Effect of intake temperature and boost pressure on the auto-ignition of fuels with different cetane numbers and volatilities

The aim of this research is to investigate the effect of air inlet temperature and boost pressure on the auto-ignition of fuels that have different CNs and volatilities in a single cylinder diesel engine. The inlet air temperature is varied over a range of 30°C to 110°C at a constant intake pressure of 1.1 bar. The boost pressure is varied from 1.1 bar to 1.5 bar at a constant intake temperature of 60°C. All engine tests are run at steady-state conditions. The fuels used are ultra-low-sulfur-diesel (ULSD), JP-8 (two blends with CN 50 & 31) and F-T SPK. Detailed analysis is made of the rate of heat release during the ignition delay period, to determine the effect of fuel volatility and CN on the auto-ignition process. A STAR-CD CFD model is applied to track the effect of intake temperature and pressure on fuel evaporation, start of exothermic reactions, formation of different species and their significance in the auto-ignition process. CHEMKIN is used to study the chemical reactions under different equivalence ratio, pressure and temperatures. Special attention has been given to LT (low-temperature) and NTC (negative-temperature coefficient) regimes during the ignition delay period. Effect of intake pressure and temperature on these regimes has been studied in detail.