Investigation of the volume impact on cascaded latent heat storage system by coupling genetic algorithm and CFD simulation

A cascaded latent heat storage (CLHS) system has been proven to have obvious advantages in improving the heat transfer rate and heat storage capacity. However, in all studies in the literatures, on CLHS system, the PCM at each stage is evenly distributed. The influence of PCM volume distribution on the performance of a CLHS system has not attracted much attention. In this study, a CLHS exchanger with double heat transfer fluid channels is designed, and the volume distribution is optimized innovatively by coupling genetic algorithm and the CFD simulation. The effects of different performance indicators on the optimization results are also explored. The results show that the heat storage performance of a CLHS system can be improved by optimizing the volume distribution. Compared with charged energy and entransy, the charged exergy as the optimization performance indicator has more performance benefit with more uniform PCM volume distribution. Under the constraint of a fixed total PCM volume, the optimal volume ratios of the individual cascaded PCMs at stage-1, stage-2 and the stage-3 are 15.63%, 42.37% and 42.00%, respectively. Compared with the non-cascaded latent heat storage system, the charged energy, exergy and entransy of the optimized system increase by 13.79, 14.85 and 14.45%.