| Premixed combustion within a ceramic foam inert medium is investigated analytically and experimentally. The unique feature of this new technology is to use a porous ceramic matrix as a flame stabilizer. As the flammable gas mixture flows through the medium, the product gases heat the ceramic matrix by convection. Because of the high emissivity of the ceramic in comparison to the gases, radiation from the high temperature post-flame zone serves to heat the preflame zone of the porous material which, in turn, convectively heats the incoming reactants. This study reveals the advantages of combustion within porous inert media compared with a freely propagating adiabatic flame: higher flame speeds, higher peak flame temperatures, increased combustion stability, ease of flame control, and combustion of fuel with low energy content. The numerical model in this study predicts the combustion phenomena within the porous ceramics with reasonable accuracy. The model can be utilized to guide the experimental burner tests. The parametric study of the transport property variations provides some clues for practical burner design.;In order to predict the flame behavior accurately, an understanding of the transport properties of the porous ceramic materials is very important. An effective conductivity measurement experiment using a guarded-hot-plate apparatus is performed. With a combined conduction-radiation model, i.e. the equation of transfer under the diffusion approximation, the thermal conductivity and radiative properties are simultaneously inverted from the experimental data. |
