Metal-Foam-Enhanced PCM Storage System: The Cylindrical Shell Geometry

2011 ◽  
Author(s):  
Nihad Dukhan
Keyword(s):  
Heat Transfer ◽  
Cylindrical Shell ◽  
Phase Change ◽  
Change Process ◽  
Metal Foam ◽  
Storage System ◽  
Open Loop ◽  
High Porosity ◽  
Phase Change Process ◽  
Thermal Conductivities

Phase-change systems remain to be widely used for storage of thermal energy such as the energy harnessed by solar collectors. The major disadvantage of phase change materials (PCMs) is their low thermal conductivities, which drastically slows the phase change process and causes wide temperature variations within PCMs, while requiring heat transfer area. Metal foams are one class of porous media that possess thermal conductivities that are an order of magnitude higher than PCMs. When embedded in PCMs, the random internal structure and high porosity of metal foam enhance and accelerate the phase change process without significantly reducing PCMs’ heat storage capacity. Unlike traditional PCM systems, the distribution of the foam ligaments in PCMs makes the melting and solidification processes uniform and less dependent on location inside PCMs. This also leads to shorter charging and discharging times. The design, fabrication and characterization of a small PCM-metal-foam thermal storage system are described in this paper. The core of the system is a cylindrical shell composed of 90%-porous open-cell aluminum foam filled with Paraffin-based PCM. The foam occupies only 10% of the total volume. The shell walls were fabricated from copper. The system was tested in an open loop wind tunnel. Results for the convection heat transfer coefficient and the effect of volumetric flow rate on the system’s performance were obtained. The heat transfer rate from the system was computed and discussed.

Direct Simulation of Interstitial Heat Transfer Coefficient Between Paraffin and High Porosity Open-Cell Metal Foam

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Change Process ◽  
Energy Equation ◽  
Metal Foam ◽  
Equation Model ◽  
High Porosity ◽  
Direct Simulation ◽  
Open Cell ◽  
Transfer Region

The interstitial heat transfer coefficient (IHTC) is a key parameter in the two-energy equation model usually employed to investigate the thermal performance of high porosity open-cell metal foam/paraffin composite phase change material. Due to the existence of weak convection of liquid paraffin through metal foam during phase change process, the IHTC should be carefully determined for a low Reynolds number range (Re = 0–1), which however has been rarely addressed in the literature. In this paper, a direct simulation at foam pore scale is carried out to determine the IHTC between paraffin and metal foam at Re = 0–1. For this purpose, the cell structures reflecting realistic metal foams are first constructed based on the three-dimensional (3D) Weaire–Phelan foam cell to serve as the representative elementary volume (REV) of metal foam for direct simulation. Then, by solving the Navier–Stokes equations and energy equation for the REV, the influences of Reynolds number (Re), Prandtl number (Pr), foam porosity (ε), and pore density (PPI) on the dimensionless IHTC, i.e., the Nusselt number Nuv, are investigated. According to the numerical results, a correlation of Nuv at Re = 0–1 is proposed for metal foam/paraffin composite material, which covers both diffusion-dominated interstitial heat transfer region (Re ≤ 0.1) and convection-dominated interstitial heat transfer region (0.1 < Re ≤ 1). Finally, the applicability of this correlation in the two-energy equation model for solid–liquid phase change of paraffin in metal foam is validated by comparing the model predicted melting front with that of experimental observations made in this study. It is found that the IHTC correlation proposed in this study can be used in the two-energy equation model for well predicting the phase change process of paraffin in metal foam.

scholarly journals On Numerical Modeling of Thermal Performance Enhancementof a Heat Thermal Energy Storage System Using a Phase Change Material and a Porous Foam

Computation ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Riheb Mabrouk ◽  
Hassane Naji ◽  
Hacen Dhahri ◽  
Zouhir Younsi
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Thermal Performance ◽  
Metal Foam ◽  
Storage System ◽  
Porous Metal ◽  
Metal Structure ◽  
Entropy Generation Rate ◽  
High Porosity ◽  
Change Material

