汽油和柴油掺混燃料的着火特性:高压下的点火延迟实验和反应动力学模型的研究

Auto-ignition Characteristics of Gasoline and Diesel Fuel Blends:A High-Pressure Ignition Delay and Kinetic Modelling Study

研究了两种已经认证的汽油和柴油掺混燃料的点火延迟时间。所有的实验测量都在激波管和快速压缩机中完成,实验条件覆盖了宽泛的发动机工况:(φ=0.5~2.0,T=700~1400 K and p=10~20 bar)。此外,测得的点火延迟时间也同另外两个相关的汽油燃料:Coryton汽油和Haltermann汽油的实验结果做了系统性的对比。两种简单的汽油替组分:正标准参考燃料(PRF)和甲苯标准参考燃料(TPRF),以及两个反应动力学模型被用来模拟预测实验结果。实验结果展示出:1)对于各个不同的燃料,压力和当量比对点火延迟时间的典型性影响;2)对于四种不同的燃料,在负温度系数区(700~900 K)的反应活性的较大差异。具体定量的来讲,在温度为750 K时,两种不同的汽油和柴油掺混燃料的点火延迟时间相差为1.5~2.0倍。对于高辛烷值和高敏感性的燃料(Coryton汽油)来说,用甲苯标准参考燃料(TPRF)来模拟的结果显示出非常规的低反应活性,这主要是由于燃料组分中大量的甲苯的存在(77.6%的体积比例)。为了探究此现象背后的反应动力学规律,本文对于甲苯以及甲苯跟烷烃(正庚烷和异辛烷)的相互作用,进行了深入的反应物的浓度消耗曲线,反应通量的分析,以及敏感性分析。

The ignition delay times(IDTs)of two different certified gasoline and diesel fuel blends are reported.These measurements were performed in a shock tube and in a rapid compression machine over a wide range of experimental conditions(φ=0.5-2.0,T=700-1400 K and p=10-20 bar)relevant to internal combustion engine operation.In addition,the measured IDTs were compared with two relevant gasoline fuels:Coryton gasoline and Haltermann gasoline systematically under the same experimental conditions.Two different gasoline surrogates a primary reference fuel(PRF)and toluene PRF(TPRF)were formulated,and two different gasoline surrogate models were employed to simulate the experiments.Typical pressure and equivalence ratio effects were obtained,and the reactivity of the four different fuels diverge in the negative temperature coefficient(NTC)regime(700-900 K).Particularly at 750 K,the discrepancy is about a factor of 1.5-2.0.For the high Research Octane Number(RON)and high-octane sensitivity fuel,the simulation results obtained using the TPRF surrogate was found to be unreasonably slow compared to experimental results,due to the large quantity of toluene(77.6%by volume)present.Further investigation including reactants′concentration profile,flux and sensitivity analyses were simultaneously carried out,from which,toluene chemistry and its interaction with alkane(n-heptane and iso-octane)chemistry were explained in detail.