Comparison of simplified and solidification-melting model: Numerical simulation with experimental validation

Although the solidification-melting model is accurate, it is too time-consuming and complex to be combined with long-term simulation-building applications. However, the simplified model is necessary for quick performance prediction of the PCM melting process. Therefore, in the present study, several shapes of storage capsules were numerically and experimentally analyzed at various shapes (circular, vertical oval, and horizontal oval), sizes (small and big), and heat transfer fluid (HTF) temperatures to get the differences between the simplified model and the solidification-melting model. There is a good match when the model was validated against earlier work in the literature. The solidification-melting model has a well-matching with the present experimental outcomes. The results showed that the shape of the capsules has a great effect on the melting process, and the horizontal oval capsules have the lowest melting time due to the larger recirculation region in the lower part than in other capsules. Due to the convection effect, the difference between the results of the simplified model and the solidification-melting model exists and increases with increasing capsule size. There is a slight difference between the results of the two models at the low HTF temperature and increases with the rise of the HTF temperature. The horizontal oval capsule has a slight difference between the two models in the small size of 1.94 degrees C, and 2.88 degrees C in the melting and solidification process, respectively. The horizontal oval capsule can be used in long-period building applications of the simplified model to save simulation time with an acceptable error in the melting and solidification process.