Granular phase change materials for thermal energy storage: Experiments and numerical simulations

Rady, Mohamed

doi:10.1016/j.applthermaleng.2009.04.018

Cited by 55 publications

(26 citation statements)

References 21 publications

(26 reference statements)

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“…For the fixed bed experiments, the phase change takes place at different times at different heights because of the temperature stratification, in accordance with results presented by Rady [11]. In contrast, in the fluidized bed, the phase change of the material takes place uniformly throughout the whole bed.…”

Section: Resultssupporting

confidence: 77%

“…The material that changes its phase is paraffin, and it is bound within a secondary supporting structure of SiO 2 . This composite material is commercially available in two sizes: a coarser grade with a particle size between 1 and 3 mm, which is suitable for use in a fixed bed Rady [11,16], and a finer grade with a particle size between 0.2 and 0.6 mm. The sand and the finer GR50 material correspond to group B according to Geldart's classification [17], which means that the sand and the finer GR50 composite fluidize easily with vigorous bubbling action and that bubbles grow large [18].…”

Section: Experimental Apparatus and Materialsmentioning

confidence: 99%

“…The utilization of encapsulated phase change materials with a small particle diameter is advantageous in terms of heat transfer rates and pumping requirements when 1) storage systems of small characteristic length are applicable [11], and 2) the time required for the phase change is inversely proportional to the superficial gas velocity and depends on the air supply temperature [12]. A PCM encapsulated in spheres with a diameter of 25 mm and agitated in a liquid-fluidized bed has been tested by Sozen et al [13], who demonstrated improvements over fixed bed thermal energy storage systems and enhanced the performance of the system by increasing the superficial water velocity.…”

Section: Introductionmentioning

confidence: 99%

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Thermal energy storage in a fluidized bed of PCM

Izquierdo-Barrientos

Sobrino

Almendros-Ibáñez

2013

Chemical Engineering Journal

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The objective of the present work was to research the storage behavior of a fluidized bed filled with a granular phase change material (PCM) with a small particle diameter (d p = 0.54 mm). The performance of the fluidized bed was compared to that of well-known storage methods such as fluidized beds with sand and packed beds based of sand and PCM. For this purpose, heating experiments were conducted in a cylindrical bed with air as the working fluid.The influence of the bed height and flow rate on the storage and recovery efficiencies of the fluidized bed of PCM was analyzed. Additionally, the stability of the PCM during various charging-discharging cycles was studied.The results indicate that this PCM is an alternative material that can be used in fluidized bed systems to increase the efficiency of storing thermal * Corresponding author. NOTICE: this is the author's version of a work that was accepted for publication in Chemical Engineering Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. The cycling test shows that the PCM is stable under bubbling conditions up to 15 cycles, which corresponds to approximately 75 hours of continuous operation. A definitive version was subsequently published in Chemical Engineering

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Section: Resultssupporting

confidence: 77%

Section: Experimental Apparatus and Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal energy storage in a fluidized bed of PCM

Izquierdo-Barrientos

Sobrino

Almendros-Ibáñez

2013

Chemical Engineering Journal

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“…The granular PCM consists of paraffin, which is the material that changes its phase, bounded within a secondary supporting structure of SiO 2 , which ensures that the paraffin does not leak from the granulate when in its liquid form. This material is commercialized by Rubitherm and is similar to that used by Rady [20] and Izquierdo-Barrientos et al [3] in their studies. This PCM is available in two sizes involving particle diameters of 1-3 mm and 0.2-0.6 mm.…”

Section: Materials and Experimental Apparatusmentioning

confidence: 99%

“…Rady [20] used a granular PCM (Rubitherm GR42) with a particle size in the range of 1-3 mm in a fixed bed for thermal energy storage, and Regin et al…”

Section: Introductionmentioning

confidence: 99%

Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Izquierdo-Barrientos

Sobrino

Almendros-Ibáñez

2015

Applied Thermal Engineering

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This work presents an experimental study to determine the capacity of a phase change material (PCM) in granular form to be used in fixed and bubbling fluidized beds for thermal energy storage. The experimental measurements are focused on determination of the heat transfer coefficient between a heated surface immersed in the bed and the granular PCM. The flow rate is varied to quantify its influence on the heat transfer coefficient. The PCM used is Rubitherm GR50 with a phase change temperature of approximately 50• C. The PCM is available in two different particle sizes, 0.54 mm and 1.64 mm, of which the finer is used in the fluidized bed and the coarser is used in the fixed bed. In addition, the results obtained for the PCM are compared with the heat transfer coefficients measured for sand, a material commonly used for thermal storage. * Corresponding author. NOTICE: this is the author's version of a work that was accepted for publication in Applied Thermal Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Thermal Engineering 78 (2015) pp. 373-379. doi:10.1016/j.applthermaleng.2014.12.044 In comparing the heat transfer coefficients for fixed and fluidized beds, the heat transfer coefficients in the fluidized bed with PCM are nearly three times higher than those for the fixed bed at the same gas flow rate. This increase in the heat transfer is a result of two main factors: first, the continuous renewal of PCM particles from the heated surface when they are fluidized, and second, the large quantities of energy in latent form absorbed by the PCM. In the fixed bed there is no renovation of particles, consequently only a small percentage of particles are able to change its phase. Hence, there is no increase in the heat transfer coefficient due to this fact.

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Recent Advances in TES Methods, Technologies, and Applications

Dinçer

Rosen

2010

Thermal Energy Storage

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Granular phase change materials for thermal energy storage: Experiments and numerical simulations

Cited by 55 publications

References 21 publications

Thermal energy storage in a fluidized bed of PCM

Thermal energy storage in a fluidized bed of PCM

Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Recent Advances in TES Methods, Technologies, and Applications

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