Impact of hydrogen induction on atomization combustion performance and emissions in diesel engines fueled with heated biodiesel blends

Even with the recent rapid development of electric and hybrid vehicles, transportation is dominated by internal combustion engines, and further development for performance and emission characteristics with renewable fuels is under demand. The present study focuses on the effect of hydrogen addition in air on atomization, combustion, performance, and emission characteristics of a diesel engine operating on B20-a mixture of waste cooking oil biodiesel and diesel-preheated at 60 °C. After that, hydrogen was added as an auxiliary fuel at different flow rates of 2, 5, 10, and 15 L per minute. Some of the important results were as follows: (i) biodiesel has a constantly higher sauter mean diameter than diesel under all conditions of surrounding pressure, and this difference stabilized after 5 MPa. (ii) At a hydrogen flow rate of 15 lpm, both heat release rate and in-cylinder pressure were lower than those observed with B20 alone. Notably, brake thermal efficiency at hydrogen flow rates of 5lpm was highest at 36.33 %, followed by 2lpm 35.9 %, while brake specific fuel consumption at 5lpm presented lowest 0.23kg/kWh followed by 2lpm flow rate 0.28kg/kWh (iii) At full load, H15B20 exhibited lowest CO2, CO, and HC emissions of 4.8 %V, 0.12 %V and 22 ppm respectively. At the same time, H15B20 showed the highest nitric oxide emission of 2300 ppm at full load.