Study on performance and emissions of a passenger-car diesel engine fueled with butanol–diesel blends

• Effects of butanol addition are investigated experimentally on a high-speed diesel engine.
• The studied butanol blending ratio is up to 40% by volume.
• Engine maximum power output cannot be affected as fueled by the 40% butanol blend.
• Effects of butanol addition on exhaust emissions are varied with loads.
• Butanol could be used conveniently up to high blending ratio with diesel fuel in diesel engines.

In this work, the commercially available diesel fuel (Bu00), butanol(20%)–diesel(80%) (by vol.) (Bu20), butanol(30%)–diesel(70%) (Bu30), and butanol(40%)–diesel (60%) (Bu40) fuels were tested. Experiments were conducted on a high-speed direct injection (DI) diesel engine for passenger-car application for varied loads at two representative engine speeds. The results showed that butanol–diesel blends slightly increased combustion pressure and accelerated burning rate. As fueled by the Bu40 blend, the maximum power output of the engine cannot be affected. Besides, butanol–diesel blends increased BSFC and brake thermal efficiency. Moreover, the effects of butanol addition on diesel engine exhaust emissions were varied with loads. Under low-load conditions, CO emissions obviously increased while NOx emissions decreased as butanol blending ratio increased. Under high-load conditions, on the contrary, CO emissions decreased but NOx emission increased. For the 40% butanol–diesel blend, in addition, HC emissions were higher than the neat diesel and lower percentage of butanol–diesel blends, especially at low-load. It is interesting that smoke decreased significantly at all conditions with the use of butanol–diesel blends, and the more butanol blending ratio the less smoke. Overall butanol is a potentially promising biofuel, which could be used conveniently up to high blending ratio with diesel fuel in diesel engines.