Experimental investigation of hydrogen-producer gas mixtures in an optically accessible SI engine

Producer gas from biomass gasification offers a renewable alternative to fossil fuels. However, its low energy density results in low conversion efficiency in engines. Blending producer gas with higher-ranked fuels such as hydrogen has been proposed to overcome this issue. This study investigates the combustion of artificially made producer gas and hydrogen mixtures in an optical SI engine. The molar fraction of hydrogen in producer gas ranged from 14 to 62%, which simulated additions of hydrogen to a low calorific producer gas. The experiments are conducted at a constant speed and stoichiometric ratio. The spark timing is varied to achieve the highest power for each mixture. Results include data on emissions, thermodynamics, and flame morphology. The molar fraction of 33% hydrogen on producer gas improves the flame morphology of the mixture to resemble that of pure natural gas, while 24-36% was found to be the optimal range for engines initially designed to run on natural gas with lower NOx and UHC emissions.