Low Thermal Loss Cryogenic Pump

It is of great importance in most cryogenic pumping systems to minimize heat addition to the cryogen by the pump. The two main areas of heat addition are from inefficiency of the pump and conduction from the motor and ambient surroundings into the cryogen. Optimally, low heat leak cryogenic pumps are designed with a long shaft (and outer housing)between the motor and wet end to minimize heat from the motor and ambient surroundings from entering the cryogen. The shaft and outer housing are usually thin-walled tubing made of stainless steel. This limits the conductive heat to a function of the cross sectional area of the shaft and housing and the thermal conductivity of the stainless steel. The long shaft may also limit the speed at which the pump may operate, however. The speed limitation usually increases pump inefficiency thus adding more heat to the cryogen. This proposal presents an innovative solution to this problem. A composite material with lower thermal conductivity and higher stiffness will be used for the shaft. This will lower heat from conductance and allow the pump to operate at a higher, more efficient speed.