Effect of nanoparticles and metal foams on heat transfer properties of PCMs

Abstract

Phase change material (PCM) are often used to realize thermal energy storage, which is regarded as an effective way to solve the problem of time difference between energy supply and demand. However, conventional phase change materials hinder the energy exchange rate and affect the storage efficiency due to their low thermal conductivity. To solve this problem, this study proposed three types of composite materials “nanoparticle/paraffin”, “metal-foam/paraffin” and “nanoparticle/metal-foam/paraffin”. The heat transfer properties of proposed composite materials were investigated based on the heat flux method and the heat storage and release test. The effects of metal foams and nanoparticles on the properties of phase change materials with different parameters were obtained, and the effect of the pore density of metal foams on the natural convection process of phase change materials was considered. The results show that the heat transfer performance of the composite phase change material is significantly improved compared with the traditional phase change material. With the increase of metal foam pore density, the heat transfer performance first increases and then decreases which caused by the enhanced obstruction to natural convection, 40 PPI pore density shows better comprehensive performance. In terms of thermal conductivity, nanoparticle/paraffin, metal-foam/paraffin (40 PPI) and nanoparticle-metal foam-paraffin (40 PPI) have been enhanced in turn, which are 123.27%, 740.39%, 847.15% higher than pure paraffin, respectively. The melting time and solidification time are shortened by 6.74%, 62.72%, 72.61% compared with pure paraffin and 26.46%, 49.47%, 38.62%.