scholarly journals Theoretical and numerical analysis on phase change materials (PCM): A case study of the solidification process of erythritol in spheres

2018 ◽  
Vol 119 ◽  
pp. 523-532 ◽  
Author(s):  
J.H. Nazzi Ehms ◽  
R. De Césaro Oliveski ◽  
L.A. Oliveira Rocha ◽  
C. Biserni
Keyword(s):  
Numerical Analysis ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solidification Process ◽  
Theoretical And Numerical Analysis

scholarly journals Chaotic behavior in Casimir oscillators: A case study for phase-change materials

2017 ◽  
Vol 96 (4) ◽  
Author(s):  
Fatemeh Tajik ◽  
Mehdi Sedighi ◽  
Mohammad Khorrami ◽  
Amir Ali Masoudi ◽  
George Palasantzas
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Chaotic Behavior

Solidification of Phase Change Materials Infiltrated in Porous Media in Presence of Voids

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Mahmoud Moeini Sedeh ◽  
J. M. Khodadadi
Keyword(s):  
Phase Change ◽  
Porous Structure ◽  
Phase Change Materials ◽  
Solidification Process ◽  
Volume Shrinkage ◽  
Freezing Process ◽  
Infiltration Process ◽  
Noticeable Increase ◽  
Melting Characteristics ◽  
Micron Size

Infiltration of phase change materials (PCM) into highly conductive porous structures effectively enhances the thermal conductivity and phase change (solidification and melting) characteristics of the resulting thermal energy storage (TES) composites. However, the infiltration process contributes to formation of voids as micron-size air bubbles within the pores of the porous structure. The presence of voids negatively affects the thermal and phase change performance of TES composites due to the thermophysical properties of air in comparison with PCM and porous structure. This paper investigates the effect of voids on solidification of PCM, infiltrated into the pores of graphite foam as a highly conductive porous medium with interconnected pores. A combination of the volume-of-fluid (VOF) and enthalpy-porosity methods was employed for numerical investigation of solidification. The proposed method takes into account the variation of density with temperature during phase change and is able to predict the volume shrinkage (volume contraction) during the solidification of liquids. Furthermore, the presence of void and the temperature gradient along the liquid–gas interface (the interface between void and PCM) can trigger thermocapillary effects. Thus, Marangoni convection was included during the solidification process and its importance was elucidated by comparing the results among cases with and without thermocapillary effects. The results indicated that the presence of voids within the pores causes a noticeable increase in solidification time, with a sharper increase for cases without thermocapillary convection. For verification purposes, the amount of volume shrinkage during the solidification obtained from numerical simulations was compared against the theoretical volume change due to the variation of density for several liquids with contraction and expansion during the freezing process. The two sets of results exhibited good agreement.

scholarly journals Phase Change Materials-Assisted Heat Flux Reduction: Experiment and Numerical Analysis

Energies ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Hussein Akeiber ◽  
Seyed Hosseini ◽  
Mazlan Wahid ◽  
Hasanen Hussen ◽  
Abdulrahman Mohammad
Keyword(s):  
Heat Flux ◽  
Numerical Analysis ◽  
Phase Change ◽  
Phase Change Materials ◽  
Reduction Experiment

Detailed Numerical Modeling of a Hybrid PCM-Air Heat Sink

2013 ◽  
Author(s):  
Y. Kozak ◽  
G. Ziskind
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Void Formation ◽  
Solidification Process ◽  
Melting Process ◽  
Significant Rise ◽  
Air Interface ◽  
Vof Model

The ability of phase-change materials (PCMs) to absorb large amounts of heat without significant rise of their temperature during the melting process may be utilized in thermal energy storage and passive thermal management. This paper deals with numerical modeling of a hybrid PCM-air heat sink, in which heat may be either absorbed by the PCM stored in compartments with conducting walls, or dissipated to the air using fins, or both. Under the assumptions of perfect insulation (except for the air fins), identity and symmetry between all PCM channels, and negligible 3-D boundary effects, a 2-D model of the problem for half a PCM compartment of the heat sink is solved, saving calculation time and yet taking into account the essential physical phenomena. A commercial program, ANSYS Fluent, is used in order to solve the governing conservation equations. Phase-change is solved using the enthalpy-porosity method. PCM-air interface is modeled using the volume-of-fluid (VOF) approach. The model takes into account natural convection in the liquid PCM and air, volume change, phase- and temperature-dependence of thermal properties, and PCM-air interface interaction. Various scenarios for the hybrid heat sink operation are simulated and compared. The difference in the melting patterns is analyzed for the cases of heating with and without the fan operating. The solidification process with the fan operating is also simulated. It is shown that the VOF model enables simulating realistic void formation in the solidification process.

scholarly journals Numerical analysis of mechanical reliability of multi-coated phase change materials

2021 ◽  
Vol 321 ◽  
pp. 02019
Author(s):  
Josep Forner-Escrig ◽  
Nuria Navarrete ◽  
Roberto Palma ◽  
Damiano La Zara ◽  
Aristeidis Goulas ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Phase Change ◽  
Metallic Nanoparticles ◽  
Phase Change Materials ◽  
Mechanical Performance ◽  
Atomic Layer ◽  
Element Model ◽  
Failure Criteria ◽  
Mechanical Reliability ◽  
Geometrical Properties

Nanoencapsulated phase change materials (nePCMs) are nowadays under research for thermal energy storage purposes. NePCMs are composed of a phase change core surrounded by a shell that confines the core when molten. One of the main concerns of nePCMs when subjected to thermal processes is the mechanical failure of the passivation shell initially present in commercial metallic nanoparticles. In order to overcome this issue, multi-coated nePCMs, based on the synthesis of an additional coating by atomic layer deposition, appear to be as a candidate solution. With the objective of studying the influence of the composition and thickness of the additional nePCM shells on their probability of failure, a numerical tool combining a thermomechanical finite element model with phase change and Monte Carlo algorithms is developed. This tool also allows including the uncertainty of material and geometrical properties into the numerical analysis to account for their influence in the mechanical performance of nePCMs. In the present work, the mechanical reliability of SiO2 and Al2O3 coatings on Sn@SnOx nanoparticles is assessed by considering both deterministic and probabilistic failure criteria and Al2O3 coatings appear to have a better mechanical performance than their SiO2 counterparts.

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