Abstract: An oil separator is provided for separating oil from a refrigerant gas and returning the oil to a compressor. The separator includes a housing which has means associated therewith for conducting a mixture of refrigerant gas and oil into the housing and therein separating the oil from the gas. The separated oil is stored in a reservoir forming a part of the housing. A plurality of oil pickup devices are located within the oil reservoir. Each of the oil pickup devices has an oil pickup opening associated therewith. The oil pickup openings are located at different depths within the oil reservoir. The pickup devices are designed so that they are substantially more receptive to the flow of lubricating oil therethrough than to the flow of refrigerant gas. In one embodiment, the oil pickup devices are capillary tubes having their open ends located at different depths within the oil reservoir.

Abstract: A closed refrigeration system is provided with a mass flow limiting device located upstream of the suction inlet of a compressor. The device limits the mass flow supplied to the compressor during pulldown and startup to prevent overloading the motor or engine driving the compressor but has minimal influence on the refrigeration system under equilibrium conditions since it is designed for the specific system parameters.

Abstract: To prevent defrost melt from refreezing during a defrost cycle, the hot gas bypass line is branched to heat the metal plate across which the defrost melt flows as well as the drain pan.