Volume 53

Numerical evaluation of melting of phase change materials in two-dimensional rectangular vessels with different aspect ratios under vibration conditions Qi Deng, Hua Chen, Wen-long Cheng

Abstract

The vibration phenomenon widely existing in engineering is often ignored when considering the effect of the aspect ratio of the container on the melting of phase change material (PCM). In this paper, a melting model of PCM in a two-dimensional rectangular container with constant temperature boundary and variable length is constructed, and the influence of rectangular aspect ratio (AR) on the melting process of PCM under vibration is studied by numerical calculation. Our findings reveal that at a static state, larger aspect ratios enhance natural convection within the vessel, thereby modestly accelerating PCM melting. Paradoxically, this also leads to increased paraffin content, prolonging the melting of the contracting solid phase. However, when subjected to vibrations, every aspect ratio experiences an accelerated melting process, with the enhancement more pronounced at higher vibration frequencies. For example, when frequency is 5Hz, melting time in vessel (AR=0.4) is 2.4% shorter than static, while (AR=2) vessel’s time is 7% shorter. Notably, the larger aspect ratio vessels exhibit a more significant acceleration with frequency increase. Furthermore, the average Nusselt number during melting oscillates periodically with vibration, consistently exceeding its static-state counterpart.

Keywords energy storage, rectangular vessel, phase change material melting, vibrate, aspect ratio