Effect of phase separation and supercooling on the storage capacity in a commercial latent heat thermal energy storage: Experimental cycling of a salt hydrate PCM

Tan, Pepe; Lindberg, Patrik; Eichler, Kaia; Löveryd, Per; Johansson, Pär; Kalagasidis, Angela Sasic

doi:10.1016/j.est.2020.101266

Cited by 50 publications

(7 citation statements)

References 19 publications

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“…Thus, there is a need to fully understand the behavior of the developed PEG with regard to thermal conditions. This is critical to reducing the discrepancy found, for some PCMs, between the material’s performance on a small scale and at real scale applications. − …”

Section: Introductionmentioning

confidence: 99%

Cycling Stability of Poly(ethylene glycol) of Six Molecular Weights: Influence of Thermal Conditions for Energy Applications

Paberit

Rilby

Göhl

et al. 2020

ACS Appl. Energy Mater.

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Utilizing energy storage technologies is beneficial for bridging the gap between supply and demand of energy and for increasing the share of renewable energy in the energy system. Phase change materials (PCMs) offer higher energy density and compact storage design compared to conventional sensible heat storage materials. Over the past years, poly(ethylene glycol) (PEG) has gained attention in the PCM field, and several new composites of PEGs have been developed for thermal energy storage purposes. PCMs are investigated at a given heating/cooling rate to evaluate their phase change temperature and enthalpy. In the case of PEG, some molecular weights show a melting behavior that depends on the thermal history, such as the crystallization conditions. This study investigates the relationship between the molecular weights of PEGs (400−6000 g/mol), cooling/heating rates, and the behavior during phase transitions, to evaluate the performance of PEGs as a PCM under various thermal conditions. Experiments were performed using differential scanning calorimeter and the transient plane source method. All PEG molecular weights were subjected to the same cooling and heating conditions, cooling and heating rate, and number of cycles, to decouple the thermal effects from molecular weight effects. The behavior of phase transition for different thermal conditions was thoroughly analyzed and discussed. It was found that the melting temperature range of PEGs with different molecular weight was between 5.8 and 62 °C (at 5 °C/min). Each PEG showed unique responses to the cooling and heating rates. Generally, the behavior of the crystallization changed most between the thermal cycles, while the melting peak was stable regardless of the molecular weight. Finally, it is recommended that the characterization of PEGs and their composites should be conducted at a heating and cooling rate close to the thermal conditions of the intended thermal energy storage application.

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Section: Introductionmentioning

confidence: 99%

Cycling Stability of Poly(ethylene glycol) of Six Molecular Weights: Influence of Thermal Conditions for Energy Applications

Paberit

Rilby

Göhl

et al. 2020

ACS Appl. Energy Mater.

Self Cite

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“…Despite the poor thermal conductivity of PCMs, a common problem in the solidification of some phase change materials (such as salt hydrates, sugar alcohols, and alkanes) is supercooling [24,25]. In supercooling, the PCM solidifies below its typical solidus temperature, limiting its thermal stability in long-term applications.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study of Solidification in the Shell-And-Tube Energy Storage System with a Novel Dual-PCM Configuration

Mozafari

Lee

2022

Energies

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This study proposes a novel dual-PCM configuration with outstanding solidification response in a horizontal shell-and-tube energy storage system. To demonstrate that the proposed PCM configuration is superior in its thermal responses, results from a range of numerical simulations are presented and compared between different configurations of dual-PCM. As the melting/solidus point is a crucial factor for the solidification rate, dual PCMs are chosen such that the average of their melting point is equal to the melting point of the single-PCM in the reference case. Additionally, equal-area sectors are considered for all cases to ensure the same quantities of PCMs are compared. The temporal liquid fraction and temperature contours reveal that solidification is delayed in the upper half of the system due to strong natural convection motions. Therefore, a dual-PCM configuration is offered to improve the solidification rate in this region and accelerate the full solidification process. Results show that placing a PCM with a lower solidus point in the lower half or an annulus-shaped zone around the cold tube can save the full recovery time up to 8.51% and 9.36%, respectively. The integration of these two strategies results in a novel and optimum design that saves the solidification time up to 15.09%.

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“…Thus, in order to maximize an LHTES system’s performance, these elements should be addressed concurrently. According to a study in the literature, PCM has many shortcomings, including poor specific heat and thermal conductivity [ 6 , 7 ], phase separation [ 8 ], corrosion potential [ 9 ], leakage problems [ 10 ], and supercooling [ 11 ]. As a consequence, much work has been devoted to creating a variety of methods for enhancing PCMs, including shape-stabilized PCM [ 12 , 13 ], additives [ 14 ], and micro- or nano-encapsulation [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Melting Process of Shell-and-Tube PCM Thermal Energy Storage Unit Using Modified Tube Design

et al. 2022

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Recently, phase change materials (PCMs) have gained great attention from engineers and researchers due to their exceptional properties for thermal energy storing, which would effectively aid in reducing carbon footprint and support the global transition of using renewable energy. The current research attempts to enhance the thermal performance of a shell-and-tube heat exchanger by means of using PCM and a modified tube design. The enthalpy–porosity method is employed for modelling the phase change. Paraffin wax is treated as PCM and poured within the annulus; the annulus comprises a circular shell and a fined wavy (trefoil-shaped) tube. In addition, copper nanoparticles are incorporated with the base PCM to enhance the thermal conductivity and melting rate. Effects of many factors, including nanoparticle concentration, the orientation of the interior wavy tube, and the fin length, were examined. Results obtained from the current model imply that Cu nanoparticles added to PCM materials improve thermal and melting properties while reducing entropy formation. The highest results (27% decrease in melting time) are obtained when a concentration of nanoparticles of 8% is used. Additionally, the fins’ location is critical because fins with 45° inclination could achieve a 50% expedition in the melting process.

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Effect of phase separation and supercooling on the storage capacity in a commercial latent heat thermal energy storage: Experimental cycling of a salt hydrate PCM

Cited by 50 publications

References 19 publications

Cycling Stability of Poly(ethylene glycol) of Six Molecular Weights: Influence of Thermal Conditions for Energy Applications

Cycling Stability of Poly(ethylene glycol) of Six Molecular Weights: Influence of Thermal Conditions for Energy Applications

Simulation Study of Solidification in the Shell-And-Tube Energy Storage System with a Novel Dual-PCM Configuration

Enhancing the Melting Process of Shell-and-Tube PCM Thermal Energy Storage Unit Using Modified Tube Design

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