Investigation Of The Problem Of Heat And Mass Transfer Under Microscale Condition

Heat and mass transfer is the very normal transfrom phenomenon in the nature and practical engineering. For hundreds of years people have used the traditional transform laws, to solve many practical problems. But With the development and progress of science and technology, the micromation of temporal and spatial dimensions and the extremity of exterior conditions causes the traditional transform laws can not describe the transform phenomenon well and truly. So the research of heat and mass transform phenomenon under the microscale and extreme conditions is gradually growing the new research focus.In this dissertation I study the heat and mass transform process under the microscale and extreme conditions and analyze the physical mechanism and constitution relation of the transform phenomenon in gas and solid material by using the mature method of simple mean free path of a molecular. I introduce the conception relaxation time to correct the traditional transform laws in microcosmic and found the corrected laws can describe the transform phenomenon under the microscale and extreme conditions well.I use the hyperbolic heat conduction and mass transform equation to solve the heat conduction problem with complicated boundary conditions and coupled heat and mass transfer problem by FDM numerically. The calculation result shows the velocity of heat and mass transfer is finite and has the characteristics of wave. The compare of the results of hyperbolic equation and those of parabolic equations shows there is a delay between both the thermal and the mass of the former and those of latter.