Cascade cold climate heat pump system

Abstract

Cascaded Cold Climate Heat Pump systems (“CCCHP”) and methods are disclosed. A CCCHP provides efficiency improvements over traditional heat pump systems by utilizing a connected cascaded circuit configuration, to apportion compressor load of a heat pump circuit between two or more circuits. One embodiment that allows the CCCHP to achieve this efficiency improvement includes connecting multiple cold climate heat pump circuits through an intermediary heat exchange unit in a cascaded configuration, where energy is displaced from one refrigerant flow of a circuit into the refrigerant flow of another circuit. This allows each circuit to deploy a smaller compressor that operates within a narrower pressure and temperature range, than it otherwise would if it utilized a single larger compressor in a single circuit operating within a larger pressure range, which has a larger pressure differential between its initial state and its desired state causing inefficiency in the system.

1 . A cascaded cold climate heat pump system, comprising:
 a high-pressure circuit comprising a first compressor, a first outer heat exchange unit, a first metering device, and a first reversing valve for flowing a first refrigerant through the high-pressure circuit;   a low-pressure circuit fluidly isolated from the high-pressure circuit and comprising a second compressor, a second outer heat exchange unit, a second metering device, and a second reversing valve for flowing a second refrigerant through the low-pressure circuit; and   an intermediary heat exchange unit thermally connecting the fluidly isolated high pressure circuit and the low pressure circuit to facilitate heat exchange between the first refrigerant and the second refrigerant within the intermediary heat exchange unit to reduce a temperature lift of each of the high pressure circuit and the low pressure circuit, the high pressure circuit operating within a first pressure differential, and the low pressure circuit operating within a second pressure differential.   
     
     
         2 . The system of  claim 1 , wherein at least one of the high-pressure circuit or the low-pressure circuit further comprises an accumulator. 
     
     
         3 . The system of  claim 1 , wherein at least one of the first reversing valve or the second reversing valve is a 4-way reversing valve. 
     
     
         4 . The system of  claim 1 , wherein at least one of the first compressor or the second compressor comprises a variable speed compressor. 
     
     
         5 . The system of  claim 1 , wherein the system may operate in a cooling mode or a heating mode. 
     
     
         6 . The system of  claim 1 , wherein the first outer heat exchange unit and the second outer heat exchange unit may function as a condenser or evaporator. 
     
     
         7 . The system of  claim 1 , further comprising an additional pressure circuit for flowing a refrigerant comprising:
 a refrigerant flowing through a channel in the additional pressure circuit;   a compressor to modulate a flow pressure of the refrigerant;   a reversing valve to determine a flow direction of the refrigerant, wherein the flow direction determines a mode of operation;   an outer heat exchange unit capable of operating as a condenser or evaporator and capable of connecting to other additional pressure circuits;   a metering device; and   wherein the additional pressure circuit is thermally coupled either with the high-pressure circuit via the first outer heat exchange unit, or the low-pressure circuit via the second outer heat exchange unit to allow customization of the system with the additional pressure circuit configured to perform within a specific pressure differential to improve system efficiency.   
     
     
         8 . The system of  claim 1 , wherein the metering device comprises an expansion valve, an electronic expansion valve, a capillary tube, a thermostatic expansion valve, or a piston device. 
     
     
         9 . The system of  claim 1 , wherein at least one of the high-pressure circuit and the low-pressure circuit further comprises a vapor injection configuration, the vapor injection configuration comprising:
 an auxiliary circuit, to receive at least a portion of a redirected main refrigerant flow from a main flow channel to an auxiliary flow through an auxiliary flow channel, wherein the auxiliary flow channel is a connected sub-part of the main flow channel;   an auxiliary metering device to depressurize the auxiliary flow in the auxiliary circuit; and   an auxiliary heat exchange unit, wherein the auxiliary flow channel and a portion of the main flow channel pass through the auxiliary heat exchange unit to facilitate the exchange of heat between the auxiliary flow and the main refrigerant flow.   
     
     
         10 . The system of  claim 1 , wherein the low-pressure circuit further comprises an economizer vapor injection configuration, the economizer vapor injection configuration comprising:
 an auxiliary circuit in fluid communication with the low-pressure circuit and fluidly isolated from the high-pressure circuit and comprising:
 an auxiliary metering device, wherein at least a portion of the second refrigerant is flowable through the auxiliary circuit and depressurized by the auxiliary metering device; and 
 an economizer heat exchange unit that receives the depressurized second refrigerant; 
   wherein the high-pressure circuit also comprises the economizer heat exchange unit to facilitate heat exchange between the depressurized second refrigerant and the first refrigerant in the high-pressure circuit; and   wherein the auxiliary circuit is configured to flow the second refrigerant from the economizer heat exchange unit to the second compressor.   
     
     
         11 . A cascaded heat pump system, comprising:
 a plurality of fluidly isolated heat pump circuits, each of the heat pump circuits being thermally connected to another of the heat pump circuits via an intermediary heat exchange unit and each heat pump circuit comprising:
 a refrigerant flowing through the heat pump circuit; 
 a compressor; 
 a reversing valve operable to direct a flow of the refrigerant in a first direction or a second direction opposite the first direction depending on a mode of operation; 
 a metering device; and 
 one of the intermediary heat exchange units usable as a condenser or an evaporator depending on the mode of operation; and 
   wherein the plurality of fluidly isolated heat pump circuits allows each heat pump circuit to operate within a specific pressure differential to improve efficiency of the compressor.   
     
