An Experimental Study of Reaction - Coupled Flow and Mass Transport in Porous Media

本实验研究了多孔介质中流动和反应物质的耦合过程。令人感兴趣的是反应传输过程，它涉及通过密度效应和可能改变介质水力特性的多相化学反应的耦合。本研究的目的是提供有关反应耦合传质的基础知识。用流动槽进行的二维和三维实验将用来阐明多孔介质中反应前沿和流体化学的时空演变，并解释密度驱动流动和反应传质之间存在的反馈的性质。实验将包括将稀释的Fe(CIO4)3溶液通过石英砂和少量粉碎的方解石的混合物泵送。溶液的初始酸度会促进方解石的溶解，导致氢氧化铁的析出。由此产生的孔隙堵塞将导致水力传导性模式，并改变流经储罐的流体的路线。这些图案可以在二维实验中以照片形式记录下来。三维实验在技术上更具挑战性，需要用现场水力传导性测量和永久安装的电极阵列的电学测量来描述反应前沿。这项研究建立在我们对变密度流中不稳定性的研究基础上，并将在耦合过程和污染物支持的实际问题这一新兴领域贡献新的知识。

This experimental study investigates coupled processes of flow and reactive mass in porous media. Of interest are reactive transport processes that involve coupling both through density effects and heterogeneous chemical reactions that may alter the hydraulic character of the medium. The goal of this study is to contribute fundamental knowledge concerning reaction-coupled mass transport. Two and Three-dimensional experiments with flow tanks will be used to elucidate the time-space evolution of reaction fronts and fluid chemistry in porous media, and to interpret the nature of the feedbacks that exist between density-driven flow, and reactive mass transport. The experiments will involve pumping a dilute Fe(CIO4) 3 solution through a mixture of quartz sand and a small quantity of crushed calcite. The initial acidity of the solution will promote calcite dissolution and lead to the precipitation of ferric oxyhydroxide. The resultant pore plugging will result in patterning in hydraulic conductivity and reroute fluid flow through the tanks. These patterns can be documented photog raphically in two-dimensional experiments. The three-dimensional experiments are technically more challenging and require that reaction fronts be described with both in situ hydraulic conductivity measurements and electrical measurements with a permanently installed electrode array. This research builds on our studies of instabilities in variable density flows, and will contribute new knowledge in the emerging area of coupled processes and practical problems of contaminant support.