Refrigerated merchandiser with modular evaporator coils and electronic evaporator pressure regulator control

摘要

There is disclosed a method of controlling exit air temperature from an evaporator coil (22) in a commercial refrigerated merchandiser (M) for food products, in which the evaporator coil has a refrigeration mode and a defrost mode and the suction side of the evaporator coil has an electronic evaporator pressure regulator (EEPR) valve (24) operated by a valve controller circuit (25), said control method being characterized by the steps of: (a) sensing the exit air temperature from the evaporator coil and generating a signal corresponding thereto; (b) operating the EEPR valve in the refrigeration mode of the evaporator coil by modulating refrigerant vapor flow therethrough to maintain a preselected exit air temperature; (c) operating the EEPR valve in the defrost mode of the evaporator coil, (1) by first closing the EEPR valve during a preselected de-icing period of said evaporator coil until reaching a predetermined drip temperature, and (2) then activating the valve controller circuit in response to detection of exit air temperatures exceeding a preselected value during a final drip period to provide limited refrigeration to maintain the preselected temperature during the remainder of the defrost mode.