Diesel/Methane Dual Fuel Strategy to Improve Environmental Performance of Energy Power Systems

Methane represents an attractive energy source for power production generated by internal combustion engines because of its renewable nature and environmental friendly characteristics. The most suitable way to utilize methane in compression ignition engines is the dual fuel (DF) technology. In diesel/methane DF operation the gas is injected into the intake manifold to mix uniformly with air; the premixed air-methane mixture is drawn into the cylinder and it is ignited by diesel fuel injected directly in the chamber. This paper deals with the energetic potentiality of a small compression ignition engine modified to run in diesel/methane DF mode. The engine is a three-cylinder, 1.0 L, equipped with a common rail injection system. Experiments were performed at different speeds and loads. For each operating condition, a part of the total energy was supplied by the diesel combustion and the remaining by methane. Combustion process was analyzed by in-cylinder pressure signal. Optical diagnostics were applied to investigate the effect of methane addiction to diesel fuel on combustion evolution and pollutant formation. Pollutant emissions were measured at exhaust. It was found out that DF operation represents a feasible way to reduce both particulate matter and nitrogen oxides emissions.