Influence of operating parameters on hydrogen DISI engine at injection pressure-drop by experimental investigation and Taguchi method

Hydrogen, as a low -density, zero -carbon energy source, often faces injection pressure drop when used as an alternative fuel for multi -parameter regulation in direct injection spark ignition (DISI) engines. In this paper, the effects of operating parameters including torque, excess air coefficient (lambda), ignition timing, and injection timing on combustion, emissions, and energy distribution of a hydrogen DISI engine were first investigated at injection pressures of 100 bar and 30 bar, respectively, followed by Taguchi methodology and analysis of variance (ANOVA) to determine the optimal parameter combinations and their contribution to typical indicators of engine performance. The results showed that injection pressure -drop deteriorated the coefficient of variation (COVIMEP), nitrogen oxides (NOx) emissions, and brake specific fuel consumption (BSFC) in the set of cases. And the deteriorating BSFC is mainly due to the increase in heat loss power (PHL) or the exhaust power (PEx). Taguchi method and ANOVA showed that injection pressure drop changed COVIMEP and BSFC regarding optimal ignition timing selection and PEx regarding optimal injection timing selection and it also increased the torque contribution to COVIMEP by 26.54 %. PHL and PEx should be simultaneously considered because their choice of optimal operating parameters is a "Trade-off" relationship in most cases.