     
         12 . The system of  claim 11 , wherein the plurality of fluidly isolated heat pump circuits are synchronized in a mode of operation, wherein the mode of operation is either a cooling mode or a heating mode. 
     
     
         13 . The system of  claim 11 , wherein each heat pump circuit further comprises an accumulator. 
     
     
         14 . The system of  claim 11 , wherein the compressor comprises a variable speed compressor. 
     
     
         15 . The system of  claim 11 , wherein the metering device comprises an expansion valve, an electronic expansion valve, a capillary tube, a thermostatic expansion valve, or a piston device. 
     
     
         16 . The system of  claim 11 , wherein a heat pump circuit of the plurality of fluidly isolated heat pump circuits comprises a vapor injection configuration, the vapor injection configuration comprising:
 an auxiliary circuit, to receive at least a portion of a redirected main refrigerant flow from a main flow channel to an auxiliary flow through an auxiliary flow channel, wherein the auxiliary flow channel is a connected sub-part of the main flow channel;   an auxiliary metering device to depressurize the auxiliary flow in the auxiliary circuit; and   an auxiliary heat exchange unit, wherein the auxiliary flow channel and a portion of the main flow channel pass through the auxiliary heat exchange unit to facilitate the exchange of heat between the auxiliary flow and the main refrigerant flow.   
     
     
         17 . The system of  claim 11 , wherein a heat pump circuit further comprises an economizer vapor injection configuration, the economizer vapor injection configuration comprising:
 an auxiliary circuit in fluid communication with the heat pump circuit and fluidly isolated from an additional heat pump circuit of the plurality of fluidly isolated heat pump circuits, and comprising:
 an auxiliary metering device, wherein at least a portion of the main refrigerant is flowable through the auxiliary circuit and depressurized by the auxiliary metering device; and 
 an economizer heat exchange unit that receives the depressurized main refrigerant; 
 wherein the additional heat pump circuit comprises the economizer heat exchange unit to facilitate heat exchange between the depressurized main refrigerant and another refrigerant flowable through the additional heat pump circuit; and 
 wherein the auxiliary circuit is configured to flow the main refrigerant from the economizer heat exchange unit to the compressor. 
   
     
     
         18 . A method of operating a cascaded cold climate heat pump system, comprising:
 pressurizing a first refrigerant by a first compressor to a first pressure in a first heat pump circuit;   pressurizing a second refrigerant by a second compressor to a second pressure in a second heat pump circuit fluidly isolated from the first heat pump circuit;   circulating the first refrigerant through the first heat pump circuit, wherein the first heat pump circuit further comprises a first outdoor heat exchange unit, a first metering device, a first accumulator, and a first reversing valve;   circulating the second refrigerant through the second heat pump circuit, wherein the second heat pump circuit comprises a second outer heat exchange unit, a second metering device, a second accumulator, and a second reversing valve;   flowing the first refrigerant in the first heat pump circuit through an intermediary heat exchange unit of the first heat pump circuit;   flowing the second refrigerant flowing in the second heat pump through the intermediary heat exchange unit, the second heat pump circuit also comprising the intermediary heat exchange unit; and   exchanging heat between the first refrigerant and second refrigerant via the intermediary heat exchange unit to reduce a temperature lift of each of the first heat pump circuit and the second heat pump circuit allowing the first heat pump circuit to operate within a first pressure differential, and the second heat pump circuit to operate within a second pressure differential.   
     
     
         19 . The method of  claim 18 , further comprising:
 diverting at least a portion of the first refrigerant from the first heat pump circuit to a first auxiliary circuit;   diverting at least a portion of the second refrigerant from the second heat pump circuit to a second auxiliary circuit;   depressurizing the diverted first refrigerant in the first auxiliary circuit with a first auxiliary metering device in the first auxiliary circuit;   depressurizing the diverted second refrigerant in the second auxiliary circuit with a second auxiliary metering device in the second auxiliary circuit;   flowing the first refrigerant in the first heat pump circuit and the diverted first refrigerant in the first auxiliary circuit through a first auxiliary heat exchange unit to exchange heat between the first refrigerant and the diverted first refrigerant;   flowing the second refrigerant in the second heat pump circuit and the diverted second refrigerant in the second auxiliary circuit through a second auxiliary heat exchange unit to exchange heat with between the second refrigerant and the diverted second refrigerant; and   wherein multiple heat exchange points improve control of heat exchange between the first heat pump circuit and the second heat pump circuit.   
     
     
         20 . The method of  claim 18 , further comprising:
 diverting at least a portion of the second refrigerant from the second heat pump circuit to a second auxiliary circuit;   depressurizing the diverted second refrigerant in the second auxiliary circuit with a second auxiliary metering device in the second auxiliary circuit;   flowing the diverted second refrigerant in the second auxiliary circuit through an auxiliary heat exchange unit;   flowing the first refrigerant in the first heat pump circuit through the auxiliary heat exchange unit; and   exchanging heat between the diverted second refrigerant in the second auxiliary circuit and the first refrigerant in the first refrigerant circuit via the auxiliary heat exchange unit to provide additional cooling to the first refrigerant by the diverted second refrigerant.