应用MRI研究CO_2在癸烷中的扩散

Diffusion of CO_2 in Decane Studied by Magnetic Resonance Imaging

应用核磁共振成像(MRI)技术可视化研究CO2在癸烷中的扩散,在MRI系统采集图像的同时,应用双室压力衰减法(PVT法)监测压力,通过对MRI图像进行信号强度分析,可得到CO2的无量纲浓度分布,然后基于菲克定律应用有限体积法可计算得出与扩散距离和扩散时间有关的扩散系数,并可得到任意扩散时间范围内的整体平均扩散系数,MRI方法得出的扩散平衡时间范围内的整体平均扩散系数与PVT法相比较误差为2.7%,并且与相似条件下的前人实验结论具有相同的数量级(10–9).根据实验结果得出,扩散系数沿扩散方向下降且随时间以指数形式降低,整体平均扩散系数随扩散时间的增加而减小.

Magnetic resonance imaging （MRI） was used to visualize the diffusion of CO2 in decane, while the pressure was monitored via a double-chamber pressure decay method （PVT）. The signal intensities on the MRI images were analyzed to reveal the distribution of dimensionless CO2 content. Based on Fick＆#39;s law, we computed the diffusion coefficient related to diffusion time and diffusion distance using the finite volume method. The overall average diffusion coefficient can be obtained at any diffusion time. Comparing the overall average diffusion coefficient obtained by the MRI method during diffusion equilibrium time with that obtained by the PVT method showed a 2.7% error. The diffusion coefficient decreased along the diffusing direction, and declined exponentially with time. The overall average diffusion coefficient decreased with the extension of diffusion time. The results obtained in this study were comparable to previous results obtained under similar experimental conditions.