scholarly journals Melting of PCMs Embedded in Copper Foams: An Experimental Study

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1195
Author(s):  
Andrea Diani ◽  
Luisa Rossetto
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Cooling System ◽  
Morphological Characteristics ◽  
Power Input ◽  
Heat Fluxes ◽  
Foam Material ◽  
Melting Temperatures ◽  
Copper Foam ◽  
Passive Cooling System

A smart possible way to cool electronics equipment is represented by passive methods, which do not require an additional power input, such as Phase Change Materials (PCMs). PCMs have the benefit of their latent heat being exploited during the phase change from solid to liquid state. This paper experimentally investigates the melting of different PCMs having different melting temperatures (42, 55 and 64 °C). Two copper foams, having 10 PPI and relative densities of 6.7% and 9.5%, i.e., porosities of 93.3% and 90.5%, respectively, are used to enhance the thermal conductivity of PCMs. The block composed by the PCM and the copper foam is heated from one side, applying three different heat fluxes (10, 15 and 20 kW m−2): the higher the heat flux, the higher the temperature reached by the heated side and the shorter the time for a complete melting of the PCM. The copper foam with a relative density of 9.5% shows slightly better performance, whereas the choice of the melting temperature of the PCM depends on the time during which the passive cooling system must work. The effect of the foam material is also presented: a copper foam presents better thermal performances than an aluminum foam with the same morphological characteristics. Finally, experimental dimensionless results are compared against values predicted by a correlation previously developed.

Numerical Thermal Performance Investigation of an Electric Motor Passive Cooling System Employing Phase Change Materials

2021 ◽  
Author(s):  
Ali Deriszadeh ◽  
Filippo de Monte ◽  
Marco Villani
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Electric Motor ◽  
Phase Change Materials ◽  
Cooling System ◽  
Passive Cooling ◽  
Time Step ◽  
Cooling Performance ◽  
Passive Cooling System ◽  
Change Material

Abstract This study investigates the cooling performance of a passive cooling system for electric motor cooling applications. The metal-based phase change materials are used for cooling the motor and preventing its temperature rise. As compared to oil-based phase change materials, these materials have a higher melting point and thermal conductivity. The flow field and transient heat conduction are simulated using the finite volume method. The accuracy of numerical values obtained from the simulation of the phase change materials is validated. The sensitivity of the numerical results to the number of computational elements and time step value is assessed. The main goal of adopting the phase change material based passive cooling system is to maintain the operational motor temperature in the allowed range for applications with high and repetitive peak power demands such as electric vehicles by using phase change materials in cooling channels twisted around the motor. Moreover, this study investigates the effect of the phase change material container arrangement on the cooling performance of the under study cooling system.

Heat Transfer Enhancement of Finned Copper Foam/Paraffin Composite Phase Change Material

2021 ◽  
Vol 14 ◽  
Author(s):  
Tingting Wu ◽  
Yanxin Hu ◽  
Xianqing Liu ◽  
Changhong Wang ◽  
Zijin Zeng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Transfer Rate ◽  
Flow Resistance ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Melting Process ◽  
Copper Foam ◽  
Composite Phase Change Material ◽  
Change Material

Background: The employment of Phase Change Materials (PCMs) provides a potential selection for heat dissipation and energy storage. The main reason that hinders the wide application is the low thermal conductivity of PCMs. Combining the proper metal fin and copper foam, the fin/composite phase change material (Fin-CPCM) structure with good performance could be obtained. However, the flow resistance of liquid paraffin among the porous structure has seldom been reported, which will significantly affect the thermal performance inside the metal foam. Furthermore, the presence of porous metal foam is primarily helpful for enhancing the heat transfer process from the bottom heat source. The heat transfer rate is slow due to the one-dimensional heat transfer from the bottom. It should be beneficial for improving the heat transfer performance by adding external fins. Therefore, in the present study, a modified structure by combining the metal fin and copper foam is proposed to further accelerate the melting process and improve the temperature uniformity of the composite. Objective: The purpose of this study is to research the differences in the heat transfer performance among pure paraffin, Composite Phase Change Materials (CPCM) and fin/Composite Phase Change Material (Fin-CPCM) under different heating conditions, and the flow resistance of melting paraffin in copper foam. Methods: To experimentally research the differences in the heat transfer performance among pure paraffin, CPCM and Fin-CPCM under different heating conditions, a visual experimental platform was set up, and the flow resistance of melting paraffin in copper foam was also analyzed. In order to probe into the limits of the heat transfer capability of composite phase change materials, the temperature distribution of PCMs under constant heat fluxes and constant temperature conditions was studied. In addition, the evolution of the temperature distributions was visualized by using the infrared thermal imager at specific points during the melting process. Results: The experimental results showed that the maximum temperature of Fin-CPCM decreased by 21°C under the heat flux of 1500W/m2 compared with pure paraffin. At constant temperature heating conditions, the melting time of Fin-CPCM at a temperature of 75°C is about 2600s, which is 65% less than that of pure paraffin. Due to the presence of the external fins, which brings the advantage of improving the heat transfer rate, the experimental result exhibited the most uniform temperature distribution. Conclusion: The addition of copper foam can accelerate the melting process. The addition of external fins brings the advantage of improving the heat transfer rate, and can make the temperature distribution more uniform.

