An experimental and numerical study on the energy storage and release performance of shell and tube heat exchangers with phase change material for the data center

In this study, we have established an experimental platform featuring a shell and tube heat exchanger (STHE) combined with phase change material (PCM) to investigate its energy storage and release performance. Paraffin 25 and water have been selected as the energy storage material (ESM) and the heat transfer fluid (HTF), respectively. Besides, numerical simulations of different energy storage units by changing the phase change unit structures are carried out with FLUENT software. The effect of different specific surface area (surface area per bulk volume, m⁻¹) and length-to-diameter (L/D) ratios on the energy storage and release process is numerically studied. The findings show that as the specific surface area rises, the heat conduction effect gets stronger. When the specific surface area rises by 223.8 %, the melting time and solidification time can be cut by about 75.9 % and 87.4 %, respectively. Furthermore, the L/D ratio also has a great influence on the average energy storage rate since the average energy storage rate decreases by 9.6 % when the L/D ratio is increased from 7.9 to 10.5. In contrast, the average energy release rate decreases by only 1.6 %. Additionally, the cooling capacity of the STHE has been extensively explored in this research. For instance, under specific conditions (e.g., with a L/D of 7.9 and a specific surface area of 111.1), the cooling performance is evaluated. The study reveals that when the power of data center servers is set at 100 W and 200 W, the emergency cooling periods are observed to be 1680 s and 330 s, respectively.