Performance enhancement and emissions reduction of ethanol-fueled spark ignition engine with hydrogen

This study deals with the effect of hydrogen on the performance, combustion and regulated [carbon monoxide (CO), non-methane hydrocarbons (NMHC), nitric oxide (NO), nitrogen dioxide (NO2)] and unregulated [nitrous oxide (N2O), ethanol, ethene, acetaldehyde, methanol] emissions of a spark ignition engine fueled with ethanol (E100). The engine was operated at a constant torque of 5.5 Nm and various speeds of 3500, 3800 and 4000 rpm, and both fuels (ethanol and hydrogen) were independently injected into the intake manifold of the engine during the suction stroke. The optimum hydrogen energy share at all speeds was 15% based on the combustion stability compared with base ethanol. The brake thermal efficiency with E100 at an engine speed of 4000 rpm increased from 14.4 to 15%, with a 15% hydrogen energy share (15% HES)-E100. The emissions such as CO, NMHC, unburned ethanol, ethene and acetaldehyde decreased significantly with the optimum HES-E100 compared with E100. However, the NO, NO2 and N2O emissions increased with hydrogen. Hydrogen addition to an ethanol-fueled spark ignition engine could significantly reduce carbonaceous emissions along with improving energy efficiency.