Theoretical Prediction of Laminar Burning Speed and Ignition Delay Time of Gas-to-Liquid Fuel

Abstract

Gas-to-liquid (GTL), an alternative synthetic jet fuel derived from natural gas through Fischer–Tropsch (F–T) process, has gained significant attention due to its cleaner combustion characteristics when compared to conventional counterparts. The effect of chemical composition on key performance aspects such as ignition delay, laminar burning speed, and emission characteristics has been experimentally studied. However, the development of chemical mechanism to predict those parameters for GTL fuel is still in its early stage. The GTL aviation fuel from Syntroleum Corporation, S-8, is used in this study. For theoretical predictions, a mixture of 32% iso-octane, 25% n-decane, and 43% n-dodecane by volume is considered as the surrogate for S-8 fuel. In this work, a detailed kinetics model (DKM) has been developed based on the chemical mechanisms reported for the GTL fuel. The DKM is employed in a constant internal energy and constant volume reactor to predict the ignition delay times for GTL over a wide range of temperatures, pressures, and equivalence ratios. The ignition delay times predicted using DKM are validated with those reported in the literature. Furthermore, the steady one-dimensional premixed flame code from CANTERA is used in conjunction with the chemical mechanisms to predict the laminar burning speeds for GTL fuel over a wide range of operating conditions. Comparison of ignition delay and laminar burning speed shows that the Ranzi et al. mechanism has a better agreement with the available experimental data, and therefore is used for further evaluation in this study.