Soret effect on the diffusion of CO2 in aqueous solution under high-pressure
Soret effect on the diffusion of CO2 in aqueous solution under high-pressure
复制标题
DOI：
10.1016/j.ijheatmasstransfer.2017.10.058
复制
发表时间：
2018-02
影响因子：
5.2
通讯作者：
Huirong Guo;Qian Zhou;Zhe Wang;Yiqian Huang
中科院分区：
文献类型：
--
作者：
Huirong Guo;Qian Zhou;Zhe Wang;Yiqian Huang
在石英毛细管中，研究了20和30 MPa压力下CO2在水溶液中的扩散溶解过程。通过定量拉曼光谱同时测量温度和浓度分布。在稳态条件下，CO2饱和浓度沿水平方向温度梯度沿着分布的热力学分布表明，热力学贡献占主导地位，动力学贡献可以忽略不计。基于稳态热力学饱和浓度分布假设，计算了0.1 ~ 50 MPa、273.15 ~ 623.15 K压力范围内溶解CO2的Soret系数（热扩散系数与质扩散系数之比，ST）。在恒定压力下，ST表现出“V”形的温度的非单调函数，最小值在T0。温度T_0（ST最小值）随压力的增加而增加，ST随压力的增加而减小，当压力大于7.5MPa时，在T_0附近温度范围内，ST可由正变负。Soret系数在CO2临界点附近是不连续的。
Diffusive dissolution processes of CO2into aqueous solution subjected to temperature gradients were investigated under 20 and 30 MPa in a silica capillary tube. The temperature and concentration profiles were measured simultaneously by quantitative Raman spectroscopy. Thermodynamic CO2saturated concentration profiles along the temperature gradients in horizontal direction at steady state were observed, which indicates that the thermodynamic contribution is dominant and kinetic contribution can be neglected. Based on the assumption of thermodynamic saturated concentration profile at steady state, Soret coefficients (the ratio of the thermal and mass diffusion coefficients,ST) of dissolved CO2were calculated atP-Tranges from 0.1 to 50 MPa and from 273.15 to 623.15 K. At constant pressure,STshows a “V” shaped non-monotonic function of temperature with a minimum atT0. The temperatureT0(at whichSTreaches its minimum value) increases with increasing pressure.STgenerally decreases with increasing pressure, and could change sign from positive to negative in the temperature ranges aroundT0at pressures higher than 7.5 MPa. Soret coefficients are discontinuous near the critical point of CO2.