分子水平预测汽油馏分的蒸气压

Prediction of the Vapor Pressure of Gasoline at a Molecular Level

依据汽-液相平衡,建立了由汽油馏分的分子组成预测其蒸气压的计算模型。该模型将汽油馏分简化为烃化合物的理想混合物,不考虑空气和水的影响,计算了密闭容器内的汽油在某指定温度和充满率下,达到闪蒸平衡时的蒸气压。该计算方法可用于预测与燃料蒸发性相关的参数如雷氏蒸气压(RVP)、蒸发损失等。利用该算法计算了5个已知组成的汽油样品的RVP,与实测值相比较,平均相对误差低于10%。

Based on the principle of vapor-liquid phase equilibrium, a mathematical model of evaporation of gasoline fuel was built at a molecular level. A flash equilibrium was calculated for gasoline fraction of known molecular composition at a specific temperature in a closed container. The assumption of the proposed model is that the gasoline is considered as an ideal hydrocarbon mixture free of water and air. The model outputs are the fuel parameters such as vapor pressure （including RVP）,evaporation emission and other fuel characteristics. The calculation results were validated by a comparison with measured values from five gasoline samples. Good agreement was found with the average relative error less than 10 % between the measured RVP values and calculated values.