Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements
文章來源： | 發(fā)布時間：2013-06-28 | 【打印】 【關閉】
出版物：Geochimica et Cosmochimica Acta 卷：115 頁：183–204
DOI：http://dx.doi.org/10.1016/j.gca.2013.04.010 出版年份：April 2013
摘要：Accurate values of diffusion coefficients for carbon dioxide in water and brine at reservoir conditions are essential to our understanding of transport behavior of carbon dioxide in subsurface pore space. However, the experimental data are limited to conditions at low temperatures and pressures. In this study, diffusive transfer of carbon dioxide in water at pressures up to 45 MPa and temperatures from 268 to 473 K was observed within an optical capillary cell via time-dependent Raman spectroscopy. Diffusion coefficients were estimated by the least-squares method for the measured variations in carbon dioxide concentration in the cell at various sample positions and time. At the constant pressure of 20 MPa, the measured diffusion coefficients of carbon dioxide in water increase with increasing temperature from 268 to 473 K. The relationship between diffusion coefficient of carbon dioxide in water [D(CO2) in m2/s] and temperature (T in K) was derived with Speedy–Angell power-law approach as:
D(CO2)=D0[T/Ts-1]mD(CO2)=D0[T/Ts-1]m
where D0 = 13.942 × 10?9 m2/s, Ts = 227.0 K, and m = 1.7094. At constant temperature, diffusion coefficients of carbon dioxide in water decrease with pressure increase. However, this pressure effect is rather small (within a few percent).
I.M.Chou(周義明)：博士，資深研究員。1974年獲得美約翰霍普金斯大學地球化學博士學位。常年任海外華人地球科學技術協(xié)會主席。回國工作?；貒熬吐氂诿绹鴩业刭|調查局，從事礦物及天然流體熱力學、地質流體的物理化學、天氣水合物的物理化學及二氧化碳開發(fā)等研究工作。
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