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.