An Overview of Hydrogen Application Technologies in Spark-Ignition Engines

Abstract

This article explores the prospects of using hydrogen as an environmentally friendly fuel for spark-ignition (SI) engines. Based on a comprehensive literature review, a comparative analysis between hydrogen-powered and gasoline-fueled internal combustion engines (ICE) was conducted. The study identifies hydrogen's advantages in terms of power output and brake mean effective pressure (BMEP), achieved by increasing the compression ratio to 14.5:1. This is attributed to hydrogen's high auto-ignition temperature (858°C) and its exceptional heating value, which is nearly three times that of gasoline (120 MJ/kg versus 44 MJ/kg). The analysis reveals a higher exergy efficiency for the hydrogen engine (69.40% compared to 60.49%) due to reduced irreversibility. The paper systematizes primary approaches for adapting existing ICEs to hydrogen fuel, including partial gasoline substitution, full hydrogen conversion, and fuel delivery methods (direct and manifold injection). Particular emphasis is placed on analyzing combustion anomalies, such as detonation and pre-ignition, occurring during hydrogen operation, alongside the benefits of utilizing lean mixtures for their mitigation. A Toyota patent proposing water injection to minimize nitrogen oxide (NOx) emissions and optimize thermodynamic efficiency is examined. Furthermore, the study provides a detailed analysis of two hydrogen engine configurations equipped with exhaust gas recirculation (EGR) systems. Finally, the fundamental architecture of an experimental setup designed for bench testing is presented.