A Comparative Assessment of Port Fuel Injection and Direct Injection of Hydrogen in Internal Combustion Engines: Performance, Efficiency, and Emissions

With the transition toward low-carbon fuels-based transportation systems, hydrogen is becoming increasingly promising as a sustainable internal combustion engine (ICE) fuel. There are two pathways for introducing hydrogen: Port Fuel Injection (PFI) and Direct Injection (DI) in an engine, which greatly affects performance, efficiency, and emissions. In the Port Fuel Injection (PFI); hydrogen is introduced into the intake manifold and mixed with air before reaching the combustion chamber. This approach is preferred due to its affordability, ease of use, and compatibility with current engine configurations. Because of PFI's more uniform air-fuel mixture, combustion is smoother, and NOx emissions are reduced. On the other hand, it raises the possibility of pre-ignition, particularly when engine loads are high, and a decrease in volumetric efficiency due to a reduction in the volume of intake air as hydrogen replaces it. Direct injection gives exact control over the timing and volume of fuel injected by delivering hydrogen straight into the combustion chamber. This method increases power output, thermal management, and combustion efficiency. Injecting hydrogen closer to the top dead center (TDC) decreases premature ignition. DI also lowers the danger of pre-ignition and knock. Despite these benefits, DI systems are more expensive and complicated, requiring precise control mechanisms and cutting-edge injector technology. The study examines through comparative assessment of the two introduction mechanisms for a country like India and suggests that although DI is better suited for high-performance engines, providing greater efficiency and power but with extra complexity, PFI is favorable for cost-sensitive applications where simplicity and emission reduction are prioritized.