Thermal Energy Storage for CSP plants

Two-tank molten salt storages are the most widespread thermal energy storage technology within concentrated solar power plants. In spite of this, there are design aspects such as thermal losses control, optimisation of the storage or how these devices scale up with the increase in power capacity of the plant which still should be considered. In this sense, numerical modelling of these systems can be a powerful tool for reducing their cost.

A parallel modular object-oriented methodology for modelling molten salt tanks is being considered. In this methodology the different elements of the storage (e.g. tank walls, insulation material, tank foundation, molten salt storage media, etc.) are considered as independent systems. Each of these elements can be solved independently and using different levels of modelling (from global to fully three-dimensional models), while at the same time they are linked to each other through their boundary conditions.  

In the study, the transient  behaviour of the whole system is taking into account and includes: (i) the gas ullage; (ii) the convection and radiation effects between the molten salt free surface and its surroundings; (iii) the tank walls and insulation; (iv) the different material in the foundation and the passive cooling of the foundation and, (v) the natural or forced convection of the molten salt within the tank.