Effect of using external vertical fins in phase change material modules for domestic hot water tanks.

Abstract

The effect of using external vertical fins in Phase Change Materials (PCM) modules to improve the natural convection coefficient in water is studied in this paper. The use of PCM in a water tank working with a solar system is able to store a lot of energy, but it is necessary to transfer this energy to the water during demand. Optimization of the natural convection to the water is of great importance for the heat transfer. External fins increase the heat transfer surface and the heat transfer coefficient changes. Experimental work was carried out to determine natural convection heat transfer coefficients for PCM modules with two different external vertical fin geometries. Results were presented as a temperature variation over time of the PCM and the water, and the heat transfer coefficient as a function of the temperature difference for different fins. These results were used to validate a simulation code to determine the behaviour of the system using finned PCM modules. The results prove the technical potential of external fins for heat storage systems using PCM. The experimental results were used to determine different correlations for Nusselt number as a function of different dimensionless numbers.

Effect of Perforated and Smooth Fins on Thermal Performance of a Latent Heat Energy System

“…because of high specific heat [16]. However using of (PCM) for heating the water in a solar system had been investigated in many studies [12]. The solidification process within PCM is started directly after the melting process is completed and started around 60•C.…”

“…The second phenomenon about the solidification of molten paraffin, that the paraffin contacted with the pipes will solidify faster than the other inside the capsule because of the fast loss of wax heat to the cold water through the pipe as shown in figure (12). This is the main snag that preventing using all the heat in the molten paraffin, some of which were exceeded by placing fins to take advantage of the thermal energy in the melting paraffin wax distanced from the tube.…”

“…The technique of finned tubes is one effective and reliable of these methods [8] [9] [10] while the perforated fins is one of the enhancement method of heat transfer [11]. (Castell, et al,) [12] studied the effect of using vertical external fins in PCM units to increase the heat transfer coefficient as natural convection in the water. Paraffin wax was used as phase change material with a solar unit.…”

Review on Phase Change Materials in Thermal Energy Storage System

“…The PCM is embedded inside a graphite matrix to increase the thermal heat conductivity in the PCM without much reduction in energy storage. Albert Castell et al [8] designed hot water storage tank and determine natural convection heat transfer coefficients. The system consists of PCM cylindrical modules with two different external vertical fin geometries.…”

Modelado Y Análisis De Un Depósito De Almacenamiento Latente De Energía Térmica Con Intercambiador De Tipo Serpentín

“…Entre los modelos de geometrías aleteadas se encuentra el modelo analítico de Lamberg [41] en el que hace uso del método de capacidad calorífica efectiva. Castell et al [42] realizaron un modelo de módulos de PCM con aletas externas situados en tanques de agua. Ismail et al modelaron la solidificación de PCM alrededor de tubos aleteados tanto radial [43] como axialmente [44], y Kayansayan y Acar [45] modelaron la formación de hielo en un intercambiador de tubo aleteado.…”