Reduction in emissions of nitrogen oxides, particulate matter, and polycyclic aromatic hydrocarbon by adding water-containing butanol into a diesel-fueled engine generator

Abstract

Three groups of n-butanol–diesel blends with 0, 0.5, and 1.0wt.% water-content were investigated to simulate the hydrated butanol produced by acetone–butanol–ethanol fermentation and a simple distillation treatment. Both 30-day standing and centrifugal test results showed that 15wt.% n-butanol (BT) was the minimum additive ratio to stabilize the 1.0wt.% water content diesel blend, while those blends that contained 0 or 0.5wt.% water could remain as stable one-phase clear liquids by adding just 5wt.% BT. These stable diesel blends were further examined in a heavy-duty diesel-fueled engine generator (HDDEG). Using BT-diesel blends increased the indicated specific fuel consumption (ISFC) because of the lower heating value of n-butanol, while the micro-explosions that occurred could reduce the ISFC when using 0.5wt.% water-containing BT-diesel blends. NOx emissions increased with the increasing BT content at a low additive ratio (5–15wt.%), and reduced when adding a higher amount of BT (>15wt.%). PM, total-PAHs, and total-BaPeq emissions were all significantly reduced when the increasing BT additive ratio contained either 0, 0.5, or 1.0wt.% water because of the lower sulfur and higher oxygen fuel contents. On the other hand, the CO emission level went up with the addition of BT. Notably, the diesel blends with 0.5wt.% water only slightly increased ISFC when low fractions of BT were added, i.e. 0.40% and 0.81% ISFC increases with the addition of 5 and 10wt.% BT, respectively. In addition, there were significantly lower NOx, PM, Total-PAHs and Total-BaPeq, emissions with the blends than with regular diesel. With the aim of achieving both good energy performance and less pollutant emissions, the 5 and 10wt.% BT additive with 0.5% water content blends were the most suitable for practical use in an HDDEG without any engine modifications or changes in controls.