Thermal creep effects on fluid flow and heat transfer in a microchannel gas cooling

Abstract

This work presents a numerical analysis of the effect of thermal creep on gas flow and heat transfer in a microchannel under gas cooling conditions. The hydrodynamic equations in vorticity-stream function form are solved together with the energy equation using a finite difference scheme. Axial conduction, pressure work, and viscous dissipation effects are included in the analysis. Solutions are obtained with and without thermal creep effects to illustrate the thermal creep effect on gas cooling. The results show that thermal creep becomes more pronounced as the wall temperature decreases relative to the inlet gas temperature. The results also show that the thermal creep effect on gas cooling becomes more significant as Reynolds number decreases. Furthermore, increasing Knudsen number has caused thermal creep effects to extend further into the channel. Additionally, the work has concluded that thermal creep causes an increase in the hydrodynamic entrance length. Moreover, the work also showed that for low enough wall temperature, Knudsen number, and Reynolds number, the slip velocity can reach negative values resulting in a significant change in the wall velocity allowing vortices to form. The work has also concluded that, at least for most practical purposes, thermal creep has no tangible effects on the thermal part of the problem, where the solution with and without thermal creep effect, is producing almost the same results for temperature field, total heat transfer, and thermal entrance length.