Refrigerant charge management in a heat pump water heater

摘要

Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, methods of managing refrigerant charge, and methods for heating and cooling a space and heating water. Various embodiments deliver refrigerant gas to a heat exchanger that is not needed for transferring heat, drive liquid refrigerant out of that heat exchanger, isolate that heat exchanger against additional refrigerant flowing into it, and operate the heat pump while the heat exchanger is isolated. The heat exchanger can be isolated by closing an electronic expansion valve, actuating a refrigerant management valve, or both. Refrigerant charge can be controlled or adjusted by controlling how much liquid refrigerant is driven from the heat exchanger, by letting refrigerant back into the heat exchanger, or both. Heat pumps can be operated in different modes of operation, and segments of refrigerant conduit can be interconnected with various components.

主权项

1. A method of managing refrigerant charge in a heat pump that heats or cools a space and that also heats water, the heat pump comprising an outdoor heat exchanger that transfers heat between refrigerant and outdoor air or a heat source/sink, an indoor heat exchanger that transfers heat between the refrigerant and indoor air, a water heat exchanger that transfers heat from the refrigerant to water, a compressor, and at least one expansion device, the method comprising, in any order except where a particular order is explicitly indicated, at least the acts of:
during conditions under which a particular heat exchanger of the heat pump is not needed for transferring heat, delivering refrigerant gas to the particular heat exchanger and driving liquid refrigerant out of the particular heat exchanger and through the at least one expansion device; while the refrigerant gas is in the particular heat exchanger, isolating the particular heat exchanger against additional refrigerant flowing into the particular heat exchanger; and while the particular heat exchanger is isolated against additional refrigerant flowing into the particular heat exchanger, operating the heat pump, including running the compressor; wherein the act of driving liquid refrigerant out of the particular heat exchanger comprises monitoring at least one of: compressor discharge temperature, compressor discharge pressure, or duration of the act of driving liquid refrigerant out of the particular heat exchanger; and the act of driving liquid refrigerant out of the particular heat exchanger is terminated when at least one of: the compressor discharge temperature exceeds a predetermined compressor discharge temperature threshold, the compressor discharge pressure exceeds a predetermined compressor discharge pressure threshold, or the duration of the act of driving liquid refrigerant out of the particular heat exchanger exceeds a predetermined duration of the act of driving liquid refrigerant out of the particular heat exchanger.