Transient performance of a thermocline energy storage system using the two-energy equation model

Rodrigues, Fernando A.; Lemos, Marcelo J. S. de

doi:10.1016/j.ijheatmasstransfer.2020.119323

Cited by 10 publications

(4 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second-order upwind differential scheme was applied for momentum and standard method for pressure. SIMPLE method was used for the pressure-velocity coupling in order to correct the pressure field oscillations [Rodrigues & Lemos, 2020]. Simulations were performed under transient state with fixed time step of 0.2 s. The solution was considered to be converged when (i) normalized residuals were smaller than 10 -5 for mass and momentum equations and 10 -7 for energy equation, and (ii) the inlet static pressure become constant (less than 0.5% variation).…”

Section: Geometries and Simulation Parametersmentioning

confidence: 99%

Single-tank thermal energy storage systems for concentrated solar power: Flow distribution optimization for thermocline evolution management

Lou

Fan

Luo

2020

Journal of Energy Storage

View full text Add to dashboard Cite

Concentrated Solar Power (CSP) technology captures solar radiation and converts it into heat for electricity production. It has received an increasing attention because integrated thermal energy storage (TES) systems can largely enhancing the reliability and the dispatchability. Over the last decade, low-cost single storage tank based on the thermocline technology becomes an alternative to commonly-used two-tank TES system. However, the improper inlet/outlet manifolds may cause the strong mixing of hot and cold fluids and disturb the temperature stratification, resulting in reduced thermal performances of the storage tank. This study aims at solving the flow maldistribution problem in the single-tank thermocline storage system by appropriately structuring the inlet/outlet manifolds. The technical solution is based on the insertion of optimized perforated baffles in the manifolds. 2D Computational fluid dynamics simulations were performed to calculate the transient flow and temperature profiles in the storage tank during the charging and discharging operations. The optimal size distribution of orifices on the upper baffle has been determined for homogenizing passage times of the thermal front, so as to enhance the temperature stratification. A novel intermediate evaluation indicator was introduced to characterize the real-time thermal behavior, which could reduce the computational cost of the optimization problem by a factor of 6 at least. Numerical results shown that the proposed optimization algorithm could significantly improve the thermal performances, indicated by the increased values of charging/discharging efficiency, the capacity ratio and the overall efficiency, ex., the fully charging efficiency be increased by 29% by comparing the unstructured manifold geometry and the one with optimized baffles. The parametric study on certain geometry and operating factors also demonstrated that the proposed method for flow distribution optimization was robust, effective and efficient.

show abstract

Section: Geometries and Simulation Parametersmentioning

confidence: 99%

Single-tank thermal energy storage systems for concentrated solar power: Flow distribution optimization for thermocline evolution management

Lou

Fan

Luo

2020

Journal of Energy Storage

View full text Add to dashboard Cite

show abstract

“…86 It should be noted, however, that although this is not favorable in terms of fluid flow performance, this lower permeability and higher pressure drop is usually accompanied by a thinner thermocline (the layer where there is a sharp temperature gradient between the hot and cold fluid) and a better thermal performance due to the better heat exchange between the HTF and porous media. 87 Accordingly, there needs to be a trade-off between the positive and negative effects on heat transport and fluid flow, respectively. 88,89 Effect of porosity and permeability on the overall performance of TES is discussed in detail in the review paper by Palomba and Frazzica.…”

Section: Design Criteria Of Rtes Systemsmentioning

confidence: 99%

“…The permeability of the storage, however, decreases due to the shrinkage in the space between the particles, which makes it harder for the fluid to pass through the passage 86 . It should be noted, however, that although this is not favorable in terms of fluid flow performance, this lower permeability and higher pressure drop is usually accompanied by a thinner thermocline (the layer where there is a sharp temperature gradient between the hot and cold fluid) and a better thermal performance due to the better heat exchange between the HTF and porous media 87 . Accordingly, there needs to be a trade‐off between the positive and negative effects on heat transport and fluid flow, respectively 88,89 .…”

Section: Rtes Systemsmentioning

confidence: 99%

Progress on rock thermal energy storage (RTES): A state of the art review

Amiri

Ermagan

Kurnia

et al. 2023

Energy Science & Engineering

View full text Add to dashboard Cite

Thermal energy is one of the most widely encountered energy forms in our daily life. To ensure efficient utilization and conversion of this energy, the balance between supply and demand needs to be maintained. For this purpose, thermal energy storage is required. There are various thermal energy storage systems available; one of the most basic is sensible thermal energy storage which includes rock thermal energy storage (RTES). This rock‐based energy storage has recently gained significant attention due to its capability to hold large amounts of thermal energy, relatively simple storage mechanism and low cost of storage medium. Accordingly, numerous studies have been conducted to elucidate the basic flow and heat transfer mechanism and to evaluate the performance of this energy storage. The major technical challenges hindering the wide adoption of this technology are the enormous pressure drop across the storage and nonoptimal heat transfer from the heat transfer fluid to the storage medium and vice versa. These issues will directly and indirectly affect the overall cost (capital, operational, and maintenance costs) of the system. To eliminate this issue and assist further development of this technology, it is crucial to compile and extract important findings from these previous studies, identify the challenge and research gap, and draw guidelines for the upcoming research and development. At the moment, this kind of compilation does not exist. Hence, this paper is prepared with the primary objective to comprehensively review the current technology and development of RTES and to propose a potential way forward based on the pain point identified. Discussion on the nontechnical aspect such as policy and regulations as well as community awareness will also be outlined and discussed.

show abstract

“…Further, the study of turbulence though porous media can find application in several areas, including engineering and environmental research. Examples of the former are studies in porous combustors [13], moving bed reactors [14], thermal energy systems [15], volumetric solar collectors [16], impinging jets for cooling or heating [17], among others. Applications of the study of turbulence in porous media can also be useful to environmental research such as simulation of forest fires [18] and flows over vegetations [19].…”

Section: Introductionmentioning

confidence: 99%

Modeling Turbulence in Permeable Media: The Double-Decomposition Concept Revisited

Lemos¹

2022

Physics

View full text Add to dashboard Cite

In this article, a concept named double decomposition, which is used to model turbulent flows in porous media, is examined. This concept is based on the idea that in a turbulent flow through a porous matrix, local instantaneous variables can be averaged in time and space, simultaneously. Depending on how these operators are applied, averaged equations take different forms. In this article, instantaneous local equations are averaged using both operators and a different set of equations resulting from such operations are commented upon. Additional terms proposed for the averaged equations are discussed.

show abstract

Transient performance of a thermocline energy storage system using the two-energy equation model

Cited by 10 publications

References 51 publications

Single-tank thermal energy storage systems for concentrated solar power: Flow distribution optimization for thermocline evolution management

Single-tank thermal energy storage systems for concentrated solar power: Flow distribution optimization for thermocline evolution management

Progress on rock thermal energy storage (RTES): A state of the art review

Modeling Turbulence in Permeable Media: The Double-Decomposition Concept Revisited

Contact Info

Product

Resources

About