Effect of twisted fins on the melting performance of PCM in a latent heat thermal energy storage system in vertical and horizontal orientations: Energy and exergy analysis

Abstract

• Performance of a LHTES unit in the presence of twisted fins is studied. • Different number of fins in vertical and horizontal orientations were considered. • Paraffin wax was used as PCM. • Triple fin and double fin outperformed other cases in vertical and horizontal cases. • The best case is a trade-off between the fin number and length of fins. Solar energy and other renewable energy resources are of great importance to solve the energy crisis in the 21th century. In this regard, the energy storage systems play a vital role as a means of harnessing solar energy. In this study, performance enhancement of a shell and tube latent heat thermal energy storage (LHTES) system in terms of energy and exergy has been assessed by implementing twisted fins in a PCM enclosure with both vertical and horizontal orientations by using Finite Volume Method and the Enthalpy-Porosity method has been used for simulating the melting process. The fins have constant heat transfer surface with different configurations including single, double, triple and quadruple fins along with a case study about effect of penetrating the fin inside the tube. Paraffin wax was used as PCM. The results have been presented in terms of melt fraction, temperature and velocity magnitude contours, melt fraction and temperature curves, average Nusselt number and total melting time for both horizontal and vertical orientations. In order to better evaluate the optimizations made, exergy analysis has also been performed and the exergetic efficiency has also been presented. It was revealed that the triple fin in vertical orientation and double fin in horizontal orientation have the best effect on melting enhancement of PCM with 11.2% and 10.7% of enhancement in melting time in comparison with the worst finned case, and 37.4% and 30.5% enhancement in comparison with the base case. It was also shown demonstrated that the triple fin in vertical orientation and double fin in horizontal orientation have the best exergy efficiency.