Impact of fin type and orientation on performance of phase change material-based double pipe thermal energy storage

In this study, a numerical analysis using computational fluid dynamics (CFD) is performed on a proposed horizontal concentric (DPHX) filled with N-eicosane phase change material (PCM), investigating the impact of fin type and orientation, on charging (melting PCM) and discharging (solidification PCM). In this study, various Cases including fin orientation (longitudinal and transversal arrangement) and fin types (corrugated and flat fins) are simulated and compared for best thermal and heat transfer performance. The results captured are based on Liquid Fraction, temperature, and velocity streamline contour illustrations. The contours show that natural convection positively affects the melting performance in the upper region during the melting/charging process, however, conduction is the main mode of heat transfer in the solidification/discharging process. For the melting process, the transversal corrugated fin arrangement outperforms the other Cases with over 88% reduction in melting time as opposed to the unfinned base Case. The longitudinal corrugated fin Case had a 58% reduction in melting time, which was 2% slower than the longitudinal flat fin Case and overall, transversal corrugated fin Case 11.5 times faster than unfinned Case. In the solidification process, the transversally arranged fins releases the stored energy at a faster rate with reduced time for total solidification. The longitudinal flat finned Cases perform similarly for discharging with improved discharging rate and slightly less solidification time than the unfinned Case. The transversal corrugated fin design is shown to have greater improvement in charging and discharging compared to all other Cases, with the shortest overall processing time. Significant results are also seen in the total process time with the longitudinal flat finned arrangements 1.2 times faster and the transversal flat finned arrangements 8.7 times faster than the unfinned Case.