A New Approach to Energy and Exergy Analyses of Latent Heat Storage Unit

In this article, a new approach for energy and exergy efficiencies and effectiveness of latent heat storage systems is developed and applied to a shell-and-tube type latent heat storage system for its charging process. First, a numerical model is introduced to study the heat transfer and thermodynamic parameters and aspects (shell radius and pipe length, Reynolds number, inlet temperature of heat transfer fluid [HTF], etc.), and solved through the governing equations for HTF, pipe wall, and phase change material. Second, some extensive parametric studies are conducted to investigate how the solidification fronts, stored heat, heat transfer rates, entropy generation number, and both energy and exergy efficiencies change with time, particularly in the dimensionless form as the Fourier number. Third, both energetic and exergetic effectiveness concepts are newly developed and applied to a latent heat storage system. The results show that energy and exergy efficiency and effectiveness concepts appear to be significant tools for assessment and optimization of the thermal energy storage systems.