Merits of Employing Foam Encapsulated Phase Change Materials for Pulsed Power Electronics Cooling Applications

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. Lafdi ◽  
O. Mesalhy ◽  
A. Elgafy
Keyword(s):  
Phase Change ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Electronics Cooling ◽  
Volume Averaging ◽  
Equation Model ◽  
Heat Diffusion ◽  
Solid Matrix ◽  
Design Parameters ◽  
Heat Diffusion Equation

In the present work, the potential of using foam structures impregnated with phase change materials (PCMs) as heat sinks for cooling of electronic devices has been numerically studied. Different design parameters have been investigated such as foam properties (porosity, pore size, and thermal conductivity), heat sink shape, orientation, and use of internal fins inside the foam-PCM composite. Due to huge difference in thermal properties between the PCM and the solid matrix, two energy equation model has been adopted to solve the energy conservation equations. This model can handle local thermal nonequilibrium condition between the PCM and the solid matrix. The numerical model is based on volume averaging technique, and the finite volume method is used to discretize the heat diffusion equation. The findings show that, for steady heat generation, the shape and orientation of the composite heat sink have significant impact on the system performance. Conversely, in the case of power spike input, use of a PCM with low melting point and high latent heat is more efficient.

On the Design of Phase Change Materials based thermal management systems for electronics cooling

2021 ◽  
pp. 117276
Author(s):  
Giulia Righetti ◽  
Claudio Zilio ◽  
Luca Doretti ◽  
Giovanni A. Longo ◽  
Simone Mancin
Keyword(s):  
Phase Change ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Electronics Cooling ◽  
Management Systems

scholarly journals Computational and Mathematical Model with Phase Change and Metal Addition Applied to GMAW

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Alfredo dos Santos Maia Neto ◽  
Marcelo Gonçalves de Souza ◽  
Edson Alves Figueira Júnior ◽  
Valério Luiz Borges ◽  
Solidônio Rodrigues de Carvalho
Keyword(s):  
Mathematical Model ◽  
Phase Change ◽  
Thermal Model ◽  
Complex Geometry ◽  
Golden Section ◽  
Simulated Data ◽  
Heat Diffusion ◽  
Data Logger ◽  
Heat Diffusion Equation ◽  
Metal Addition

This work presents a 3D computational/mathematical model to solve the heat diffusion equation with phase change, considering metal addition, complex geometry, and thermal properties varying with temperature. The finite volume method was used and the computational code was implemented in C++, using a Borland compiler. Experimental tests considering workpieces of stainless steel AISI 304 were carried out for validation of the thermal model. Inverse techniques based on Golden Section method were used to estimate the heat transfer rate to the workpieces. Experimental temperatures were measured using thermocouples type J—in a total of 07 (seven)—all connected to the welded workpiece and the Agilent 34970A data logger. The workpieces were chamfered in a 45° V-groove in which liquid metal was added on only one weld pass. An innovation presented in this work when compared to other works in scientific literature was the geometry of the weld pool. The good relation between experimental and simulated data confirmed the quality and robustness of the thermal model proposed in this work.

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.

Avionics Passive Cooling With Microencapsulated Phase Change Materials

1998 ◽  
Vol 120 (3) ◽  
pp. 238-242 ◽  
Author(s):  
A. J. Fossett ◽  
M. T. Maguire ◽  
A. A. Kudirka ◽  
F. E. Mills ◽  
D. A. Brown
Keyword(s):  
Phase Change ◽  
Weight Reduction ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Aluminum Plate ◽  
Passive Cooling ◽  
Design Problems ◽  
Solid Aluminum ◽  
Microencapsulated Phase Change Materials ◽  
Good Agreement

Analysis for an avionics application typical of remotely located, intermittently operated avionics on aircraft and missiles show that a large weight reduction (about 9:1) can be obtained by using recently developed microencapsulated phase change materials technology instead of a solid aluminum plate for a passive heat sink. Tests with a configuration based on the typical avionics application used for analysis show good agreement with analysis. Use of microencapsulated rather than bulk phase change materials avoids a number of design problems previously encountered with application of such materials.

scholarly journals Investigation of Thermal Properties of Novel Phase Change Material Mixtures (Octadecane-Diamond) with Laser Flash Analysis

2019 ◽  
Vol 26 (4) ◽  
pp. 211-218
Author(s):  
Mateusz Sierakowski ◽  
Wojciech Godlewski ◽  
Roman Domański ◽  
Jakub Kapuściński ◽  
Tomasz Wiśniewski ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Phase Change ◽  
Power Plants ◽  
Large Scale ◽  
Phase Change Materials ◽  
Heat Dissipation ◽  
Electronics Cooling ◽  
Diamond Powder ◽  
Heat Of Fusion

AbstractPhase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.

