Experimental and surrogate modeling study of gasoline ignition in a rapid compression machine

The use of gasoline in Homogeneous Charge Compression Ignition engines has propelled the need to better understand compression ignition processes for gasoline under engine-like conditions. In order to quantify low-temperature heat release and to provide fundamental validation data for chemical kinetic models, it is imperative to study autoignition phenomena under well-controlled conditions. However, there is a significant lack of autoignition delay data in the low temperature regime. Recognizing the need for kinetic information at high pressures and low-to-intermediate temperatures, this work aims to fill this void by conducting an experimental study of gasoline autoignition in a Rapid Compression Machine (RCM) to characterize the ignition response of gasoline + air mixtures over a wide range of compression temperatures at compression pressures of 20 and 40 bar with equivalence ratios ranging from 0.3 to 1.0. Results from the RCM experiments are also simulated using a four-component gasoline surrogate model which includes n-heptane, iso-octane, toluene, and 2-pentene. For the conditions investigated, good agreement between the experiments and the four-component surrogate model, in terms of first-stage and total ignition delay times as well as the comparison of measured and simulated pressure traces, is demonstrated. Kinetic analysis is further conducted to understand the role of the different hydrocarbon classes present in gasoline in controlling autoignition.