In this investigation, a comprehensive numerical analysis of the flow involved in an open-ended straight channel fully filled with a porous metal foam saturated and a phase change material (paraffin) has been performed using a single relaxation time lattice Boltzmann method (SRT-LBM) at the representative elementary volume (REV) scale. The enthalpy-based approach with three density functions has been employed to cope with the governing equations under the local thermal non-equilibrium (LTNE) condition. The in-house code has been validated through a comparison with a previous case in literature. The pore per inch density (10≤PPI≤60) and porosity (0.7≤ε≤0.9) effects of the metal structure were analyzed during melting/solidifying phenomena at two Reynolds numbers (Re = 200 and 400). The relevant findings are discussed for the LTNE intensity and the entropy generation rate (Ns). Through the simulations, the LTNE hypothesis turned out to be secure and valid. In addition, it is maximum for small PPI value (=10) whatever the parameters deemed. On the other hand, high porosity (=0.9) is advised to reduce the system’s irreversibility. However, at a moderate Re (=200), a small PPI (=10) would be appropriate to mitigate the system irreversibility during the charging case, while a large value (PPI = 60) might be advised for the discharging case. In this context, it can be stated that during the melting period, low porosity (=0.7) with low PPI (=10) improves thermal performance, reduces the system irreversibility and speeds up the melting rate, while for high porosity (=0.9), a moderate PPI (=30) should be used during the melting process to achieve an optimal system.

Numerical simulation of the effect of using nanofluid in phase change process of cooling fluid

2019 ◽  
Vol 30 (6) ◽  
pp. 2913-2934 ◽  
Author(s):  
Farzad Pourfattah ◽  
Saeid Yousefi ◽  
Omid Ali Akbari ◽  
Mahsa Adhampour ◽  
Davood Toghraie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Phase Change ◽  
Vapor Phase ◽  
Change Process ◽  
Volume Fraction ◽  
Cooling Fluid ◽  
Content Type ◽  
Phase Change Process ◽  
Boiling Process

Purpose The purpose of this paper is to numerically simulate the nanofluid boiling inside a tube in turbulent flow regime and to investigate the effect of adding volume faction of CuO nanoparticles on the boiling process. Design/methodology/approach To make sure the accuracy of the obtained numerical results, the results of this paper have been compared with the experimental results and an acceptable coincidence has been achieved. In the current paper, by Euler–Euler method, the phase change of boiling phenomenon has been modeled. The presented results are the local Nusselt number distribution, temperature distribution of wall, the distribution of volume fraction of vapor phase and fluid temperature at the center of the tube. Findings The obtained results indicate that using nanofluid is very effective in the postponement of the boiling process. Hence, by change the amount of volume fraction of nanoparticles in base fluid, the location of phase change and bubble creation are changed. Also, at the Reynolds numbers of 50,000, 100,000 and 150,000 with the volume fraction of 2 per cent, the beginning locations of phase change process are, respectively, 2D, 10D and 13D, and for the volume fraction of 4 per cent, the beginning locations of phase change are 4D, 18D and 19D, respectively. These results indicate that, as the volume fraction of nanoparticles increases, the location of the start of the phase change process is postponed that this issue causes the increment of heat transfer from wall to fluid and the reduction of wall temperature. In general, it can be stated that, in boiling flows, using nanofluid because of the delay in boiling phenomenon has a good effect on heat transfer enhancement of heated walls. Also, the obtained results show that, by increasing Reynolds number, the created vapor phase reduces that leads to increase of the Nusselt number. Originality/value The paper investigates the effect of using nanofluid in phase change process of cooling fluid.

scholarly journals A Review of Thermo-Hydraulic Performance of Metal Foam and its Application as Heat Sinks for Electronics Cooling

2020 ◽  
Author(s):  
Yongtong Li ◽  
Liang Gong ◽  
Minghai Xu ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Metal Foam ◽  
Flow Boiling ◽  
Electronics Cooling ◽  
Metal Foams ◽  
Hydraulic Performance ◽  
Heat Sinks ◽  
Research Progress ◽  
High Porosity

Abstract High porosity metal foams offer large surface area per unit volume and have been considered as effective candidates for convection heat transfer enhancement, with applications as heat sinks in electronics cooling. In this paper, the research progress in thermo-hydraulic performance characterization of metal foams and their application as heat sinks for electronics cooling are reviewed. We focus on natural convection, forced convection, flow boiling, and solid/liquid phase change using phase change materials (PCMs). Under these heat transfer conditions, the effects of various parameters influencing the performance of metal foam heat sink are discussed. It is concluded that metal foams demonstrate promising capability for heat transfer augmentation, but some key issues still need to be investigated regarding the fundamental mechanisms of heat transfer to enable the development of more efficient and compact heat sinks.

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