A novel wavy channels triple-tube latent heat storage (LHS) unit accompanied by variable wavelength is examined in charging/discharging mechanisms. The LHS triple-tube LHS unit is filled with phase change material (PCM) in the middle tube while water is passed in the inner and outer tubes as the heat transfer fluid (HTF) in opposite directions. Different wavy configurations with variable sinusoidal wavelength and wave amplitude are studied and compared with the smooth channels unit. The performance of the unit is assessed based on the charging/ discharging time and heat storage/recovery rate using different contour plots for the temperature and liquid fraction. The results show the significant effects of channel waviness on the performance of the system. For the best unit, the charging and discharging times reduce by almost 50% and 48%, respectively, compared with the smooth walls LHS system. Moreover, the rates of heat storage and recovery for the best configuration are increased by 100% and 99%, respectively, compared with the LHS unit with no wavy walls. This study also aims to develop the possibility of the practical application of high-performance LHS units using geometry modification.
