Exhaust emissions from an indirect injection dual-fuel engine

Diesel engines operating on gaseous fuels are commonly known as dual-fuel e ngines. In the present work, a single-cylinder, compression ignition, indir ect injection research (Ricardo E6) engine has been installed at United Ara b Emirates University for investigation of the exhaust emisssions when the engine is operating as a dual-fuel engine. The influence of changes in majo r operating and design parameters, such as the concentration of gaseous fue l in the cylinder charge, pilot fuel quantity, injection timing and intake temperature, on the production of exhaust emissions was investigated. Diese l fuel was used as the pilot fuel, while methane or propane was used as the main fuel which was inducted in the intake manifold and mixed with the int ake air. The experimental investigations showed that the poor emissions at light loads can be improved significantly by increasing the concentration o f gaseous fuel (total equivalence ratio), employing a large pilot fuel quan tity, advancing the injection timing of the pilot fuel and increasing the i ntake temperature. It is demonstrated that, in general, any measure that te nds to increase the size of the combustion regions within the overly lean c ylinder charge will reduce markedly the concentrations of unburned hydrocar bons and carbon monoxide in the exhaust gases.