EXPERIMENTAL-ANALYSIS AND NUMERICAL MODELING OF INWARD SOLIDIFICATIONON A FINNED VERTICAL TUBE FOR A LATENT-HEAT STORAGE UNIT

The enhancement of heat transfer in a thermal storage system consistin g of a cylindrical vertical tube with internal longitudinal fin arrang ement is discussed in this paper. This configuration that forms a V-sh aped enclosure for the phase change material(PCM) gives maximum benefi t to the fin arrangement. A theoretical model that also accounts for t he circumferential heat how through the tube wall is developed using e nthalpy formulation and is employed in conjunction with the fully impl icit finite difference method to solve the solidification in the conve ctively cooled vertical tube. A generalised enthalpy-temperature (H-T) relationship, developed by Date, is suitable for constant phase chang e temperature and this is modified in the present work to accommodate materials having either constant or a range of phase change temperatur es. The numerical model is validated with experimental data. The insta ntaneous surface heat flux and the solidified fraction for different n umber of fins and tube radii, that are of interest for the design of l atent heat thermal storage system consisting of an array of vertical c ylindrical tubes containing PCM inside it, are also discussed in this article. (C) 1997 Elsevier Science Ltd.