Doctor of Philosophy, The Ohio State University, 2008, Physics

This thesis describes an approach to magnet leads in research cryostats which permits the incorporation of High Temperature Superconducting elements. The approach is based on a novel method for utilizing the cooling capability of the Helium gas generated by the boiling of Helium liquid, in which the radiaton baffles of the cryostat are used as heat exchangers between the magnet leads and the emerging gas. Magnet leads based on this method not only reduce liquid Helium consumption, but also permit further design enhancements. The basic concept and calculations that models all the essential thermal fluxes are first discussed. Two kinds of magnet leads based, on these calculations, are described. The first of these magnet leads is for a storage Dewar which successfully reduces liquid Helium consumption under current carrying conditions. Described next are magnet leads for an conventional cryostat that include a high temperature superconducting section which is an design enhancement made possible by the baffle based approach. This is the first successful implementation of high temperature superconducting leads for Helium based cryostat. The design and assembly procedure of these leads is described.

Committee: Thomas Gramila (Advisor) Subjects: Physics, Condensed Matter

Master of Science (MS), Ohio University, 2011, Mechanical Engineering (Engineering and Technology)

Flow uniformity through channels of a complex fuel cell stack is studied for several baffle arrangements using ANSYS Fluent, a computational fluid dynamics (CFD) package. Flow mal-distribution occurs from pressure differentials throughout the flow structure and causes a drop in stack performance. Three baffle arrangements were introduced into the flow structure and compared to a control case with no baffle in an attempt to improve the flow regime. A flow uniformity coefficient Γ was introduced to compare results from case to case. It was found that all three arrangements significantly increased flow uniformity, with the slotted baffle arrangement providing the most uniform flow. By increasing flow uniformity, the efficiency of the stack is also increased.

Committee: David Bayless (Advisor); Gregory Kremer (Committee Member); John Cotton (Committee Member); Greg Van Patten (Committee Member) Subjects: Engineering; Fluid Dynamics; Mechanical Engineering