Effect of spark plug alteration on performance and emissions using hydrogen enriched gasoline in si engine under various loads and compression ratios

In this study, performance and emission parameters of a variable compression spark ignited engine was investigated with different spark plugs and hydrogen enrichment. The tests were carried out with a four stroke, single cylinder, naturally aspirated, variable compression ratio (VCR) engine. Two different compression ratios (CR) of 8.5:1 and 10:1 under %50 part throttle condition were implemented throughout the experiments. Moreover, engine loads of 8 Nm, 13 Nm and 17 Nm were applied to evaluate effects of different spark plugs and hydrogen usage at different engine loads. Copper, iridium and platinum spark plugs were tested for each experiment condition. In addition, hydrogen was added through the intake manifold with flow rates of 0, 2 and 4 lit/min to enhance combustion of VCR engine. Brake power (BP), brake specific fuel consumption (BSFC), carbon monoxide (CO), carbon dioxide (CO2) nitric oxides (NOx) and unburned hydrocarbons (UHC) values were determined with this study. According to test results, iridium and platinum spark plug usage, hydrogen addition and higher compression ratio improved BP and BSFC values and the engine emitted lower CO and UHC. However, higher CO2 emitted because of increased completeness of the combustion and NOx gases have risen due to increment in-cylinder temperatures. These variances occurred more obvious with platinum spark plug usage comparing to iridium spark plug. In addition, effects of spark plug alteration, hydrogen addition and higher CR on enhancements of BP, BSFC and CO were comparatively lower at higher engine loads.