Because of its distinctive physicochemical properties, 1-heptanol has the potential to be widely used for fueling compression ignition direct injection (CIDI) engines. Its renewability also makes 1-heptanol an attractive option for this and other applications. In this study, we investigated the combustion of different 1-heptanol/diesel blends with up to 50 vol% 1-heptanol in a stationary CIDI engine under low injection pressure. The substitution ratios of 1-heptanol/diesel used were 10/90, 20/80, 30/70, 40/60, and 50/50 (v/v%), denoted in the text as Hep10, Hep20, Hep30, Hep40, and Hep50. This work utilized a one-cylinder naturally-aspirated air-cooled CIDI research engine. Steady-state tests were performed at various loads ranging from 10% to 100% and engine speeds between 900 and 1500 rpm. Our findings from the thermogravimetric experiment revealed that the 1-heptanol/diesel mixture evaporates faster than pure diesel. The 1-heptanol/diesel mixtures show longer ignition delay and are more likely to burn during the premixed combustion phase than diesel. Also, Hep10-50 blends release more heat in the premixed fast-burn mode, in contrast to regular diesel. Hep10-50 mixtures showed higher cyclic variation than diesel. The highest cyclic variation was for Hep30, with a COVimep of 3.25%. At 75% load, compared to standard diesel, Hep50 showed a higher BTE and combustion efficiency by 1% and 3%, respectively, while the BSEC was lower than diesel by 5.8%. At 100% load, the peak cylinder pressure of Hep50 was higher than diesel by 3.8%, while the BTE and the combustion efficiency of Hep50 were lower than diesel by 2.5% and 2%. For engine loads of 10–75%, there were some improvements in engine performance for Hep10-50 mixtures compared to diesel, while a slight deterioration in engine performance was noted at 100% for Hep10-50 blends. For the Hep50 mixture, soot and NOx emissions were reduced by 70% and 25%, respectively, compared to diesel. |
