An Alternative Method Based on Toluene/n-Heptane Surrogate Fuels for Rating the Anti-Knock Quality of Practical Gasolines

Gautam Kalghatgi, Robert Head, Junseok Chang, Yoann Viollet, Hassan Babiker, Amer Amer
2014 SAE International Journal of Fuels and Lubricants  
anti-knock quality of the fuel. Fuel anti-knock quality has to be described by empirical measures because the fundamental auto-ignition chemistry cannot be adequately quantified for practical fuels given their complexity. Anti-knock quality is traditionally measured by the Research Octane Number (RON) and Motor Octane Number (MON) of the fuel used. The RON test is run in a single-cylinder Cooperative Fuels Research (CFR) engine at an engine speed of 600 rpm and an intake temperature of 52 °C,
more » ... erature of 52 °C, while the MON test is run at 900 rpm and a higher intake temperature of 149 °C. These tests are run in accordance with sets of specific procedures 4 -ASTM D2699 for RON and ASTM D2770 for MON. The octane scale is based on two paraffins, n-heptane and iso-octane. Blends of these two primary components are referred to as primary reference fuels (PRFs) and define the intermediate points in the RON or MON scale. The specific RON or MON represents the volume percent of iso-octane in the PRF. For example, a blend of 95% iso-octane and 5% n-heptane by volume is assigned the octane number of 95 in both RON and MON scales. A gasoline is assigned the RON (or MON) value of the PRF that matches the gasoline's knock behavior in the RON (or MON) test. The refining industry has developed over the past 80 years or so on the assumption that PRFs are suitable knock surrogates for practical gasolines. Yet the auto-ignition chemistry of the nonparaffinic components in gasoline is different from that of the PRFs, and the RON or MON describes the anti-knock behavior of the gasoline only at the RON or MON scale test condition. The true anti-knock quality of a gasoline is best described by an octane index (OI) 3, 5-7 , which is defined as
doi:10.4271/2014-01-2609 fatcat:yp22ksbnwbdbtat7llchzv4ggm