Investigation on H2/CH4 blended combustion in a micro-tube with dual-inlet at varied operating conditions

Abstract

Combustion characteristics of premixed H2/CH4/Air in a combustor with dual-inlet are investigated under various operating conditions. Effects of reactants ratio in the two inlets, dual-inlet setting and flow rates on the combustion characteristics and heat transmission are compared and analyzed. Results demonstrate that the setting of dual-inlet strongly affects burning such as OH generation and consumption, and the weak flame is formed in the second-inlet, modifying the species distribution and gas temperature. For the seven conditions with 28 cases under a kept H2/CH4 blended ratio mCH4 = 5%, the case of 20% H2/CH4/Air imported via the second-inlet achieves a better thermal performance, where reactions around the second-inlet contribute to the sufficient burning, heat release, heat transfer of gas-wall and gases. It also reduces the heat loss through exhaust gases, resulting in a higher burner radiation temperature, and the mean radiation temperature of case 19 is 55 K higher than that of case 21. Moreover, the radiation power of the combustor can be further improved by optimizing the second-inlet setting. The combustor with the distance of the two inlets L = 14 mm obtains a higher thermal performance, where the Tm reaches 1254 K and is 16 K higher than the stepped tube and the radiation power reaches 44.1 W under condition of mf = 3.339 × 10-5kg/s andmCH4 = 5%.