Importance

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Abstract

An improved system for control of defrost in a refrigeration system of the type wherein one or more evaporators are defrosted by hot gas from the compressor while one or more evaporators remain in refrigeration operation. Prior to operating diverting valves to establish defrosting gas flow in an evaporator, a liquid line valve is closed and the system is pumped down to a predetermined amount of refrigerant charge in the defrost loop. In a preferred embodiment, this is accomplished by first opening the liquid line valve to flood the system, then closing it for a predetermined time interval to pump down to the predetermined amount of charge prior to operating the diverting valves. The predetermined amount of refrigerant charge in the defrost loop, together with a flow through defrost receiver incorporated in the defrost loop assures optimum efficiency by avoiding situations of two little or too much charge in the defrost loop, either of which would impair efficiency of the defrosting and the ongoing refrigeration in the other evaporator or evaporators.

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First Claim