Thermal conductivity of porous oxide layer: A numerical model based on CT data

Abstract

This paper presents a novel method to determine the effective thermal conductivity of porous oxides formed on steel. This advanced approach enables more accurate numerical modeling of the oxide layer impact on the spray cooling of steel. Although the thermal conductivity of the oxide layer is highly influenced by the porous structure of iron oxides, the microstructure of the oxide layer was generally not considered in the studies of the thermal conductivity. In this paper a detailed 3D finite element model of the oxide layer based on a data acquired by computed tomography was created. The image acquisition and image processing are described. An unconventional method of converting image voxels directly into finite elements was used. Two distinct segmentation approaches were implemented and results of simulations were averaged. Obtained temperature-dependent results of the effective conductivity of the oxide layer was used as an input material parameter for the subsequent numerical simulation of the spray cooling of steel. The impact of the oxide layer with different thicknesses was quantified by plotting the temperature-dependent effective heat transfer coefficient. The limitations of the commonly used alternative analytical approach were identified.