A comparative study on combustion characteristics of methane, propane and hydrogen fuels in a micro-combustor

The combustion characteristics of three hydrocarbon fuels are investigated so as to study the applicability of fuels in a micro-planar combustor. Experiments are performed to analyze the differences in flame stabilization, temperature distribution of external wall and flammable channel-heights. At different equivalence ratios, it is found that the mixture of hydrogen/air has a much wider and stable flammable range. The reaction positions of methane and propane cases will significantly move downstream along with the increase in mixture flow rate. Under the same chemical energy inputs, the external wall temperature distribution of methane case is most uniform, and the average wall temperature is also the highest among the three fuels. When hydrogen is selected as a fuel, the temperature gradient of the combustor wall becomes very large, which is caused by the flame position near the inlet. The flammable channel-heights of the three fuels in the micro-planar combustor are different. It is observed that stable combustion of methane/air cannot be achieved when the channel-height is less than 2.5 mm. However, the minimum flammable channel-height of propane/air case is 2 mm, and hydrogen/air can be ignited in a 1 mm height micro-combustor.1