The effects of variable excess air ratio and ignition timing on the performance and exhaust emissions in a direct injection Hydrogen-CNG fueled engine

Abstract

This study investigates a direct injection (DI) engine fueled with compressed natural gas (CNG) enrichment with hydrogen blend (HCNG) in counter from the conversion of the port injection gasoline engine. The intention of the investigation was to examine the performance and exhaust gases from the effect of excess air ratio and timing angle changes in consequence of hydrogen increment to natural gas in comparison to gasoline engine performance and exhaust gases as a single fuel. The compression ratio was set at 14:1 with varying load at 3000 rpm, and the ignition timing was applied at −17, −19, −21, and −34°bTDC at WOT, and the amount of hydrogen enrichment to natural gas was applied at 10%, 20%, 30%, and 40%. The conditions on torque, power, heat release rate, brake specific fuel consumption, CO, and NOx were studied. Results showed that the power and torque increased by 8% with increasing the hydrogen content to 40% in fuel composition and advancing ignition timing and heat release rate as well as decreasing λ from 1.4 to 1.2 relative to the stoichiometric state. Also, the specific fuel consumption decreased by 18.5% in the optimal condition.

Studying the effects of manifold pressure boosting and EGR on combustion and NOx emission of hydrogen-fueled SI engine

“…A common observation from the previous research is that the engine efficiency improves by boosting, while NO x emission increases. Lee et al 25 had observed retarded ignition to reduce NO x slightly; similarly, Zareei and Ghadamkheir 26 had also reported a slight drop in NO x emission with retarded ignition. However, the NO x reduction was not satisfactory under minimum performance drop range.…”