Preprint
Multi-layered solid-PCM thermocline thermal storage concept for CSP plants. Numerical analysis and perspectives
Fecha
2015Registro en:
Autor
Galione, Pedro
Pérez-Segarra, C.D.
Rodríguez, I.
Oliva, A.
Rigola, J.
Institución
Resumen
Thermocline storage concept has been considered for more than a decade as a possible solution to
reduce the huge cost of the storage system in concentrated solar power (CSP) plants. However, one of
the drawbacks of this concept is the decrease in its performance throughout the time. The objective
of this paper is to present a new thermocline-like storage concept, which aims at circumventing this
issue. The proposed concept consists of a storage tank filled with a combination of solid material
and encapsulated PCMs, forming a multi-layered packed bed, with molten salt as the heat transfer
fluid. The performance evaluation of each of the prototypes proposed is virtually tested by means of
a detailed numerical methodology which considers the heat transfer and fluid dynamics phenomena
present in these devices. The virtual tests carried out are designed so as to take into account several
charging and discharging cycles until periodic state is achieved, i.e. when the same amount of energy is
stored/released in consecutive charging/discharging cycles. As a result, the dependence of the storage
capacity on the PCMs temperatures, the total energy and exergy stored/released, as well as the
efficiencies of the storing process are compared for the different thermocline, single PCM, cascaded
PCM and multi-layered solid-PCM (MLSPCM) configurations. The analysis shows that the multi-
layered solid-PCM concept is a promising alternative for thermal storage in CSP plants.