On the Knock Characteristics of LPG in a Spark Ignition Engine

An investigation on some knock characteristics of commercial LPG with 83…87% propane and 9…15% alkenes has been carried out on a spark ignition engine for heavy-duty vehicle. It was concerned with the development of a simple correlation of an Arrhenius type for knock delay time, based on experimental data of pressure and knock occurrence crank angle and simulated temperatures of unburned gas. These temperatures were calculated with a two-zone combustion model, and checked with the KIVA 2 code. Some characteristics of LPG autoignition in engine were also put forth, considering the heat release rates due to autoignition, and were compared with previous findings for pure propane.