Experimental assessment of performance and emissions for hydrogen-diesel dual fuel operation in a low displacement compression ignition engine

The combustion of pure H 2 in engines is still troublesome, needing further research and development. Using H 2 and diesel in a dual-fuel compression ignition engine appears as a more feasible approach. Here we report an experimental assessment of performance and emissions for a single-cylinder, four-stroke, air-cooled compression ignition engine operating with neat diesel and H 2 -diesel dual-fuel. Previous studies typically show the performance and emissions for a specific operation condition ( i.e . a fixed engine speed and torque) or a limited operating range. Our experiments covered engine speeds of 3000 and 3600 rpm and torque levels of 3 and 7 Nm. An in-house designed and built alkaline cell generated the H 2 used for the partial substitution of diesel. Compared with neat diesel, the results indicate that adding H 2 decreased the air-fuel equivalence ratio and the Brake Specific Diesel Fuel Consumption Efficiency by around 14–29 % and 4–31 %. In contrast, adding H 2 increased the Brake Fuel Conversion Efficiency by around 3–36 %. In addition, the Brake Thermal Efficiency increased in the presence of H 2 in the range of 3–37 % for the lower engine speed and 27–43 % for the higher engine speed compared with neat diesel. The dual-fuel mode resulted in lower CO and CO 2 emissions for the same power output. The emissions of hydrocarbons decreased with H 2 addition, except for the lower engine speed and the higher torque. However, the dual-fuel operation resulted in higher NO x emissions than neat diesel, with 2–6 % and 19–48 % increments for the lower and higher engine speeds. H 2 emerges as a versatile energy carrier with the potential to tackle current energy and emissions challenges; however, the dual-fuel strategy requires careful management of NO x emissions.