Design of Optimal Micro-Porous Structures for Multiphase Transport

Portland State University, Portland OR

Investigators

Abstract

ABSTRACT National Science Foundation Proposal Number: CTS-0521890 Principal Investigator: Weislogel, Mark M Affiliation: Portland State University Proposal Title: Design of Optimal Micro-Porous Structures for Multiphase Transport Abstract This proposal was received as an unsolicited submission to the Chemical and Transport Systems Division and was funded by the Thermal Transport and Thermal Processing Program. The successful design of optimal liquid propellant storage tanks for spacecraft has produced specific knowledge of capillary flows and phenomena in containers that largely consist of baffles and interconnected interior corners. In the proposed theoretical and experimental investigation, methods of analysis developed for capillary flows in large complex containers in space are applied to microscale networks of interconnected repeat units to develop design methodologies to compute optimal geometries for high performance microporous materials and structures on Earth. The specific objectives of the research focus on the optimization of high performance wick structures employed in advanced two-phase passive cooling systems for microelectronic thermal control. Experimental verification of theoretically determined structures and performance is pursued through fabrication and testing of the media. The research is novel in its representation and use of the governing transport equations in a cell-by-cell approach to compute optimal pore structures in the low saturation limit where the media may be effectively modeled as a nodal network of interconnected interior corners and solved by matrix methods. A close connection between microfabrication methods and theory development is established in this research team providing a foundation from which a comprehensive methodology for cost effective high performance structures can be established. New structures considering benign fabrication methods optimizing fluid flow, heat and mass transfer, thermal capacitance and conductivity, strength, and media mass are pursued as well as methods to analyze traditional randomized media. The 'all analytic' method proposed does not employ empirically determined constants or highly varying numerical coefficients. Example pore geometries solved to date clearly identify the origins of manifold improvements possible in select porous structures. Applications for such methods improve transport processes in porous media, fabrics, fuel cells, membranes, and Lab-On-Chip modules. The impact of this work extends to ground water flows, oil recovery processes, and biological systems. The project will support the work of at least one post-doctoral researcher, one graduate student, and six undergraduate students.