Effects of boron-based additives on combustion characteristics, emission reduction, and performance improvement in internal combustion engines

Abstract

This study examines the impact of methylamine-borane (MAB), a hydrogen-enriched fuel additive, on the combustion dynamics, emission characteristics, and performance metrics of gasoline engines. The evaluation was conducted at volumetric concentrations of 5 % (MAB5) and 10 % (MAB10). The results indicated a substantial reduction in carbon monoxide (CO) emissions by 76.79 % for MAB5 and 66.39 % for MAB10, as well as a decrease in hydrocarbon (HC) emissions by 21.39 % and 35.39 %, respectively. Carbon dioxide (CO₂) emissions were also reduced by 15.29 % for MAB5 and 9.76 % for MAB10, suggesting an improvement in combustion efficiency. However, an increase in nitrogen oxides (NO_x) emissions was observed, likely due to higher peak combustion temperatures. Elevated oxygen (O₂) levels in the exhaust were noted, reflecting alterations in in-cylinder oxygen dynamics and combustion stoichiometry. Performance analysis revealed that MAB use resulted in higher brake-specific fuel consumption (BSFC) and lower thermal efficiency, with reductions of 7.69 % and 9.93 % for MAB5 and MAB10, respectively, attributable to the lower energy density of MAB relative to gasoline. A decrease in exhaust gas temperature was observed, suggesting a complex interaction of energy release and heat transfer processes. Despite the reduction in emissions, the increase in NOx formation highlights the intensification of combustion phases and greater thermal stress within the engine cylinder. The findings suggest that MAB, as a hydrogen-enriched fuel additive, offers notable benefits in emission reduction, but presents challenges such as reduced performance efficiency and increased thermal management requirements. These results underscore the need for optimizing additive formulations and operational parameters to balance the emission reduction potential with performance efficiency in gasoline engine applications.