INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol.47, no.42, pp.18532-18550, 2022 (SCI-Expanded)
Alternative fuels are extremely important in terms of both performance and emission values. Natural gas and hydrogen are the foremost effective alternative fuels due to the high energy density and the environmentalist. In the present study, the effects of adding the hydrogen on the performance and emission values in a single-cylinder natural gasdiesel dual fuel engine at partial load was numerically investigated by ANSYS Forte CFD program. In addition, taking into account the effects of different diesel fuel injection advances, the study was expanded. Analyzes were based on two different modes. The first mode (Mode 1) was based on the sharing of energy between gas fuels (natural gashydrogen). The second mode (Mode 2) included the effects of hydrogen enrichment on natural gas. Natural gas and hydrogen mixtures in appropriate proportions provided improvements in performance and emission. Increasing the diesel fuel injection advance (after 30o CA BTDC) caused results to deteriorate, especially at high hydrogen ratios. The fact that the hydrogen ratio in the gas mixture was above 50% caused the engine to operate with knock tendency. In the study, highly effective improvements were achieved without knock tendency in the proper diesel injection advance (10o-18o CA BTDC) and gas mixtures (below 50% hydrogen). There was a 21% and 30% improvement in power and total BSFC values for Mode 1 (14o CA BTDC of SOI and D25NG50H25 mixture), respectively, and 36% and 23% for Mode 2 (10o CA BTDC of SOI and D25NG75H15 mixture). On the other hand, NOx emission was found to be increased by 12% and 11%. The main reason for the increase in NOx emissions was that hydrogen increased local temperatures. However, CO, UHC and PM emissions were sharply reduced as a result of the increase the hydrogen content in the gas fuel. For Mode 1 and Mode 2, CO, UHC and PM emissions decreased by 86%, 89%, 78% and 80%, 76%, 84%, respectively. While increasing the hydrogen ratio was not very effective on ignition delay at low injection advances (10o- 14o CA BTDC), it was extremely effective for thermal efficiency. The thermal efficiency showed an improvement of 21% and 18% for the optimum cases of Mode 1 and Mode 2, respectively.