Heat conduction

Abstract

This chapter discusses conduction heat transfer in a porous medium. For steady heat conduction under local thermal equilibrium conditions, the governing equation for heat conduction in a porous medium can be rewritten in a form similar to classical heat conduction equation with an effective stagnant thermal conductivity consisting of two components: the first component represents the volumetric averaging of the thermal conductivities of the solid and the fluid phases and the second component represents the tortuosity effect because of the undulating thermal path across the fluid-solid interface. Exact numerical evaluations of the thermal conductivities of some idealized two-dimensional, spatially periodic media are also obtained in the chapter based on closure modeling, or solving the two-dimensional conjugate heat conduction problem in the fluid and solid phase of a unit cell. Further various analytical models for the calculation of the stagnant thermal conductivity are also reviewed in the chapter.