Influence of variable gravity on the phase change material for enclosed vertical channels with helical fins

This study numerically investigates the influence of variable gravity on the melting behaviour of a phase change material (PCM- paraffin wax RT27) contained within an enclosed vertical channel under different gravity conditions, specifically those found on the Earth, the Moon, and under the microgravity environments. Furthermore, the impacts of incorporating various number of helical fins within the PCM unit under different gravitational conditions are assessed for the first time. The findings indicate that the melting efficiency of PCM is considerably affected by the reduced gravity conditions, due to changes in the natural convection, velocity, and temperature; the melting time is twice as long under the moon-gravity conditions and sixfold longer under the microgravity conditions compared to the earth-gravity. It is also observed that reduced efficiency can be remedied by the insertion of fins into the PCM unit. The breakdown of the natural convection vortices with different number and orientation of fins expedites the melting process for all gravity conditions thus leading to improved performance in melting and energy storage.