Modelling the Effective Thermal Conductivity in Polydispersed Bed Systems: A Unified Approach using the Linear Packing Theory and Unit Cell Model

Abstract

A comprehensive, unified approach, using the Linear Packing Theory and Unit Cell Model, is proposed for calculating of the effective thermal conductivity of polydispersed packed beds. In this new approach, the effect of packing density is incorporated by the use of (i) an initial porosity to take into account the packing of mono‐sized particles, and (ii) the packing size ratio as a measure of the particle‐particle interaction. The proposed approach was validated with the experimental measurements of binary and ternary beds. This new approach demonstrates that the effective thermal conductivity of beds composed of polydispersed particles can be simulated for any composition without the need to measure the in situ porosity.

Permeability and effective thermal conductivity of bisized porous media

“…ETC (or K e ) of fluid saturated porous media can be experimentally determined by different techniques -in steady state [4] or transient state conditions [5,6], the latter presuming the existence of local thermal equilibrium between the fluid phase and the discontinuous phase [7,8].…”

Measurement and analysis of thermal conductivity of ceramic particle beds for solar thermal energy storage

“…Due to the lack of experimental results, efforts over the last decades have been made to predict the thermal conductivity of the ceramic particle beds using analytical models [20][21][22][23][24][25][26][27][28][29][30][31][32][33] accounting gas and solid conduction and radiation contribution. These models predict the effective thermal conductivity (𝑘 𝑒𝑓𝑓 ) of packed particle beds with sizes, shapes, porosities, packing structures and different materials as input parameters.…”

“…These models predict the effective thermal conductivity (𝑘 𝑒𝑓𝑓 ) of packed particle beds with sizes, shapes, porosities, packing structures and different materials as input parameters. The Zehner, Bauer, and Schlünder (ZBS) model is one of the widely used models, which is constructed based on a representative geometry method [15,[31][32][33] assuming particles in contact within a cylindrical unit cell. Although the ZBS model has been used to predict the thermal conductivity of HSP 40/70 and CP 40/100 [15], it is yet to be validated with experimental measurements.…”