A Study of Flame Structure in the Gas-Solid Two-Phase Systems Containing Inert Particle Suspensions. (3rd Report, Effectsof the Furnace Wall).

Abstract

This study constitutes a part of the attempt to clarify the effects of radiative heat transfer on the flame structure and burning velocity in a gas-solid two-phase system. Although the one-dimensional model developed in the previous papers was useful to clarify the fundamental aspects of the matter based on a strict treatment of radiative heat transfer, the one-dimensionality is getting worse for a smaller system. A system of a combustible gas mixture with inert particle suspensions flowing through a circular tube is adopted and the effects of the duct wall on the energy transport in the system have been clarified in this paper. The result shows that the radiative heat transfer between walls becomes the leading mechanism of the energy recirculation from burned gas to unburned mixture when the optical thickness in the radial direction is small, and that the main role of the suspended particles shifts to the enhancement of heat transfer between the flowing gas and the duct wall. As a result, the burning velocity of the system shows its maximum at a lower loading ratio of the particles than that of the one-dimensional model.