Effect of spark plug position and ignition timing on performance, exergy, exergoeconomic, environmental, and enviro-cost in a hydrogen-SI engine

Hydrogen is considered the fuel of the future due to its high energy density, flammability, and carbon-free nature. Enhancing the use of hydrogen in internal combustion engines can contribute to reducing carbon-based emissions originating from fossil fuels. Previous studies on hydrogen-powered engines have predominantly focused on the effects of fuel mixture properties on performance and emissions, while the number of studies addressing engine modifications remains quite limited. In this study, the combined effects of different spark plug positions and ignition timings on performance, emissions, exergy, exergoeconomic, environmental, and enviroeconomic parameters in a hydrogen-fueled SI engine are investigated. In this respect, the present study addresses a significant research gap in the literature by comprehensively assessing the performance aspects from a novel perspective involving engine modification in hydrogen-powered SI engines. Three different spark plug positions (SPP) are used in the experiments: SPP1 (near the intake port), SPP2 (equidistant from the intake and exhaust ports), and SPP3 (near the exhaust port). Additionally, the study is conducted at different ignition timings, a constant engine speed, and an equivalence ratio of 0.6. The results show that moving the SPP closer to the exhaust port improves performance, exergy efficiency, and exergoeconomic effect, but also increases environmental and enviroeconomic effect. For example, in the SPP3 condition, compared to SPP1, brake power, brake specific fuel consumption (BSFC), and exergy efficiency improve by an average of 7.5 %, 6.9 %, and 7.5 %, respectively. Additionally, it reduces exergy destruction by an average of 2.2 % and the specific exergy cost of shaft work by an average of 7.4 %. However, the significant increase in NOx emissions in SPP3 compared to SPP1 leads to an average increase of 2.8 % in the total cost rate.