Enhancing diesel engine efficiency and emission performance through oxygenated and non-oxygenated additives: A comparative study of alcohol and cycloalkane impacts on diesel-biodiesel blends

Abstract

This study evaluates the impact of renewable fuel additives on diesel engine performance, combustion, and emissions. Safflower seed oil was converted into biodiesel (BD) through transesterification, achieving a 94.12 % conversion yield, verified by spectroscopic analysis. Test fuels were prepared by adding 5 %, 15 %, and 25 % n-pentanol (PE, oxygenated) and cyclohexane (CHx, non-oxygenated) to diesel fuel (DF) and BD. These blends were tested in a single-cylinder diesel engine under varying loads. At maximum load, BSFC values were 0.251 for DF, 0.333 for 25 % PE, and 0.269 kg/kWh for 25 % CHx. BTE values were 32.184 % for DF, 27.028 % for 25 % PE, and 31.147 % for 25 % CHx. The peak in-cylinder pressure and net heat release for the 25 % PE blend, which were the highest among the test fuels, were 58.148 bar and 37.010 J/°CA, respectively. Average NOx emissions were 171 for DF, 135.75 for 25 % PE, and 170.50 ppm for 25 % CHx. CO emissions were 171 for DF, 149.25 for 25 % PE, and 170.25 ppm for 25 % CHx. Smoke opacity values were 0.75 for DF, 0.308 for 25 % PE, and 0.675 m-1 for 25 % CHx. Despite higher costs, CHx offers reduced environmental impact without significantly compromising engine performance.