Investigation of Radial Inward Porous Inert Media combustor for NH₃/CH₄/H₂ Combustion

An experimental study is conducted on a radial inward flow porous media burner (PMB) for ammonia (NH3)air combustion. In this flow configuration, the cylinder surface area increases with its radius, and its velocity distribution is inversely proportional to the radius. As the flow travels through the porous media, it accelerates and is able to find a location at which it tends to stabilize as the kinematic balance between the burning velocity and the fresh mixture velocity are equal. The unique features of porous media enhance heat, mass, and momentum transfer, leading to an increase in the burning rate and improved stabilization of premixed flames to extend the flammable limit. Accordingly, radial PMBs offer a wider range of flame stability and power modulation rate compared to cylindrical axial burners, which are only dynamically balanced in a narrow range of flow rates. The present study utilizes a graded SiSiC Voronai-based lattice porous structure with a linear pore density of 10 to 20 PPI (pores per inch), progressing from the outer to inner radial sections. For various equivalence ratios and mass flow rates, temperature measurements conducted across various points of the combustion systems, including inlet mixture, pre-heated reactant mixture (before the porous media), and exhaust, are analyzed to understand the combustion characteristics of ammonia-air flames. In addition, exhaust emissions such as NO and unburned H₂ are discussed in detail.