Effect of various ethanol/diesel cosolvents addition on combustion and emission characteristics of a CRDI heavy diesel engine

Abstract

Solubility between ethanol and diesel impedes the application of ethanol in diesel engines. The objective of the experiment is to compare combustion and emission characteristics of ethanol/diesel fuels using biodiesel, n-pentanol, tetrahydrofuran (THF) as cosolvents respectively on a diesel engine under variable engine loads, exhaust gas recirculation (EGR) rates, and injection timings. The results show: All tested blends increase the indicated thermal efficiency (ITE) except at low load, and THF/ethanol/diesel fuel exhibits a higher ITE. The Coefficient of Variations of Indicated Mean Effective Pressure (COVIMEP) of ethanol/diesel blends is higher than that of diesel at low load. Under EGR conditions, ethanol/diesel blends run at lower COVIMEP, especially for biodiesel/ethanol/diesel fuel. At higher loads, all ethanol/diesel blends can decrease carbon monoxide (CO) emissions, especially for THF/ethanol/diesel fuel. Excessive retard of injection timing will increase CO and total hydrocarbon (THC) emissions of ethanol/diesel fuels. The soot emissions of THF/ethanol/diesel fuel are lower than those of n-pentanol/ethanol/diesel fuel under higher EGR rates. The effect of injection timing on soot emissions becomes more pronounced at slightly higher EGR rates. Compared to diesel, biodiesel/ethanol/diesel fuel increases nitrogen oxide (NOx) emissions, especially at medium-low load, whereas n-pentanol/ethanol/diesel and THF/ethanol/diesel fuels reduce NOxat low and high loads, slightly increase NOxemissions at medium loads. In conclusion, THF may be a more promising ethanol/diesel cosolvent compared with high alcohols and biodiesel in terms of fuel economy and emissions, especially under EGR and heavy load conditions.

Keywords

• THF (tetrahydrofuran)
• n-pentanol
• Biodiesel
• Ethanol/diesel cosolvent
• Combustion and emissions