Experimental study on the charging characteristics of a horizontal shell-and-tube latent heat thermal energy storage exchanger with mobile inner tube mechanism

While the shell-and-tube latent heat thermal energy storage exchanger (S-LHTES) exhibits merits of high thermal storage density and reduced temperature fluctuation, its thermal performance faces persistent limitations in achieving higher heat transfer rates due to the inherently low thermal conductivity of phase change materials (PCMs). To enhance charging performance, this study utilized a horizontal exchanger with a mobile inner tube mechanism (HS-LHTES-M), with imaging techniques. The effects of varying inner tube movement speeds, distances and directions on charging performance were investigated. The results show that movement greatly improves performance. When subjected to reciprocating motion at 0.1 mm/s, the inner tube displacement increased from 5 mm to 20 mm in the vertical downward direction, reducing the total charging time by 33.73%. Compared to the stationary inner tube, optimized movement strategies (20 mm reciprocating motion at 0.1 mm/s along the -Y axis) increased the overall temperature rise rate of the PCM by up to 81.96% and the thermal storage capacity within a fixed period of time by 34.78%. These findings provide valuable references for performance enhancement research on S-LHTES and lay a foundation for the optimization of inner tube movement strategies in phase change thermal energy storage systems.