Modeling of Joule heating and convective cooling in a thick-walled micro-tube

Abstract

The heating of a fluid in a metallic micro-tube can be realized at the inlet and/or within a certain section of micro-scale heat and fluid flow devices by using Joule heating which is a heat generation mechanism that occurs when an electric current is passed through the metallic wall. For the thermal analysis of fluid flow in an electrically heated micro-tube, the solution of conjugate heat transfer (to include effect of the axial conduction through the channel wall) together with Joule heating is required. An analytic solution is presented for conjugate heat transfer in an electrically-heated micro-tube in this study. The solution is obtained in the form of integrals by the method of Green's functions for the hydrodynamically fully-developed flow of a constant property fluid in a micro-tube. The current analytical model can predict the fluid temperature for a given wall thickness, wall material and applied voltage across the micro-tube. The effects of the wall thickness and the wall material on the normalized temperature distribution and the effectiveness parameter are discussed. The comparison of the normalized temperature for Joule heating and a spatially uniform heating is also presented.