Abstract

The present investigation studies the use of hydrogen as a supplementary fuel in existing diesel vehicles to evaluate the potential of dual-fuel operation on fuel efficiency and emissions in the context of on-road transport decarbonization. A diesel pick-up truck was modified using a commercial gaseous fuel kit to inject hydrogen as a complementary fuel. A chassis dynamometer was used to perform tests operating the vehicle under dynamic conditions. The New European Driving Cycle (NEDC) was defined as the base cycle. Three hydrogen energy shares (HES) were examined: 2.3 %, 13.4 % and 17.2 %. Diesel fuel consumption was measured gravimetrically, and hydrogen consumption was measured with a thermal mass flow meter. Emissions (CO2, CO, and THC) were measured with a Portable Emissions Measurement System (PEMS). Diesel energy consumption decreased by 2.9-5.2 %, while CO2 emissions dropped by up to 7.95 % and CO by 40.4 %. However, the overall energy consumption, comprising diesel and hydrogen, rose by up to 13.9 %-22.9 % due to the absence of recalibration, and THC emissions increased by up to 16.3 %. Exhaust temperatures also rose by 18.2 degrees C at higher HES. In conclusion, Hydrogen substitution in diesel engines can reduce carbon-based emissions, but efficiency penalties occur without optimized calibration. Properly combustion-adjusted conversion systems are needed to balance emission benefits with energy efficiency.