Cooling Technique for Outdoor Electronic Enclosures Using Phase Change Materials

2000 ◽  
Author(s):  
Hamid A. Hadim ◽  
Igbal Mehmedagic
Keyword(s):  
Phase Change ◽  
Thermal Management ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Theoretical Study ◽  
Peak Load ◽  
Ambient Conditions ◽  
Moderate Amount ◽  
Ambient Temperatures ◽  
Cooling Technique

Abstract A theoretical study is conducted to investigate a new cooling technique for thermal management of outdoor telecommunication equipment enclosures. The technique consists of using a phase change material (PCM) combined with a heat sink to dissipate the heat to the ambient. The main advantages of using the PCM include: fully passive technique with no maintenance, no power is required, and relatively low cost. The use of the PCM for more effective thermal management of electronic enclosures is investigated for both the high end cooling (i.e. when the enclosure is exposed to high ambient temperatures) and the low end cooling (i.e. when the enclosure is exposed to very low ambient temperatures). The results from this preliminary theoretical study showed that with the use of a moderate amount of a properly selected PCM combined with the heat sink, the temperature within the enclosure can be maintained within the specified operating range. Potential applications with the use of the PCM include: peak load usage (e.g. during high communications traffic periods), extreme ambient conditions, reduced temperature fluctuations (to improve reliability), and more efficient implementation in smaller size enclosures.

Modeling of Heat Transfer in a Moving Packed Bed: Case of the Preheater in Nickel Carbonyl Process

2005 ◽  
Vol 73 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Redhouane Henda ◽  
Daniel J. Falcioni
Keyword(s):  
Heat Transfer ◽  
Packed Bed ◽  
Outer Wall ◽  
Volume Averaging ◽  
Equation Model ◽  
Operating Conditions ◽  
Design Parameters ◽  
Gas Phases ◽  
Calculation Results ◽  
The Difference

Heat transfer in a two-dimensional moving packed bed consisting of pellets surrounded by a gaseous atmosphere is numerically investigated. The governing equations are formulated based on the volume averaging method. A two-equation model, representing the solid and gas phases separately, and a one-equation model, representing both the solid and gas phases, are considered. The models take the form of partial differential equations with a set of boundary conditions, some of which were determined experimentally, and design parameters in addition to the operating conditions. We examine and discuss the parameters in order to reduce temperature differences from pellet to pellet. The calculation results show that by adopting a constant temperature along the preheater outer wall and decreasing the velocity of the pellets in the preheater, the difference in temperature from pellet to pellet is reduced from ∼120°C to ∼55°C, and the thermal efficiency of the preheater is tremendously improved.

scholarly journals Thermal Management of Transient Power Spikes in Electronics: Phase Change Energy Storage or Copper Heat Sinks??

2003 ◽  
Author(s):  
Shankar Krishnan ◽  
Suresh V. Garimella
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Electronics Cooling ◽  
Thermal Control ◽  
Heat Sinks ◽  
Melting Time ◽  
Power Semiconductors ◽  
Design Calculations ◽  
Change Material

A transient thermal analysis is performed to investigate thermal control of power semiconductors using phase change materials, and to compare the performance of this approach to that of copper heat sinks. Both the melting of the phase change material under a transient power spike input, as well as the resolidification process, are considered. Phase change materials of different kinds (paraffin waxes and metallic alloys) are considered, with and without the use of thermal conductivity enhancers. Simple expressions for the melt depth, melting time and temperature distribution are presented in terms of the dimensions of the heat sink and the thermophysical properties of the phase change material, to aid in the design of passive thermal control systems. The simplified analytical expressions are verified against more complex numerical simulations, and are shown to be excellent tools for design calculations. The suppression of junction temperatures achieved by the use of phase change materials when compared to the performance with copper heat sinks is illustrated. Merits of employing phase change materials for pulsed power electronics cooling applications are discussed.

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