THERMAL RADIATIVE TRANSPORT IN DENSE ABSORBING AND SCATTERING NANO AND MICRO PARTICULATE MEDIA

摘要

Dispersion relation (relation between frequency and wave vector) for electromagnetic wave is obtained in dense (high volume fraction of particulates) nano/micro paniculate media using effective field approximation (EFA) and quasi crystalline approximation (QCA) with Percus-Yevick distribution function. This work is the extension of the previous work by the author where absorption was assumed to be negligible (Prasher, R.S., 2005, J. Heat Transfer, Vol. 127, pp. 903-910). The particulates are both scattering and absorbing. Nano/micro particles are considered due to their promise for future applications such as nanofluids and also for current technologies such as fluidized and packed beds combustors. Only Rayleigh regime is investigated which is a good approximation for nano and micro particles assuming that the photon wavelength is much larger than the size of nano and micro particles. Comparison of photon velocity and effective attenuation based on EFA and QCA are made. Results show that heat flux and temperature predictions made by models in the literature for multiple and dependent scattering and absorption are not very accurate as these models do not take the modification of equilibrium emissive power due to the modification of photon velocity into account.