Vapor-cooled lead and stacks thermal performance and design analysis by finite difference techniques

Investigation of the combined thermal performance of the stacks and vapor-cooled leads for the Mirror Fusion Test Facility-"B" (MFTF-B) (Figure 1) demonstrates considerable interdependency. For instance, the heat transfer to the vapor-cooled lead (VCL) from warm bus heaters, environmental enclosure, and stack is a significant additional heat load to the joule heating in the leads, proportionately higher for the lower current leads that have fewer current-carrying, counter flow coolant copper tubes. Consequently, the specific coolant flow (G/sec-kA-lead pair) increases as the lead current decreases. The definition of this interdependency and the definition of necessary thermal management has required an integrated thermal model for the entire stack/VCL assemblies.