Experimental Investigation of Changes in Performance, Emissions, and Engine Vibration in Diesel Engines Using Four Fuel Combinations of Diesel, Biodiesel, Octanol, and Hydrogen

Abstract Energy efficiency is a vital concept in our modern world. The most efficient use of energy resources is crucial for sustainability. A significant portion of global energy consumption is attributed to the transportation sector. The efficient operation of internal combustion engines, which power the transportation sector, and the efficiency of the fuels they use are becoming increasingly important. Therefore, researchers continue their work to improve fuel efficiency and find alternative fuels. In this study, test fuels created from four-fuel combinations of diesel, biodiesel (obtained from a mixture of 10% spent coffee grounds oil and 90% waste cooking oil), octanol, and hydrogen were investigated at 150 N m (half load) and 300 N m (full load) to improve engine performance and emissions. The effect of the test fuels on engine vibrations was also examined using accelerometer sensors positioned on the horizontal and vertical axes of the diesel engine. Since this four-fuel combination and the investigation of its effects on engine vibration are very rare in the literature, this study fills an important gap. The main objective of this study was to investigate the impact of octanol and biodiesel blends with hydrogen reinforcement on engine performance, vibrations, and emissions. The study results showed that the highest brake thermal efficiency values were obtained with the D90O10 mixture at both low and high loads. The D90O10 test fuel achieved thermal efficiency of 27.45% at 150 N m load and 33.72% at 300 N m load. These values are higher than those of D100 (BTE; 26.43% at 150 N m load and 33.24% at 300 N m load). The most important finding of this study is that the addition of 10% octanol to pure diesel fuel increases thermal efficiency. Among the important findings regarding vibration, it is the fact that blended fuels containing biodiesel reduce vibration at low loads (150 N m) compared to pure diesel fuel. While the combined vibration of D100 at 150 N m is 51.861 mm/s2, it was determined that the mixtures containing octanol and biodiesel (D90O10 and D70B20O10) are below this value (at levels of 46.178 mm/s2 and 46.353 mm/s2, respectively). However, at high loads (300 N m), vibration increased in fuels containing biodiesel. Hydrogen supplementation was found to have an enhancing effect on vibration at both 150 N m and 300 N m loads. Biodiesel-containing test fuels generally improved carbon monoxide emissions.