Effect of n-pentanol addition on the combustion, performance and emission characteristics of a direct-injection diesel engine

In this study, experiments were conducted to examine the effect of using a mixture of diesel and n-pentanol, which is one of the second-generation biofuels with comparable properties to diesel fuel, as fuel on the combustion, performance, and gaseous and particulate emissions of a naturally-aspirated, four-cylinder, direct-injection diesel engine. Three n-pentanol fractions in the fuel mixture were selected: 10, 20 and 30% by volume. Results show that, the addition of n-pentanol leads to longer ignition delay and increases the peak heat release rate in the premixed combustion phase. The brake specific fuel consumption increases with increase of n-pentanol, while the brake thermal efficiency is not affected. Regarding the gaseous emissions, n-pentanol addition results in the following consequence: (a) HC (hydrocarbon) and CO (carbon monoxide) emissions increase for 30% n-pentanol in the blended fuel at low engine load but decrease at high engine load; (b) a slight increase (maximum 8%) in NOx emissions but noticeable increase in NO2 emissions. Regarding the particulate emissions, n-pentanol is found to be very promising in terms of reducing both the mass concentration and the particulate number concentration simultaneously.