Numerical simulation of the improvement of latent heat storage unit performance in solidification process by eccentric fractal finned tube

Abstract

In order to explore the mechanism of eccentric fractal finned tube on enhancing the solidification performance of latent heat storage unit, the solidification of paraffin in latent heat storage unit of eccentric fractal finned tube was simulated by two-dimensional unsteady state. Under the consideration of natural convection, the heat transfer characteristics of eccentric rectangular fins and eccentric fractal fins are firstly studied, and then the improvement of solidification process by two local strengthening schemes with fins on the upper part and fins on the lower part is compared. Then the influence of fin angle is studied. Finally, the lower part of the secondary branch fin with an angle of 60° was selected to add a fin strengthening structure to further strengthen the paraffin solidification process in the latent heat storage of eccentric fractal fin. Concluded that compared with eccentric rectangular finned, eccentric fractal fin shorten the coagulation time by 41.2 %, upper add fin and lower add fin both local reinforcement schemes are made the whole process of solidification rate has increased, about 1000 s, the upper encryption fin make solidification rate increased by 16.7 %, the lower encryption fin make solidification rate increased by 50 %, the total solidification time of the lower fin is basically unchanged, while the structure of the upper fin reduces the total solidification time by 15.3 %. Three structures with fin angles of 45°, 60° and 90° were simulated and the total solidification time was shortened with the increase of fin angle. Compared with the original eccentric fractal fin structure, the solidification time of the final strengthened structure is reduced by 70 %.