EXPERIMENTAL ANALYSES AND NUMERICAL SIMULATIONS OF PARAFFIN AS A PHASE CHANGE MATERIAL WITH FILLERS OF Al2O3, TiO2, AND MgO IN A RECTANGULAR ENCLOSURE

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Thermal management is a very important factor in renewable energy devices that generate heat, such as fuel cells, solar cells, and lithium batteries. The cooling device of a system needs to be explored by implementing new technology, such as phase change materials (PCMs). PCMs can dissipate the heat passively due to their natural behavior of melting and solidification. In the present study, we synthesized, characterized, and developed numerical simulations (computational fluid dynamics) of paraffins as phase change materials (PCMs) with fillers of Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and MgO (10 and 20 vol.%) in a rectangular enclosure. The addition of particles could improve the thermal conductivity to effectively remove the heat that PCMs absorbed by improving the melting rate. The characterizations of the PCMs included scanning electron microscopy (SEM), density, differential scanning calorimetry (DSC), thermal conductivity, and specific heat. These properties obtained from the characterizations were used as input parameters in the numerical simulations. The two-dimensional numerical model has a geometry of 12 × 50 mm, where a heat flux of 1150 W/m<sup>2</sup> was applied as a heat source on one side (left wall). The other three sides of the top, bottom, and right walls were perfectly insulated to minimize heat loss. The numerical model was validated using an experimental investigation (paraffin melting in a rectangular enclosure) to compare the melting behavior as a function of time. The PCMs characterizations confirmed that the addition of fillers (20 vol.%) to the PCMs as a matrix enhanced the thermal conductivity up to 0.473, 0.406, and 0.466 W/m K for the Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and MgO fillers. However, the latent heat decreased to 80.10, 65.79, and 62.58 J/g for the Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and MgO fillers, respectively. The results suggested that the simulation results are in good agreement with the experimental test results. Therefore, the model was further developed to analyze the effect of material fillers in the PCMs. According to the melting contours, PCMs with 20 vol.% of MgO additives have a faster melting rate and larger cooling area than other samples due to their higher thermal conductivity.