speed device, wherein the control adjusts the mass flow rate of the refrigerant using the variable speed device when the control determines that the coefficient of performance is not an optimal coefficient of performance.   
   
   
       22 . The system as recited in  claim 21  wherein the coefficient of performance is relative to a heating capacity of the system and an amount of work of the compression device plus an amount of work of the fan, wherein the heating capacity of the system is an amount of heat transfer in the heat rejecting heat exchanger. 
   
   
       23 . A method of optimizing a coefficient of performance of a transcritical refrigeration system comprising the steps of:
 compressing a refrigerant to a high pressure;   sensing a coefficient of performance of the system;   determining whether the coefficient of performance of the system is optimal: and   adjusting a speed of the refrigerant flowing through the compression device if the step of determining determines that the coefficient of performance is not optimal to optimize the coefficient of performance of the system.   
   
   
       24 . The system as recited in  claim 16  wherein the system runs transcritically. 
   
   
       25 . The system as recited in  claim 16  further comprising a heat rejecting heat exchanger for cooling said refrigerant. 
   
   
       26 . The system as recited in  claim 16  further comprising an expansion device for reducing said refrigerant to a low pressure. 
   
   
       27 . The system as recited in  claim 16  further comprising a heat accepting heat exchanger for evaporating said refrigerant, wherein an airflow exchanges heat with said refrigerant in said heat accepting heat exchanger. 
   
   
       28 . The method as recited in  claim 23  further comprising the step of cooling the refrigerant. 
   
   
       29 . The method as recited in  claim 23  further comprising the step of expanding the refrigerant to a low pressure. 
   
   
       30 . The method as recited in  claim 23  further comprising the step of evaporating the refrigerant.