A One-Dimensional Model and the Influence of the Mass Flow Rate in a Structured Thermal Energy Storage System for Concentrated Solar Power Plants

This study presents a one-dimensional model to simulate structured thermocline thermal energy storage tanks. The structure consists of a solid filler material made of waste ceramic products and a series of channels through which the heat transfer fluid flows. The mathematical model is validated against a more advanced model as there are no experimental results for this type of unit. An investigation is carried out on the influence of the mass flow rate on the behaviour of the system, and several parameters such as accumulated energy, outlet temperature, discharge time, discharge power, temperature profiles along the bed, and the exergy of the system for various cases are studied. The results show that an increase in mass flow rate leads to a reduction in accumulated energy because the fluid has less residence time in the structure, reaching the cutoff temperature earlier. The influence of the mass flow rate on the outlet temperature and how it affects the temperature profiles are also examined, resulting in a smaller hot upper zone and a reduction in the exergy of the system for higher mass flow rates.