Natural convection heat transfer coefficients in phase change material (PCM) modules with external vertical fins

• Published in: Applied thermal engineering Vol. 28; no. 13; pp. 1676 - 1686
• Main Authors: Castell, Albert, Solé, Cristian, Medrano, Marc, Roca, Joan, Cabeza, Luisa F., García, Daniel
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-09-2008; Elsevier
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Experimental correlation; Heat transfer; Heat transfer enhancement; Nusselt number; Phase change material (PCM); Rayleigh number; Theoretical studies. Data and constants. Metering; Heat transfer enhancement; Phase change material (PCM); Experimental correlation; Nusselt number; Rayleigh number; Geometry; Sodium; Fin; Natural convection; Heat transfer coefficient; Heat transfer; Physical Sciences
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2007.11.004

To determine the heat transfer coefficient by natural convection for specific geometries, experimental correlations are used. No correlations were found in the literature for the geometries studied in this work. These geometries consisted of a cylindrical module of 88
mm of diameter and 315
mm height with external vertical fins of 310
mm height and 20 and 40
mm length. To determine the heat transfer coefficient by natural convection, experimental work was done. This module, containing PCM (sodium acetate trihydrate), was situated in the middle upper part of a cylindrical water tank of 440
mm of diameter and 450
mm height. The calculated heat transfer coefficient changed by using external fins, as the heat transfer surface was increased. The temperature variation of the PCM and the water are presented as a function of time, and the heat transfer coefficient for different fins is presented as a function of the temperature difference. Experimental correlations were obtained, presenting the Nusselt number as a function of different dimensionless numbers. Different correlations were analysed to find which one fit better to the experimental data.