These storage systems store energy (charge) when solar energy is available and release energy (discharges) when there is a demand for domestic hot water.
As mentioned in the previous section, the energy storage/release is initially associated withsensible heat changes, i.e., by reducing the temperature of the PCM to the melt temperature, after which the phase change process in the form of latent heat governs the energy gained/release in a stable condition.
The simultaneous charging and discharging process of a molten-salt packed-bed storage tank needs further investigations. In order to maximize the power load regulation capability of the CSP plants, the molten-salt packed-bed thermocline storage tank is supposed to operate both the charging and discharging at the same time.
On behalf of all authors, the corresponding author states that there is no conflict of interest. Taheri, M., Pourfayaz, F., Habibi, R. et al. Exergy Analysis of Charge and Discharge Processes of Thermal Energy Storage System with Various Phase Change Materials: A Comprehensive Comparison. J. Therm.
In this type of operation, the discharging process is operated continuously during the whole simulation, while the charging process is carried out periodically. Four charging cycles are typically operated. Each proper period of charging about 30 min and the first cycle starts at the first 30th minutes.
Due to the irregular demand for thermal energy (discharging) and the variability of solar irradiation during the day, LHTES systemscan be charged and discharged at either separate time intervals or simultaneously.