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A Study of Fischer-Tropsch Diesel (FTD) Fuel Effects on Combustion and Emissions Characteristics
Published October 22, 2006 by Society of Automotive Engineers of Japan in Japan
FTD fuels have many advantages as an alternative cleaner diesel fuel. Higher Cetane number and the absence of Poly-Aromatic Hydrocarbon (PAH) content, which are the principal properties of FTD fuels, have a potential to reduce Particulate Matter (PM) emissions. Further the absence of sulfur content will result not only in the PM emission reduction, but also in the deterioration restraint of aftertreatment catalyst activities.
One of the purposes of the study is to evaluate the effects of FTD fuels on combustion and emissions characteristics of the latest diesel engines. And the other is to clarify the best FTD fuel properties.
Three Turbocharged and Aftercooled (TCA) diesel engines with different displacement (2, 4, and 8 liter) were used in this study to confirm the universality of the test results (taking account of engine size).
In this study, the 90 percent distilled temperature (T90) was chosen as a parameter for designing the suitable FTD fuel property. Three FTD fuels were designed (named from the highest T90, FUEL A, FUEL B, and FUEL C) and produced while keeping high Cetane number to be above 70. FUEL A has almost the same T90 as the (Japanese market) base fuel. FUEL C synthesizes to obtain the same Initial Boiling Point (IBP) temperature as the base fuel. FUEL B has a middle property of FUEL A and FUEL C.
The effects of FTD fuel properties on the engine performance such as max torque, power, energy consumption, exhaust emissions, were firstly compared with the base diesel fuel. The engine hardware and its calibration data were not modified from the production-based specifications through the test. The emissions tests were carried out not only under steady-state conditions, but also under transient condition (JE05: Japanese emissions test procedure). In addition to these tests, a single-cylinder engine with optical access was used for the combustion analysis by means of the laser shadow graph and the two-color method. Then, by using these test results, the modification of the engine hardware specification was implemented and evaluated to emphasize the characteristics of the FTD fuel.