Physical and Chemical Properties of GTL−Diesel Fuel Blends and Their Effects on Performance and Emissions of a Multicylinder DI Compression Ignition Engine

An analysis of physical and chemical properties of Fischer−Tropsch fuel gas-to-liquids (GTL) blends with a conventional diesel was conducted. Then, engine performance, combustion, and emission investigations were performed to better understand the differences in regulated emissions between diesel, GTL, and their blends using a six-cylinder turbocharged direct-injection compression ignition (DICI) engine at different load-speed conditions and pump timings. Most of the properties of blended fuels have a good linear relation with the GTL volume fraction in the blends. Density, sulfur, polyaromatics, and total aromatics of blends decrease, while the cetane number and lower heating value increase as the GTL fraction increases. Both the maximum combustion pressure and peak value of heat release rate for neat GTL are slightly lower, and the locations of the two peaks are slightly retarded versus those of the diesel. GTL blends, especially neat GTL, show improvements in fuel economy and thermal efficiency. GTL blends can reduce CO, HC, soot, particulate matter (PM), and NOx emissions simultaneously at different engine operating conditions. There is a trend that the magnitude of reductions in emissions increases with an increasing GTL proportion in blends. The use of retarding pump timings and GTL fuel instead of a conventional diesel on a DICI engine is an effective means to reduce NOx without significantly compromising PM emissions.