thermocline layer thickness is key to energy storage efficiency

Experimental and numerical investigation of a thermocline …

A few simplified, one-dimensional energy-based models are available for tracking the movement of the thermocline layer inside the thermal energy storage tank. However, these models largely assume the thermocline layer to be a thin horizontal plane within the tank, without quantifying the thermocline thickness.

Thermocline storage for concentrated solar power plants: …

The growing interest of the CSP community in thermocline rock storage technology is not recent. From Table 1, it can be clearly observed that many projects have relied on the application of thermocline to store thermal energy for reuse in electrical power generation either by producing steam or hot liquids om this list, two thermal storages …

Thermodynamic Analysis of Packed Bed Thermal Energy Storage …

To solve this problem, a steady thermodynamics model of PBTES with fixed temperatures on both ends was built. By using this model, the exergy destruction, thermocline thickness, thermal storage capacity, thermal storage time, and other key parameters can be calculated in a simple way.

Numerical characterization of thermocline behaviour of combined ...

The Thermocline thickness profile is a key indicator to predict the thermal performance of single tank energy storage and can clearly explain the formation of thermal gradients for fluid, SRS and PCM capsules along the flow direction. ... The thermocline layer moves upward during discharging process with little expansion except during phase ...

Sensitivity analysis of the numerical study on the ...

The general layout of the thermocline storage system is illustrated in Fig. 1a, which is similar to Yang et al.''s work [27], [28], [29]. As can be seen, the thermocline storage system mainly composes of a vertically standing cylindrical tank and the contained storage material, i.e., the molten salt and solid fillers.

Influence of flow distribution on the thermal ...

Good insulation of the tank could reduce the thermocline thickness by about 20%, and increase the energy efficiency and the capacity ratio by 5–7% and 3–5%, respectively. Experimental investigation of the impact of fluid distribution on thermocline storage performance

Numerical research on the thermal characteristics and mechanical ...

As the temperature difference between the inlet and outlet of the molten salt increases from 100 K to 250 K, the maximum thermocline layer thickness increases from 1.965 m to 2.625 m during the charging process, and the maximum thermocline layer thickness increases from 2.350 m to 3.615 m during the discharging process.

Molten-salt thermal energy storage in thermoclines under …

A few simplified, one-dimensional energy-based models are available for tracking the movement of the thermocline layer inside the thermal energy storage tank. However, these models largely assume the thermocline layer to be a thin horizontal plane within the tank, without quantifying the thermocline thickness.

Numerical Study of a Structured Thermocline Storage Tank Using ...

In a thermocline storage unit, the overall efficiency of the system is a function of the effective thermocline thickness (Fig.2), defined here in a similar way as Xu and al [25], and calculated as the ratio of the height h where the temperature is 20 % hotter than the cold fluid and 20 % colder than the hot fluid, by the total tank height: Ý ...

Geometry optimisation of an industrial thermocline Thermal Energy ...

The results showed that the initial thermocline thickness is minimised when the fluid distributor is located in the highest part of the tank. Keilany et al. [28] investigated the influence of particle diameter, porosity and thermophysical properties of two fillers (cofalit and alumina) on the discharging energy efficiency. Increasing the ...

Thermocline vs. two‐tank direct thermal storage system for ...

A two-tank direct Thermal Energy Storage (TES) system is currently integrated in the CSP plant, serving as a direct interface between solar field and ORC. ... leading to reduction in the mean ORC efficiency (18.2% as against 19.7% obtained with the two-tank TES). Conversely, higher energy storage density and lower thermal losses …

Numerical study on the thermodynamic performance of a packed …

The thermocline thickness decreased with a decrease in the G in. ... PHSs and CAESs have a large capacity, long storage term, and high energy storage efficiency, ... A thermocline layer is observed between the fluids inside the packed bed and the packing medium, indicating that the temperature gradient of the fluid and medium …

Thermocline characteristics of molten-salt thermal energy storage …

The experimental data for heat transfer and heat storage in the multi-scale heat storage tank are used to verify the validity of the numerical model. The performances of the heat storage system are analyzed using the thermocline thickness and heat storage efficiency with a focus on energy balance. Selected conclusions are …

Numerical analysis of thermocline evolution during charging phase …

Thermocline thickness (TLT) is the best parameter to quantify the thermal performance of stratified thermal energy storage (TES) tanks as it defines the inactive part of a storage medium. A detailed literature review reveals that there is no consensus in the community on the temperature band where the TLT is quantified.

Full article: Review on parameters influencing the efficiency of the ...

This work is a thorough review on the parameters influencing the performance of a dual-medium thermocline storage system for concentrated solar power plants. Thus, …

Numerical modeling and analysis of dual medium thermocline …

The thermal characteristics and efficiency of the system are examined under different operational and geometrical conditions for the charging and discharging processes for a fixed thermal energy storage size of 50 MWh. The Taguchi method is used to optimize the design parameters of the thermocline thermal energy storage system.

Improved realistic stratification model for estimating thermocline ...

