Effects of Rapid Boundary Heat Flux Fluctuations on Wavy Heat-Transferring Surfaces in Latent Energy Storages

Abstract

Latent energy storages associated with renewable energy devices and electronics cooling systems generally experience irregular heat transfer supplies leading to large temperature or heat flux variations in the heat transfer boundary. Wavy heat transfer surfaces are widely recognized as a heat transfer enhancement alternative in heat transfer fluid systems owing to their superior thermal performance. A detailed elucidation of melting dynamics and thermal performance of a latent energy storage with a wavy heat transfer boundary subjected to boundary heat fluctuations having a time scale comparable to that of a melt convection system is presented here. A finite volume-based computational model with enthalpy-porosity technique incorporating transient temperature boundary conditions has been developed and successfully validated with experimental visualization and temperature measurements in phase change material (PCM) storage with a wavy heat-transferring surface. Extensive numerical simulations are performed to figure out the makeovers in laminar thermal convection in molten PCM adjacent to a wavy heat transfer boundary for various levels of temperature fluctuations. Clear elucidations of melt front developments, melt convection, and resulting heat transfer estimates for different levels of boundary temperature fluctuations are presented. Correlations among key dimensionless parameters have been developed based on the detailed thermal performance estimations carried out in this study.