Influence of 1-butanol and 1-pentanol addition to diesel fuel on exhaust and noise emissions under stationary and transient conditions

Abstract

There is a growing interest in using long-chain alcohols, i.e. butanol and pentanol, in the transport sector, as a consequence of their potential production from residual biomass via fermentative processes. There is evidence that incorporation of alcohols to diesel fuel enables to overcome the well-known smoke-NOx trade-off under steady state compression ignition engine operation. Nevertheless, the impact of long-chain alcohols under engine transient conditions is not understood and their behavior under Worldwide Harmonized Light Vehicles Test Procedure (WLTP) cycle has not been reported. This investigation addresses the above-mentioned research gaps by characterization of noise and exhaust emissions (CO, total hydrocarbon content or THC, NOx and particulate matter or PM mass, PM number and PM distribution) of a diesel engine running on ultra-low sulfur diesel (ULSD) fuel and its mixtures with 1-pentanol and 1-butanol under stationary and transient conditions (WLTP).Transient PM number, mass and size distribution have been monitored using Dekati electrical pressure low impactor ELPI + coupled by Dekati Fine Particle Sampler FPS-4000, whereas transient gaseous emissions have been measured with Horiba Mexa 7100D. Increasing the long-chain alcohol content in fuel blends, significantly reduces PM number and mass for both stationary and WLTP tests, being mainly attributed to oxygen content of 1-butanol and 1-pentanol. Addition of long-chain alcohols causes a decrease of emitted NOx in stationary operation, but the opposite trend was found under WLTP. Noise levels seem to slightly increase with the use of higher alcohol/ULSD fuel mixtures. Overall, it may be concluded that utilization of higher alcohol/ULSD fuel blends appears as a favorable substitute to straight ULSD fuel.