CFD analysis of melting process in a shell-and-tube latent heat storage for concentrated solar power plants

Fornarelli, Francesco; Camporeale, Sergio Mario; Fortunato, Bernardo; Torresi, Marco; Oresta, Paolo; Magliocchetti, Laura; Miliozzi, Adio; Santo, Gilberto

doi:10.1016/j.apenergy.2015.11.106

Cited by 142 publications

(36 citation statements)

References 33 publications

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“…For the PCM, the enthalpy-porosity method [34][35][36][37][38][39] was applied to model the dynamic melting process, modelling equations including the continuity, momentum, and energy equations are shown below:…”

Section: Numerical Modellingmentioning

confidence: 99%

“…Also for a constant Grashof number (9.09 × 104), the PCM melted at a faster rate when the Stefan number increased from 0.077 to 0.097. Fornarelli et al [39] identified the natural convective flows within the molten PCM by temperature gradients and gravity, and the enhanced heat flux can reduce 30% of the charging time. Tao and Carey [40] sequenced the PCM thermal properties affecting TES performance, which was in the order of melting temperature, thermal conductivity, specific heat, density and melting enthalpy, successively.…”

Section: Introductionmentioning

confidence: 99%

“…Compared to the experimental and analytical approaches, numerical simulations are more effective in dealing with influential factors, such as natural convection [33][34][35][36][37][38][39], geometric configuration [33][34][35][36], dynamic melting process [37] and non-dimensional number [38], etc. Fan et al [33] studied a constrained melting process in a circumferentially finned spherical capsule, the influence of fin height on the TES performance was In general, TES systems can be divided into two types: sensible heat thermal energy storage (SHTES) systems and latent heat thermal energy storage (LHTES) systems [21].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

et al. 2017

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Abstract:In this study, the dynamic melting process of the phase change material (PCM) in a vertical cylindrical tube-in-tank thermal energy storage (TES) unit was investigated through numerical simulations and experimental measurements. To ensure good heat exchange performance, a concentric helical coil was inserted into the TES unit to pipe the heat transfer fluid (HTF). A numerical model using the computational fluid dynamics (CFD) approach was developed based on the enthalpy-porosity method to simulate the unsteady melting process including temperature and liquid fraction variations. Temperature measurements using evenly spaced thermocouples were conducted, and the temperature variation at three locations inside the TES unit was recorded. The effects of the HTF inlet parameters were investigated by parametric studies with different temperatures and flow rate values. Reasonably good agreement was achieved between the numerical prediction and the temperature measurement, which confirmed the numerical simulation accuracy. The numerical results showed the significance of buoyancy effect for the dynamic melting process. The system TES performance was very sensitive to the HTF inlet temperature. By contrast, no apparent influences can be found when changing the HTF flow rates. This study provides a comprehensive solution to investigate the heat exchange process of the TES system using PCM.

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Section: Numerical Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

et al. 2017

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“…Allouche et al [3] simulated fluid flow in the steam ejector of a solar refrigeration system while enhanced heat transfer of parabolic trough absorber pipes are considered by Muños et al [4]. The analysis of CSP heat storage systems using CFD has been a recent development, with Fornarelli et al [5], Pointner et al [6] and Xu et al [7] being significant examples. In terms of using this modelling approach for solar power plants, Fasel et al.…”

Section: Introductionmentioning

confidence: 99%

Finite-volume ray tracing using Computational Fluid Dynamics in linear focus CSP applications

et al. 2016

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The modelling of solar irradiation in concentrated solar power (CSP) applications is traditionally done with ray-tracing methods, e.g. the Monte Carlo method. For the evaluation of CSP receivers, the results from ray-tracing codes are typically used to provide boundary conditions to Computational Fluid Dynamics (CFD) codes for the solution of conjugate heat transfer in the receivers. There are both advantages and disadvantages to using separate software for the irradiation and heat transfer modelling. For traditional ray-tracing methods, advantages are the cost-effectiveness of the Monte Carlo method in modelling reflections from specular surfaces; the ability to statistically assign a sun shape to the rays; the statistical treatment of reflectivity and optical errors (e.g. surface slope errors), to name a few. When considering a complex mirror field and a complex receiver with secondary reflective surfaces, especially with selective coatings to enhance absorption and limit re-radiation losses, standard ray tracers may be limited in specifying emissivity and absorptivity, which are both specular and temperature dependent, and are hence not suitable as radiation analysis tool. This type of scenario can be modelled accurately using CFD, through the finite volume (FV) treatment of the radiative transfer equation (RTE) and a banded spectrum approach at an increased computational cost. This paper evaluates the use of CFD in the form of the commercial CFD code ANSYS Fluent v15 and v16 to model the reflection, transmission and absorption of solar irradiation from diffuse and specular surfaces found in linear CSP applications. 2-D CFD solutions were considered, i.e. line concentration. To illustrate and validate the method, two sources were used. The first source was test cases from literature with published solutions and the second a combined modelling approach where solutions were obtained using both FV and ray tracing (with SolTrace). For all the test cases, good agreement was found when suitable modelling settings were used to limit both ray-effect and false scattering errors.

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“…The transition from a conductive to a convective regime produced a significant increase in thermal exchange with a reduction in charging and discharging times and consequent increase in available thermal power and system efficiency. The conditions necessary to establish these convective motions have been extensively studied both experimentally [30,[34][35][36] and numerically [37][38][39][40][41]. The last goal is to promote this sort of heat exchange within the LHTES to achieve an optimized and efficient system.…”

Section: Advancements In Energy Storage Technologiesmentioning

confidence: 99%

Heat Exchange Analysis on Latent Heat Thermal Energy Storage Systems Using Molten Salts and Nanoparticles as Phase Change Materials

Miliozzi¹,

Liberatore²,

Nicolini³

et al. 2018

Advancements in Energy Storage Technologies

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The increase of carbon dioxide emissions is the most important contributor to climate change. A better use of produced energy, increasing systems efficiency and using renewable sources, can limit them. A key technological issue is to integrate a thermal energy storage (TES). It consists in stocking thermal energy through the heating/cooling of a storage material for future needs. Among various technologies, latent heat TES (LHTES) provides high energy storage density at constant temperature during melting/solidification of storage media. The bottleneck in the use of typical PCMs is their low thermal conductivity. To improve the heat exchange between heat transfer fluid and PCM, three methods are possible and here experimentally analyzed: conductivity systems enhancements; convective flows promotion in liquid phase; and improvement of PCM thermal properties including small amounts of nanoparticles. CFD models were used to evaluate physical phenomena that are crucial for optimized LHTES systems design. The study of the heat exchange mode allowed some useful indications to achieve an optimized LHTES, taking advantage by convective flows and conductivity promotion systems. The use of NEPCM, to maximize the stored energy density and realize compact systems, makes necessary the improvement of its thermal diffusivity. These will be the future research topics.

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CFD analysis of melting process in a shell-and-tube latent heat storage for concentrated solar power plants

Cited by 142 publications

References 33 publications

Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

Finite-volume ray tracing using Computational Fluid Dynamics in linear focus CSP applications

Heat Exchange Analysis on Latent Heat Thermal Energy Storage Systems Using Molten Salts and Nanoparticles as Phase Change Materials

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