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.

What is claimed is: 
     
         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 connected by a first flow channel for flowing a first refrigerant through the high-pressure circuit as a first main flow;   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;   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; and   a vapor injection compressor configuration comprising:
 an auxiliary flow channel in fluid communication with the second flow channel between the second outer heat exchange unit and the intermediary heat exchange unit to divert a portion of the second refrigerant into the auxiliary flow channel as auxiliary flow; 
 an auxiliary metering device in the auxiliary flow channel and configured to cool the auxiliary flow more than the first main flow; and 
 an economizer heat exchange unit thermally connecting the first main flow, between the first outer heat exchange unit and the intermediate heat exchange unit, and the cooled auxiliary flow to facilitate heat exchange between the first main flow and the cooled auxiliary flow to cool the first main flow and evaporate the auxiliary flow, 
 wherein the evaporated auxiliary flow is directable into the second compressor to improve the performance of the second compressor as compared to not using the evaporated auxiliary flow. 
   
     
     
         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 . A cascaded heat pump system, comprising:
 a high-pressure heat pump circuit and a low-pressure heat pump circuit, each of the heat pump circuits being thermally connected to other 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 
 an outer heat exchange unit usable as a condenser or an evaporator depending on the mode of operation; and 
   a vapor injection compressor configuration comprising:
 an auxiliary flow channel in fluid communication with a flow channel between the outer heat exchange unit of the low-pressure circuit and the intermediary heat exchange unit to divert a portion of a main flow of the low-pressure refrigerant into the auxiliary flow channel as auxiliary flow; 
 an auxiliary metering device in the auxiliary flow channel and configured to cool the auxiliary flow more than a main flow of the high-pressure refrigerant; and 
 an auxiliary heat exchange unit thermally connecting the high-pressure main flow refrigerant, between the high-pressure outer heat exchange unit and the intermediate heat exchange unit, and the cooled auxiliary flow to facilitate heat exchange between the high-pressure main flow and the cooled auxiliary flow to cool the high-pressure main flow and evaporate the auxiliary flow, 
 wherein the evaporated auxiliary flow is directable into the low-pressure circuit compressor to improve the performance of the low-pressure circuit compressor as compared to not using the evaporated auxiliary flow; 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 each compressor.   
     
     
         10 . The system of  claim 9 , 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. 
     
     
         11 . The system of  claim 9 , wherein each heat pump circuit further comprises an accumulator. 
     
     
         12 . The system of  claim 9 , wherein each compressor comprises a variable speed compressor. 
     
     
         13 . The system of  claim 9 , wherein the metering device comprises an expansion valve, an electronic expansion valve, a capillary tube, a thermostatic expansion valve, or a piston device. 
     
     
         14 . 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 high-pressure heat pump circuit;   pressurizing a second refrigerant by a second compressor to a second pressure in a low-pressure heat pump circuit fluidly isolated from the high-pressure heat pump circuit;   circulating the first refrigerant through the high-pressure heat pump circuit in a first flow channel as a first main flow, wherein the high-pressure heat pump circuit further comprises a first outer heat exchange unit, a first metering device, a first accumulator, and a first reversing valve;   circulating the second refrigerant through the low-pressure heat pump circuit, wherein the low-pressure 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 high-pressure heat pump circuit through an intermediary heat exchange unit of the high-pressure heat pump circuit;   flowing the second refrigerant flowing in the low-pressure heat pump through the intermediary heat exchange unit, the low-pressure heat pump circuit also comprising the intermediary heat exchange unit;   exchanging heat between the first refrigerant and second refrigerant via the intermediary heat exchange unit to reduce a temperature lift of each of the high-pressure heat pump circuit and the low-pressure heat pump circuit allowing the high-pressure heat pump circuit to operate within a first pressure differential, and the low-pressure heat pump circuit to operate within a second pressure differential;   diverting at least a portion of the second refrigerant from the low-pressure heat pump circuit to a vapor injection compressor configuration comprising an auxiliary flow channel as an auxiliary flow, the auxiliary flow channel in fluid communication with the second flow channel between the second outer heat exchange unit and the intermediary heat exchange unit;   cooling the auxiliary flow with an auxiliary metering device in the auxiliary flow channel;   flowing the first main flow and the cooled auxiliary flow through an economizer heat exchange unit to facilitate heat exchange between the first main flow and the cooled auxiliary flow to cool the first main flow and evaporate the auxiliary flow; and   flowing the evaporated auxiliary flow into the second compressor to improve the performance of the second compressor as compared to not using the evaporated auxiliary flow.