Thermal‐fluid flow within innovative heat storage concrete systems for solar power plants

Abstract

Purpose -The purpose of this paper is to describe an experience of R&D in the field of new technologies for solar energy exploitation within the Italian context. Concentrated solar power systems operating in the field of medium temperatures are the main research objectives, directed towards the development of a new and low-cost technology to concentrate the direct radiation and efficiently convert solar energy into high-temperature heat. Design/methodology/approach -A multi-tank sensible-heat storage system is proposed for storing thermal energy, with a two-tanks molten salt system. In the present paper, the typology of a below-grade cone shape storage is taken up, in combination with nitrate molten salts at 5658C maximum temperature, using an innovative high-performance concrete for structures absolving functions of containment and foundation. Findings -Concrete durability in terms of prolonged thermal loads is assessed. The interaction between the hot tank and the surrounding environment (ground) is considered. The developed FE model simulates the whole domain, and a fixed heat source of 1008C is assigned to the internal concrete surface. The development of the thermal and hygral fronts within the tank thickness are analysed and results discussed for long-term scenarios. Originality/value -Within the medium temperature field, an innovative approach is here presented for the conceptual design of liquid salts concrete storage systems. The adopted numerical model accounts for the strong coupling among moisture and heat transfer and the mechanical field. The basic mathematical model is a single fluid phase non-linear diffusion one based on the theory by Bažant; appropriate thermodynamic and constitutive relationships are supplemented to enhance the approach and catch the effects of different fluid phases (liquid plus gas).

Conceptual Study of a Thermal Storage Module for Solar Power Plants with Parabolic Trough Concentrators

“…In fact, by considering the humidity transport and dehydration phenomena effectively taking place in concrete (see e.g. [2,11]) so that this section will be subjected to the highest thermal flux, it will sustain even the highest internal overpressures with the possibility of being exposed to spalling [12]; such a phenomenon is to be clearly avoided during first heating.…”

“…The fluid system is treated via a 1D model whereas the solid domain is analysed via the FEM so that for each element the energy balance equation is solved (see e.g. [2]);…”

“…Technologies and methods for thermal energy storage have been well tested in CSP -Concentrated Solar Power -plants [1,2]. Solar tower plants (e.g.…”

New Trends in Designing Parabolic trough Solar Concentrators and Heat Storage Concrete Systems in Solar Power Plants

“…Economic thermal storage is a technological key issue for the future success of solar thermal technologies. In our days, among eight thermal storage systems in thermo-electric solar plants, seven have been of experimental or prototypal nature and only one has been a commercial unit (Salomoni et al, 2008). All the considered systems are "at sensible heat storage": two singletanks oil thermo-cline systems, four two-tanks single medium systems (one oil-and three molten salt-) and two single-tanks double medium systems.…”

“…The proposed model couples non-linear geometric relations with empirical relations; to enhance its predictive capabilities, a predictor-corrector procedure is supplemented to check the exactness of the solution. For additional details the reader is referred to (Salomoni et al, 2007 (b) ;Salomoni et al, 2008;Salomoni et al, 2009). …”