Thermodynamic analysis of a J-T heat exchanger used in G-M/J-T helium refrigerator for a cryoadsorption test facility.

A G-M/J-T helium refrigerator system is designed for a cryoadsorption test facility at 4.5K. The refrigerator includes a heat exchanger consisted by counterflow of J-T valve and a helically twined single finned-tube. A nonlinear variable specific heat capacity model for helium gas under 15K has been developed by the law of thermodynamics to study the thermal characteristics of the heat exchanger. Its performance is discussed for the test works in various operation conditions and the results indicate that weakening the interact surrounding environment and enhancing the number of Cr are practical and reasonable for the heat exchanger and useful for performance analysis of similar heat exchangers.