Investigation on the effects of hydrogen addition with watermelon seed oil biodiesel in a CI engine operated with different compression ratio: An analysis of combustion, performance and emission properties

The current work investigated the feasibility of hydrogen-enriched biodiesel extracted from watermelon seed oil as a potential alternative fuel for CI engines, focusing on its impact on various characteristics of the engine. This experimental study involved in conducting experiments on a Kirloskar1 cylinder, 4 stroke CI engine under load ranges from 0% to 100%, at a steady speed of 1500 rpm using watermelon seed oil biodiesel with 9 liters/min H2 addition at compression ratios of 17.5:1 and 19:1. With the exception of a minor rise in NOx emissions, the investigation concludes that the analyzed characteristics of the CI engine showed significant improvements. When evaluated against diesel, the WMSOB20 + H2 9 LPM with CR 17.5:1 and WMSOB20 + H2 9 LPM with CR 19:1 yielded the following results: 4.2% and 7.5% increase in cylinder pressure, 8% and 12% reduction in BSFC, 6.89 % reduction and 20.18% increase in CO, 12.65% reduction and 7.5% increase in HC, 7.49% and 0.72% reduction in CO2, 6.97% and 12.36% reduction in smoke emissions, respectively. These findings demonstrate that the WMSOB20 + H2 9 LPM blend is an excellent alternative fuel for unmodified CI engines operating at a compression ratio of 17.5:1. KEY WORDS: CI engine, Sustainable energy, Hydrogen addition, Compression ratio Bull. Chem. Soc. Ethiop. 2025, 39(10), 1949-1960. DOI: https://dx.doi.org/10.4314/bcse.v39i10.6