With the increase of energy needs and environmental pollution, alcohol-based alternative fuels are used in spark-ignited (SI) engines. Fusel oil, which is a by-product obtained through distillation of ethanol, contains some valuable alcohols. As alcohols are high-octane, they have an important place among the alternative fuels. Fusel also takes its place among those alternatives as it is high-octane and low on exhaust emissions. In this research, the effects of using blends of unleaded gasoline and improved fusel oil on engine performance and exhaust emissions were analyzed experimentally. A four-stroke, single-cylinder, spark-ignited engine was used in the experiments. The tests were conducted at a fixed speed and under different loads. The test fuels were blended supplying with fusel oil at rates incremented by 10%, up to 50%. Under each load, the engine’s performance and emissions were measured. Throughout the experiments, it has been observed that engine torque and specific fuel consumption increases as the amount of fusel oil in the blend is increased. Nitrogen oxide (NO_x), carbon monoxide (CO), and hydrocarbon (HC) emissions are reduced as the amount of fusel oil in the blends is increased.

In this study, the effects of the use of improved fusel oil on engine performance and on exhaust emissions in a spark-ignition engine were investigated experimentally in consideration of the water, gum, and moisture content at high compression ratios according to TS EN 228 standards. In the study, a four-stroke, single-cylinder, air-cooled, spark plug ignition engine with an 8/1 compression ratio was used at three different compression ratios (8/1, 8.5/1, 9.12/1). Experiments were performed for six different ratios of fuel blends (F0, F10, F20, F30, F40, and F50) at a constant speed and different loads. The data obtained from the experiments were compared with the original operating parameters of the engine while using gasoline. According to the test results, the optimal engine performance was at a 9.12/1 compression ratio and with a F30 fuel blend. With the increase from an 8/1 to 9.12/1 compression ratio for the F30 fuel blend, the overall efficiency increased by 6.91%, and the specific fuel consumption decreased by 2.35%. The effect of the optimum fusel blend on the emissions was also examined and CO emissions were reduced by 36.82%, HC emissions were reduced by 23.07%, and NO_x emissions were reduced by 15.42%, while CO₂ emissions were increased by 13.88%.

The high cetane number of the fuel used in diesel engines is extremely important as it provides some improvements in combustion in the cylinder. Therefore, the addition of cetane improver to diesel fuel has been highly preferred in recent years. In this study, the effects of 2-ethylhexyl nitrate (EHN) addition, a cetane improver, on compression ignition engine performance and emissions were analyzed at various engine loads. Four different fuels were used in the experiments as 100% diesel (D100), 99% diesel + 1% EHN (D99EHN1), 98% diesel + 2% EHN (D99EHN2) and 97% diesel + 3% EHN (D99EHN3). The results obtained from the experiments showed that the addition of 2-EHN positively affected the brake thermal efficiency (BTHE), hydrocarbon (HC) and carbon monoxide (CO) values, while the brake specific fuel consumption (BSFC), nitrogen oxide (NOx) and smoke emission levels were negatively affected. With high engine load, 2-EHN supplement marginally rises NOx emissions but significantly declines HC and CO emissions. EHN addition had small impacts on BSFC. Compared to D100 fuel, the highest BTHE value was obtained by D99EHN2 fuel, with an increase of 11.57% at 3000-Watt load value. With the D97EHN3 fuel, compared to diesel, HC emission decreased 60.61%, while CO emission decreased 31.25%. The results show that the 2-EHN cetane improver can be used successfully in a diesel engine.