An experimental setup was developed to investigate the physical characteristics of ceramic foam, used in reaction layer, on the performance of a porous burner. This premixed burner included mainly four sections: premixed, preheating, combustion zone and an integrated heat exchanger. The objective of this work was to investigate effects of different kinds of ceramic foams with various porosity, pore density and materials on the burner performance. The combustor was operated with natural gas and diverse structures of alumina and silicon carbide foam utilized in the reaction layer. Temperature distribution along the centerline, thermal efficiency, emission concentration and pressure drop were thoroughly investigated. Results showed a decrease in the porosity of ceramic foams, causing emission and pressure drop to increase while efficiency declined. More stable combustion was achieved by using finer foams with higher pore density. These foams indicated lower pollution and higher efficiency in low excess air, while coarser foams—ceramic foams with low pore density—resulted in lower pollution and higher efficiency in high excess air. Investigation effect of material exhibited silicon carbide foams causing higher temperature of the combustion and more temperature variation through the burner. Generally, material effect was negligible in terms of efficiency. But role of material highlighted in pollution where silicon carbide resulted in higher amount of NO.

Growing application and use of ceramic foams has intensified the necessity to determine a precise and inexpensive method for prediction of pressure drop through these materials. In this paper, a new experimental model is presented for pressure drop through ceramic foams. In order to measure pressure drop, a set up was made in which air flow rate and temperature varied. Effects of variation in temperature and flow velocity on the pressure drop were investigated through open-cell SiC and Al2O3 foams with different values of porosity and pore density. Results of this study revealed the leading role of parameters such as viscosity, porosity, density, velocity and mean hydraulic diameter of pores of foam. Since there are several parameters affecting the problem, dimensional analysis was adopted as a convenient approach. Euler number, porosity and two Reynolds numbers, one based on the pores’ diameter and the other one based on total bed length, have been shown to be important in the analysis. Finally, an empirical model is developed for the pressure drop which is based on dimensionless numbers.

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