In-Depth Experimental Investigation into Performance and Emission Characteristics of a Diesel Light-Duty Engine Fuelled with Pure Hydrogen

Transitioning to zero-carbon fuels is pivotal for expediting the reduction of carbon emissions. Hydrogen demonstrates significant adaptability and emerges as a principal zero-carbon alternative fuel for carbon-based internal combustion engine (ICE) platforms. Implementing hydrogen in both spark ignition (SI) and compression ignition (CI) engines has proven to be both economically viable and timely; nevertheless, it presents several technical challenges that must be addressed. The study analyses the performance and emissions of a single-cylinder boat engine converted from diesel to 100% hydrogen.  A port fuel injection (PFI) system was adopted to operate the engine with hydrogen by replacing the diesel injector with a spark plug engine without any modification to the cylinder head. The engine features an automated shutdown system to mitigate intake backfire risks associated with hydrogen PFI systems. A comprehensive engine characterization was conducted at a wide range of relative air-to-fuel ratios, with Lambda from 1.5 to 4.5. The combustion and heat release analysis was performed with an integrated in-cylinder pressure transducer in the spark plug. The study used an advanced Bandpass, Rectify, Integrate, Compare (BRIC) knock detection method for monitoring abnormal combustion and engine stability. The study findings indicate that hydrogen can function effectively in a diesel light-duty engine utilizing Port Fuel Injection (PFI) and Spark Ignition (SI) modes, achieving an indicated thermal efficiency of approximately 40.3%. The engine operates with exceptional stability, reflected in a Coefficient of Variation of Indicated Mean Effective Pressure (COVimep) of less than 1.6% at a maximum lambda of 4.2. Additionally, it maintains a high combustion efficiency of 97.4%, with minimal hydrogen slip observed in the exhaust. The hydrogen fuel demonstrates nearly zero carbon emissions, with NOx levels recorded below 50 ppm at lambda 2.5 and approaching zero NOx at lambda 3.