Revolutionizing latent heat storage: boosting discharge performance with innovative undulated PCM container shapes in vertical shell-and-tube systems

This paper examines the impact of various parameters, including frames, zigzag number, and enclosure shape, on the solidification process and thermal energy storage rate of phase change materials (PCM). The study also assesses the effects of the flow rate of the heat transfer fluid as well as changing the materials of the PCM between RT35 and RT35HC. In addition, the study compares the framed vs unframed systems and, subsequently, the best case was tested with various zigzag pitch numbers before changing the zigzag shape structure to arc and reversed arc. The findings are examined by contrasting the different scenarios' liquid fractions, temperature distributions, solidification rates, and heat storage rates. The results show that the framed geometry is 66% faster to reach the target temperature compared to the unframed geometry and employing a zigzag enclosure in a PCM can significantly improve its solidification time and heat recovery rate. As the number of pitches in the zigzag enclosure increases, the improvement rate decreases but still improves the solidification time and heat recovery rate. The reverse arc-shaped structure has the best performance compared with the other undulated surfaces. For the system with RT35HC, the discharge time is 55% higher compared to that of the system with RT35, while the discharge rate is 8.2% higher for the former during the first 3000s of the discharging process.