Abstract: An integral combination of expansion valve and evaporator in a cryostat using a single support member. The valve includes two flow orifices, one orifice being used primarily for steady-state operation and the other orifice being used only during cool-down. An actuator having a high coefficient of thermal expansion moves a needle positioned in the cool-down orifice such that a large orifice flow area at the start of cool-down is automatically and continuously reduced as the actuator temperature decreases as refrigerant is throttled through the orifice. Within a range of approximately 30 K from the desired steady-state evaporator temperature, the needle completely blocks the cool-down orifice. Then, refrigerant flows through the steady-state orifice which has a remotely adjustable needle. In the final stage of cool-down, the refrigerant system is entirely controlled by the steady-state orifice and its associated needle.

Abstract: A heat exchanger has a set of tubes through which fluid pass. In thermal communication with these tubes are fins of high thermal conductivity material which disperse the heat contained within the fluid. Also useful in dispersing the heat contained within the passing fluid are rods inserted within the tubes to substantially decrease the hydraulic diameter of the tubes. This heat exchanger may be used in a cryogenic refrigeration system which also includes a compressor for compressing refrigerant gas, a separator for separating refrigerant gas and oil used by the compressor, and a cryogenic refrigerator for expanding the refrigerant gas.

Abstract: In accordance with the invention, a hermetic refrigerant compressor pump which is used to compress helium is cooled by fins which are press fitted to the compressor's housing. The compressor is further cooled by a heat exchanger which cools oil in an oil sump located within the compressor housing. Preferably, a fan is located between the fins and the heat exchanger to help cool the pump.

Abstract: In a cryogenic refrigeration system, a hermetic refrigerant compressor pump is used to compress helium. The compressor pump 10 is oil cooled by a heat exchange jacket 46 surrounding a compressor housing 28. Oil from an oil sump 30 within the compressor housing 28 is pumped through an external heat exchanger 44 where it is cooled, to the heat exchange jacket 46. From the heat exchange jacket 46, oil is recycled back to the oil sump 30. Pressure developed by the compressor pump 10 is used to pump the oil.