Investigating C3 and C4 esters and alcohols in a diesel engine: Combined influence of carbon chain length, oxyfuel type, and oxygen content

Diesel engines fueled by liquid fuels will continue to dominate the transportation and heavy machinery application market despite the advancement of other technologies. Studies have yet to be conducted to investigate the combined influence of carbon chain length, oxyfuel type, oxygen content, and blending ratio of esters and alcohols as additives in diesel fuel. The present study addresses this by preparing two sets of experiments using three-carbon (C₃) and four-carbon (C₄) additives, one at an equal blending ratio of 4% and the other at an equal oxygen mass content of 1.94%. Although the additives caused up to 24.84% rise in brake specific fuel consumption at low load, the value diminished to 7.86% at medium load and 11.63% at high load. The C₄ fuels were found to have better NOx reduction potential than the C₃ fuels. However, most additives significantly increased CO emissions, except for EE4.9 (4.9% ethyl ethanoate and 95.1% diesel), leading to 3.7% and 7.1% lower CO emissions than neat diesel at low and medium loads, respectively. Smoke emissions were also reduced by up to 32.84% when oxygenated additives were used. Although all blends tested are promising fuel alternatives in a diesel engine, EE4.9 provided the most suitable trade-off between engine performance and emissions.