Temperature instability comparison of micro- and mesoscale Joule-Thomson cryocoolers employing mixed refrigerants

Published

June 13, 2011

Author(s)

Peter E. Bradley, Ray Radebaugh, Ryan J. Lewis, Mu Hong Lin, Yung-Cheng Lee

Abstract

Previously we demonstrated cryogenic cooling in a Joule-Thomson microcryocooler (MCC) with mixed refrigerants operating at pressure ratios of 16:1 that achieved stable temperatures of 140 K with transient temperatures down to 76 K with precooling of the refrigerant to 240 K. Pre-cooling improves the minimum enthalpy difference, (ΔHT)min compared with pure fluids. Micro-scale compressors have been unavailable to meet 16:1 ratios. By reducing the ratio to 4:1 mini-compressors become viable in the near term. Utilizing mixed refrigerants optimized for 4:1 pressure ratios we compare the performance stability of this micro-JT employing a 25mm long multichannel glass fiber heat exchanger (outer low pressure capillary ID/OD=536µm/617µm, inner high pressure channels ID/OD=75µm/125µm) with a scaled up (mesoscopic) version employing a 20cm long single channel stainless steel heat exchanger (outer low pressure channel ID/OD=580µm/760µm, inner high pressure channel ID/OD=150µm/266µm). This easy to fabricate and modify meso-scale version was fabricated to investigate the temperature instabilities of mixed refrigerants for similar operating conditions but for proportionally higher flows of ~30 cm3/min. compared with ~10 cm3/min. We compare measured pressures, flow rates, temperatures, and stabilities for both micro- and meso-JT cryocoolers to better understand the causes for the temperature instabilities within the micro-JT cryocooler.

Proceedings Title

Cryogenic Engineering Conference of the Cryogenic Engineering Conference and International Cryogenic Materials Conference 2011

Volume

1434

Issue

690

Conference Dates

June 13-17, 2011

Conference Location

Spokane, WA

Pub Type

Conferences

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DOI Link

Keywords

Cryocooler, Joule-Thomson, micro-cryocooler, micro-JT, mixed refrigerants.

Citation

Bradley, P. , Radebaugh, R. , Lewis, R. , , M. and Lee, Y. (2011), Temperature instability comparison of micro- and mesoscale Joule-Thomson cryocoolers employing mixed refrigerants, Cryogenic Engineering Conference of the Cryogenic Engineering Conference and International Cryogenic Materials Conference 2011, Spokane, WA, [online], https://doi.org/10.1063/1.4706980 (Accessed October 28, 2025)