Investigation and optimization of solidification performance of concentration tube type latent heat storage unit with herringbone wavy fin designs

The solidification rate of the latent heat storage units is relatively low and can be significantly improved using fins. The current study investigates the solidification performance of concentric tube-type latent heat storage unit with different designs of herringbone wavy fins. A validated two-dimensional transient solidification heat transfer model for latent heat storage unit with different herringbone wavy fin designs has been utilized and solved in a commercially available CFD solver. For all the studied cases, the fin's volumetric fraction is 5.5 % of the LHSU volume in the numerical solution. Initially, the solidification performance of different herringbone wavy fins and conventional longitudinal fins have comparatively analyzed. The fin-D design has been found to be the most effective, with a 22 % reduction in the solidification time compared to conventional longitudinal fins. Additionally, the effects of geometrical parameters, viz. relative fin height, relative divergence angle, and wave number for fin-D have also been investigated. The optimum values of relative fin height, relative divergence angle and wavenumber have been found at 1, 0.667 and 0.12 mm⁻¹, respectively. The solidification time has been found to be 29 % less for the optimum herringbone wavy fin design than the conventional longitudinal fins.