Annabelle Joulin

A numerical study of the melting of phase change material heated from a vertical wall of a rectangular enclosure

This article presents the first research effort of our group to formulate, implement and validate a numerical method in order to optimise the design of solar passive walls involving phase change materials (PCMs). The fusion of ice, gallium and the commercially available PCM 27 (hydrated salt), engineered by Cristopia and later embedded within an experiment unit, was studied. Comparisons against other prediction methods and experimental data for the fusion of gallium were carried out with good agreement of the solutions. The proposed enthalpy-based method is found to be excellent to predict the fusion, but still fails to reproduce adequately the exact solidification pattern measured for the PCM 27. Further research is going on to improve the model.

TURBULENT FORCED CONVECTION IN A HORIZONTAL CHANNEL WITH RECTANGULAR OBSTACLE

This paper presents a numerical investigation of turbulent forced convective f low in a horizontal channel filled with rectangular obstacles located on the lower surface. An exchanger isothermal test plate is embedded in the lower wall, in the fully developed region of the flow. Immediately above this plate, on the upper surface, a black coated isothermally heating resistance facing downwards is installed. This perfectly absorbing surface provides a controlled radiative heat flux on the lower test plate. In this study, custom-built tangential gradient fluxmeters (TGFM) are used to provide local measurements of convective heat transfer so as to validate the numerical predictions. Then, parametric studies are carried out. The profiles for the heat flux densities are presented for different Reynolds numbers in the flow direction along the cold isothermal lower plate. The influence of the presence of an obstacle on the heat flux densities is also investigated. All numerical predictions are carried out with Fluent, previously calibrated against benchmark problems and experimental measurements. In the paper, special emphasis is given in the systematic comparison between experimental and numerical results.