Although several researchers have developed one-dimensional energy-based models, there is a dearth of an effective and computationally efficient realistic …

Technical Challenges and Their Solutions for Integration of

Dual-media thermocline thermal energy storage serves to be a better techno-economic option for thermal energy storage. It leads to nearly 62% reduction in …

Journal of Energy Storage

It is noticed that initially thermocline thickness is low and as the storage medium releases its stored energy thermocline thickness increases along height of TES tank. The maximum thermocline thicknesses achieved for 0.2, 0.3 and 0.4 kg/s are 0.57, 0.62, 0.63 m after the discharging times of 60 min, 50 min and 40 min, respectively.

Thermocline vs. two‐tank direct thermal storage system for ...

Owing to the potentiality of thermocline TES system in terms of high energy storage density and relative low costs, numerous studies have been presented …

Thermocline characteristics of molten-salt thermal energy storage …

The numerical model is validated by comparing the simulation results with the experimental data. The performance of the heat storage system is analyzed using the thermocline thickness and the heat storage efficiency with a focus on energy balance. The results show that stable thermocline layers can form during heat storage or heat …

Thermocline packed bed thermal energy storage system: a review

Thermal energy storage (TES) is applied to overcome the intrinsic deficiency of solar energy by migrating the dispatching between the energy supply and …

On the thermal stratification inside a spherical water storage …

The thermocline layer is fixed between the cold and hot water layers. This behavior formed a thermal stratified tank. The open literature provide several models of thermal energy storage tanks. The main objective of all existing models is to keep the storage tank well stratified by avoiding the destruction of the thermocline layer.

Stability analysis of the thermocline thermal energy storage …

The thickness of the thermocline plays a vital role in the thermal energy storage system. The temperature histories are identified for various Reynolds numbers …

Sensitivity analysis for thermocline thermal storage tank design

Thermocline thermal energy storage has been proposed as an efficient and cost-competitive alternative to the traditional two-tank design. The thermocline thickness is directly linked to the efficiency of the storage tank. Sensitivity analysis is thus applied to a model of the thermocline thickness to identify the parameters that …

Impact of buoyant jet entrainment on the thermocline behavior …

This paper presents the characterization and management of dynamic thermocline behaviors in a single-medium thermocline (SMT) thermal energy storage tank with the aim of its performance improvement. In particular, the flow mixing induced by the entering thermal jet, its impact on the temperature stratification and its mitigation …

Comparative Evaluation of Circular Truncated-Cone and

Experiments conducted on the in-house cylindrical thermal energy storage are used to validate the numerical model. The performance of the storage tanks is analyzed based on performance parameters, i.e. Richardson number, storage efficiency, stratification number and initial thermocline thickness, for various aspect ratios. The …

Thermal cycle performance of thermocline storage: numerical and ...

Exergy efficiency increases for shorter charges and longer discharges. The performance of a dual-media thermocline storage is studied in stationary periodic operation. Successive cycles are carried out until a stabilised behaviour is obtained. Numerical …

Numerical study on the thermodynamic performance of a packed …

Cold energy storage devices improve the round-trip efficiency of cryogenic energy storage systems, where a solid packed bed for cold energy storage (PBCES) is widely utilized. ... A thermocline layer is observed between the fluids inside the packed bed and the packing medium, indicating that the temperature gradient of the fluid and medium ...

Computational Fluid Dynamics Analysis of a Thermocline Thermal …

The thermocline layer thickness and the heat storage efficiency were main focus of the analysis. The results, which were compared against experimental data, …

Experimental evaluation of vitrified waste as solid fillers used in ...

It evaluates the actual thermal behavior of thermocline considering three leading performance indicators: process duration, thermocline thickness, and process efficiency. The investigation shows a 22% shorter charge duration in Cofalit® compared to alumina and 16% shorter discharge duration.

A thermocline thermal energy storage system with filler …

The thermal energy storage system operated from 1982 to 1986. It supplied 8 hours of additional electrical production to the power plant and showed a very thin thermocline layer. The tank was composed of a carbon steel wall with a diameter of 18.2 m and a height of 12 m. The wall thickness was 2.89 cm at the bottom and 0.79 cm near …

Journal of Energy Storage

This article will conduct research on single tank thermocline layer heat storage through a combination of numerical simulation and experiments, as shown in Fig. 1 (a). By …

Short and long-term sensitivity of lab-scale thermocline based …

A tank with a thin thermocline exhibits superior storage efficiency compared to a tank with a thicker thermocline. The thickness of the thermocline depends on various factors like the temperature difference between hot and cold fluid, fluid properties and charging rate [4], [7], [8] .

Constrained multi-objective optimization of thermocline packed …

Fig. 16 (a) shows the exergy efficiency as a function of the outer insulation-layer thickness consisting of foam glass. As expected, the more efficient designs have a larger insulation-layer thickness, which reaches the upper and lower limits of 1.0 m and 0.01 m for the most efficient and for the cheapest designs, respectively.

Exergy efficiency and thermocline degradation of a

1. Introduction. A packed bed thermal energy storage (PBTES) is a sensible type of thermal energy storage (TES) that uses a packed bed of solids as heat storage material, a gas (or liquid [1]) as heat transfer fluid (HTF) [2], [3] and is capable of storing high-temperature heat. The fact that the HTF in a PBTES gets in direct contact …

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