Electrohydrodynamic acceleration of charging process in a latent heat thermal energy storage module

Phase change material (PCM) based latent heat thermal energy storage (LHTES) is a popular technique owing to its high energy storage density, scalability, and near-constant temperature operation. However, common PCMs suffer from low intrinsic thermal conductivity, limiting the energy storage rate of the LHTES units. To address this issue, the present work proposes a novel design of an LHTES module that is assisted with charge injection-induced electrohydrodynamic (EHD) flow to enhance the charging rate. A numerical solver based on the finite-volume method (FVM) is built within the framework of OpenFOAM to simulate the EHD assisted melting process. The evolution of critical parameters such as total liquid volume fraction, mean kinetic energy density and mean temperature are mapped as a function of time. The key objective of the study is to evaluate the performance under different (weak, medium, and strong) charge injection regimes. The EHD flow intensifies the flow velocity, alters the flow structure, and increases the heat transfer. The melting process gets more uniform and faster with the assistance of EHD flow. EHD flow at strong charge injection regime nullifies the effect of gravity and leads to equal performance irrespective of the orientation. Shorter melting times and increased power storage capacity are achieved in the presence of EHD flow. The charging time is shortened up to 2.65 times, and the net power storage capacity is increased up to 63% by EHD flow. Meanwhile, the additional power required to generate EHD flow is six orders of magnitude smaller than the increase in net power storage capacity achieved. Results presented in this work aid in developing more profound insights on charging acceleration by an electric field and will help in designing EHD assisted LHTES modules.