Application of Phase Change Materials to Thermal Control of Electronic Modules: A Computational Study

1997 ◽  
Vol 119 (1) ◽  
pp. 40-50 ◽  
Author(s):  
D. Pal ◽  
Y. K. Joshi
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Cooling System ◽  
Computational Study ◽  
Power Level ◽  
Thermal Control ◽  
The Other ◽  
Three Dimensions ◽  
Temperature Isotherm ◽  
Laminate Thickness

A computational model is developed to predict the performance of phase change materials(PCMs) for passive thermal control of electronic modules during transient power variations or following an active cooling system failure. Two different ways of incorporating PCM in the module are considered. One is to place a laminate of PCM outside the multichip module, and the other is to place the PCM laminate between the substrate and the cold plate. Two different types of PCMs are considered. One is n-Eicosene, which is an organic paraffin, and the other one is a eutectic alloy of Bi/Pb/Sn/In. Computations are performed in three dimensions using a finite volume method. A single domain fixed grid enthalpy porosity method is used to model the effects of phase change. Effects of natural convection on the performance of PCM are also examined. Results are presented in the form of time-wise variations of maximum module temperature, isotherm contours, velocity vectors, and melt front locations. Effects of PCM laminate thickness and power levels are studied to assess the amount of PCM required for a particular power level. The results show that the PCMs are an effective option for passive cooling of high density electronic modules for transient periods.

Air-cooling system based on phase change materials for a vehicle cabin

2020 ◽  
Author(s):  
Sangeetha Krishnamoorthi ◽  
L. Prabhu ◽  
Glen Kuriakose ◽  
Dave Jose lewis ◽  
J. Harikrishnan
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Cooling System ◽  
Air Cooling ◽  
Vehicle Cabin ◽  
Air Cooling System

Analysis of Passive Temperature Control Systems Using Phase Change Materials for Application to Secondary Batteries Cooling

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Roberto Bubbico ◽  
Francesco D'Annibale ◽  
Barbara Mazzarotta ◽  
Carla Menale
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Temperature Control ◽  
Phase Change Materials ◽  
Heat Fluxes ◽  
Battery Thermal Management ◽  
Thermal Management System ◽  
Battery Thermal Management System ◽  
Safe Limits ◽  
Computational Fluid Dynamics Cfd

Abstract Temperature control is one of the most significant factors to improve the performance and extend the cycle life of a battery. It is, therefore, important to design and implement an effective battery thermal management system (TMS). Phase change materials (PCMs) can be used as a cooling means for batteries. In the present paper, a preliminary analysis of the thermal behavior of PCMs used to cool down a heated metal surface was carried out. Tests have shown that pure PCMs are able to limit the temperature increase, but only for relatively low-heat fluxes. At higher values of the heat produced, the thermal conductivity of the PCM was increased by using solid foams characterized by higher thermal conductivity; it was, thus, possible to keep the surface temperature within safe limits for longer times. A computational fluid dynamics (CFD) model of the composite material (PCM + solid foam) was also developed, which allowed to predict the temperature trend within the system under different boundary conditions. However, the average thermal conductivity of the composite system that best fitted the experimental results was found to be much lower than that theoretically predicted by using common semiempirical correlations.

On Development of a Semi-Mechanistic Wall Boiling Model

2013 ◽  
Author(s):  
Saurish Das ◽  
Hemant Punekar
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Stresses ◽  
Cooling System ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Wall Heat Transfer ◽  
Cooling Systems ◽  
Transfer Phenomenon

In modern cooling systems the requirement of higher performance demands highest possible heat transfer rates, which can be achieved by controlled nucleate boiling. Boiling based cooling systems are gaining attention in several engineering applications as a potential replacement of conventional single-phase cooling system. Although the controlled nucleate boiling enhances the heat transfer, uncontrolled boiling may lead to Dry Out situation, adversely affecting the cooling performance and may also cause mechanical damage due to high thermal stresses. Designing boiling based cooling systems requires a modeling approach based on detailed fundamental understanding of this complex two-phase heat and mass transfer phenomenon. Such models can help analyze different cooling systems, detect potential design flaws and carry out design optimization. In the present work a new semi-mechanistic wall boiling model is developed within commercial CFD solver ANSYS FLUENT. A phase change mechanism and wall heat transfer augmentation due to nucleate boiling are implemented in mixture multiphase flow framework. The phase change phenomenon is modeled using mechanistic evaporation-condensation model. Enhancement of wall heat transfer due to nucleate boiling is captured using 1D empirical correlation, modified for 3D CFD environment. A new method is proposed to calculate the local suppression of nucleate boiling based on the flow velocity, and hence this model can be applied to any complex shaped coolant passage. For different wall superheat, the wall heat fluxes predicted by the present model are validated against experimental data, in which 50-50 volume mixture of aqueous ethylene glycol (a typical anti-freeze coolant mixture) is used as working fluid. The validation study is performed in ducts of different sizes and shapes with different inlet velocities, inlet sub-cooling and operating pressures. The results are in good agreement with the experiments. This model is applied to a typical automobile Exhaust Gas Recirculation (EGR) system to study boiling heat transfer phenomenon and the results are presented.

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