Technical feasibility study of butanol–gasoline blends for powering medium-duty transportation spark ignition engine

Amongst primary alcohols, butanol is considered as the most promising alternative fuel candidate because of its favourable chemical and physical properties, which are quite similar to gasoline. Butanol is completely miscible with gasoline in any proportion and forms a stable blend. It is not hygroscopic in nature therefore does not absorb moisture from the atmosphere similar to ethanol and methanol, which makes it a superior alternate fuel. Experiments are conducted on 5, 10, 20, 50 and 75% butanol–gasoline blends for evaluating their engine performance, emissions and combustion characteristics in a medium-duty transportation spark ignition (SI) engine. The engine was suitably instrument for the experiments. Engine performance was evaluated by finding performance parameters such as brake specific fuel consumption (BSFC), power output and torque, thermal efficiency and exhaust gas temperature of butanol–gasoline blends vis-a-vis baseline gasoline. Regulated emissions were compared for butanol–gasoline blends vis-a-vis baseline gasoline and an attempt was made to find the reason for these variations. Combustion characteristics of butanol–gasoline blends were evaluated for parameters such as in-cylinder pressure history, heat release rate, rate of pressure rise, mass burn fractions and combustion duration. Overall, butanol–gasoline blends showed performance, emissions and combustion characteristics similar to gasoline.