Hvac system with thermal storage

Abstract

A vapor compression system includes a compressor, a condenser, an expansion device, and an evaporator fluidly connected to form a closed fluid loop having a fluid circulating therethrough. A thermal storage device including a phase change material is fluidly connected to and is arranged downstream from an outlet of the compressor relative to a flow of the fluid. A storage expansion device is arranged downstream from the thermal storage device and upstream from the evaporator and a valve is adjustable between a plurality of positions to control the flow of the fluid from the compressor to the thermal storage device.

What is claimed is: 
     
         1 . A vapor compression system comprising:
 a compressor, a condenser, an expansion device, and an evaporator fluidly connected to form a closed fluid loop having a fluid circulating therethrough;   a thermal storage device including a phase change material, the thermal storage device being fluidly connected to and arranged downstream from an outlet of the compressor relative to a flow of the fluid;   a storage expansion device arranged downstream from the thermal storage device and upstream from the evaporator; and   a valve, the valve being adjustable between a plurality of positions to control the flow of the fluid from the compressor to the thermal storage device.   
     
     
         2 . The vapor compression system of  claim 1 , wherein the thermal storage device and the condenser are arranged in parallel downstream from the compressor. 
     
     
         3 . The vapor compression system of  claim 2 , wherein the condenser and the thermal storage device are both fluidly connected to the outlet of the compressor. 
     
     
         4 . The vapor compression system of  claim 2 , wherein the compressor includes a first stage having a first outlet and a second stage having a second outlet, the thermal storage device being fluidly connected to and arranged downstream from the first outlet and the condenser being fluidly connected to and arranged downstream from the second outlet. 
     
     
         5 . The vapor compression system of  claim 1 , wherein the condenser is operable to receive the fluid at a first pressure and the thermal storage device is operable to receive the fluid at a second pressure, the first pressure being greater than the second pressure. 
     
     
         6 . The vapor compression system of  claim 1 , wherein an outlet of the expansion device is fluidly connected to an outlet of the storage expansion device at a location upstream from an inlet of the evaporator. 
     
     
         7 . The vapor compression system of  claim 1 , wherein the phase change material is a melting salt. 
     
     
         8 . The vapor compression system of  claim 1 , wherein the valve is positioned downstream from the compressor and upstream from an inlet of the thermal storage device. 
     
     
         9 . The vapor compression system of  claim 1 , wherein the valve is adjustable between the plurality of positions to minimize a condensing temperature of the fluid. 
     
     
         10 . The vapor compression system of  claim 9 , wherein the valve is arranged at a position to direct the flow of the fluid from the compressor to the thermal storage device when a phase change temperature of the phase change material is less than an ambient temperature. 
     
     
         11 . The vapor compression system of  claim 1 , wherein at one of the plurality of positions, the fluid is provided to the condenser and the thermal storage device simultaneously. 
     
     
         12 . A method of operating a vapor compression system comprising:
 providing a compressor, a condenser, an expansion device, and an evaporator fluidly connected to form a closed fluid loop, the closed fluid loop having a fluid circulating therethrough;   comparing a condensing temperature of a cooling fluid with a condensing temperature of a phase change material to determine a lowest condensing temperature;   in response to determining that the condensing temperature of the phase change material is the lowest condensing temperature, adjusting a valve to direct the fluid from the compressor to a thermal storage device containing the phase change material; and   removing heat from the fluid via the phase change material.   
     
     
         13 . The method of  claim 12 , further comprising expanding the fluid output from the thermal storage device via a storage expansion device. 
     
     
         14 . The method of  claim 13 , further comprising providing the fluid from the storage expansion device to the evaporator. 
     
     
         15 . The method of  claim 12 , wherein adjusting the valve directs only a portion of the fluid from the compressor to the thermal storage device containing the phase change material. 
     
     
         16 . The method of  claim 15 , further comprising providing another portion of the fluid from the compressor to the condenser, a flow of the fluid provided to the condenser being arranged in parallel with the flow of the fluid provided to the thermal storage device. 
     
     
         17 . The method of  claim 16 , further comprising mixing the portion of fluid at a location downstream from the thermal storage device with the another portion of the fluid at a location downstream from the condenser at a location upstream from the evaporator. 
     
     
         18 . The method of  claim 17 , wherein the portion of the fluid output from the thermal storage device is provided to a storage expansion device, the portion of the fluid downstream from the storage expansion device being mixed with the another portion of the fluid downstream from the expansion device. 
     
     
         19 . The method of  claim 12 , further comprising regenerating the phase change material during off-peak energy hours. 
     
     
         20 . The method of  claim 12 , further comprising regenerating the phase change material when the condensing temperature of the cooling fluid is less than the condensing temperature of the phase change material.