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Tung biodiesel is a promising alternative fuel type produced from the tung tree. In the current study, the effect of the addition of 20%, by volume, of tung biodiesel to diesel fuel was evaluated in terms of energetic-exergetic analyses based on the first and second laws of thermodynamic at various high engine speeds (2,400, 2,600, and 2,800 rpm). Additionally, this study aimed to assess the thermoeconomic and exergoeconomic aspects of a diesel engine. The findings revealed that the amount of energy converted to useful work for the diesel fuel was higher than that of the DTB20 fuel, even though the fuel energy obtained from DTB20 fuel was higher than that of diesel fuel at all engine speeds. The highest energy and exergy efficiencies for the engine fueled with diesel fuel were obtained as 31.07% and 29.15% respectively, while the corresponding values for the engine fueled with DTB20 fuel were determined as 27.15% and 25.19% at the engine speed of 2,400 rpm, respectively. However, at 2,800 rpm, a significant decrease in both the energy and exergy efficiencies was observed for both diesel and tung biodiesel blended fuels due to the increased mechanical friction of the engine components. Furthermore, at the highest engine speed, entropy generation increased, owing to a higher exergy destruction rate. The entropy generation rate increased to 0.38 kW/K for diesel fuel and 0.46 kW/K for DTB20 fuel since the enhancement of the engine speed caused the ascent of the fuel consumption rate. Regarding thermoeconomic-exergoeconomic analyses, for both diesel and tung biodiesel blended fuels, there is no distinct difference in the thermoeconomic-exergoeconomic parameters at 2,400 and 2,600 rpm as the values of these parameters at the engine speed of 2,800 rpm increased significantly. In light of all the findings, it can be concluded that the engine speed of 2,800 rpm is not applicable to run the engine due to higher friction and corresponding energy destruction in the engine system. [ABSTRACT FROM AUTHOR]

In this study, the influence of diesel and biodiesel fuels with various flow rate of hydrogen (3 L per minute and 6 L per minute) addition through the intake manifold of a diesel engine was investigated at three different engine speed (1500 rpm, 1800 rpm, and 2100 rpm) by considering second law of thermodynamic as a different perspective. Energy, exergy, and sustainability analysis were evaluated by utilizing the data from the experiments. According to the results, it is enlightened that useful work energy ascends with the hydrogen addition in all engine speeds and the net work rates of all test fuels were found as highest at 1800 rpm engine speed while the rate of energy heat loss decreased with hydrogen addition. Furthermore, exergy input is also increased with the hydrogen addition to the engine whereas exergy destruction and exergy heat lost decreased with the increment of the hydrogen. The highest values of energy efficiency and exergy efficiency obtained at 1800 rpm engine speed by using diesel fuel with 6 L per minute hydrogen addition as 38.67 % and 35.09 %, respectively. The highest entropy generation occurred at 2100 rpm as 0.288 kW/K for the biodiesel fuel and the lowest value was observed as 0.201 kW/K for DH6 fuel at 1800 rpm. The analyses showed that the sustainability index values determined to be in the range of 1.437–1.541 and the increase in hydrogen ratio enhanced the sustainability index at all engine speeds and the DH6 and BH6 fuels are more sustainable fuels than the other experimental fuels. • Energy and exergy input augment with the enhancement of the hydrogen. • Energy heat loss, exergy heat lost, and exergy destruction and decreased with hydrogen addition. • The max. values of energy and exergy efficiency were obtained at 1800 rpm with DH6. • DH6 and BH6 fuels are more sustainable fuels than the other experimental fuels. [ABSTRACT FROM AUTHOR]