Abstract: The disclosure relates to a closed refrigeration system wherein refrigerant travelling between heat exchangers in the system is diverted to the evaporator in response to operation of a controller which responds to the temperature at the evaporator. Preferably the diverted refrigerant is the liquid phase thereof, separation of the liquid from the gaseous phase taking place between heat exchangers in a preferred embodiment of the invention. When the temperature at the evaporator is at a predetermined value, the controller can shut off the refrigerant diverting portion of the system to provide standard system operation.

Abstract: The disclosure relates to a closed circuit refrigerator having both rapid heating/defrost and cooling rates for the cryosurface and which operates on a continuous basis. The system is based upon a refrigeration process of the type which employs compression of a mixture of vapor refrigerant components with partial condensation and partial evaporation with steps of intermediate cooling and at least partial phase separation. The evaporator of the refrigeration system is placed in a vacuum system as a "Meissner" coil. The cryosurface has, thermally coupled thereto, both a defrost tube and an evaporator tube, the defrost tube carrying refrigerant fluid therein at raised temperature when made operational during a defrost cycle and the evaporator tube carrying low temperature refrigerant fluid therein when made operational during a cool down operation. Appropriate valves determine the refrigerant fluid both, i.e., through cooling heat exchangers or through a heating heat exchanger.