Experimental validation of high-temperature latent heat storage model using melting front propagation data

Abstract

Renewed interest in concentrated solar power has sparked increase in research concerning high temperature phase change materials. A large number of these studies are focused on numerical modeling and heat transfer optimization. However, most of these models are validated using either inadequate (low temperature) experimental data for low-temperature melting or temperature measurements acquired during melting in very specific geometries. The goal of this paper is to help fill the gap in the available experimental data for model validation by providing unique directly measured front propagation data for high temperature phase change materials.The experimental setup for direct melting front propagation acquisition during the sodium nitrate melting is presented. Three experiments with different Rayleigh numbers and orientation are presented. The acquired data was used for numerical model validation. The model was based on the finite volume approach using the frequently used enthalpy-porosity method. It is shown that the best results are obtained using much larger values of the mushy zone constant than those found in literature. Furthermore, by comparing temperature profiles between the experiment and simulations it is shown that temperature measurements (which are one of the most used validation methods) can, in some cases, lead to a false validation.