Emissions reduction in an automotive compression ignition engine using hydrogen and exhaust gas recirculation

This paper deals with the experimental investigation of an automotive compression ignition (CI) engine under dual fuel mode (hydrogen-diesel) with exhaust gas recirculation (EGR). The engine was operated under different speeds at 16 Nm (maximum torque). Smoke, CO, and HC emissions decreased drastically with hydrogen. However, maximum hydrogen energy share (HES) is limited to 56% at 2000 rpm and 63% at 2400 rpm due to combustion with knock and NOx emission raised drastically. EGR technique was used to enhance the knock limited HES and reduce NOx emission. The maximum HES without knock is extended to 68% with 20% EGR (2000 rpm). NOx emission decreased to near-zero level. Brake thermal efficiency increased. CO and HC emissions decreased significantly. However, smoke increased but still lower than base diesel. The combined effect of hydrogen and EGR could reduce the emissions, energy efficiency improvement, and extend the maximum HES limit.