Numerical investigations of C1-C3 alkanes and H2 premixed flame-wall interaction: Effectiveness of insulation wall on heat loss reduction

Conjugate heat transfer analyses of premixed flames propagating toward the insulation or Al alloy wall are performed for C1 to C3 alkanes and H-2 flames at different equivalence ratios of phi = 0.6, 0.8, 1.0 and 1.2 under a high pressure condition of 2MPa in terms of one-dimensional numerical simulations with detailed reaction mechanisms (70 species and 321 reactions for alkanes, 9 species and 19 reactions for H-2). The effects of the equivalence ratio and fuel properties on the heat loss reduction through the wall due to the insulation are investigated in detail. The results show that for all the alkanes and H-2 flames, the temperature at the surface of the insulation wall increases more and faster than that of the Al alloy wall, and the heat loss is reduced due to the insulation. Furthermore, the heat loss reduction rate Lambda for the insulation wall to the Al alloy wall becomes higher both with the increase and decrease in the equivalence ratio from the stoichiometric ratio, regardless of the fuel. The value of Lambda reaches up to 2.1%. The reason for this tendency of Lambda against the equivalence ratio can be explicitly explained by the time variations of gas thermal conductivity and gas temperature gradient in the vicinity of the wall, which control the heat flux through the wall.