The unified gas kinetic scheme (UGKS) is introduced to simulate the near transition regime gas flow and heat transfer in microchannel confined between isothermal and non-isothermal parallel plates. The argon gas is used and its inlet Knudsen number ranges from 0.0154 to 0.0715. It is found that: 1) both microchannel gas flows under isothermal and non-isothermal parallel plates display a trend of speed acceleration and temperature decrease along flow direction, for which the microscopic mechanism explanation is firstly proposed; 2) inlet gas streamlines under non-isothermal plates condition deviates from the parallel distributions under isothermal plates condition due to the dual driving effects of pressure drop along flow direction and temperature difference along cross section; 3) gas temperature, pressure, density and viscosity distributions along cross section under non-isothermal plates condition deviate from the parabolic distributions under isothermal plates condition, while the gas velocity keeps the parabolic distribution due to the effect of Knudsen layer; 4) as channel height increases or channel length and gas molecular mean free path decrease, the gas temperature distribution along cross section under non-isothermal plates condition tends to transition from linear to curve one due to the decreasing effect of heat transfer along cross section and increasing effect of gas acceleration along flow direction, this transition from linear to curve one becomes more obvious along flow direction. The effects of inlet temperature, lower plate temperature and Knudsen number on non-isothermal microchannel flow and heat transfer characters are also analyzed.

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