混配柴油分子系统相容性的分子动力学模拟

Molecular Dynamics Simulation on Compatibility of the Mixed Bio-Diesel Systems

采用分子动力学模拟方法,利用计算得到的溶解度参数,对模拟的石化柴油和大豆油混配柴油系统的相容性进行了研究。选用了几种和模拟系统分子相关的长链烷烃和不饱和脂肪酸甲酯作为参照物,将其模拟溶解度参数计算值和实验或经验值进行了对比,发现偏差较小,验证了文中模拟方法的可信性。然后,构建了由正十六烷模拟的石化柴油和几种不饱和脂肪酸甲酯模拟的大豆油按不同比例混配得到的7种柴油分子系统。对7种系统在293K时的溶解度参数进行了计算,结果发现,混合柴油系统的相容性随大豆油的配比增加呈现先减后增现象,在大豆油的物质的量比约0.6左右,系统的溶解度参数出现了最大的正偏差,表明此时两种油的相容性最佳。本结论将为柴油的混配研究提供一定的理论参考。

The compatibility of the modeled mixed diesel system of petrochemical diesel oil and soybean oil were studied by comparing the solubility parameters calculated with molecular dynamics simulation method.Several long chain alkanes and unsaturated fatty acid methyl esters which are similar to the molecules in simulating systems were chosen as references.By comparing the calculated values of solubility parameter of the references with their experimental or empirical ones,small deviations were found,and this verified the reliability of the simulation method.By regarding n-hexadecane as a representative of petroleum diesel（A）and the mixture of several unsaturated fatty acid methyl esters as a representative of soybean oil（B）,seven diesel molecular systems were established at different proportion of A and B.Then,the solubility parameters of each system at 293Kwas calculated.The results showed that,with increasing ratio of soybean oil,the compatibility of blended diesel system decreases then increases,and the maximum positive deviation of the solubility parameter is achieved in soybean oil molar ratio of about 0.6,which showed that the compatibility of two oils is best at this time.This conclusion will provide some theoretical reference for the diesel mixing research.