The combustion and emission characteristics of diesel-ethanol blends with THF as cosolvents in a diesel engine operating with EGR

Abstract

Tetrahydrofuran (THF) is not only an excellent co-solvent for ethanol but also a promising clean oxygen-containing fuel. The objective of the diesel engine test is to reveal the effects of exhaust gas recirculation (EGR) rates and THF as co-solvents between ethanol and diesel on the combustion and emissions. Results show that the maximum rate of pressure rise increases with the growth of the additive proportion of ethanol or THF under low EGR rates. The indicated thermal efficiency (ITE) of mixedfuels is slightly higher than that of neat diesel fuel when the EGR rate is below 30%. With the increase of THF and ethanol fraction, carbon monoxide (CO) and soot emissions of blends decrease greatly, while total hydrocarbons (THC) emissions gradually increase, especially under medium and high EGR rates. Finally, E30T10 fuel (30% ethanol, 10% THF, and 60% diesel by vol.) presents ultra-low soot emissions under all EGR rates and breaks the conventional trade-off between soot and nitrogen oxides (NOx). Under medium EGR rates, NOx emissions of E30T10 are reduced markedly, but THC and CO emissions are still at low levels. Meanwhile, the ITE of E30T10 still maintains a high level.