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Measurement of Thermal Accommodation and Temperature Jump Coefficients Between Stainless Steel and Rarefied Helium
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The objective of this thesis is to study rarefied gas heat transfer through an annular gap of 1 mm, and to measure the thermal accommodation coefficient at the interface between stainless-steel and rarefied helium. The thermal accommodation and temperature jump coefficients are used to characterize the interaction between gas molecules and wall at the molecular level. It is important to determine its value with precision for better determination of heat transfer at low pressure. The experimental procedure consists of measuring the temperature difference between the inner and outer cylinders as the pressure is decreased in the gap. By measuring the temperature difference and heat flux across the gap the thermal accommodation coefficient can be extracted from the theoretical expression relating the temperature difference to the radial heat flux. Three-dimensional simulations utilizing ANSYS/Fluent commercial code are conducted to determine the legitimacy of the design of the experimental apparatus. These simulations confirmed that the apparatus design is effective to study the heat transfer across rarefied gas and to determine the thermal accommodation coefficient for helium on a stainless steel surface. The comparison between the measured and simulated temperature differences at different pressures, which cover the continuum and slip regimes, enabled the extraction of the thermal accommodation coefficient.