An Experimental Investigation on a Diesel Engine with Hydrogen Fuel Injection in Intake Manifold

During the last decade the use of alternative fuels for diesel engine has received renewed attention. The interdependence and uncertainty of petroleum based fuel availability and environmental issues, most notably air pollution are among the principal forces behind the movement towards alternative sources of energy. The main pollutants from the conventional hydrocarbon fuels are unburned / partially burned hydrocarbon (UHC), carbon monoxide (CO), oxides of Nitrogen (NO_x), smoke and particulate matter. These emissions are harmful to human, animal and plant life. Emissions from automobiles are currently a dominant source of air pollution representing 70 % of carbon monoxide, 41 % of oxides of Nitrogen (NO_x), 38 % of hydrocarbon emissions globally. In addition 25 % of the man made CO₂ emissions globally adds to the green house effect, which results in global warming. In the present investigation hydrogen is used in a diesel engine in the dual fuel mode using diesel as an ignition source. In order to have a precise control of hydrogen flow and to avoid the backfire and pre-ignition problems hydrogen was injected into the intake manifold.

Experiments were conducted to determine the optimized injection timing, injection duration and injection quantity of the fuel in manifold injected hydrogen operated engine using diesel as ignition source for hydrogen operations. From the results it is observed that the optimized condition is start of injection at gas exchange top dead center (GTDC) with injection duration of 30° CA with the hydrogen flow rate of 7.5 lpm.

The brake thermal efficiency is found to increase by 9 % compared to diesel. Smoke emissions decrease by 4 fold at full load compared to diesel. The NO_x emission is almost similar in both hydrogen diesel dual fuel engine and diesel operated engine except at no load. The CO₂ emissions decrease substantially by 2 fold at no load where hydrogen substitution is higher compared to full load. Manifold injection system with diesel as ignition source operates smoothly and shows improved performance and emits less pollution than diesel.