A numerical investigation of the melting heat transfer characteristics of phase change materials in different plate heat exchanger (latent heat thermal energy storage) systems

•The melting of PCM in a plate heat exchanger(LHTES) systems was numerically investigated.•Melting time decreased with increasing heat transfer fluid inlet temperature.•The melting time was lowest when the steel plate thickness was 0.6 mm.•In terms of PCM, the melting time for n-octadecane was less than that of RT-35.•The melting time for geometry a LHTES was 75% less in comparison to a cylindrical LHTES. In this study, the melting heat transfer in plate heat exchanger LHTES(Latent Heat Thermal Energy Storage) systems was numerically investigated. In the numerical analyses, using the Finite Volume Method (FVM), the phase change process was examined for different heat exchanger geometries (Geometry a, b and c), different heat transfer fluid (HTF) inlet temperatures (52 °C, 57 °C and 62 °C), different steel plate thicknesses (0.4 mm, 0.6 mm and 0.8 mm) and different PCMs(Phase Change Materials) (RT-35 and n-octadecane). The numerical analyses were performed by simplifying the problem down to two dimensions. From the results, time-dependent average PCM temperatures, and liquid fraction contours and graphs were produced. The results showed that for the same PCM, boundary conditions and geometrical characteristics, the complete melting time of the PCM in a plate heat exchanger LHTES system with different geometries could be decreased by 75% in comparison to a cylindrical LHTES system of the same PCM volume. The maximum thermal performance achieved was recorded for the following conditions: Geometry a, a HTF inlet temperature of 62 °C, a steel plate thickness of 0.6 mm and n-octadecane as the PCM.