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

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.

Experimental Study of Thermal Performance of a Reduced Scale Cavity Equipped With Phase Change Material: Study of the Optimal Phase Change Material Layer Location

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Ayoub Gounni ◽  
Mustapha El Alami ◽  
Mohamed Tahar Mabouk ◽  
Abdelhamid Kheiri
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Peak Heat Flux ◽  
Building Walls ◽  
Change Material ◽  
Reduced Scale ◽  
Material Study

Phase change materials (PCMs) used in the building walls constitute an attractive way to reduce the energy consumption and to increase the occupant's thermal comfort. However, there are some challenges to be faced among which the critical one is the PCM layer location allowing the greater heat flux reduction. In this work, the potential of PCM wallboards is evaluated experimentally using a heated reduced scale cavity including walls with or without PCM in a laboratory conditions. The cavity at reduced scale provides the flexibility to test most kinds of wall constructions in real time and allows faster installation and dismantling of the test walls. Three different PCM layer locations inside the walls are examined in terms of heat flux reduction and outside surface temperatures. The results confirm that the PCM layer reduces the peak heat flux compared to a reference wall (wall without PCM). Indeed, the PCM layer hugely affects the peak heat flux when it is placed on the inner face of the walls, near to the heat source. At this location, the peak heat flux reduction, compared to the reference wall, is 32.9%. Furthermore, for numerical validation purpose, the outside overall heat coefficient of the cavity outside walls is determined based on the experimental data.

Optimization of Filling Mass Fraction for Composite PCMs Based Thermal Management System

2017 ◽  
Author(s):  
Bofeng Shang ◽  
Jinyan Hu ◽  
Xingjian Yu ◽  
Bin Xie ◽  
Ruikang Wu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Phase Change ◽  
Latent Heat ◽  
Mass Fraction ◽  
Phase Change Materials ◽  
Matrix Material ◽  
Expanded Graphite ◽  
Working Time ◽  
Transfer Model

Phase Change Materials (PCMs) have been widely investigated as a cooling solution due to their significant latent heat capacity. However, the current PCMs generally suffer a low thermal conductivity, thus hindering the application of PCMs. Composite Phase Change Materials (CPCMs) filling with high thermal conductivity materials have been proposed to solve this issue. Nevertheless, the latent heat of the CPCMs decreases with the mass fraction of fillings, thus leading to a lower allowable working time under safe operating temperature. Therefore, an optimal filling mass fraction of CPCMs is in urgent needed to improve the application of CPCMs. In this study, we developed a one-dimensional conduction heat transfer model of CPCMs to predict the optimal filling mass fraction of CPCMs to realize the maximum allowable working time. The filling mass fraction was introduced into the model and the relationship between the thermal conductivity and latent heat was built. We adopted paraffin as the matrix material and Expanded Graphite (EG) as the thermal conductivity enhancer. The allowable working time of the CPCMs as the function of filling mass fraction was obtained. Based on the principle of the maximum allowable working time, the optimal filling mass fraction was calculated. Comparative experiments were also conducted to validate the accuracy of the prediction model. The parameters which affect the maximum allowable working temperature were also investigated, including input heat flux, safe temperature, and height of CPCMs. The results show that a higher heat flux and height requires a larger filling mass fraction, and it’s opposite for the safe temperature.

Thermal Behavior of a Building Provided With Phase-Change Materials on the Roof and Exposed to Solar Radiation

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Amina Mourid ◽  
Mustapha El Alami
Keyword(s):  
Heat Flux ◽  
Solar Radiation ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solar Irradiation ◽  
Outer Face ◽  
Two Factors ◽  
Insulation Effect ◽  
Identical Test ◽  
Energy Efficiency Potential

This paper evaluates the effectiveness of phase change materials (PCMs) for the improvement of summer thermal comfort in lightweight buildings. Experiments have been carried out using PCM in the form of DuPont Energain wallboards in combination with a roof. Two factors influencing the effectiveness of PCM (thickness and location of PCM layer) have been investigated. An experimental study was carried out using two identical test cavities submitted to Casablanca weather. Thermal performance such as the roof surface temperatures and heat flux densities, through the envelope, have been studied. The results indicated that, compared with reference room (without PCM), the thermal storage allows solar radiation to be stored and released up to 6–7 h after solar irradiation; this has effects on both the reduction of daily temperature swings (up to 2 °C) and heat flux (more than 88%). It has been proved that the PCM with a thickness of 10.52 mm on the outer face of the roof has good thermal insulation effect and energy efficiency potential.

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