A numerical study on the effects of nanoparticles and stair fins on performance improvement of phase change thermal energy storages

Nakhchi, M.E.; Hatami, M.; Rahmati, Mohammad

doi:10.1016/j.energy.2020.119112

Cited by 62 publications

(15 citation statements)

References 46 publications

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“…They noted that employing downward stepped fins instead of conventional horizontal fins can achieve improvements of up to 65.5% in the melting process. Additionally, Nakhchi et al 17 numerically investigated the addition of conductive nanoparticles alongside stepped fins, with results showing enhanced energy storage capacities that reach a maximum of 474.1 kJ for a stair ratio of 4 and volume concentration of 1.5%. Yang et al 18 investigated the performance of metal foams in melting of PCMs with positive and negative gradient designs in pore parameters.…”

Section: Introductionmentioning

confidence: 99%

Application of partial wire mesh and particle image velocimetry for rectangular phase change material containers as efficient thermal energy storage systems

Nabilou

Gharali

Ebadi

et al. 2022

Energy Science & Engineering

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An experimental setup is built to improve the charging process of a bio‐based phase change material inside a rectangular latent heat thermal energy storage (LHTES) system. In addition to experimenting with different porosities of full‐coverage wire mesh, a novel method of partial wire mesh placement at a proper location is used for improving conduction and maintaining natural convection, proven by the particle image velocimetry (PIV) method. Although acquiring PIV images from coconut oil is challenging because of the laser reflection, the image capturing and processing have been completed successfully. Temperatures inside the enclosure were measured using four K‐type thermocouples, and the melt fraction was calculated using captured images. The full‐size mesh results in a more uniform temperature distribution, and its charging time for porosities of 88% and 82% is decreased by 41% and 52%, respectively. The results of partial wire mesh placements indicate that a top‐only approach leads to a time reduction of only 7%. However, the bottom‐only approach yields a time reduction of 34% and the value of 3.8 for the charging time reduction over the porosity reduction parameter, which is the highest among all experiments. Additionally, this placement eliminates sudden temperature spikes, which improves the performance of the LHTES system and results in an economical and practical configuration. Moreover, the PIV test shows sustained convective velocities at the top half of the enclosure with a partial mesh at the bottom, demonstrating improved natural convection compared to that of a full‐size mesh implementation which weakens convection. Therefore, contrary to full‐size meshes used in previous works, a bottom‐only mesh placement can enhance conduction and convection simultaneously, which can be utilized in practical applications.

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Section: Introductionmentioning

confidence: 99%

Application of partial wire mesh and particle image velocimetry for rectangular phase change material containers as efficient thermal energy storage systems

Nabilou

Gharali

Ebadi

et al. 2022

Energy Science & Engineering

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“…Jing et al [3] used the calculation of the fin efficiency of a serrated type of finned surface for more complicated research on the air-water heat exchanger for the data center. Nakhchi et al [4] used the calculation of the effectiveness of stepped fins' area on the performance improvement of phase change thermal energy storage.…”

Section: Introductionmentioning

confidence: 99%

Calculating the Efficiency of Complex-Shaped Fins

Marcinkowski

Taler

2021

Energies

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Calculation of fin efficiency is necessary for the design of heat exchangers. This efficiency can be calculated for individual finned tubes or continuous fins. Continuous fins are mostly used in plate-fin and tube heat exchangers (PFTHEs). In most cases, the basic elements of those PFTHEs are circular, oval or flattened pipes, which contain circular or polygonal fins. Continuous fins, as can be observed in PFTHEs, are divided into virtual fins. Those fins can have a rectangular shape for an inline arrangement of pipes or a hexagonal shape for a staggered arrangement of pipes. This research shows a methodology of using the finite element method for calculating the efficiency of fins of any shape, placed on pipes of any shape. This paper presents examples of determining the efficiency of seeming fins, which are most commonly used in PFTHEs. In the article, we also compare the precision of calculations of the efficiency of complex-shaped fins using exact analytical methods and approximated methods: the equivalent circular fin method (Schmidt’s method) and the sector method. The results of the analytical methods and the approximate methods are compared to the results of numerical simulations. The calculations for continuous fins with complicated shapes of virtual fins, e.g., hexagonal elongated or segmented, are also presented.

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“…The available studies in the literature have reported that combining heat transfer enhancement techniques can lead to a better heat transfer performance of the storage unit [22,23]. Studies can be found using a combination of fins and heat pipes [24], nanoparticles and fins [25,26], nanoparticles and metal foams [27], metal foams, and heat pipes [28]. Ren et al [29] studied the application of triangular fins in a rectangular LHTES with and without the presence of nanoparticles in the PCM.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Melting Performance in a Conical Latent Heat Thermal Unit Having Variable Length Fins

et al. 2021

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A conical shell-tube design with non-uniform fins was addressed for phase change latent heat thermal energy storage (LHTES). The shell was filled with nano-enhanced phase change material (NePCM). The cone aspect ratio of the shell and the fins aspect ratio were adopted as the geometrical design parameters. The type and volume fraction of the nanoparticles were other design parameters. The investigated nanoparticles were alumina, graphite oxide, silver, and copper. The finite element method was employed to solve the natural convection flow and phase change thermal energy equations in the LHTES unit. The Taguchi optimization method was utilized to maximize the melting rate in the unit. Two cases of ascending and descending conical shells were investigated. The outcomes showed that the shell-aspect ratio and fin aspect ratio were the most important design parameters, followed by the type and concentration of nanoparticles. Both ascending and descending designs could lead to the same melting rate at their optimum design. The optimum design of LHTES could improve the melting rate by up to 18.5%. The optimum design for ascending (descending) design was a plain tube (a cone aspect ratio of 1.17) filled by 4.5% alumina-Bio-PCM (1.5% copper-Bio-PCM).

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A numerical study on the effects of nanoparticles and stair fins on performance improvement of phase change thermal energy storages

Abstract: Using nano-enhanced phase change materials is a widespread passive method to improve the melting performance, and also the storage capacity of the thermal energy storage units. In this study, the effects of CuO nanoparticles  

Cited by 62 publications

References 46 publications

Application of partial wire mesh and particle image velocimetry for rectangular phase change material containers as efficient thermal energy storage systems

Application of partial wire mesh and particle image velocimetry for rectangular phase change material containers as efficient thermal energy storage systems

Calculating the Efficiency of Complex-Shaped Fins

Evaluation of the Melting Performance in a Conical Latent Heat Thermal Unit Having Variable Length Fins

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