A simple method for the design of thermal energy storage systems

One of the key factors that currently limits the commercial deployment of thermal energy storage (TES) systems is their complex design procedure, especially in the case of latent heat TES systems. Design procedures should address both the specificities of the TES system under consideration and those of the application to be integrated within. This article presents a fast and easy to apply methodology for the selection of the design of TES systems suitable for both direct and indirect contact sensible and latent TES. The methodology is divided into four steps covering: (a) description of the thermal process or application, (b) definition of the specifications to be met by the TES system, (c) characterization of the specific TES system under consideration and (d) the determination of the TES design. This methodology needs as major inputs the operation conditions of the energy system where the TES system will be integrated, that is, temperatures and mass‐flow; as well as the charging and discharging time performed by the TES system under different conditions. The latter can be generally deduced from the Fourier number, which can be obtained both theoretically (ie, by simulation) or empirically from the analysis of the TES technology under consideration. The methodology is then applied to a 10 kW residential cogeneration application considering two TES technologies. One consists of a direct‐contact hot water storage tank and the other, of an indirect‐contact plate‐based latent heat TES system developed by the authors. The resulting volume needs for the hot water storage tank is approximately twice the volume of the latent heat TES system, respectively, 5.97 and 2.96 m3. The presented methodology eases the design process of TES systems and decreases the amount of time needed to size them from days/hours to minutes.