Burn Rate and Instantaneous Heat Flux Study of Iso-octane, Toluene and Gasoline in a Spray-Guided Direct-Injection Spark-Ignition Engine

The burn rate and the instantaneous in-cylinder heat transfer have been studied experimentally in a spray-guided direct-injection spark-ignition engine with three different fuels: gasoline, iso-octane and toluene. The effects of the ignition timing, air fuel ratio, fuel injection timing and injection strategy (direct injection or port injection) on the burn rate and the in-cylinder heat transfer have been experimentally investigated at a standard mapping point (1500 rpm and 0.521 bar MAP) with the three different fuels.

The burn rate analysis was deduced from the in-cylinder pressure measurement. A two-dimensional heat conduction model of the thermocouple was used to calculate the heat flux from the measured surface temperature. An engine thermodynamic simulation code was used to predict the gas-to-wall heat transfer. A modified Woschni correlation was adopted to model the engine heat transfer and this showed good agreement with the experimentally obtained in-cylinder heat flux results.