Hydrogen energy share improvement along with NOx (oxides of nitrogen) emission reduction in a hydrogen dual-fuel compression ignition engine using water injection

The study aims at enhancement of Hydrogen (H2) energy share and reduction of Oxides of Nitrogen (NOx) emission in a 7.4 kW-CI engine at 1500 rpm using water injection. The test engine was modified to run under dual-fuel operation with diesel-biodiesel blend (B20) and H2 fuels for different Specific Water Consumption (SWC) of 130, 200, and 270 g/kWh. Under conventional H2 dual-fuel mode, energy efficiency and NOx emission increased significantly while Hydrocarbon (HC), Carbon Monoxide (CO) and smoke emissions decreased. The maximum H2 energy share increased from 20% without water to 32%, 36%, and 39% with SWC of 130, 200, and 270 g/kWh respectively. However, SWC of 200 g/kWh was selected as an optimum water quantity for knock free operation, better performance and lower emissions. At the optimum SWC with 20% H2 energy share, the NOx emission and energy efficiency decreased about 24% and 5.7%, while HC and smoke emissions increased about 38% and 69%. At 20% H2 energy share, the CO emission increased from 0.0 g/kWh without water to 1.2 g/kWh with the optimum SWC. However, reduction of these HC and CO emissions using oxidation catalysts needs to be studied further. A new methodology for determining heat release rate with consideration of crevice gas was proposed in the study.