Efficiency assessment of oxyhydrogen-enhanced engine tested experimentally with multiple fuel blends

This paper presents the results of a set of experimental tests designed to study the effects of oxyhydrogen blending with the fuels of gasoline, propane, methane, ethanol and methanol on their thermodynamic efficiencies (including energy and exergy efficiencies and power outputs) and carbon dioxide, carbon monoxide, unburned hydrocarbons and nitrogen oxide emissions in a spark-ignition (SI) engine-driven power generator. Each fuel is blended with oxyhydrogen at volumetric ratios of 5 %, 10 %, 15 %, and 20 %. The results demonstrate that oxyhydrogen addition consistently improves engine performance and avoids incomplete combustion. For all tested fuels, an addition of oxyhydrogen leads to a significant reduction in carbon-based emissions, with specific carbon monoxide, unburned hydrocarbons, and carbon dioxide emissions for gasoline decreasing by up to 59 %, 55 % and 52 %, respectively. This is coupled with an increase in power output and thermodynamic efficiencies; methane blends, for instance, achieved a 17 % boost in power output and reached an energy efficiency of over 46 %. Also, these benefits are accompanied by a substantial increase in NOx emissions, for example, NOx emissions for gasoline rising from 10 g/kg fuel to 47.8 g/kg fuel, which is attributed to higher in-cylinder combustion temperatures. The findings reveal a critical trade-off between reducing carbon-based emissions and controlling NOx formation. This work provides a clear evidence-based analysis that underscores the potential of oxyhydrogen as an efficiency booster and decarbonization agent for SI engines, while also highlighting the crucial need for integrated NOx mitigation strategies for environmentally sustainable power generation.