Mixed Gas Joule-Thomson Refrigeration Cycles

Gregory F. Nellis, Ph.D.
Assistant Professor, University of Wisconsin
1500 Engineering Drive, Madison, WI 53706
USA; Phone: 608/265-6626; Fax: 608/262-8464
E-Mail: [email protected]

ABSTRACT:
Economically attractive, compact, and reliable alternatives for achieving very low temperatures become increasingly important as more applications requiring cryogenic refrigeration are developed. This seminar will discuss refrigeration cycles that avoid using any moving parts in the cold portion of the system and therefore allow high reliability and low cost. The basic cycle that will be discussed is the Joule-Thomson refrigeration cycle – a recuperative cycle that is energized by an isenthalpic expansion. The performance of this cycle is fundamentally limited by the thermodynamic properties of the working fluid. The thermodynamic advantage associated with using mixtures rather than pure substances will be described. Optimization strategies for selecting the mixture will be discussed. Finally, the application of this technology to cryosurgical applications will be described.

BIO:
Gregory Nellis is an Assistant Professor of Mechanical Engineering at the UW-Madison. Dr. Nellis received his B.S. at the UW-Madison and his M.S. and Ph.D. degrees at M.I.T. Following graduate school, Dr. Nellis worked for several years at Creare Inc. on the development of miniature, turbo-machine-based reverse-Brayton systems. His research at the UW-Madison is related to the model and test of a variety of thermal-fluid systems.