实际气体效应对碳氢燃料点火延迟时间的影响

Real Gas Effect on Modeling Ignition Delay Time of Hydrocarbons

当前商业软件或数值计算方法基于理想气体假设对点火延迟时间等碳氢燃料基础燃烧数据进行仿真模拟,在高压或超临界压力条件下可能导致较大误差。本研究依托开源化学反应动力学计算平台Cantera,构建了考虑实际气体效应的模拟仿真框架,进行了平台可靠性的验证,计算了丙烷、正庚烷和正十二烷等典型燃料体系在不同压力条件下的点火延迟时间,分析了实际气体效应对碳氢燃料点火延迟时间的影响。结果表明:高压条件下实际气体效应对点火延迟时间的影响较为显著,仿真计算中须考虑该效应以获得准确结果;燃料物化性质的非理想性随压力升高而增加,采用实际气体状态方程可以恰当地描述该变化特征;点火延迟时间的非理想性偏差与压力、温度存在较明显关联,且随着压力升高而单调增大,与温度的关联则呈现非单调性,在负温度系数区域出现峰值。本研究可为碳氢燃料在热力设备高压或超临界压力条件下燃烧反应过程的高精度模拟提供理论支持。

Calculation of ignition delay time(IDT)of hydrocarbon fuels based on ideal gas assumption in combustion kinetic simulation tools or codes may cause notable deviations to lead to the non-ideality under high or supercritical pressure.In this research,a new framework is developed incorporating the real gas effect with an open-source platform Cantera for kinetic simulations.The physical and chemical properties of the hydrocarbons considering real gas effect are investigated and validated against experimental data from literatures.Then propane,n-heptane and n-dodecane are selected as the representative fuels to examine the impact of real gas effect on IDT at pressures ranging from atmospheric to supercritical conditions.The results show that the non-ideality of hydrocarbons is enhanced with the elevation of pressures;the non-ideality of physical and chemical properties of the hydrocarbons is enhanced with the rising pressure,which can be accurately described by real gas equation of state(EOS)instead of ideal gas EOS.The non-ideality deviation of ignition delay time caused by real gas effect strongly relates to pressure and temperature,which is enhanced with the increasing pressure,and peaks appear in negative temperature coefficient(NTC)region.This approach provides a useful framework for accurate kinetic simulation of hydrocarbon combustion reactions under engine-relevant conditions.