Hvac cascade heat pump

Abstract

An assembly includes a heat pump and a cascade module fluidly couplable to the heat pump. The cascade module is fluidly connected to the heat pump during a first mode of operation to increase a capacity of the heat pump and the cascade module is not fluidly connected to the heat pump during a second mode of operation.

What is claimed is: 
     
         1 . An assembly comprising:
 a heat pump;   a cascade module, the cascade module being fluidly couplable to the heat pump; and   wherein the cascade module is fluidly connected to the heat pump during a first mode of operation to increase a capacity of the heat pump and the cascade module is not fluidly connected to the heat pump during a second mode of operation.   
     
     
         2 . The assembly of  claim 1 , wherein the heat pump includes an indoor unit and an outdoor unit. 
     
     
         3 . The assembly of  claim 2 , wherein the cascade module is a separate module, removably mounted at the outdoor unit. 
     
     
         4 . The assembly of  claim 2 , wherein the cascade module is a separate module, removably mounted at the indoor unit. 
     
     
         5 . The assembly of  claim 2 , wherein the cascade module is a separate module, positioned remotely from both the indoor unit and the outdoor unit. 
     
     
         6 . The assembly of  claim 1 , wherein the cascade module is integral with the heat pump. 
     
     
         7 . The assembly of  claim 1 , wherein the heat pump further comprises a compressor, a first heat exchanger, at least one expansion device, and a second heat exchanger and the cascade module further comprises a second compressor and a cascade heat exchanger. 
     
     
         8 . The assembly of  claim 7 , wherein when the cascade module is fluidly connected to the heat pump during the first mode of operation, the assembly includes a first vapor compression loop associated with the compressor and a second vapor compression loop associated with the second compressor and the first vapor compression loop and the second vapor compression loop are thermally coupled at the cascade heat exchanger. 
     
     
         9 . The assembly of  claim 8 , wherein in the first mode of operation, the compressor, the cascade heat exchanger, the at least one expansion device and the second heat exchanger are fluidly connected and in combination form the first vapor compression loop. 
     
     
         10 . The assembly of  claim 8 , wherein in the first mode of operation, the second compressor, the first heat exchanger, the at least one expansion device, and the cascade heat exchanger are fluidly connected and in combination form the second vapor compression loop. 
     
     
         11 . The assembly of  claim 7 , wherein during the second mode of operation, the assembly includes a single vapor compression loop defined by the heat pump. 
     
     
         12 . The assembly of  claim 6 , further comprising a controller operably coupled to the compressor and the second compressor, and at least one valve, the controller being configured to:
 identify a mode of operation associated with a demand on the fluid conditioning system; and   operate the at least one valve to initiate operation in the identified mode.   
     
     
         13 . The assembly of  claim 12 , further comprising at least one sensor operably coupled to the controller, the at least one sensor being configured to monitor at least one parameter or operating condition associated with the heat pump. 
     
     
         14 . A method of operating a heat pump, the method comprising:
 receive a demand on the heat pump;   determine a mode of operation in response to the demand by comparing the demand with a heating capacity of the heat pump; and   wherein if the demand is greater than the heating capacity of the heat pump, fluidly connecting a cascade module to the heat pump.   
     
     
         15 . The method of  claim 14 , wherein fluidly connecting the cascade module to the heat pump further comprises operating at least one valve to control a flow of refrigerant to the cascade module. 
     
     
         16 . The method of  claim 14 , wherein if the demand is less than the heating capacity of the heat pump, fluidly isolating the cascade module from the heat pump. 
     
     
         17 . The method of  claim 14 , further comprising:
 monitoring the heating capacity of a heat exchanger of the fluid conditioning system; and   initiating a defrost mode when the heating capacity of the heat exchanger is less than or equal to a threshold.   
     
     
         18 . The method of  claim 17 , wherein initiating the defrost mode further comprises:
 fluidly connecting the cascade module to the heat pump; and   transforming at least one reversing valve from a first position to a second position.   
     
     
         19 . The method of  claim 18 , wherein monitoring the heating capacity of the heat exchanger further comprises monitoring at least one parameter or operating condition of the heat pump associated with the heating capacity. 
     
     
         20 . The method of  claim 19 , wherein the at least one parameter or operating condition of the heat pump is at least one of temperature, pressure, and refrigerant mass flow.