Colorless distributed combustion characteristics of hydrogen/air mixtures in a micro combustor

Abstract

Colorless distributed combustion technique enables less pollutants emissions for a fuel/oxidizer mixture to be combusted. In this study, colorless distributed combustion characteristics (CDC) of hydrogen/air mixtures were numerically investigated in a micro combustor to overcome the difficulties associated with micro combustion and to obtain a more uniform temperature profile on the outer wall. To that end, hydrogen/air combustion was simulated by using ANSYS/Fluent CFD code at a constant equivalence ratio (1.0) and thermal input (100 W) and different mixture inlet temperatures of 300 K, 600 K and 1000 K to seek colorless distributed combustion. CDC conditions were tried to be achieved by decreasing the oxygen concentration from 21 % to 9 % at an interval of 3 %. In conclusion, colorless distributed combustion conditions could be achieved at different O2 concentrations, irrespective of the mixture inlet temperature. At 300 and 600 K, such conditions did not make any positive contribution to the power output of the micro combustor. Nevertheless, at 1000 K and 9 % O2 concentration, all combustion and emission performance metrics were improved in a manner that could increase the power output of the micro power generator.