Effect of eccentricity and V-shaped fins on the heat transfer performance of a phase change heat storage system

Thermal energy storage plays a crucial role in the efficient use of solar energy and the recovery of waste heat from plants. This paper introduces an eccentric V-shaped fin latent heat storage unit. The influence of multiple geometric parameters including eccentricity, fin angle, height and thickness, on the system performance was studied, and the influence of four new fin arrangement and distribution on the melting process was proposed and compared. Finally, the fin structure was optimized by the response surface method. The results show that when the inner tube moves downward (the eccentricity is positive), the natural convection in the system is enhanced, the melting rate increases, and the optimal eccentricity is +3 mm. In addition, with the increase of the fin angle, the total melting time first decreases and then increases, and the total melting time is the shortest when the fin angle is 75°. Increasing the fin height can shorten the total melting time by up to 22.25 %; the fin thickness has less influence on the melting process. It is worth noting that after changing the fin arrangement and distribution mode, the total melting time is shortened by 4.91 %. Moreover, the optimal fin parameters under the most finned arrangement and distribution mode were obtained by the response surface test, and the total melting time was shortened by 60.67 % compared with the concentric tube without fins on the surface under the above parameters. Combining eccentricity and V-shaped fins can greatly shorten the total melting time, and reasonable changes in the arrangement and distribution of fins can further accelerate the melting rate.