摘要
采用SPC/E-UA、SPC/E-AA、TIP4P-UA和TIP4P-AA分子模型研究了NVE系综下甲烷水合物的微观分解特性。对比分析了不同模型下水合物的平衡温度及分解热。研究了F3随空间及时间的变化,对液态水-水合物的界面进行了界定。比较了不同区域的势能的变化规律,发现分解过程具有显著的非平衡传热特性。分析了水和甲烷密度的空间分布规律及逸出的甲烷分子数随时间的变化规律,发现甲烷逸出速度逐渐减小。对不同模型下分解所需的活化能进行了计算,并与实验值进行对比。对比不同区域均方位移及扩散系数发现分解呈现显著的非平衡传质特性。研究表明甲烷分子模型对分解影响甚微,而水分子模型影响较为明显,在NVE系综下通过SPC/E模型表征的平衡温度、活化能及分解热与实验值更加吻合。
The microscopic nature of methane hydrate decomposition is simulated in NVE ensemble by SPC/E-UA,SPC/E-AA, TIP4P-UA, and TIP4P-AA molecular models. The equilibrium temperature and decomposition heatunder different models are calculated and comparatively analyzed. The hydrate-liquid water interface isdistinguished by calculating order parameter F3, and the time-varying and space-varying hydrate-liquid boundaryis monitored. The variations of potential energy at different zones are compared which indicate the decompositionprocess has significant non-equilibrium heat transfer characteristics. The spatial density distribution of hydratewater and methane is contrastively analyzed and the variation of the number of methane molecules that escape fromthe methane hydrate during decomposition is determined. It’s found that the escape velocity decreases graduallywith decomposition. The activation energies required for decomposition under different models are calculated andcompared with the experimental results. By comparing the mean square displacements and diffusion coefficients indifferent decomposition regions, it’s found that the decomposition exhibits significant non-equilibrium mass transfercharacteristics. The study shows that the methane molecular model has little influence on decomposition, while thewater molecular model has observable influence. The SPC/E water model can better reproduce the experimentalvalues of equilibrium temperature, activation energy and decomposition heat in methane hydrate decomposition under NVE ensemble.
作者
李佳
梁贞菊
王照亮
赵健
唐大伟
LI Jia;LIANG Zhenju;WANG Zhaoliang;ZHAO Jian;TANG Dawei(New Energy College,China University of Petroleum,Qingdao 266580,Shandong,China;School of Energy and Power Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2020年第3期955-964,共10页
CIESC Journal
基金
国家自然科学基金项目(51876223,U1262112)
中央高校基本科研业务费专项资金(18CX06035A)。
关键词
分子模拟
分解
水合物
势函数
界面
平衡温度
molecular simulation
decomposition
hydrate
potential function
interface
equilibrium temperature
