Influence of fuel properties, hydrogen, and reformate additions on diesel-biogas dual-fueled engine

Biomethane and biogas produced from waste (i.e., from an anaerobic digester) have shown themselves to be promising fuels for internal combustion engines. They can improve fuel security and contribute in reducing emissions, including CO2, when used as a supplement to diesel fuel in dual-fueled diesel engines. In this work the influence of diesel fuel properties, H2 and reformate (H2 and CO) additions on the performance of diesel-biogas dual-fueled engines are studied. Biogas, with a composition of 60% CH4 and 40% CO2 by volume, was introduced to the engine intake manifold; reducing the utilization of the in-cylinder injected diesel fuel. Under diesel-biogas fueling, engine out NOX, PM and smoke emissions were reduced. However, the combustion patterns were altered, and under high biogas concentrations (those that were greater than 60% reduction of the diesel fuel) combustion stability became an issue, leading to increased CO and HC emissions. The influence of the in-cylinder injected diesel fuels, on dual-fueled engine operation, were studied by blending low sulfur diesel with 30% by volume synthetic Gas to Liquid (GTL) diesel (named GD30) and pure GTL. Increasing GTL concentration in the diesel fuel blend enhanced combustion stability, fuel economy and improved the emissions of HC, NOX and PM in diesel-biogas fueled engines. Hydrogen or reformate (H2 and CO) addition to a diesel-biogas fueled engine improved engine emissions.