Performance investigation and optimization of latent heat storage exchangers with sandwiched tree-channels

Abstract The inefficient thermal transport of latent heat storage exchangers (LHSEs) restricts its engineering applications. To address this challenge, we design an innovative shell-and-tube LHSE with sandwiched tree-channels. The numerical approach using an enthalpy-porosity algorithm is conducted to research the melting performance of innovative LHSEs, focusing on comparisons with traditional LHSE units. Moreover, the response surface method (RSM) is adopted for structure optimizations of innovative LHSE units. The results indicate that the inherent high-efficiency thermal path of sandwiched tree-channels enhances the melting rate, while their fully extended spatial layout improves the temperature uniformity level. Compared with traditional ones, the innovative LHSE unit shortens the melting duration by 51.5% and improves the temperature uniformity by 21.1%. Interestingly, the melting convection of vertical directions is more intense than horizontal directions during the middle stage, and the overall melting performance depends heavily on the late stage. RSM results show that structural parameters of sandwiched tree-channels contribute to melting performance in the order of branch level, thickness fractal dimension, and length fractal dimension. To minimize the melting duration of LHSE units, fractal level, thickness fractal dimension, and length fractal dimension of 5, 2.89, and 1.99 are recommended for engineering applications meeting the dimensional range herein.