Numerical and Experimental Study of Solidification in a Spherical Shell

The present study explores numerically and experimentally the process of a phase-change material (PCM) solidification in a spherical shell. At the initial state, the PCM liquid occupies 98.5% of the shell. The upper segment of 1.5% contains air, which flows in as the solidification progresses. In the experiments, a commercially available paraffin wax is used. Its properties are engaged in the numerical simulations. The investigation is performed for solidification in spherical shells of 20 mm, 40 mm, 60 mm, and 80 mm in diameter at the wall uniform temperature, which varied from 10°C to 40°C below the mean solidification temperature of the phase-change material. Transient numerical simulations are performed using the FLUENT 6.2 software and incorporate such phenomena as flow in the liquid phase, volumetric shrinkage due to solidification, and irregular boundary between the PCM and air. The numerical model is validated versus the experimental results. Shrinkage patterns and void formation are demonstrated. Dimensional analysis of the results is performed and presented as the PCM melt fractions versus the product of the Fourier and Stefan numbers. This analysis leads to a generalization that encompasses the cases considered herein.

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Effect of Aerogel Incorporation in PCM-Containing Thermal Liner of Firefighting Garment

Clothing and Textiles Research Journal ◽

10.1177/0887302x18755464 ◽

2018 ◽

Vol 36 (3) ◽

pp. 151-164 ◽

Cited By ~ 8

Author(s):

Abu Shaid ◽

Lijing Wang ◽

Stanley M. Fergusson ◽

Rajiv Padhye

Keyword(s):

Thermal Properties ◽

Thermal Resistance ◽

Heat Resistance ◽

Phase Change ◽

Phase Change Material ◽

Protective Clothing ◽

Ignition Time ◽

Current Case ◽

The Mean ◽

Change Material

Phase change material (PCM) in firefighting garment enhances protection and comfort. Wearing a protective clothing containing PCM, while fighting the fire, is a direct risk to the wearer as most PCMs used are flammable. This article reports a solution by using aerogel. Thermal liner fabric was treated with PCM and/or aerogel and then their thermal properties were analyzed. It has been found that the mean ignition time of PCM-containing thermal liner is around 3.3 s in current case while this value significantly increased to 5.5 s when the combination of aerogel and PCM was used. Moreover, the weight of the liner fabric with aerogel decreased in comparison to PCM-containing liner. Aerogel also slowed down the spreading of flame in PCM-containing fabric. Aerogel–coated liner showed superior heat resistance and the combination of aerogel with PCM increased the thermal resistance of PCM-containing liner.

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Review on numerical simulations for nano-enhanced phase change material (NEPCM) phase change process

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-019-09038-2 ◽

2019 ◽

Vol 141 (2) ◽

pp. 669-684

Author(s):

M. A. M. Irwan ◽

C. S. Nor Azwadi ◽

Y. Asako ◽

J. Ghaderian

Keyword(s):

Phase Change ◽

Numerical Simulations ◽

Phase Change Material ◽

Change Process ◽

Phase Change Process ◽

Change Material

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Transient Performance of a Finned PCM Heat Sink

Advances in Electronic Packaging, Parts A, B, and C ◽

10.1115/ipack2005-73113 ◽

2005 ◽

Author(s):

V. Shatikian ◽

G. Ziskind ◽

R. Letan

Keyword(s):

Phase Change ◽

Melting Temperature ◽

Phase Change Material ◽

Heat Sink ◽

Geometrical Parameters ◽

Transient Performance ◽

The Mean ◽

Liquid States ◽

Fin Thickness ◽

Change Material

The present study explores numerically the transient performance of a heat sink based on a phase change material (PCM), during the process of melting. Heat is transferred to the sink through its horizontal base, to which vertical fins made of aluminum are attached. The phase change material is stored between the fins. Its properties, including the melting temperature, latent and sensible specific heat, thermal conductivity and density in solid and liquid states, are based on a commercially available paraffin wax. A parametric investigation is performed for melting in a relatively small system, 10mm high, where the fin thickness is 1.2mm, and the distance between the fins varies from 2mm to 8mm. The temperature of the base varies from 12°C to 24°C above the mean melting temperature of the PCM. Transient numerical simulations are performed, yielding temperature evolution in the fins and the PCM. The computational results show how the transient phase-change process, expressed in terms of the volume melt fraction of the PCM, depends on the thermal and geometrical parameters of the system, which relate to the temperature difference between the base and the mean melting temperature, and to the thickness of the PCM layer. This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

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Experimental Research on Thermal Performance of Shape-Stabilized Phase Change Material Floor

Solar Energy ◽

10.1115/isec2004-65078 ◽

2004 ◽

Author(s):

Xu Xu ◽

Hongfa Di ◽

Kunping Lin ◽

Yinping Zhang ◽

Rui Yang

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Thermal Performance ◽

Comfort Level ◽

Indoor Temperature ◽

Simulation Research ◽

Temperature Swing ◽

The Mean ◽

Saving Effect ◽

Change Material

Experimental study was conducted on the thermal performance and energy saving effect of a room with shape-stabilized phase change material (PCM). The results showed that the mean indoor temperature of the room with PCM floor was about 2°C higher than that of the room with normal floor and the indoor temperature swing range narrowed greatly. The results also manifested that by applying shape-stabilized PCM in room suitably, the thermal comfort level could be raised and space heating energy in winter could be saved. Finally, the experimental results enriched the database for the further modeling and simulation research.

