Frequent short-cycle zero peak heat pump defroster

摘要

A heat pump system is configured to have a defrost cycle operable during a heating mode of operation. The system uses: larger than conventionally sized capillary tubes at the liquid refrigerant entry end of an exterior air-source heat exchanger; a special amount of additional refrigerant charge; a supplemental hot gas refrigerant transport line extending from the compressor; a special valve in the new supplemental hot gas refrigerant transport line; and another special valve controlling a restriction to the refrigerant flow in the common consolidated vapor refrigerant transport line exiting the exterior heat exchanger. A controller opens the valve in the new supplemental hot gas refrigerant transport line and to simultaneously engages, for a special period of time, the valve controlling the specially sized restriction to the refrigerant flow in the common consolidated vapor refrigerant transport line exiting the exterior heat exchanger at periodic intervals during potential frost conditions. Additionally, the exterior heat exchanger fan is disabled during a part of the defrost cycle.

主权项

1. A heat pump having a heating mode, the heat pump comprising: a compressor having an inlet and an outlet; which outlet from the compressor directs heated refrigerant vapor into a vapor refrigerant transport line, having a first interior cross-sectional area, that transports heated refrigerant vapor exiting the compressor into an interior heat exchanger, which interior heat exchanger has a fan, and which interior heat exchanger includes distributed interior heat exchanger tubing; which distributed interior heat exchanger tubing is re-combined into at least one liquid refrigerant transport line, which liquid refrigerant transport line has a second interior cross-sectional area smaller than the first interior cross-sectional area, exiting the interior heat exchanger; which line with the second interior cross-sectional area, exits the interior heat exchanger and is next operably connected to a heating mode expansion device, which expansion device is positioned after the refrigerant exists the interior heat exchanger through the second interior cross-sectional area, but prior to the liquid refrigerant being next directed into a third refrigerant transport line, with an interior cross-sectional area equal to the first interior cross-sectional area; which liquid refrigerant transport line exiting the expansion device is comprised of the third refrigerant transport line between an exiting end of the expansion device and an entry point into a distributor, which distributes the refrigerant working fluid into heat exchange tubing within an interior of an exterior heat exchanger; which exterior heat exchanger includes distributed heat exchanger tubing within the exterior heat exchanger and an exterior heat exchanger fan; which distributed interior heat exchanger tubing is re-combined into at least one consolidated vapor refrigerant transport line upon exiting the exterior heat exchanger, which consolidated vapor refrigerant transport line has an interior cross-sectional area larger than the first interior cross-sectional area, which consolidated vapor refrigerant transport line ultimately transports vapor refrigerant back to an accumulator and then to the compressor; a connecting segment of vapor refrigerant transport tubing fluidly communicating between the refrigerant hot gas compressor discharge vapor line, with the first interior cross-sectional area exiting the compressor, but at a location before the hot gas compressor discharge vapor line enters the interior heat exchanger, and between the third refrigerant transport line with the interior cross-sectional area equal to the first interior cross-sectional area, situated at a location after the heating mode expansion device but before the third refrigerant transport line enters the exterior heat exchanger and the exterior heat exchanger's distributor; which connecting segment of vapor refrigerant transport line has a valve, that is operably connected to at least one controller, and which valve can be one of alternately opened and closed by the controller; which connecting segment of vapor refrigerant transport line has an interior cross-sectional area that is the same as the interior cross-sectional area of the first interior cross-sectional area of the hot gas refrigerant line transporting vapor refrigerant out of the compressor; which exterior heat exchanger has the fan controlled by the at least one controller, and which exterior heat exchanger includes the distributed exterior heat exchanger tubing; which distributed exterior heat exchanger tubing is re-combined into the at least one consolidated vapor refrigerant transport line, exiting the exterior heat exchanger; which consolidated vapor refrigerant transport line, transporting refrigerant fluid out of the exterior heat exchanger, is in fluid communication with, and ultimately transports refrigerant vapor to the accumulator and then into the compressor inlet; at least one of a restrictor valve with a by-pass line being disposed in the consolidated vapor refrigerant transport line, with the interior cross-sectional area larger than the first interior cross-sectional area, at a location between a consolidated vapor refrigerant transport line's exit point from the exterior heat exchanger and a consolidated vapor refrigerant transport line's entry point into the accumulator, which consolidated vapor refrigerant transport line next travels into the compressor, and which the restrictor valve is operably coupled/connected to the controller, whereby the restrictor valve operates so as to be fully open when the system is not in a defrost cycle, and operates in the defrost operation mode so as to close off and block about 94-96% of the interior cross-sectional area of the consolidated vapor refrigerant transport line, with the restrictor valve being positioned in the consolidated vapor refrigerant transport line between an exit point of the exterior heat exchanger and an entry point of the accumulator; the at least one controller operatively coupled to the exterior heat exchanger fan, the valve within the connecting segment of the vapor refrigerant transport line, and the restrictor valve within the consolidated vapor refrigerant transport line between the exit point of the exterior heat exchanger and the entry point to the accumulator, the at least one controller being programmed to operate the heat pump: in the heating mode in response to a heating demand, in which the compressor, the interior heat exchanger fan, and the exterior heat exchanger fan are engaged and the valve within the connecting segment of the vapor refrigerant transport line and the restrictor valve are in a fully open position; and in the defrost mode, in which the compressor is engaged, the interior heat exchanger fan is engaged, and the valve within the connecting segment of the vapor refrigerant transport line and restrictor valve are actuated to a respective refrigerant flow blocking position for a defrost period; wherein the defrost period lasts for approximately 20 to 45 seconds; wherein the exterior heat exchanger fan is disengaged about 15 seconds after the commencement of the defrost cycle, and is re-engaged at the earliest of: (a) about 20 seconds after the respective refrigerant flow blocking valves are returned to their fully open position during a continuing normal and non-defrost heating mode of system operation; and (b) when the entire system is re-engaged in response to a heating demand, after the entire system has been disengaged due to a lack of a continuing heating demand following termination of the defrost operation mode.