Discussion on the methodology of the lubricity determination of diesel fuels, containing non petroleum components

The paper describes the usability of current test methods employed in fuels for CI engines testing for fuels containing non-petroleum components. The paper describes test results that justify the necessity for test method modification and for establishing new criteria for assessment of such fuels usability. The analysis covered typical courses of friction coefficient and electrical contact potential as film thickness during test. During standard test the wear stages were isolated, and then referenced to actual operation of friction pair in fuel supply system of diesel engine. Test results show that methodology used up to date is not useful. The restriction to standard corrected wear scar diameter (WS 1.4) is not enough for proper interpretation of course and effects of model wear. Moreover, it is impossible to reference to actual operation conditions, which is inconsistent with tribological testing rules. Such rules mean that testing conditions reflect the actual ones as much as possible. Characteristics of test technique using HFRR, discussion on test method usability for testing the modified fuels, lubricity change vs. the increase of concentration of hydrocarbons typical for biohydrocarbons from Fischer-Tropsch process, comparison of changes of friction coefficient and lubrication film thickness for samples are presented in the paper.