Combustion and Smoke Emission Studies on a Hydrogen Fuel Supplemented DI Diesel Engine

Hydrogen addition to ethylene and acetylene -air laminar diffusion flames has shown substantial reduction in soot formation. In the present study, hydrogen was carbureted in a single cylinder, naturally aspirated DI diesel engine, and combustion events and smoke emissions were studied. With hydrogen induction particularly when its energy share increased above 15%, contrary to the results reported by earlier investigators a sharp decrease in ignition delay (ID), very high peak pressure rates, increase in smoke and loss in fuel efficiency were observed. At hydrogen energy share of about 30%, ignition delay drops to nearly 0-1degree CA and peak rates of pressure rise to 25-30 bar/deg CA. Smoke emissions at low hydrogen induction rates reduced slightly but increased sharply above 15 to 20% hydrogen energy share. Hydrogen mixed with air appears to actively participate in precombustion reactions leading to decrease in ID and its consequent effects on combustion pressure -time history, smoke emissions and efficiency. Combustion control with hydrogen induction or direct injection of hydrogen in the engine cylinder to evaluate smoke reduction potential of hydrogen is required.