Development of Modified Engine Architecture for Hydrogen–Electric Hybrid Vehicles

Abstract

The global pursuit of carbon-neutral transportation has accelerated the development of powertrain technologies that combine high efficiency with near-zero emissions. While battery–electric vehicles (BEVs) provide significant environmental benefits, their limitations long charging time, battery degradation, reduced range in extreme climates, and dependency on critical minerals necessitate parallel exploration of alternative technologies. Hydrogen–electric hybrid vehicles (HEHVs) offer a promising pathway by integrating hydrogen combustion with electric propulsion, thereby retaining fast refuelling, high energy density, and improved power availability. However, hydrogen’s unique combustion characteristics wide flammability range, high flame speed, low ignition energy, pre-ignition tendency, and propensity for NOx formation demand substantial modifications to conventional internal combustion engine (ICE) architectures. This study focuses on the design, development, and optimization of a modified engine architecture explicitly tailored for hydrogen–electric hybrid applications. The proposed system integrates a redesigned combustion chamber, a high-pressure direct hydrogen injection (HPDI) system, variable compression ratio (VCR) technology, and an intelligent hybrid power management controller. The aim is to enhance thermodynamic efficiency, ensure safe and stable combustion, and reduce emissions while achieving seamless interaction between the hydrogen engine and the electric drivetrain. The modified engine achieved 12–15% higher brake thermal efficiency (BTE) compared to a baseline gasoline engine. Brake Specific Hydrogen Consumption (BSHC) was reduced through optimized combustion phasing and improved thermal management. Emission analysis indicated 35–40% reduction in NOx, minimal CO and HC emissions, and improved greenhouse gas performance compared to conventional fuels. In conclusion, the proposed modified hydrogen–electric hybrid engine architecture shows substantial potential as a transitional technology between conventional ICE vehicles and fully electric platforms. The research highlights key advancements in hydrogen combustion control, thermal efficiency improvement, emissions reduction, and hybrid system integration.