Abstract: A refrigeration unit and methods of operating a refrigeration unit for an HVACR system are disclosed. The refrigeration unit includes a refrigerant circuit, including a compressor, a condenser, an expansion device, and an evaporator fluidly connected. The condenser includes a condenser portion and a subcooler portion. A single receiver tank is fluidly connected to an output of the condenser portion and an input of the subcooler portion. A restrictor is fluidly connected to the receiver tank. The restrictor can induce a pressure drop in a working fluid flowing from the subcooler portion.

Abstract: A refrigeration unit and methods of operating a refrigeration unit for an HVACR system are disclosed. The refrigeration unit includes a refrigerant circuit, including a compressor, a condenser, an expansion device, and an evaporator fluidly connected. The condenser includes a condenser portion and a subcooler portion. A single receiver tank is fluidly connected to an output of the condenser portion and an input of the subcooler portion. A restrictor is fluidly connected to the receiver tank. The restrictor can induce a pressure drop in a working fluid flowing from the subcooler portion.

Abstract: A heat pump includes a valve system that connects a receiver tank in fluid communication with an indoor heat exchanger, wherein the valve system, operating under a novel control scheme, works in conjunction with the receiver to control the heat pump's effective refrigerant charge. To avoid suction or discharge pressure faults and to help prevent slugs of liquid refrigerant from entering the heat pump's compressor as the heat pump switches between heating and cooling modes or switches between heating and defrost modes, the control scheme provides momentary periods of transition between those modes of operation. In some embodiments, the valve system comprises a check valve connected in parallel flow relationship with a two-position receiver valve, wherein the check valve has an appreciably higher flow coefficient than that of the receiver valve.

Abstract: A reversible HVAC heating/cooling refrigerant system includes a novel valve system that allows an outdoor heat exchanger to function as a subcooler during a cooling or defrost mode and function as a receiver tank for storing excess liquid refrigerant during a heating mode. In the heating mode, a cooling expansion valve is kept slightly open to flood the subcooler with liquid refrigerant while a heating expansion valve is regulated to maintain a desired level of superheat at the suction side of the refrigerant system's compressor. The novel valve system also serves as a pressure relief valve to protect the subcooler from excess pressure caused by thermal expansion of liquid refrigerant trapped within the subcooler.

Abstract: A heat pump includes a valve system that connects a receiver tank in fluid communication with an indoor heat exchanger, wherein the valve system, operating under a novel control scheme, works in conjunction with the receiver to control the heat pump's effective refrigerant charge. To avoid suction or discharge pressure faults and to help prevent slugs of liquid refrigerant from entering the heat pump's compressor as the heat pump switches between heating and cooling modes or switches between heating and defrost modes, the control scheme provides momentary periods of transition between those modes of operation. In some embodiments, the valve system comprises a check valve connected in parallel flow relationship with a two-position receiver valve, wherein the check valve has an appreciably higher flow coefficient than that of the receiver valve.

Abstract: A reversible HVAC heating/cooling refrigerant system includes a novel valve system that allows an outdoor heat exchanger to function as a subcooler during a cooling or defrost mode and function as a receiver tank for storing excess liquid refrigerant during a heating mode. In the heating mode, a cooling expansion valve is kept slightly open to flood the subcooler with liquid refrigerant while a heating expansion valve is regulated to maintain a desired level of superheat at the suction side of the refrigerant system's compressor. The novel valve system also serves as a pressure relief valve to protect the subcooler from excess pressure caused by thermal expansion of liquid refrigerant trapped within the subcooler.