Compression ignition engine performance and emissions: An experimental study on the impact of aqueous ammonia, hydrogen, and diesel fuel blends

In this study, experiments are carried out using aqueous ammonia, hydrogen, and diesel fuels in a compression ignition engine . A heavy-duty diesel engine with a cylinder volume of 11 L is used as the test engine. Experiments are conducted at four different torque levels: 25 %, 50 %, 75 %, and 100 %, where 300 Nm represents full load. The engine operates at a constant speed of 660 rpm. Initially, neat diesel is used, followed by blends containing 10 wt% and 20 wt% aqueous ammonia. Hydrogen is also added through the intake manifold at 1 bar pressure, supplying 10 % of the total energy content of each mixture. Aqueous ammonia addition increases in-cylinder pressure and improves thermal efficiency . The highest thermal efficiency is observed with A20D80 (20 wt% ammonium hydroxide) at 39.18 %. Thermal efficiencies for A10D90, A10D90H10, A20D80H10, D100, and D100H are 34.26 %, 32.83 %, 31.67 %, 29.21 %, and 28.34 %, respectively. • D80A20 fuel blend (20 % NH 4 OH) increased brake thermal efficiency (BTE) by 34.12 % vs. pure diesel. • Hydrogen addition (10 % energy) reduced in-cylinder pressure by 1.72 % and caused 1° CA ignition delay. • NH 4 OH reduced peak exhaust temperatures by 14.93 % and stabilized combustion at high loads. • NH 4 OH lowered CO 2 and HC emissions, while hydrogen reduced NO x at low/medium loads. • Optimal NH 4 OH-hydrogen balance is critical for emission control and combustion efficiency.