Abstract: A refrigerant metering device for a vapor compression refrigeration system. The metering device employs a restrictor fabricated of a porous material to achieve the desired pressure reduction across the device. The porous material is housed in a casing that provides support for the restrictor and enables installation of the device into the system. Any suitable porous material may be used to make the restrictor, but in the preferred embodiments, a porous polyethylene material is used. In the preferred embodiments, a filter is provided upstream in the refrigerant flow path to reduce the possibility of restrictor fouling and resultant system performance degradation. In one embodiment, the filter and restrictor are combined as two sections of an integral filter and restrictor. The device is effective in reducing refrigerant flow noise during both steady state operation and post shutdown transients.

Abstract: A method and apparatus for defrosting the outside heat exchanger of a reversible vapor compression refrigeration (heat pump) system. The method and apparatus are particularly suited for use with smaller systems that employ a single fan motor to drive both the inside and outside heat exchanger fans. A heat storage apparatus is mounted in heat exchange relationship with the refrigerant piping between the system flow reversing valve and the inside heat exchanger. During operation in the heating mode, heat from the refrigerant is transferred to and stored in the heat storage apparatus. During operation in the defrosting mode, the refrigerant flow in the system is aligned as in the cooling mode but both fans are shut off. Heat stored in the heat storage apparatus is transferred to and used for defrosting the outside heat exchanger. The apparatus has little or no effect on system operation in the cooling mode.