二氧化碳在水中扩散系数的实验测定和计算

The Experimental and Modeling Studies on the Diffusion Coefficient of CO_2 in Pure Water

当二氧化碳注入海底后,液体二氧化碳或者二氧化碳水合物能否稳定存在,其中重要的参数之一就是不同情况下二氧化碳在液体中的扩散系数。在水温4～30℃,压力为1MPa下,用自制的实验设备测量了二氧化碳的扩散系数。结果表明,在高压条件下,扩散系数是一个与浓度有关的量。根据短时间内扩散量与时间平方根之间存在着线性关系,引入不定函数描述与浓度有关的扩散过程,得到了二氧化碳-水体系与浓度相关的扩散系数的数据,并拟合得到了所研究情况下二氧化碳的扩散系数与温度、浓度等因素之间的计算式。

When carbon dioxide was injected into the seafloor,the diffusion coefficients of carbon dioxide in the water under different conditions,is one of the important parameters to decide whether liquid carbon dioxide or carbon dioxide hydrate can exist stably or not.In the project,the diffusion coefficients of carbon dioxide in the water were measured at 4~30 ℃,with the pressure under 1 MPa.The results show that the diffusion coefficient is a parameter related with concentration in high pressure condition.By Importing the indeterminate function to describe the process of diffusion related with concentration,the data that refers to diffusion coefficient of carbon dioxide-water system were obtained and the calculated mode that contains the relationships between carbon dioxide＇s diffusion coefficient and temperature,concentration was fitted on the base of linear relation of short-time diffusing capacity and the root of time.