First Steps in Cryocooling Using Solid Nitrogen Continuous Sublimation: Design, Operation, and Best Practices

Abstract

A solid cryocooler is defined as any device by which standard cryogenic working fluids are eschewed in whole or in part and are replaced with working solids. Despite its overall greater potential for reaching lower temperatures, this basic idea is relatively unexplored due to its difficulty and unorthodoxy. Previous forays into the topic have typically been batch-cooling or load-leveling systems, much more akin to a lower-temperature version of the Thermal Energy Storage systems developed in other branches of the UW-Madison Solar Energy Lab than a primary component of a true thermal cycle that could feasibly be integrated into future cryocooler designs for long-term use. In this work, we attempted to expand on the sole previous work (of which we are aware) that sought to create design parameters for continuous solid cooling by expanding the breadth and designs of such coolers to include a new working solid, Diatomic Nitrogen (N2), and to provide qualitative performance data for functioning designs. The results show at least one promising design and also lay out attempted designs and ideas that do not function with the new solid and should not be attempted, as well as the reasons for which these ideas do or do not function in detail, with easy-to-understand models included, as well as with photographic evidence and qualitative descriptions.