Molecular dynamics simulation of infinite dilution diffusivity of carbon dioxide in supercritical water
Molecular dynamics simulation of infinite dilution diffusivity of carbon dioxide in supercritical water
复制标题
超临界水中二氧化碳无限稀释扩散系数的分子动力学模拟
DOI：
10.1142/s021797921850296x
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发表时间：
2018-10
影响因子：
1.7
通讯作者：
Xin-Rong Zhang
中科院分区：
文献类型：
--
作者：
Shengjia Cai;Zhan-Chao Hu;Jiawei Li;Yan-Ling Zhan;Xin-Rong Zhang
我们采用平衡分子动力学模拟研究无限稀释扩散系数的二氧化碳在近和超临界水（SCW）在宽的温度范围从647至973 K在115，217，426和663公斤/立方米。用Einstein均方位移法计算了超临界水的扩散系数和二氧化碳的无限稀释扩散系数。结果表明，超临界水中CO2的IDDC比正常水中高1-2个数量级。对二氧化碳的IDDC的温度依赖性的分析表明，它们不符合Arcidius方程。在近临界区，二氧化碳的IDDC并不随温度的变化而单调变化，而是在远离临界状态的区域随着温度的升高而逐渐增加。二氧化碳在超临界水中扩散的温度依赖性的异常可以用不同状态水的微观结构特征来解释。此外，我们观察到，在相同的条件下，氧气的IDDC略大于二氧化碳。
We apply equilibrium molecular dynamic simulations for investigating the infinite dilution diffusivity of carbon dioxide in near- and supercritical water (SCW) over the wide temperature ranging from 647 to 973 K at 115, 217, 426 and 663 kg/m3. The diffusion coefficients of SCW and infinite dilution diffusion coefficients (IDDCs) of carbon dioxide are calculated by using the Einstein mean-square displacement method. It is observed that the IDDCs of carbon dioxide in SCW are approximately 1–2 orders of magnitude higher than that in normal water. The analysis of the temperature dependence of the IDDCs of carbon dioxide reveals that they do not conform to the Arrhenius equation. In the near critical region, the IDDCs of carbon dioxide do not exhibit a monotonic change with a variation in temperature, but increase gradually with an increase in the temperature in a region far from the critical state. The anomaly of the temperature dependence of the diffusion of carbon dioxide in SCW can be explained using the microstructure features of the different states of the water. In addition, we observe that the IDDCs of oxygen are slightly larger than those of carbon dioxide under the same conditions.
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