A sub-pore model for multi-scale reaction–diffusion problems in porous media

Journal Article · Fri Jan 23 00:00:00 EST 2015 · International Journal of Heat and Mass Transfer

DOI:https://doi.org/10.1016/j.ijheatmasstransfer.2014.12.034· OSTI ID:1225774

Nagendra, Krishnamurthy ^[1]; Tafti, Danesh K. ^[1]

---

1. National Energy Technology Laboratory (NETL), Pittsburgh, PA, (United States); Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA (United States)

Applications of reaction–diffusion systems in porous media pose a challenging problem for computational modeling approaches due to their multi-physics and multi-scale nature. The length scales usually span 3–4 orders of magnitude while physical phenomena involved include heat and mass transfer processes, and surface reactions. In this paper, a novel methodology that accounts for all the length scales and physical phenomena involved in a single framework is described. A length scale based dual approach is proposed – the larger pore channels (macro-pores) are resolved using conventional numerical techniques and a novel ‘sub-pore’ model is used to account for the unresolved pore channels (sub-pores) and the important physics therein. The porous network in the sub-pore system is composed of a fractal-like hierarchical system of straight cylindrical pores. Simplified governing equations for mass and energy transport are solved within the sub-pore system along with a reaction kinetics model to account for surface adsorption. An implicit coupling strategy is used to couple the macro-pore and the sub-pore systems so as to ensure conservation. The developed methodology is then applied to a few test cases and it is established that the proposed framework is necessary for problems where the adsorption time scale is much smaller than (diffusion-limited) or comparable to the diffusion time scale. Furthermore, it is also demonstrated that the framework can be potentially used to model the network of porous channels in its entirety thus significantly reducing computational costs.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• Grant/Contract Number: FE0004000
• OSTI ID: 1225774
• Report Number(s): A-UNIV-PUB--133; PII: S0017931014011429
• Journal Information: International Journal of Heat and Mass Transfer, Journal Name: International Journal of Heat and Mass Transfer Journal Issue: C Vol. 84; ISSN 0017-9310
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Knudsen effects
heat and mass diffusion
porous media
reaction–diffusion systems
surface adsorption