The Effects of Different Higher Alcohols (1-Butanol, 1-Pentanol, 1-Hexanol) Addition into the Diesel Fuel on the Performance, Combustion, and Exhaust Emission Characteristics of a Single-Cylinder Diesel Engine

Abstract

The reduction of petroleum reserves day by day all over the world depending on the increase in petroleum consumption and the reaching serious levels of environmental pollution have led researchers to search alternative and clean energy sources for internal combustion engines. The higher alcohols having four or more carbon atoms in their chemical structure come to the fore for diesel engines due to the negative properties of short-chain alcohols (methanol and ethanol) such as low energy content and cetane number. The aim of this study is to compare the performance, emissions, and combustion characteristics of a single-cylinder, four-stroke, direct injection diesel engine operating with alternative fuels which contains 15% by volume of 1-butanol, 1-pentanol and 1-hexanol alcohols (Bt15: 15% 1-butanol + 85% diesel fuel, Pt15: 15% 1- pentanol + 85% diesel fuel, Hx15: 15% 1-hexanol + 85% diesel fuel) with reference diesel fuel (D100) by testing at a fixed engine speed of 1500 rpm and different loads (25%, 50%, 75%, and 100%). As a result, it is noticed to be that alcohol-infused fuel blends caused to decrease the brake thermal efficiency and increase brake specific fuel consumption due to the lesser calorific values of the alcohols according to the diesel fuel. At 100% engine load, the maximum cylinder pressures were observed as 46.97 bar, 47.76 bar, 48.41 bar, and 48.91 bar, respectively while the peak net heat release rates of D100, Bt15, Pt15, and Hx15 were found to be at 29.55 J/o, 31.14 J/o, 32.66 J/o, and 33.80 J/o, respectively. Besides, it is determined that the ignition delay period of the alcohol-treated fuel blends is generally extended as compared to the diesel fuel because of the lower cetane number of alcohol. CO2 and O2 emissions increased with the addition of alcohol to diesel fuel while CO, HC and NOX emissions as well as exhaust gas temperatures reduced. When all experimental results were evaluated, it could be noted that the Hx15 blend gave the best results in terms of performance, emissions and combustion properties.