Effect of intake method on ammonia/oxygen non-premixed combustion in the micro combustor with dual-inlet

Abstract

MTPV systems have received extensive attention due to their high energy density, direct energy conversion, and small size. To prevent the possibility of flashback, non-premixed combustion was employed in this study, and ammonia was used as a carbon-free alternative fuel in the context of carbon neutrality. The numerical model of ammonia/oxygen combustion a vertical dual-inlet micro combustor was built and verified under various operation conditions. The simulation results showed that the non-premixed combustion has better wall thermal performance and lower NO emission than the premixed combustion in conventional combustor. Subsequently, the effects of inlet species, equivalence ratio and total inlet velocity on the thermal performance and NO emission were investigated. Thermal performance and NO emissions are best when oxygen and ammonia enter the combustion chamber through different inlets under current operating conditions. When the equivalence ratio is 0.9, the mean temperature of the outer wall is highest. As the equivalence ratio decreases, NO emissions increase and NH3 conversion ratio increases. Increasing the total inlet velocity improves wall thermal performance and reduces NO emissions. Under optimized operation condition, the mean temperature of outer wall could rise from 1129 K to 1478 K, representing an increase of 30.91%. The molar concentration of NO in exhaust could reduce from 2.87 × 10−4 kmol/m3 to 1.43 × 10−4 kmol/m3, representing a decrease of 50.17%.