A Comprehensive Investigation of Thermal and Flow-Resistance Behaviour of Metal Based Porous Media

Abstract

This thesis work presents numerical investigation of metal based porous media such as metal foams and stacked wire mesh porous structures, focusing on addressing the issue of incurred flow resistance that is always accompanied with the enhanced heat transfer associated with such media. Key features of porous medium such as their twin structural properties (porosity and pore density), thickness and method of formation (stacking types in terms wire mesh porous structures) are identified as potential influencing parameters that play a key role in the thermo-hydraulic phenomenon. In the first part, influence of porosity and pore density of porous media is demonstrated for their combined effect on flow resistance and heat transfer enhancement behavior. Significance of considering both of these twin structural properties in analyzing the characteristics of porous medium particularly in forced convection regime is further emphasized through Nusselt number correlations. In the second part, thickness of porous medium is considered as another parameter along with the structural properties, and various trade-off scenarios between enhanced heat transfer and incurred flow resistance is comprehensively analyzed. TOPSIS A multi-objective, multi-attribute decision making technique is utilized in this regard, and unique potentials of a porous medium corresponding to its various combination of structural and thickness conditions are evaluated in terms of their ability to minimize flow resistance and maximize heat transfer. In the last part, potentials of stacked wire mesh porous structures are investigated for their various trade-off scenarios between enhanced heat transfer and incurred flow resistance. Expressions pertaining to key morphological features such as porosity, pore density and specific surface area of wire mesh porous structures of various stacking types are derived and used in the porous media modeling to comprehensively analyze the phenomenon of increased pressure drop with increase in heat transfer corresponding to variations in structural properties (porosity and pore density), stacking types and thickness scenarios.