Effect of exhaust gas recirculation (EGR) on performance and emissions of a constant speed DI diesel engine fueled with pentanol/diesel blends

Abstract

In this work, the effects of blending n-pentanol, a second generation biofuel with diesel on the performance and emission characteristics of a diesel engine under exhaust gas recirculation (EGR) conditions are investigated. Tests were performed on a single-cylinder, constant-speed, un-modified, direct-injection diesel engine using four n-pentanol/diesel blends: 10%, 20%, 30% and 45% (by volume). The possibility of using a high pentanol/diesel blend (45%) was also explored with an objective to maximize the renewable fraction in the fuel. Three EGR rates (10%, 20% and 30%) were utilized with an intention to reduce the high nitrogen oxides (NOx) that were prevalent at high engine loads using these blends. Test results showed that increasing EGR rates brought down NOx emissions by up to 41% at medium load and 33.7% at high load. Smoke opacity hardly increased up to 20% EGR rate and beyond that it increased for all blends. It was found that simultaneous reduction of NOx and smoke emissions can be achieved using the combination of pentanol/diesel blends and a medium EGR rate (20–30%) with a small drop in performance. Increase in hydrocarbons (HC) and slight increase in carbon-monoxide (CO) emissions were experienced with all blends when compared to diesel fuel under EGR conditions. It was concluded that 45% pentanol/diesel blends can be used in diesel engines without any modifications and without causing any visible damage to the engine parts subject to long-term durability tests.