Conjugate heat transfer in a solar-driven enhanced thermal energy storage system using PCM

Abstract

In this paper, a numerical analysis of the conjugate heat transfer between a heat transfer fluid, a smooth or enhanced tube and a PCM container is accomplished. The heat transfer fluid inlet and outlet boundary conditions are coupled with the solar collector that provides the fluid with thermal energy, considering the dynamics of a solar irradiance curve. This provides the model with a realistic approach that allows for quantifying the effect of a given solar irradiance curve on the capacity of thermal energy storage. The lower latent thermal storage detected in winter conditions (peak irradiance of 500 W/m2 and 9 hours of solar light) with a standard shell and tube container can be overcome with the use of a rectangular finned tube. An increase of the heat transfer surface to PCM volume ratio of 5.7 times yields a 2.2-fold augmentation of thermal energy storage.