Exergy and Sustainability Analysis of Methylamine Borane-Enhanced Gasoline Fuel Blends

Abstract

This experimental study examines the energetic and exergetic performance of hydrogen-rich methylamineborane (MAB) fuel blends in a spark-ignition gasoline engine. To assess the efficacy of solid-state hydrogen carriers, MAB was solubilized in ethanol and mixed with gasoline at volume ratios of 5% (MAB5) and 10% (MAB10). Experiments were performed at a constant speed of 2500 rpm across different engine loads: 0%, 25%, 50%, 75%, and 100%. The findings demonstrate that MAB5 attained the highest exergy efficiency of 18.87% at full load, surpassing gasoline at 16.77% and MAB10. The observed efficiency gain results from the thermal decomposition of MAB, which releases hydrogen and enhances combustion kinetics, consequently minimizing thermodynamic irreversibilities within the system. As a result, MAB5 demonstrated the least entropy generation and exhaust exergy losses in comparison to the gasoline fuel. Increasing the additive ratio to 10% (MAB10) led to a decrease in exergetic performance, attributable to physicochemical constraints, thereby underscoring a significant tradeoff between hydrogen enrichment and fuel properties. MAB5 fuel was more efficient than others in the Sustainability Index results, which emphasize the importance of environmental impacts, with a high score of 1.23. The study presented showed that MAB fuels at low concentrations can be an effective source of hydrogen and could be practically applied in conventional spark-ignition engines to improve fuel efficiency and reduce environmental impact without requiring extensive engine modifications.