Abstract
Two-dimensional compressible momentum and energy equations are solved to obtain the heat transfer characteristics of gaseous flows in a microtube with constant heat flux whose value is positive or negative. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The computations are performed for tubes with constant heat flux ranging from -10^4 to 10^4 Wm^<-2>. The tube diameter ranges from 10 to 100μm and the aspect ratio of the length to diameter is 200. The stagnation pressure, p_<stg> is chosen in such away that the Mach number at the exit ranges from 0.1 to 0.7. The outlet pressure is fixed at the atmosphere. The wall and bulk temperatures in micro-tubes with positive heat flux are compared with those of negative heat flux case and also compared with those of the incompressible flow in a conventional sized tube. In the case of fast flow, temperature profiles normalized by heat flux have different trends whether heat flux is positive or negative. A correlation for the prediction of the wall temperature of the gaseous flow in the micro-tube is proposed.
