Study on Characteristics of Auto-Ignition and Combustion of Unsteady Synthetic Gas Jet

It is thought that the synthetic gas, including hydrogen and carbon monoxide, has a potential to be an alternative fuel for internal combustion engines, because a heating value of the synthetic gas is higher than one of hydrogen or natural gas. A purpose of this study is to acquire stable auto-ignition and combustion of the synthetic gas which is supposed to be applied into a direct-injection compression ignition engine.

In this study, the effects of ambient gas temperatures and oxygen concentrations on auto-ignition characteristics of the synthetic gas with changing percentage of hydrogen (H₂) or carbon monoxide (CO) concentrations in the synthetic gas. An electronically-controlled, hydraulically-actuated gas injector was used to control a precise injection timing and period of gaseous fuels, and the experiments were conducted in an optically accessible, constant-volume combustion chamber under simulated quiescent diesel engine conditions. Results obtained in this study are that the ambient gas temperature has a significant effect on the auto-ignition delays of the synthetic gas, and that the higher a percentage of CO in the synthetic gas results in the greater temperature dependency of the auto-ignition delay. And also, if a percentage of CO in the synthetic gas is high, auto-ignition delays is affected by the ambient gas oxygen concentration.