A NEW TECHNIQUE FOR THE ANALYSIS OF TORQUE TUBE HEAT-EXCHANGERS OF SUPERCONDUCTING GENERATORS

The torque tubes of a superconducting generator belong to a unique cla ss of heat exchangers where a single fluid stream (boil off helium vap our) exchanges heat with a metallic wall conducting heat from the ambi ent to the cold (liquid helium) space. The rate of heat leak to the co ld space is the chief indicator of the performance of the exchanger. T his rate of heat inleak has been found to be a function of two dimensi onless parameters: a generalized cooling parameter Lambda and a tempe rature range parameter Psi. A generalized design chart is presented wh ich expresses the dimensionless heat flow rate Q(c) in terms of the pa rameters Lambda and Psi. This chart will be useful for the design of t orque tubes and vapour-cooled support members in cryogenic systems.