The effects of radiative heat transfer during the melting process of a high temperature phase change material confined in a spherical shell

Archibold, Antonio Ramos; Rahman, Muhammad M.; Goswami, D. Yogi; Stefanakos, Elias K.

doi:10.1016/j.apenergy.2014.10.086

Cited by 28 publications

(12 citation statements)

References 39 publications

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“…The capsules began to melt after 750 seconds, and by 1000 seconds the first 3 capsules started melting. As was seen in previous work by the authors, melting in cylindrical capsules began at the PCM‐void interface along the capsule edge (Figure A,B). Note that Figure shows only if a cell within the capsule is solid or liquid.…”

Section: Resultssupporting

confidence: 82%

“…Using a similar approach, Archibold et al modeled a high‐temperature capsule using NaNO 3 and obtained similar results. The authors then went on to investigate the effect of radiation on the melting process of high‐temperature PCM . The effect of an internal void on the melting of various sized cylindrical EPCM capsules with an exterior convective boundary condition was investigated by Elmozughi et al Their results showed that the presence of an internal void profoundly affects the internal heat transfer.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

et al. 2018

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The capability of an encapsulated phase change material (EPCM)-based thermal energy storage (TES) system to store a large fraction of latent energy at high temperatures was examined. A 3-dimensional simulation of a prototype heat exchanger was conducted employing sodium nitrate as the phase change material (PCM). The k-ω SST model was used to capture the turbulent flow of the HTF, while the melting front was tracked using the enthalpy-porosity method.The results show that the use of metal deflectors yields a nearly constant heat transfer coefficient over the capsule's surface. Despite this, the presence of the void in the capsule and natural convection within the molten PCM influenced the storage characteristics of the system affecting the shape of the isotherms and melting front. Furthermore, the EPCM capsules consecutively undergo the same heat transfer starting from the capsule closest to the inlet. The EPCM capsules store 80% of the energy lost by the HTF. The 17.7 kg of sodium nitrate stores 14.5 MJ of energy where 20% of the energy stored is via latent heat. Of the energy released by the heat transfer fluid, 80% was absorbed by the EPCM capsules with the remaining energy going into the test section walls. A total of 14.5 MJ of energy was stored by the 17.7 kg of NaNO 3 , of which 20% is attributed to the latent heat. The fraction of energy stored as latent heat would be larger if a smaller operating temperature range was used. Thus, an EPCM-based latent heat TES system is capable of storing a large fraction of the supplied energy and presents efficient means of storing thermal energy for hightemperature applications. Additionally, the strong agreement between the numerical and experimental works demonstrates that the numerical methods employed can predict the behavior of an EPCM capsule not only within a single capsule but on the system scale as well. Therefore, the applied numerical methods can be used for further design and optimization of EPCM-based latent heat TES systems.

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Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

et al. 2018

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“…To the author's knowledge, there are few published literatures that considered the effect of thermal radiation in PCM-based thermal energy storage. Archibold et al [28] conducted a numerical study on the thermal characteristics of a single spherical capsule in consideration of the influence of radiative heat transfer during the phase change process. The discrete ordinate method was used to solve the radiative transfer equation.…”

Section: Introductionmentioning

confidence: 99%

The value of thermal radiation in assessing the charge/discharge rate of high-grade thermal energy storage using encapsulated phase change materials (PCMs)

Ding

2016

Int. J. Energy Res.

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Summary The charge/discharge rate of a spherical phase change material (PCM) capsule was assessed in consideration of phase change phenomenon and the combined effect of thermal radiation and heat convection in the charging/discharging processes. The heat transfer model was developed based on a single PCM capsule. The equivalent heat flux was evaluated by using the thermal resistance method. In consideration of the thermal radiation, the equivalent charge/discharge rate was improved, and the temperature rising of the PCM was actually much faster in the charging/discharging processes. It was indicated that the influence of the thermal radiation became more significant for PCM capsules under a small Re number (constant air velocity) and for high‐grade thermal energy storage. The analytical results showed that the highest heat flux contributed by cold thermal radiation occupied 30% and 62% of that by heat convection for PCM capsules with radius of 10 and 40 mm, respectively. This illustrated the crucial value of thermal radiation on the charge/discharge rate of PCM capsules with a large radius. However, for smaller size PCM capsules, the equivalent heat flux was larger under the same fluid flow velocity, and it decreased more promptly with time, because the heat convection that played the dominant role in charge/discharge processes was sensitively affected by the radius of the PCM capsules. Copyright © 2016 John Wiley & Sons, Ltd.

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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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The effects of radiative heat transfer during the melting process of a high temperature phase change material confined in a spherical shell

Abstract: openAccessArticle: Falsecover date: 2015-01-15pii: S0306-2619(14)01146-5Harvest Date: 2016-01-06 13:08:31issueName:Page Range: 675-675href scidir: http://www.sciencedirect.com/science/article/pii/S0306261914011465pubType

Cited by 28 publications

References 39 publications

Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

Analysis of an encapsulated phase change material-based energy storage system for high-temperature applications

The value of thermal radiation in assessing the charge/discharge rate of high-grade thermal energy storage using encapsulated phase change materials (PCMs)

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

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