Simulation of thermocline storage for solar thermal power plants: From dimensionless results to prototypes and real-size tanks

Bayón, Rocío; Rojas, Esther

doi:10.1016/j.ijheatmasstransfer.2013.01.047

Cited by 105 publications

(29 citation statements)

References 17 publications

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“…Most commercial TES systems consist of: one cold salt tank, one hot salt tank, an HTF-salt exchanger, pumps (to move the molten salt from one tank into the other), pipes and control valves [35]. This is the type of TES considered in this paper, although one-tank TES are also very popular in the literature [36][37][38]. It must be noticed that the use of TES is not limited to solar thermal plants: they can be integrated in other systems such as oil-fired conventional power plants [39], nuclear power plants [40] or many other applications such as hot water supply, air conditioning, heat pumps, buildings, cogeneration, etc.…”

Section: Methodsmentioning

confidence: 99%

On the Convenience of Using Simulation Models to Optimize the Control Strategy of Molten-Salt Heat Storage Systems in Solar Thermal Power Plants

Prieto

Martínez

Peon³

et al. 2017

Energies

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Thermal oil has been used as heat transfer fluid in many solar thermal power plants, which also use molten salts as thermal energy storage system. Since the engineering of these plants is relatively new, control of the thermal energy storage system is currently achieved in manual or semiautomatic ways, controlling its variables with proportional-integral-derivative (PID) regulators. Once the plant is running, it is very difficult to obtain permission to try new control strategies. Hence, most plants keep running on these simple, sometimes inefficient control algorithms. This paper explores the results obtained with different control strategies implemented on a complete model of energy storage systems based on molten salt. The results provided by the model allow the optimum control strategy to be selected. Comparison of the results obtained by simulation of these control strategies and actual results obtained from a real plant, confirm the accuracy of the selection made.

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Section: Methodsmentioning

confidence: 99%

On the Convenience of Using Simulation Models to Optimize the Control Strategy of Molten-Salt Heat Storage Systems in Solar Thermal Power Plants

Prieto

Martínez

Peon³

et al. 2017

Energies

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“…Bayón and Rojas presented a 1D transient model in 2013 [41], considering the solid filler material and HTF as a single effective storage medium inside a thermocline tank. Compared to these models, the current enthalpy-based 1D transient model can precisely track the interface movement in PCM, while other models cannot because temperature is a constant at the melting interface.…”

Section: Governing Equationsmentioning

confidence: 99%

“…In the general volume sizing strategies presented in Refs. [40,41], a discharge efficiency was used to determine the storage tank height. In the current model, the cutoff temperature is the chosen criterion, which is more practical in a real CSP plant.…”

Section: General Volume Sizing Strategy For Latent Heat Storage Systementioning

confidence: 99%

General volume sizing strategy for thermal storage system using phase change material for concentrated solar thermal power plant

Chan

et al. 2015

Applied Energy

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h i g h l i g h t sWe present a method of sizing a thermocline thermal storage system for a CSP plant. Phase change materials (PCM) are considered for this study. Sizing criterion is that the discharged fluid temperature is above a cutoff point. The sizing procedures were presented through one design example. Latent heat storage system (LHSS) Phase change material (PCM) General volume sizing strategy Enthalpy-based 1D transient model a b s t r a c tWith an auxiliary large capacity thermal storage using phase change material (PCM), Concentrated Solar Power (CSP) is a promising technology for high efficiency solar energy utilization. In a thermal storage system, a dual-media thermal storage tank is typically adopted in industry for the purpose of reducing the use of the heat transfer fluid (HTF) which is usually expensive. While the sensible heat storage system (SHSS) has been well studied, a dual-media latent heat storage system (LHSS) still needs more attention and study. The volume sizing of the thermal storage tank, considering daily cyclic operations, is of particular significance. In this paper, a general volume sizing strategy for LHSS is proposed, based on an enthalpy-based 1D transient model. One example was presented to demonstrate how to apply this strategy to obtain an actual storage tank volume. With this volume, a LHSS can supply heat to a thermal power plant with the HTF at temperatures above a cutoff point during a desired 6 h of operation. This general volume sizing strategy is believed to be of particular interest for the solar thermal power industry.

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“…Some of them are based on the two-phase Schumann model whose solutions are two temperature equations (one for the solid and one for the fluid) obtained mainly by numerical methods [6,7,8,9]. However, when the fluid is a liquid, an effective single-phase storage medium can be assumed and, in this case, the temperature equation can be obtained either by simple numerical methods [10] or by using analytical functions [11,12,13,14,15]. All these models have been validated considering different sets of experimental data [6,15], which usually show a completely developed temperature profile of the thermocline region inside the tank.…”

Section: Introductionmentioning

confidence: 99%

Study of thermocline development inside a dual-media storage tank at the beginning of dynamic processes

Esence

Bayón²,

Bruch

et al. 2017

AIP Conference Proceedings

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Operating results of a thermocline thermal energy storage included in a parabolic trough mini power plant AIP Conference Proceedings 1850, 080010 (2017) Abstract. This work presents some of the experimental results obtained during a test campaign performed at the STONE facility of CEA-Grenoble in collaboration with CIEMAT-PSA supported by both the SFERA-II and the STAGE-STE project. This installation consists of a thermocline tank with thermal oil and rock/sand filler and the tests aimed to study the development of the temperature profile inside the tank at the beginning of charge/discharge processes. The investigation of how this profile is created and which is its dependence on the experimental parameters is crucial for predicting the behavior of a dual-media thermocline tank. Tests have been performed for dynamic processes from initial states with constant uniform temperature or with a thermal gradient already present due to a partial thermocline zone extraction in the former process. Tests at different fluid velocities and temperatures have been carried out as well, in order to evaluate the influence of operating conditions. When a dynamic process of charge or discharge is started, the development of the thermal front is very sharp and localized at tank top or bottom if initial tank temperature is uniform, whereas it is less pronounced if the test begins from a non-thermally uniform initial state. In terms of operating conditions, it has been observed that the development of the thermocline thermal front is independent not only of the fluid velocity but also of its temperatures, within the working ranges here considered. Due to these experimental results, it will be possible to improve simulation models for thermocline tanks and hence to predict their behavior more accurately, especially when they are implemented in annual simulations of CSP plants.

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Simulation of thermocline storage for solar thermal power plants: From dimensionless results to prototypes and real-size tanks

Cited by 105 publications

References 17 publications

On the Convenience of Using Simulation Models to Optimize the Control Strategy of Molten-Salt Heat Storage Systems in Solar Thermal Power Plants

On the Convenience of Using Simulation Models to Optimize the Control Strategy of Molten-Salt Heat Storage Systems in Solar Thermal Power Plants

General volume sizing strategy for thermal storage system using phase change material for concentrated solar thermal power plant

Study of thermocline development inside a dual-media storage tank at the beginning of dynamic processes

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