Particulate Emissions from a Diesel Engine Operated with Gaseous Fuels
Particulate matter (PM) emissions from diesel engines have a great impact on human health and the environment. It is believed that the use of gaseous fuels as a supplement for liquid diesel fuel has potentials to reduce such emissions. Diesel engines, while operated on gaseous fuel, are normally referred to as dual fuel engines. In dual fuel engines, gas acts as the primary fuel and a minimum amount of diesel (referred to the pilot fuel) is used just to ignite the charge. Literature review reveals significant research gaps in the area of engine emissions (especially PM) for dual fuel engines. In this present study, natural gas (NG) and simulated biogases are used as alternative gaseous fuels. PM emissions from a single cylinder direct injection diesel engine, operated on different gaseous fuels, are measured and analyzed by using different methods. The conventional gravimetric method and a light scattering photometer (LSP) method are employed for mass measurements. Physical characterizations of the particulates are performed by using a scanning electron microscopy (SEM). A special computer software is used to analyze the digital images of filters charged in a partial dilution system. Results are compared between diesel operation and dual fuel operations, and also between NG and biogas fueling under similar engine operating conditions.
Keywords: Gaseous fuels, Dual-fuel engine, Particulate Matter, Exhaust emissions, Electron microscopy.