高浓度CO2氛围下柴油表征燃料着火和燃烧机理研究

研究发现液氧固碳闭式循环柴油机能够有效解决封闭空间CO2排放问题，但其在变工况时失火严重，亟需解决其着火和燃烧稳定性问题。申请项目拟通过平面激光诱导荧光测试技术和高速摄影/纹影法，利用得到的温度等信息，研究高浓度CO2氛围下两种柴油表征燃料（正庚烷，70%正庚烷+30%甲苯）的详细化学反应，结合热力学等规律，推导并解析着火延迟时间模型、连续流动体系下温度方程，获得温度失火边界；结合从头算过渡态理论的主方程方法，探索高温条件下CO2与表征燃料相互作用的新反应路径，获得高精度反应速率常数；结合稳定状态法，构建完整的CO2与表征燃料的反应机理；考虑柴油机缸内温度强瞬变特性的影响，采用概率密度函数方法，构建温度脉动作用的反应速率方程，提出模拟、封闭方法，并结合发动机台架实验，对模型进行检验、修改和优化，实现瞬变条件下准确预测高浓度CO2氛围下柴油表征燃料的着火、失火边界和燃烧。

The study found that the closed cycle diesel engine using liquid oxygen to solidify carbon can reduce the CO2 emission in the closed space effectively, but it has serious misfire problem in variable working conditions. It is necessary to solve the scientific problems of stability of ignition and combustion. The project is intended to use planar laser induced fluorescence testing and high-speed photography/schlieren method to study the effect of high concentration of CO2 on the detailed elemental reactions of two diesel surrogate fuels (n-heptane, 70% n-heptane + 30% toluene) with obtained temperature and other information. The ignition delay time model and temperature equations under the continuous flow system are analyzed to obtain the temperature misfire boundary using thermodynamics and other laws. Combining the master equation approach of beginning method and transition-state theory, the new reaction paths of CO2 and diesel surrogate fuels interaction under high temperature conditions are explored and high-precision reaction rate constants are obtained. Complete reaction mechanism of CO2 and surrogate fuels are constructed with steady state method. Considering the influence of temperature transient characteristics in diesel engine cylinders, it is proposed to use the probability density function method to construct the reaction rate equations for temperature pulse actions. The simulation and sealing methods are proposed, and the engine bench test is combined to test, modify and optimize the model to predict the ignition of diesel surrogate fuels, misfire boundary and combustion in high concentration of CO2 with transient conditions accurately.