Numerical Simulation And Analysis Of Gas Flow And Heat Transfer In Microchannel

Micro-scale instruments have become the darling of modern society,and the use of MEMS has become widespread in medical,military,life and scientific research area.Gas flow and heat transfer in microscale have become the focus of current research,so the further study of the gas flow and heat transfer charateristics in the microchannel has the huge commercial value and profound realistic significance,providing an important theoretical foundation for the design and use of microscale devices.In this paper,the gas flow and heat transfer in the microchannel between two parallel plates are analyzed.It is assumed that the gas in microchannels is compressible ideal gas.A two-dimensional parallel plate microchannel physical model is established.Based on the N-S equation combined with Maxwell's first-order velocity slip and temperature jump boundary conditions,the gas flow and heat transfer in microchannel slip flow region are simulated using Fluent software.For the analysis of the gas flow characteristics in the microchannel,integrating velocity slip boundary condition.With the increase of Knudsen number,the wall boundary velocity value increases,and the slip phenomenon is significant.The pressure curvature is affected by the compressibility and increase with the pressure ratio,but the pressure curvature decreases with the increase of the Knudsen number under the dual influence of compressibility and rarefaction effect.For the analysis of the gas heat transfer characteristics in the microchannel,integrating the velocity slip and temperature jump boundary conditions,and the temperature of the gas at the wall surface is lower than the wall temperature due to the temperature jump effect when the isothermal heating is performed on both sides.The Nusselt number decreases with the increase of the Knudsen number.This shows that the additional thermal resistance caused by temperature jumps weakens the heat exchange efficiency between the gas and the wall.Considering the effect of thermal creep on the gas flow and heat transfer.The gas is heated by the bottom constant heat flux,and driven by the pressure.The gas temperature gradient and pressure gradient in the microchannel are opposite to each other,which leads to the occurrence of thermal creep phenomenon.The mass flow in the microchannel increases and the temperature value decreases.The larger the Knudsen number is,the stronger the rarefaction effect is,and the tangential temperature gradient of the wall increases.The effect of thermal creep on gas heat transfer is greater.