Real Gas Effect On Modeling High-Pressure Combustion Reaction Kinetics Of Large Hydrocarbon Fuels

Practical thermo devices usually operates under high-temperature and highpressure conditions,which makes chemical reaction process occur at supercritical and non-ideal thermodynamic state.On the one hand,hydrocarbons are affected by real gas effect and behaves differently in terms of physicochemical properties and fundamental combustion characteristics compared with normal ideal pressures,and large deviation may be caused under normal pressure model or ideal gas equation of state.On the other hand,present experimental and simulation studies,along with software(Ansys Chem Kin Pro),still adopt ideal gas assumptions for the lack of high-pressure chemical kinetic framework.Hence,it is meaningful to develop a high-pressure chemical kinetic framework concerning real gas effect,for the purpose of analyzing the effect of real gas effect on combustion reaction kinetics of large hydrocarbons and predicting the performance of fuels under operation condition in thermo devices.Based on open-source chemical kinetic software Cantera,the high-pressure combustion chemical kinetic framework was developed and constructed in 3 aspects:chemical kinetic modeling,thermodynamic property correlation and transport parameter correlation.For kinetic modeling,simplified high-temperature kinetic model for n-alkanes was developed based on the understanding of high-temperature combustion of large hydrocarbons.Model validation,analysis and simplification were then conducted.For thermodynamic property and transport parameter correlation,with the secondary development of Cantera,real gas equation of state and high-pressure transport model was incorporated.The model was validated to investigate the impact of real gas effect on physical properties and transport properties.The impact of real gas effect on combustion characteristics(including ignition delay time and laminar flame speed)was further investigated,with high-pressure transport model.The results showed that simplified model captured the fundamental combustion characteristics of n-alkanes well under wide-range conditions,which provided universal modeling method for reaction mechanism.Real gas effect under high pressure is notable and should be taken into consideration properly for precise simulations.Nonideal deviation for ignition delay time caused by real gas effect showed strong correlation with temperature and pressure,which was enhanced with the rise of pressure and peaked at negative temperature coefficient region.Unburned gas pressure and temperature are crucial factors in non-ideal deviation for laminar flame speed.Nonideal deviation was pronounced over the critical pressure and slightly decreased with the elevation of temperature.