(416e) A Numerical Model of Chemically Reacting Flow through Additively Manufactured 3D Structures

There is currently a ubiquitous reliance on randomly packed powders in chemical reactors, separation columns, and other devices that manipulate fluid flow and reactive species transport. Replacing randomly arranged materials by deterministically fabricated devices with optimized geometries achieves major performance and efficiency improvements. Notable examples can be found in gas chromatography, microfluidic medical devices, and recently emerging "3D battery" structures. We explore additive manufacturing as a means to achieve such deterministic structures, and their potential benefits for exchange chromatography columns. Exchange chromatography is of scientific interest because the second-order chemical reaction between phases results in a theoretically infinitely sharp boundary that does not broaden as it progresses, although broadening mechanisms do occur in practice, and are easily studied. In our case, we examine the exchange of hydrogen and deuterium with a hypothetical 3D-printed metal hydride column in a coupled reaction and diffusion-convection numerical model. We aim to design, as a proof of principle, a hydrogen-deuterium separation column that achieves more sharply defined separations at a lower pressure drop than a similarly sized packed-powder column. Our results suggest that a front can be obtained in a hypothetical 3D structure, and that it is sharper than the one obtained in a 1D structure for the same pressure drop. Other preliminary results suggest that 1D arrays with defective pores result in broad fronts in the total flow due to varying flow rates between the tubes, whereas the 3D structure will allow mixing between inhomogeneous regions, maintaining a sharp front.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.