PCM Melting Process in a Quadruple Tube Heat Exchanger using Ansys Software

Thermal energy storage (TES) effectively contributes in the energy efficiency improving and the energy supply/demand discrepancy eliminating of solar thermal technology. Among the different types of TES, phase change materials (PCMs) exhibit a high thermal energy density per unit mass. The present work numerically investigates the melting process of PCM (RT82) in a quadruple tube heat exchanger (QTHX). ANSYS (Fluent) version 18.2 software program is used to develop a 2D numerical model for the melting process of the QTHX, and pure conduction and natural convection are considered in the simulation. Two models of QTHXs are studied with respect to the PCM position in the tubes. In model (a), the PCM inserted in the first tube and the third tube while in model (b), the PCM inserted in the second tube and the fourth tube. Moreover, the melting process of the QTHX is compared with a triplex tube heat exchanger (TTHX) and double pipe heat exchanger (DPHX). The computational results indicated that the melting rate of model (b) was achieved in a 63.2% of that of model (a). In addition, the results indicated that PCM was melted earlier in the QTHX compared to TTHX and DPHX. The numerical model was validated with a previous experimental work. Numerical results show a consistent agreement with the experimental results.