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利用能精确捕获水自由液面的VOF(Volume of fluid,体积百分比)法,建立挥发性化合物在无化学反应条件下的耦合扩散时空模型.用W*(分子拓扑指数)表征化合物分子结构,将化合物传质系数——Schmid数与W*进行关联,结合亨利常数、Schmidt数与W*的关联式,预测乙醇、苯、己醛与2,2,4-三甲基戊点源泄漏后的质量浓度时空分布,预测结果与试验吻合较好.烷基苯、醇、醛、烃类化合物的Schmidt数与W*0.25成线性关系.Schmidt数随分子间距减小而增大,烷基苯、醇、醛、烃类化合物在水中的Schmidt数约为空气中的600倍以上.相同W*的化合物,Schmidt数随分子量增加而增大.泄漏初期,亨利常数的作用高于Schmidt数,挥发强度随亨利常数的增加而增大,水中乙醇峰值浓度下降的平均速率仅是苯的45.1%;泄漏后期,Schmidt数起主要作用,挥发强度随Schmidt数减少而增大,苯的峰值浓度下降平均速率降低,乙醇峰值浓度下降平均速率比苯高120.0%.己醛的W*是2,2,4-三甲基戊的16.27倍,但二者的亨利常数和Schmidt数很接近,挥发迁移过程极其相似.
The VOF (volume of fluid) method was used to capture the free surface of water, and the coupling diffusion space-time model was established for volatile compounds under chemical-free conditions. The molecular structure of compounds was characterized by W * (topological index) Compound mass transfer coefficient - Schmid number and W * correlation, combined with the Henry constant, Schmidt number and W * correlation predicts ethanol, benzene, hexanal and 2,2,4-trimethylpentyl source leakage The results showed that the Schmidt number of alkylbenzene, alcohols, aldehydes and hydrocarbons was linear with W * 0.25.The number of Schmidt increased with the decrease of molecular distance, The Schmidt number of alcohols, aldehydes and hydrocarbons in water is about 600 times higher than that in air. The Schmidt number of compounds with the same W * increases with the increase of molecular weight. At the initial stage of leakage, the Henry constant is higher than the Schmidt number, With the increase of Henry’s constant, the average rate of decrease of peak ethanol concentration in water was only 45.1% of that of benzene. In the late stage of leakage, Schmidt number played a major role and the volatility increased with the decrease of Schmidt number. The average rate of decrease of benzene peak concentration Lower, ethanol The average peak fall rate was 120.0% higher than that of benzene. The W * of hexanal was 16.27 times that of 2,2,4-trimethylpentane, but the Henry’s and Schmidt numbers of the two were close and the volatilization processes were very similar.