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Experimental Validation of Numerical Simulations of a Closed-Loop Thermosyphon Operating With Slurries of a Microencapsulated Phase-Change Material

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-38812 ◽

2014 ◽

Author(s):

Alexandre Lamoureux ◽

Bantwal R. (Rabi) Baliga

Keyword(s):

Phase Change ◽

Numerical Simulations ◽

Phase Change Material ◽

Experimental Validation ◽

Closed Loop ◽

Effective Properties ◽

Control Volume ◽

Experimental Calibration ◽

Microencapsulated Phase Change Material ◽

Change Material

Experimental validation and calibration of numerical simulations of a closed-loop thermosyphon operating under steady-state conditions with slurries of a microencapsulated phase-change material (MCPCM) suspended in distilled water are presented. The slurries exhibited a non-Newtonian, shear-thinning, power-law rheological behavior in the range of parameters considered; and the constants in the related model were calibrated using data from specially conducted experiments. The flows of these slurries in the problems of interest were laminar. Furthermore, the velocity and temperature differences between the dispersed and conveying phases of these slurries were negligibly small, so homogeneous models could be used for mathematical representations of the fluid flow and heat transfer phenomena. A hybrid numerical method was used in the simulations: detailed two-dimensional axisymmetric control-volume finite element (CVFEM) simulations of the heated and cooled sections of the thermosyphon were coupled with segmented quasi-one-dimensional finite volume (FVM) simulations of the other portions. The CVFEM and FVM used in this work are well-established. Thus, the verification of these methods is not addressed here. Rather, the details of the thermosyphon, effective properties of the MCPCM and slurries, overviews of the hybrid model and the aforementioned numerical methods, notes on the experimental calibration and validation, and some results are presented and discussed.

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Heat Transfer Enhancements Using Vibration During Solidification of Paraffin

2010 14th International Heat Transfer Conference, Volume 7 ◽

10.1115/ihtc14-23146 ◽

2010 ◽

Author(s):

Johnathan Vadasz ◽

Josua Meyer ◽

Saneshan Govender

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Phase Change Material ◽

Wall Temperature ◽

Vibration Frequency ◽

Initial Temperature ◽

Solidification Process ◽

Solid Material ◽

Solidification Temperature ◽

Change Material

In the current study the effects of vibration on the solidification process of phase change material (PCM) paraffin in a sphere shell are investigated. The amount of PCM used was kept constant during each experiment by using a digital scale to check the weight and a thermocouple to check the consistency of the temperature. A small amount of air was present in the sphere so that the sphere was not filled completely. Commercially available paraffin wax, RT35, was used in the experiments. Experimentations were done on a sphere of 40 mm diameter, wall temperature of 20°C below mean solidification temperature, and consistent initial temperature. A constant vibration frequency of 100 Hz was applied to the setup and results compared with that of no vibration. Samples were taken at different times during the solidification process and compared with respect to solid material present. It was found that the solidification time had been reduced significantly under the vibration. This led to the conclusion that there had been an improvement in heat transfer due to the vibration.

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Effect of Finned-Tube on the Enhancement of Melting Process of PCM in Eccentric Cylinders

Mechanics and Mechanical Engineering ◽

10.2478/mme-2018-0077 ◽

2020 ◽

Vol 22 (4) ◽

pp. 975-982

Author(s):

S. Khaldi ◽

A. Nabil Korti ◽

S. Abboudi

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Numerical Simulations ◽

Phase Change Material ◽

Melting Process ◽

Finned Tube ◽

Eccentric Cylinders ◽

Horizontal Cylinders ◽

Volume Method ◽

Change Material

AbstractThe process of melting of a phase-change material (PCM) in eccentric horizontal cylinders geometry is studied numerically. Numerical simulations are performed for symmetric melting of phase change material between the two cylinders using the finite volume method. The inner cylinder is a finned-tube to enhance the heat transfer between the inner cylinder and the PCM. Inner cylindrical is considered as hot wall while outer is insulated. These simulations show the melting process from the beginning to the end. As result, it is found that the use of fins on the inner tube increases the melting process by decreasing the time of melting by 72.72 %.

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Heat Transfer in Laminar Flow With a Phase Change Boundary

Journal of Heat Transfer ◽

10.1115/1.3245185 ◽

1982 ◽

Vol 104 (4) ◽

pp. 678-682 ◽

Cited By ~ 5

Author(s):

S. Asgarpour ◽

Y. Bayazitoglu

Keyword(s):

Heat Transfer ◽

Phase Change ◽

Phase Change Material ◽

Water System ◽

Heat Transfer Fluid ◽

Bulk Temperature ◽

Solidification Temperature ◽

Interface Position ◽

Tube Heat Exchanger ◽

Change Material

Thermal analysis of a shell-and-tube heat exchanger with a phase change material (PCM) on the shell side and a heat transfer fluid flowing through the tube is presented. The phase change material was initially liquid at its solidification temperature. The heat transfer fluid originates from an isothermal reservoir at a temperature which is lower than the temperature of the phase change material. Numerical results of finite difference method are obtained with a ratio of the thermal properties of the phase change material to the fluid to represent n-octadecane, wax-water system. Variations of the temperature distribution for the fluid, and the PCM, and the interface position of the phase change material in the radial and axial directions are presented. The bulk temperature of the fluid is shown to be a function of the Stefan number, the Fourier number and the velocity profile. It is also shown that the Biot number varies in the axial direction and the heat capacity effects of the phase change material, even at low Stefan numbers are significant.

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