PRELIMINARY EXPERIMENTAL AND NUMERICAL STUDY OF TRANSIENT CHARACTERISTICS FOR A JOULE-THOMSON CRYOCOOLER

To establish a tool for computer-aided design, a preliminary experimen tal and numerical study of transient characteristics for a Joule-Thoms on (J-T) cryocooler is developed in the present work. A simplified tra nsient one-dimensional model of momentum and energy transport is used to simulate the flow and heat transfer characteristics. The computatio nal results for cool-down time agree with the experimental data. The t ransient temperature variations of high pressure gas, tube wall, low p ressure gas, glass Dewar and mandrel at the grid point near the valve exit are shown. From the spatial temperature distributions of high and low pressure gases along the finned tube at the moment of cool-down, it is proposed that the J-T cooler currently used may be reduced in te rms of both size and weight; factors which are very important in a min iature J-T cryocooler.