Melting behaviors of PCM in porous metal foam characterized by fractal geometry

摘要

The fractal Brownian motion is introduced to describe the pore distribution of porous metal foam. By the fractal description, a model of melting heat transfer for the phase change material (PCM) is developed and applied to investigate the melting behaviors in porous metal foam with a particular focus on the role of pore distribution. The dynamic response of temperature and the evolution of melting front are presented. The effects of porosity and fractal dimension on the melting heat transfer are all examined and investigated. In addition, an experiment of melting heat transfer is performed to verify the present model. The results indicate that the porous metal foam is of significance for the enhancement of melting heat transfer. When compared with PCM alone, the melting process in porous metal foam possesses the larger melting rate, the faster evolution of melting front and the higher liquid fraction. Unlike the PCM alone, the melting front is no longer continuous and many independent solid-liquid interfaces are formed inside pores owing to the interstitial heat transfer. Interestingly, the melting phase change is also affected by the fractal dimension even though the porosity is identical. A porous metal foam with smaller fractal dimension is beneficial for the melting heat transfer.