Temperature instability comparison of micro- and mesoscale Joule-Thomson cryocoolers employing mixed refrigerants
Peter E. Bradley, Ray Radebaugh, Ryan J. Lewis, Mu Hong Lin, Yung-Cheng Lee
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.
Cryogenic Engineering Conference of the Cryogenic Engineering Conference and International Cryogenic Materials Conference 2011
, Radebaugh, R.
, Lewis, R.
, , M.
and Lee, Y.
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 November 28, 2023)