Investigation of combustion, performance, emission and vibration characteristics of an engine fueled with a hydrogen-enriched biodiesel-diesel fuel blend

The carbon footprint shows the total amount of greenhouse gases emitted into the atmosphere by individuals, organizations and countries. The widespread use of fossil fuels is a major factor that increases the carbon footprint. Therefore, turning to sustainable alternatives in energy production and consumption is an effective step in combating climate change as well as efforts to prevent the depletion of fossil fuels. In this respect, biodiesel offers a solution against the depletion of fossil fuels, but with this advantage, the impacts of its production processes and use on environmental sustainability should also be considered. Many scientific studies have shown that engine performance with biodiesel fuel is substandard. To overcome the aforementioned negative aspects, the use of hydrogen as an energy carrier in the cylinder has recently become a popular topic for alternative fuel researchers. In this study, test fuels were obtained by blending diesel-biodiesel-hydrogen fuels in certain ratios. Experiments were conducted to investigate the effects of the obtained fuels on combustion, performance, emissions and vibration in a 3-cylinder, water-cooled, pre-combustion chamber diesel engine. The experiments were carried out at a constant engine speed of 2200 rpm and under different loads (15, 30, 45 and 60 Nm). First, conventional diesel fuel (D) was used to obtain reference data, followed by B20 fuel, which is obtained by mixing biodiesel produced from waste cooking oils with conventional diesel fuel at 20% by volume. The remaining 4 fuels are test fuels obtained by introducing hydrogen gas from the intake manifold at different flow rates (10, 20, 30 and 40 Lpm) in addition to B20 fuel. These fuels are named as B20+10 Lpm H2, B20+20 Lpm H2, B20+30 Lpm H2 and B20+40 Lpm H2 respectively. As a result, the specific fuel consumption value of B20 fuel increased by 8.78% compared to diesel fuel and then hydrogen addition reduced the specific fuel consumption value by 8.8%, 13.02%, 17.16% and 22.12% for B20+10 Lpm H2, B20+20 Lpm H2, B20+30 Lpm H2 and B20+40 Lpm H2, respectively. Hydrogen enrichment also had a positive impact on thermal efficiency. Although thermal efficiency decreased by 6.14% for B20 fuel compared to diesel, it increased by 4.51%, 5.05%, 5.62% and 7.12% for B20+10 Lpm H2, B20+20 Lpm H2, B20+30 Lpm H2 and B20+40 Lpm H2, respectively. Addition of 10, 20, 30 and 40 Lpm H2 to B20 fuel decreased NOx emissions by 31.25%, 33.08%, 38.87% and 41.46% respectively, while CO emissions decreased by 17.47%, 30.73%, 51.8% and 59.04% respectively. The average vibration values (at) decreased by 0.55% with B20 fuel compared to D fuel at all engine loads and increased by 2.34%, 4.07%, 6.38% and 22.84% with B20+10 Lpm H2, B20+20 Lpm H2, B20+30 Lpm H2, B20+40 Lpm H2 compared to B20 fuel.