Improvement of Phase Change Materials (PCM) Used for Solar Process Heat Applications

Prieto, Cristina; López-Román, Anton; Martínez, Noelia; Morera, Josep M.; Cabeza, Luisa F.

doi:10.3390/molecules26051260

Cited by 17 publications

(7 citation statements)

References 27 publications

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“…In [11], the authors have reported that metal wool can be used as a low-cost additive to increase the thermal conductivity of thermal storage PCMs. It was established that to achieve an increase in the effective thermal conductivity of composite PCM (epoxy resin of 90 vol.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

“…Some researches aimed to eliminate this problem and focused on finding ways to increase the thermal conductivity of existing thermal storage PCMs. Several approaches are considered: installing metal fins in TES devices [3] or capsules with thermal storage PCM [4], adding nanoparticles [5] to thermal storage PCM, including nanoparticles of metal oxide [6], carbon nanotubes and nanofibers [7][8][9], introduction of thermal storage PCMs into highly thermally conductive structures made from expanded graphite [9] or metal matrixes [10], adding highly thermally conductive metal wool [3,11,12], etc. Thus, the investigation aimed at increasing the thermal conductivity of thermal storage PCMs is currently relevant.…”

Section: Introductionmentioning

confidence: 99%

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The effect of metal wool on the charging and discharging rate of the phase transition thermal storage material

Khliyeva¹,

Zhelezny²,

Paskal³

et al. 2021

EEJET

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Thermal energy storage (TES) plays an important role in solar heat power systems. The use of phase change materials (PCM) and selecting additives to increase the rate of heat accumulation is a promising way to increase the efficiency and reliability of such systems. The objects of the study were pure paraffin wax (PW) and composite PCMs based on it (containing aluminum and copper wool of 30 and 45 μm in diameter, respectively). An experimental setup with a cylindrical measuring cell was created, which was also considered as a model of a capsule with a thermal storage material. The rate of temperature change in the pure PW sample and samples of composite PCMs was experimentally measured. Two modes of heating and cooling were investigated: from 48 to 59 °C (mode with a phase change) and from 30 to 40 °C (mode without phase changes). Heating time from 48 to 59 °C for the PW sample was 13 min., for the PW samples with the content of aluminum wool of 0.00588 and 0.01780 m3·m-3 − 11 and 10.5 min., for the PW samples with the content of copper wool of 0.00524 and 0.01380 m3·m-3 − 11 and 8 min., correspondingly. The minimum heating time from 30 to 40 °C was 6 min. for the sample of PW with 0.01380 m3·m-3 of copper wool in comparison with 9 min. for the sample of pure PW. The expediency of using copper wool as an additive to thermal storage materials of PW to increase the charging and discharging rate of TES devices without significantly raising their price was confirmed. The presence of metal wool in molten PW suppresses bottom-up convective currents, so the main mechanism of heat transfer is thermal conductivity. This fact will contribute to a faster equalization of the temperature field by the height of heat storage capsules

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Section: Literature Review and Problem Statementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of metal wool on the charging and discharging rate of the phase transition thermal storage material

Khliyeva¹,

Zhelezny²,

Paskal³

et al. 2021

EEJET

View full text Add to dashboard Cite

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“…Typical values of density of energy storage are in the order of 50 kWh/m 3 (0.02 kWh/kg). A second way is to rely on latent heat storage, − i.e., on the enthalpy variation that accompanies, at a conceptually constant temperature, the phase change (solid–solid, solid–liquid, liquid–gas) of a given substance. Here, the endothermal phase change (driven by solar energy) is the charging stage, and the reverse exothermal one is the discharging stage.…”

Section: Overviewmentioning

confidence: 99%

Salt Hydrates for Thermochemical Storage of Solar Energy: Modeling the Case Study of Calcium Oxalate Monohydrate Dehydration/Rehydration under Suspension Reactor Conditions

Garofalo

Vitiello

Montagnaro

et al. 2021

Ind. Eng. Chem. Res.

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A way to overcome issues related to the exploitation of solar energy is to refer to concentrated solar power technology coupled with systems for thermochemical energy storage (TCES) as a means to store solar energy for theoretically unlimited periods and distances at ambient temperature and with a high energy storage density. As potential candidate materials for TCES, salt hydrates are of particular interest. In this work, we focus our attention on the behavior of the coupled calcium oxalate monohydrate/anhydrous (COM/COA), a case study deserving investigation in the literature. To put the basis for large-scale application, a suspension stirred reactor has been conceptualized here with the idea of performing the process in a suspension medium. This work illustrates and discusses a modeling activity where heat balances for COM dehydration (heat charging stage)/COA rehydration (heat discharging stage), transport phenomena, and kinetics for COM dehydration are scrutinized with the corresponding evaluation of the characteristic time scales. The following aspects were critically analyzed: profiles for mass flow rates of service oil vs time for heating and reaction phases during dehydration, effects of water/COA and COA/oil feed ratios on the final temperature reached during COA rehydration, time–temperature, and time–water mole profiles inside a spherical COM particle upon dehydration, along with the results for stored/released energy (upon charging/discharging stages), characteristic times for heat transfer, mass transfer, water vapor bubble rising, and kinetics referred to the dehydration stage. Finally, the likeliness of controlling mechanisms as a function of particle and water vapor bubble size during COM dehydration has been discussed with the aid of a synoptical graph.

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“…There are different techniques which have been used to improve the heat transfer characteristics of the energy storage systems. These techniques include microencapsulation of PCM [ 1 ], adding nanoparticles [ 2 , 3 , 4 ], absorption of phase change materials in metal foam [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ] and insertion of fins [ 15 , 16 , 17 , 18 , 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Asymmetric Fins on Thermal Performance of Phase Change Material-Based Thermal Energy Storage Unit

et al. 2023

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Phase change material (PCM)-based thermal energy storage units (TESU) have very low thermal conductivity that compromise their charging and discharging rate. The present study focuses on an enhancement in charging rate as well as an increase in the uniformity of the melting rate. A rectangular cavity consisting of two horizontal partial fins is studied. The horizontal partial fins are placed symmetrically in a PCM-based TESU. In the current work, the melting rate of PCM was enhanced using asymmetric arrangement while keeping all other parameters the same, thus showing the positive effect of asymmetric configuration in such storage systems. The position and the pitch of each fin is optimized to improve heat transfer characteristics of the TESU. The numerical investigation of the problem is performed. TESU with asymmetrically placed fins show better performance in terms of higher charging rate as well as uniformity of the charging rate. The asymmetric placement of the fins suggested by present study increased the charging rate by 74.3% on average as compared to the symmetrically placed fins in the storage system. The charging rate uniformity is improved by 43.7%. The asymmetric fin’s placement conserved the convection strength for a longer melting duration and so increased the Nusselt number by 80.2% as compared to the symmetrically placed fins. Thus, it can be concluded that the performance of asymmetric fins is better in the charging of PCMs than the symmetrically placed fins in a PCM-based TESU.

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Improvement of Phase Change Materials (PCM) Used for Solar Process Heat Applications

Cited by 17 publications

References 27 publications

The effect of metal wool on the charging and discharging rate of the phase transition thermal storage material

The effect of metal wool on the charging and discharging rate of the phase transition thermal storage material

Salt Hydrates for Thermochemical Storage of Solar Energy: Modeling the Case Study of Calcium Oxalate Monohydrate Dehydration/Rehydration under Suspension Reactor Conditions

Effect of Asymmetric Fins on Thermal Performance of Phase Change Material-Based Thermal Energy Storage Unit

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