Investigation of hydrogen-air and acetylene-air flame propagation through porous media using infrared visualisation

One of the modern energy safety concerns is ensuring explosion safety when working with flammable gases. For this purpose, various methods are used, such as active chemical inhibitors and passive combustion suppression. The use of various porous materials is prevalent among passive methods for combustion suppression. This study focused on the experimental investigation of hydrogen-air and acetylene air flame propagation through polyurethane foam and through the empty channel. The use of high-speed infrared camera enabled visualization of flame propagation inside the porous material. Two types of diagnostic channels were used with the dimensions of the diagnostic section 16 x 20 mm and 40 x 20 mm. The length of the foam was 120 mm. In hydrogen-air mixtures with 10 pores per inch (PPI) polyurethane foam the flame velocity was higher than in the empty section; with 30 PPI polyurethane foam the flame was quenched in the mixture with equivalence ratio ER = 0.3, but for mixtures with ER = 0.4 and ER = 0.5 the average flame velocity was higher than in the empty channel. In the acetylene-air mixtures flame velocity was usually lower in polyurethane foam and only reached the flame velocity in the empty channel with ER = 0.8 and 10 PPI foam. Critical Peclet numbers that allowed the flame to propagate through porous materials were calculated based on the obtained experimental data. The critical Peclet numbers were 23-24 for the hydrogen-air mixture and 37-38 for the acetylene-air mixture. The channel was open near the ignition point, which allowed the obtained results to be less dependent on the channel length. Information obtained in this work can be used to improve the means of ensuring explosion safety, including in the areas of nuclear power and transport using hydrogen.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study focuses on the experimental investigation of flame propagation through porous materials in hydrogen-air and acetylene-air mixtures. The results show that the flame velocity is higher with polyurethane foam in hydrogen-air mixtures, but lower in acetylene-air mixtures. Critical Peclet numbers for flame propagation through porous materials were calculated based on the experimental data.