Higher alcohols above n-butanol can be excellent alternative fuels for diesel engines owing to their high
energy content and high cetane number. The last three years has witnessed an advent of several sustainable
pathways for n-octanol bio-synthesis using engineered-microbes like Escherichia coli and Clostridium
species. Therefore an investigation to evaluate the compatibility of n-octanol in diesel engines becomes
essential. The influence of blending n-octanol by up to 30 vol% with fossil diesel on combustion, performance
and emission characteristics of a single cylinder direct-injection (DI) diesel engine under both naturally
aspirated and exhaust gas recirculation (EGR) modes was investigated with reference to diesel.
Results showed that n-octanol prolonged the ignition delay generating higher peaks of in-cylinder pressure
and heat release rates (HRR) during the pre-mixed combustion phase. Brake thermal efficiency (BTE)
increased while brake specific fuel consumption (BSFC) decreased with an increase in n-octanol fraction.
Smoke, NOx (nitrogen oxides), HC (hydro-carbons) and CO (carbon monoxide) emissions decreased with
n-octanol addition. NOx and smoke emissions also remained low at all EGR rates. Both BTE and BSFC suffered
at increased EGR rates. HC and CO emissions increased with escalating EGR rates. n-Octanol was
found to be very promising for replacing fossil-diesel by up to 30% (subject to long term durability tests),
in terms of emissions and performance at both naturally aspirated and EGR conditions