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

Abstract

With the transition toward low-carbon fuel-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 affect 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, with extra complexity, PFI is favorable for cost-sensitive applications where simplicity and emission reduction are prioritized.

Key findings

• ▸PFI reduces NOx emissions but increases the risk of pre-ignition and decreases volumetric efficiency.
• ▸DI provides exact control over fuel injection timing and volume, but its effects on performance and emissions are not as well understood as PFI.
• ▸Hydrogen fuel injection methods significantly impact engine performance, efficiency, and emissions, making them crucial considerations for low-carbon transportation systems.

Keywords

Identifiers

DOI

10.4271/2025-01-0239

Journal

SAE Technical Paper Series

Year

2025