Experimental investigation of water injection and spark timing effects on combustion and emissions of a hybrid hydrogen-gasoline engine

This paper aimed to study the effects of water injection and spark timing on performance of a hybrid hydrogen-gasoline engine. For this aim, a modified four-cylinder turbocharged gasoline direct injection (GDI) engine equipped with hydrogen port injection and port water injection system was developed. In this study, the engine speed was maintained at 1300 rpm and the throttle opening of 30% with an excess air/fuel ratio of 1. The hydrogen energy percentage of 15%, water fuel mass ratio of 0.2 and 0.4 was added into the intake port. When the hydrogen energy percentage was changed, the gasoline fraction was also adjusted to keep the mixture at the stoichiometric. For all tested conditions, the spark timing was varied from 1 to 42 degrees CA before top dead center (BTDC) with a fixed interval of 2 degrees CA. Experimental results showed that maximum brake torque (MBT) spark timing varied when water and/or hydrogen is added. With hydrogen addition, the worsened combustion caused by water injection can be improved. Also, the variation of IMEP and COVIMEP versus spark timing became more insensitive with hydrogen addition. With water injection, the high NO emission caused by hydrogen addition can be largely reduced, however with side effect of higher HC and CO emissions.