Simulation of PCM Melting and Solidification in a Partitioned Storage Unit

Abstract

The present study explores numerically the processes of melting and solidification of a phase change material (PCM). The material used was a commercially available paraffin wax, which is non-toxic, recyclable, chemically inert, non-corrosive and can withstand an unlimited number of cycles. The phase-change material was stored in a rectangular box, open at the top. The bottom of the box could be heated or cooled. The inner space of the box was partitioned by vertical conducting plates attached to the bottom. Thus, heat was transferred to and from the PCM both through its melted/solidified layer and by conduction through the vertical plates. Transient two-dimensional numerical simulations were performed using the Fluent 6.0 software. The melting temperature of the wax, 23–25°C was incorporated in the simulations along with its other properties, including the latent and sensible specific heat, thermal conductivity and density in solid and liquid states. The simulations provided detailed temperature and phase fields inside the system as functions of time, showing evolution of the heat transfer in the system as the phase change material melts/solidifies. The dependence of the heat transfer rate on the properties of the system and on the PCM phase composition at various time instants is presented and discussed.

Numerical investigation of a PCM-based heat sink with internal fins

“…As the width decreases, Figs. 7 and 8, the phase distribution becomes similar to that observed in the preliminary study by Shatikian et al [30], where a wedge-like solid phase is at the top and the liquid is at the base. In other words, for the ''thick'' fins melting is almost uniform along the fin surface, while for the ''thin'' ones melting takes place mostly close to the base.…”

“…Hence, the liquid PCM and air are shown by the same color and the PCM-air interface does not appear in the figures. Its level rises constantly during the melting, as shown in a previous study by Shatikian et al [30]. temperature, DT, half-thickness of the PCM layer, l b /2, and the thermal conductivity of the PCM, k PCM .…”

“…As shown by Shatikian et al [30], in the large system heat was transferred to the PCM mostly through the conducting partitions, while the heat transfer directly from the heated base was less significant. For a small system considered here, the results are similar, but not identical for the systems of different thicknesses: when the PCM layer between the fins is thick, the fraction of the total heat which is transferred from the base directly to the PCM increases.…”

“…This approach has been implemented successfully in the previous study by Shatikian et al [30], where the processes of melting and solidification of a PCM have been studied numerically in one specific geometry, namely a partly enclosed space having vertical conducting plates attached to the base, which could be heated or cooled. Detailed temperature and phase fields have been obtained as functions of time, showing evolution of the heat transfer in the system as the phase-change material melts/solidifies.…”

Energy and exergy performance assessments for latent heat thermal energy storage systems

“…Regarding the latent TES investigations, there exist the comprehensive case studies with various PCMs and their applications, from experimental tests [4][5][6] to mathematical simulations [7][8][9]. More importantly, there are some TES review articles written by Farid et al [10], Sharma and Sagara [11], Kenisarin and Mahkamoy [2], Li et al [12,13].…”