Study on combustion characteristic of premixed H2/C3H8/air and working performance in the micro combustor with block

Abstract

Combustion characteristics and thermal performance of premixed H2/C3H8/air in a micro planar combustor with block insert are experimentally and numerically tested. Effects of hydrogen blended fraction, equivalence ratio, flow rate and block width on the flame stability and heat transfer are discussed and analyzed. The results indicate that hydrogen addition is beneficial to the combustion stability in the micro combustor, and the lowest hydrogen blending mole fraction of the premixed H2/C3H8/air steady flame is obtained by experimental study. The combustion stability range is the widest in the combustor with a 0.7 mm block inserted at a high fuel rate. Moreover, the wall temperature is deeply influenced by hydrogen blending ratio and block size, that is, the combustor with appropriate block width and H2/C3H8 blended burning gains a higher radiation temperature. Then, effects of the hydrogen fraction on the reaction pathways are analyzed, and the fluxes of OH and H production by the key reactions such as H + O2 = OH + O and H2 = OH + H are calculated, where flame location and reaction area are significantly affected. It also finds that the combustor C0.7 fueled with 90% hydrogen gains the highest mean wall temperature of 1150.3 K and radiation power of 27.9 W under the same chemical energy input Ec = 90.6 W.