Gas Flowin Nano-Channels: Thermal Transpirationmodelswith Application to a Si-Micromachinedknudsen Pump

This paper presents a comparative study of performance of various analytical and semi-analytical models used for the analysis of rarefied gas flow, which is responsible for the phenomenon of thermal transpiration. In particular, these are evaluated in the context of the scaling analysis of a Si-micromachined monolithic Knudsen pump. Results from these models are verified using available experimental data and are benchmarked against the simulation results from direct simulation Monte Carlo (DSMC) technique. Characterization of Sharipov's model against the DSMC technique with the help of specially designed test cases predicts that Sharipov's model is potentially the most representative model for DSMC in this context. Finally, Sharipov's model is used to evaluate the sensitivity analysis of structural and performance parameters relevant for thermal transpiration. The analysis shows that for a 200 mum long channel on a well-insulated glass substrate, with a channel height of 100 nm and 10 mum width, provides a mass flow rate of 1.5times10-6 sccm with a DeltaT of 300degC.