초록 ▼

A defrost system adapted for use with refrigeration or heat pump systems wherein an evaporator coil defrost cycle is adaptively modified in response to changing environmental conditions. Under normal conditions, a defrost operation is effected at the end of a period of frost accumulation. The period

A defrost system adapted for use with refrigeration or heat pump systems wherein an evaporator coil defrost cycle is adaptively modified in response to changing environmental conditions. Under normal conditions, a defrost operation is effected at the end of a period of frost accumulation. The period of frost accumulation is adjusted in accordance with deviation of the time required to defrost a coil from a desired defrost time. During the frost accumulation period, the differential between the temperature of the coil and ambient temperature is determined, and the frost accumulation period terminated and a defrost operation initiated if temperature differential exceeds a target differential.

대표청구항 ▼

A method for controlling the defrosting of a heat transfer unit of a temperature conditioning system by initiating a defrost operation when a predetermined amount of frost has accumulated on the unit during a frost accumulating period that occurs between defrost operations, a predetermined desired d

A method for controlling the defrosting of a heat transfer unit of a temperature conditioning system by initiating a defrost operation when a predetermined amount of frost has accumulated on the unit during a frost accumulating period that occurs between defrost operations, a predetermined desired defrost time being required to defrost said unit when it has the predetermined amount of frost accumulated thereon, said method being of the type comprising the steps: determining the time required to actually defrost said unit during an actual defrost operation; increasing the frost accumulating period before initiating the next defrost operation if the time to complete the last defrost was less than said desired defrost time period; or decreasing the frost accumulating period before initiating the next defrost operation if the time to complete the last defrost was greater than said desired defrost time period; improved wherein said method further comprises the steps of: sensing ambient temperature in the vicinity of said heat transfer unit; determining if the temperature of said unit has stabilized; determining if the system operation is within a first predetermined portion of said frost accumulation period; determining the temperature differential between said unit and ambient; and if said unit temperature has stabilized and said system operation is within said first predetermined portion of said frost accumulating period, initiating said defrost operation upon said temperature differential exceeding a threshold value.