Heat Transfer Characteristics of Gaseous Flows in a Microchannel and a Microtube with Constant Wall Temperature

Abstract

Two-dimensional compressible momentum and energy equations are solved to obtain the heat transfer characteristics of gaseous flows in a microchannel and in a microtube with constant wall temperature, whose temperature is lower than the inlet temperature (cooled case). The numerical methodology is based on the arbitrary Lagrangian-Eulerian (ALE) method. The stagnation temperature is fixed at 300 K and the computations were done for the wall temperature, which ranges from 250 to 290 K. The bulk temperature based on the static temperature and the total temperature of the cooled case are compared with those of the heated case and also compared with temperatures of the incompressible flow in a conventional-sized channel. Identical heat transfer coefficients are obtained for both cooled and heated cases of incompressible flow. However, in the case of gaseous flow, different heat transfer coefficients are obtained for each cooled and heated case. A correlation for the prediction of the heat transfer rate of the gaseous flow in a microchannel and in a microtube is proposed.