Enhancement of charging time in a shell-and-tube latent heat storage system using innovative inner-tube motion profiles: A numerical study

• Inner tube motion reduces PCM charging time by up to 61%. • Profile H, with simple downward motion, improves efficiency by 57%. • Oscillations in the upper region disrupt free convection. • Horizontal motion alone provides only minor improvements. • Study confirms targeted heat source motion accelerates PCM melting. This study investigates the enhancement of charging efficiency in a PCM-based thermal storage system by introducing innovative motion profiles for the inner cylinder within a shell-and-tube heat exchanger. Ten motion scenarios, including oscillatory and constant velocity profiles, are numerically analyzed to improve heat transfer and reduce melting time. The results demonstrate that targeted motion profiles, particularly those focusing on the lower region of the domain where free convection is weak, significantly enhance charging efficiency. Among the oscillatory profiles, Profile A (inner cylinder oscillation in the lower half of the casing) achieves a 32 % reduction in melting time, while Profile J (leftward motion followed by counterclockwise rotation) achieves the highest improvement of 61%. The study highlights the importance of optimizing inner tube movement to target inactive regions, leading to more efficient heat transfer and faster charging. These findings provide valuable insights for the design of next-generation thermal energy storage systems, with potential applications in solar energy storage and thermal management of heat-intensive systems.