Numerical study on electrohydrodynamic enhancement of PCM melting in cylindrical annulus under microgravity

TL;DR

This study demonstrates that electrohydrodynamic (EHD) significantly enhances the melting process of phase change materials in a cylindrical annulus under microgravity, achieving up to 90% time savings and revealing optimal configurations depending on electric parameters.

Contribution

It introduces a numerical analysis of EHD effects on PCM melting in microgravity, highlighting the potential for improved thermal management in space applications.

Findings

EHD enhances heat transfer and melting efficiency under microgravity.

Maximum melting time reduction exceeds 90% with EHD.

Optimal eccentric configurations depend on electric Rayleigh number.

Abstract

Latent heat thermal energy storage (LHTES) has been recommended as an effective technology to the thermal management system of space exploration for its excellent ability of storing thermal energy. However, it is well known that the low thermal conductivity of phase change material (PCM) seriously weakens the heat charging and discharging rates of LHTES system. In present study, the electrohydrodynamic (EHD), which is a popular active heat transfer enhancement technology, is introduced to enhance the PCM melting in a shell-tube LHTES system under microgravity. In our numerical simulations, we mainly focus on the combined effects of the electric Rayleigh number $T$ and the eccentricity $\Gamma$ on the melting performance under microgravity. Based on the numerical results, it is found that in contrast to the case without the electric field, the presence of the electric field causes the heat transfer efficiency and melting behavior of LHTES system to be enhanced significantly. In addition, our results indicates that the EHD technique always shows a good performance in accelerating the melting process even under microgravity, and specially, the maximum time saving in some cases is more than $90\%$. Furthermore, we note that although the concentric annulus is always the optimal configuration under no-gravity condition, the optimal eccentric position of the internal tube strongly depends on the electric Rayleigh number if the gravity effects are taken into account.