Heat Pump System and Method For Heating a Fluid

Abstract

This invention relates to a heat pump system and in particular to a heat pump system and method for heating a fluid. According to one aspect of the invention, there is provided a heat pump system for heating a fluid, said system including: an evaporator for extracting heat from a heat source to vaporise a refrigerant; a compressor fluidly connected to said evaporator for compressing said refrigerant vapour; a condenser fluidly connected to said compressor for transferring heat from said compressed refrigerant to said fluid; a main expansion device fluidly connecting said condenser to said evaporator for reducing the temperature of the refrigerant; means for diverting and reducing the temperature of a portion of said refrigerant from said condenser, and means for fluidly injecting said temperature reduced refrigerant portion into said compressor such that said temperature reduced refrigerant portion mixes with said refrigerant vapour at an intermediate pressure and induces at least quasi-two-stage compression of said refrigerant vapour and said refrigerant portion for discharge into said condenser. According to another aspect of the invention, there is provided a method for heating a fluid, said method including the steps of: extracting heat from a heat source to vaporise a refrigerant; compressing said refrigerant vapour to increase its temperature; transferring heat from said compressed refrigerant vapour to said fluid; diverting and reducing the temperature of a portion of said refrigerant after said transferring step; reducing the temperature of said refrigerant; introducing said temperature reduced refrigerant portion during said compressing step such that said temperature reduced refrigerant portion mixes with said refrigerant vapour at an intermediate pressure and induces at least quasi-two-stage compression of said refrigerant vapour and said refrigerant portion, and discharging said compressed refrigerant to transfer heat to said fluid in said transferring step.

1 . A heat pump system for heating a fluid, said system including:
 an evaporator for extracting heat from a heat source to vaporise a refrigerant;   a compressor fluidly connected to said evaporator for compressing said refrigerant vapour;   a condenser fluidly connected to said compressor for transferring heat from said compressed refrigerant to said fluid;   a main expansion device fluidly connecting said condenser to said evaporator for reducing the temperature of the refrigerant;   means for diverting and reducing the temperature of a portion of said refrigerant from said condenser, and   means for fluidly injecting said temperature reduced refrigerant portion into said compressor such that said temperature reduced refrigerant portion mixes with said refrigerant vapour at an intermediate pressure and induces at least quasi-two-stage compression of said refrigerant vapour and said refrigerant portion for discharge into said condenser.   
   
   
       2 . The heat pump system of  claim 1  wherein the diverting and temperature reducing means includes an expansion device fluidly connected to the condenser and the compressor. 
   
   
       3 . The heat pump system of  claim 2  wherein the expansion device includes a capillary tube. 
   
   
       4 . The heat pump system of  claim 2  wherein the expansion device includes an expansion valve. 
   
   
       5 . The heat pump system of  claim 2  wherein the expansion device includes a heat exchanger, such as an intercooler. 
   
   
       6 . The heat pump system of  claim 2  wherein the diverting and temperature reducing means includes a bypass passage fluidly connecting the condenser and the expansion device. 
   
   
       7 . The heat pump system of  claim 2  wherein the fluid injecting means includes a fluid injection valve for controlling the flow of the refrigerant portion into the expansion device. 
   
   
       8 . The heat pump system of  claim 1  wherein the compressor includes a fluid injection port connected to the fluid injection means. 
   
   
       9 . The heat pump system of  claim 8  wherein the fluid injection means includes a check valve connected to the fluid injection port. 
   
   
       10 . The heat pump system of  claim 1  wherein the main expansion device is fluidly connected to the condenser by a first pipe. 
   
   
       11 . The heat pump system of  claim 10  wherein the capillary tube is in close proximity with the first pipe to cool the refrigerant passing through the first pipe to the main expansion device. 
   
   
       12 . The heat pump system of  claim 11  wherein the capillary tube is helically wound around the first pipe. 
   
   
       13 . The heat pump system of  claim 1  wherein the temperature reducing means includes an expansion device and an intercooler, said intercooler fluidly connected to the condenser and the main expansion device such that refrigerant passes through the intercooler to the main expansion device and exchanges heat with the refrigerant portion passing through the intercooler. 
   
   
       14 . A method for heating a fluid, said method including:
 extracting heat from a heat source to vaporise a refrigerant;   compressing said refrigerant vapour to increase its temperature;   transferring heat from said compressed refrigerant vapour to said fluid;   diverting and reducing the temperature of a portion of said refrigerant after said transferring;   reducing the temperature of said refrigerant;   introducing said temperature reduced refrigerant portion during said compressing such that said temperature reduced refrigerant portion mixes with said refrigerant vapour at an intermediate pressure and induces at least quasi-two-stage compression of said refrigerant vapour and said refrigerant portion, and discharging said compressed refrigerant to transfer heat to said fluid in said transferring.   
   
   
       15 . The heat pump system of  claim 14  wherein said method includes the step of returning said refrigerant from said temperature reducing step to said vaporising step. 
   
   
       16 . The heat pump system of  claim 14  wherein fluid to be heated is water. 
   
   
       17 . The method of  claim 14  wherein the heat source is ambient air.