Utilize mechanical vibration energy for fast thermal responsive PCMs-based energy storage systems: Prototype research by numerical simulation

Abstract

For commercialisation of PCMs (liquid-solid phase change materials) based energy storage systems, the biggest challenge is to improve the thermal responsive rate of PCMs. In the present authors’ latest study, it is found mechanical vibration may be utilized to address the challenge as most engineering systems work under vibration conditions. However, to utilize mechanical vibration more efficiently, it is critical to accelerate melting speed of solid PCMs in the beginning of charging processes. In the present study, a fin is introduced for the purpose. Here comprehensive numerical simulation is conducted to reveal the effectiveness of the new combination of a fin and mechanical vibration. So far there is no open research on feasibility of this new combination. The present work bridges the gap. The present research shows the integration of a fin and mechanical vibration can provide an effective way to maintain a sustainable high thermal responsive rate for PCMs during charging processes. The fin and mechanical vibration are complementary: the fin can improve thermal responsive rate of PCMs significantly in the early period of the charging process but its influence will become weak; on the contrary, the enhancement effect of mechanical vibration is slight in the beginning but later will become strong. The effects of vibration frequency, vibration amplitude and fin length are investigated numerically. It is found a low/moderate vibration frequency can accelerate charging processes more effectively and the optimal vibration frequency range is around 0–200. And there is also an optimal range for fin length. If the ratio of fin length to side length of the cubic tank is more than 3/4, the benefit by introducing a fin will become slight, which indicates the length of fin is not the longer the better. The present work proposes a new way to develop commercial PCMs-based energy storage systems. The findings can serve as guides for realistic engineering applications.