Numerical investigation of natural convection behavior of molten PCM in an enclosure having rectangular and tree-like branching fins

Yıldız, Çağatay; Arıcı, Müslüm; Nižetić, Sandro; Shahsavar, Amin

doi:10.1016/j.energy.2020.118223

Cited by 118 publications

(18 citation statements)

References 51 publications

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“…The validation of the present study has been recently carried out against experimental data in Reference 50, as stated in the previous study of the authors 34 . The experimental work includes the free convection characteristics of liquid n‐hexadecane with a Prandtl number of Pr = 39.2, which is significantly close to the molten paraffin wax considered in this study ( Pr = 41.22), in an enclosure that is heated and cooled from sidewalls.…”

Section: Mathematical Formulation and Numerical Proceduresmentioning

confidence: 88%

“…As it is stated in the above‐mentioned literature, PCMs play an important role in cooling applications for PVs. However, it should be noted that the PCM inside the container can fully complete its phase change on the day and remain in liquid form where the heat transfer of melted PCM is afterwards driven by free convection 33,34 . At this point, although various BCs can be possibly defined in the modelling step, 35‐38 appropriate modelling of natural convection in enclosures and specification of BCs become important as they can significantly affect the outcomes and should be suitable and realistic for the considered problem.…”

Section: Introductionmentioning

confidence: 99%

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Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Arıcı

Yıldız

Nižetić³

et al. 2020

Int J Energy Res

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Summary Considering the significance of the appropriate selection of boundary conditions (BCs) in modelling step for practical engineering applications, this study presents a numerical work focusing on the impacts of BCs on the natural convection of molten phase change material (PCM) used for cooling of photovoltaics (PV). A rectangular enclosure loaded with liquid PCM (Pr = 41.22) is considered at an inclination angle of θ = 30° to simulate a PV‐PCM system. Heat flux is applied to the top wall, and impacts of two different BCs at the bottom wall, namely isothermal and convective BCs, on the flow and heat transfer characteristics are compared by taking six different Biot numbers (0.1 ≤ Bi ≤ 100) into account, while the reference case is considered as isothermal BC. Furthermore, the effects of various aspect ratios (AR = 1, 2 and 4) and Rayleigh numbers (Ra = 104, 105 and 106) are also included. The results revealed that Biot number has a significant effect on mean Nusselt number. Compared to the isothermal case, low Biot numbers (Bi < 10) significantly restrict convection motions inside the enclosure and result in remarkably different mean Nusselt numbers, while high Biot numbers give significantly similar results due to low thermal resistance outside the bottom wall. Moreover, the heat transfer enhancement by increasing AR and Ra is considerably high at high Biot numbers, while it is remarkably constricted at low Biot numbers. As a result of comprehensive analyses, it is deduced that utilization of isothermal BCs instead of convective BC for easiness of modelling can be a reasonable approach providing that Biot number is sufficiently large (Bi > 10). Although the inspiration of the present study is PV/PCM systems, the results can be generalized for any kind of fluids used in similar natural convection applications.

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Section: Mathematical Formulation and Numerical Proceduresmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Arıcı

Yıldız

Nižetić³

et al. 2020

Int J Energy Res

Self Cite

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“…Increasing the surface area for heat transfer via fins or geometry itself enhances the melting and solidification rates of the PCM system [ 49 , 50 , 51 ]. Sathe and Dhoble [ 52 ] analyzed the dynamic thermal efficiency of PCM charging in an inclined finned rectangular enclosure with a top surface heating source.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the charging rate is not significantly affected by combining extra fins (more than three), although it considerably enhances the PCM thermal efficiency. Yeldiz et al [ 50 ] numerically studied the thermal convection inside a PCM enclosure combined with two types of fins including rectangular and tree-shape branched fins. They found that the rectangular fin is more effective than the tree-shape fin with the same mass.…”

Section: Introductionmentioning

confidence: 99%

Phase Change Process in a Zigzag Plate Latent Heat Storage System during Melting and Solidification

et al. 2020

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Applying a well-performing heat exchanger is an efficient way to fortify the relatively low thermal response of phase-change materials (PCMs), which have broad application prospects in the fields of thermal management and energy storage. In this study, an improved PCM melting and solidification in corrugated (zigzag) plate heat exchanger are numerically examined compared with smooth (flat) plate heat exchanger in both horizontal and vertical positions. The effects of the channel width (0.5 W, W, and 2 W) and the airflow temperature (318 K, 323 K, and 328 K) are exclusively studied and reported. The results reveal the much better performance of the horizontal corrugated configuration compared with the smooth channel during both melting and solidification modes. It is found that the melting rate is about 8% faster, and the average temperature is 4 K higher in the corrugated region compared with the smooth region because of the large heat-exchange surface area, which facilitates higher rates of heat transfer into the PCM channel. In addition to the higher performance, a more compact unit can be achieved using the corrugated system. Moreover, applying the half-width PCM channel accelerates the melting rate by eight times compared to the double-width channel. Meanwhile, applying thicker channels provides faster solidification rates. The melting rate is proportional to the airflow temperature. The PCM melts within 274 s when the airflow temperature is 328 K. However, the melting time increases to 460 s for the airflow temperature of 308 K. Moreover, the PCM solidifies in 250 s and 405 s in the cases of 318 K and 328 K airflow temperatures, respectively.

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“…Nowadays, unlike above cooling method to decrease the temperature of PV cells, photovoltaics industry is moving towards ultra-thin, low-cost and flexible solar cells, which aimed at for consumer-oriented electronic products. [25][26][27][28] Perovskite solar cell has obtained tremendous interesting in the past years due to their excellent characteristics. [29,30] The perovskite solar cell is flexible due to the reduced thickness, which has a promising market applicability.…”

Section: Introductionmentioning

confidence: 99%

Design of Biomimetic Leaf-type Hierarchical Nanostructure for Enhancing the Solar Energy Harvesting of Ultra-thin Perovskite Solar Cells

Liang¹,

Lin²,

Wang³

et al. 2020

ES Energy Environ.

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Ultra-thin perovskite solar cell had the advantages of low cost, high efficiency and flexibility, which had significant potential in application. However, a severe optical loss was often observed in the ultra-thin perovskite solar cell due to the insufficient light absorption. In this study, inspired by the efficient light harvesting of hierarchical structure in leaf, a biomimetic leaf-type hierarchical nanostructure was introduced for designing highly efficient ultra-thin perovskite solar cell. In detail, three layers of hexagonal arrays of silica nanoparticles with different radius constructed the biomimetic leaf-type hierarchical structure. The biomimetic leaf-type hierarchical nanostructure was optimized by finite-difference time-domain method combined with particle swarm optimization algorithm to reduce the light reflection and increase the light absorption of the ultra-thin perovskite solar cell. The results indicated that biomimetic leaf-type hierarchical nanostructure could enhance the light absorption of ultra-thin perovskite solar cell by maximum 39% at the long wavelength. The photocurrent of the perovskite solar cell with biomimetic leaf-type hierarchical nanostructure was 8.4% higher than that of perovskite solar cell without biomimetic

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Numerical investigation of natural convection behavior of molten PCM in an enclosure having rectangular and tree-like branching fins

Cited by 118 publications

References 51 publications

Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Phase Change Process in a Zigzag Plate Latent Heat Storage System during Melting and Solidification

Design of Biomimetic Leaf-type Hierarchical Nanostructure for Enhancing the Solar Energy Harvesting of Ultra-thin Perovskite Solar Cells

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