Numerical Investigation of Cycle Cut-off Criterion on System Performance of Thermocline Tank.

The current paper investigates the cycle cut-off criterion on the thermal performance of the three-layers thermocline thermal energy storage (TES) tank system which is used in concentrating solar power (CSP) plants. The one dimensional transient dispersion-concentric (D-C) scheme is applied to calculate the phase change inside each capsule. Using MATLAB software, the numerical model equations have been figured out. Five different scenarios have been created to investigate the cycle cut-off criterion on the thermal performance of the TES tank. The results indicate that there are two important aspects to assess system performance which are the temperature distribution during the charging/discharging cycles and the time required to achieve equilibrium conditions. These aspects directly affect the overall power and external efficiency of the storage system and play a key role in understanding the system start up properties and provide insight into storage availability when designing the power cycle for CSP applications. It was also noted that the cycle times and the time required to achieve periodic conditions are very sensitive not only to the storage temperature difference but also to the cutting temperature difference. The difference in the duration of the charge cycle and the corresponding discharge cycle can be attributed to the consideration of a similar cut-off standard. [ABSTRACT FROM AUTHOR]