Accession Number : ADA329854

Title :   Heat Transfer in Microchannels.

Descriptive Note : Technical rept.,

Corporate Author : LOUISIANA TECH UNIV RUSTON

Personal Author(s) : Wang, Xianming ; Ameel, Timothy A. ; Warrington, Robert O.

PDF Url : ADA329854

Report Date : 14 SEP 1997

Pagination or Media Count : 134

Abstract : The objective of this research was to develop an analytical solution to the heat transfer problem in microchannels with slip-flow and an isothermal wall, a heat transfer problem for gases at low pressures or in extremely small geometries, and to verify this solution experimentally. In this investigation, an analytical expression for the velocity distribution with slip-flow was obtained which involved the Knudsen number Kn in an infinite series form. Kn for extremely small channels may become large enough to significantly affect the velocity distribution and consequently affect the heat transfer properties. A mathematical model of temperature distribution was established by combining the energy and momentum equations. A new technique for evaluation of eigenvalues for the solution of the heat transfer problem in microchannels was developed from the method of Frobenius. The computational results show that the method is effective. The local and average Nusselt numbers were found for 0.005<Kn<0.30 with aspect ratio a=1, 2/3, 1/2, 1/4, and 1/8. Experiments for helium flow in a rectangular microchannel of dimension 117 microns x 24 microns x 63.5 microns and a microtube with inside diameter of 52 microns were conducted.

Descriptors :   *CONVECTION(HEAT TRANSFER), *SLIP FLOW, MATHEMATICAL MODELS, EIGENVALUES, LOW PRESSURE, GAS DYNAMICS, TEMPERATURE GRADIENTS, HELIUM, INFINITE SERIES, CHANNEL FLOW, HEAT TRANSFER COEFFICIENTS, KNUDSEN NUMBER.

Subject Categories : Thermodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE