Visualized-experimental investigation on the energy storage performance of PCM infiltrated in the metal foam with varying pore densities.

To further enhance the melting rate of the metal foam composite phase change material (MFCPCM), we took partial and gradient optimizations on the pore densities of metal foams. The partially optimized models, including Partial-80-5-5 and Partial-5-5-80, were compared with the Uniform-5 model. Results show that the Partial-80-5-5 model has the most developed melting among the three models. It illustrates that enlarging the pore density in the top region is conducive to accelerating the whole melting process. Besides, through a further comparison of the Partial-80-5-5, Partial-40-5-5, and Partial-20-5-5 models, we concluded that the larger the pore-density in the top region is, the faster the melting is. Subsequently, the gradient optimizations, including Gradient-80-20-5 and Gradient-80-40-5 models, were experimented with and analyzed. It was obtained that the Gradient-80-40-5 model has the fastest melting rate among all models. The inhibition of the large pore density on natural convection at the top and middle regions causes a strong vortex at the bottom region, so the melting process is significantly reinforced. Through the optimizations on the metal foam's pore density, the energy storage rate can achieve a prominent enhancement. [Display omitted] • The metal foam composite PCM is visually studied. • The partial and gradient optimization on the pore density is conducted. • The inner heat transfer mechanism is clarified. • The enhancement of the energy storage performance is achieved. [ABSTRACT FROM AUTHOR]