Numerical Consideration of LTNE and Darcy Extended Forchheimer Models for the Analysis of Forced Convection in a Horizontal Pipe in the Presence of Metal Foam

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Prakash H. Jadhav ◽  
N. Gnanasekaran ◽  
D. Arumuga Perumal

Abstract The intent of the current research work is to emphasize the computational modeling of forced convection heat dissipation in the presence of high porosity and thermal conductivity metallic foam in a horizontal pipe for different regimes of the fluid flow for a range of Reynolds number. A two-dimensional physical domain is considered in which Darcy extended Forchheimer (DEF) model is adopted in the aluminum metallic foam to predict the features of fluid flow and local thermal nonequilibrium (LTNE) model is employed for the analysis of heat transfer in a horizontal pipe for different flow regimes. The numerical results are initially matched with experimental and analytical results for the purpose of validation. The average Nusselt number for fully filled foam is found to be higher compared to other filling rate of metallic foams and the clear pipe at the cost of pressure drop. As an important finding, it has been observed that the laminar and transition flow gives higher heat transfer enhancement ratio and thermal performance factor compared to turbulent flow. This work resembles numerous industrial applications such as solar collectors, heat exchangers, electronic cooling, and microporous heat exchangers. The novelty of the work is the selection of suitable flow and thermal models in order to clearly assimilate the flow and heat transfer in metallic foam. The presence of aluminum metal foam is highlighted for the augmentation of heat dissipation in terms of PPI and porosity. The parametric study proposed in this work surrogates the complexity and cost involved in developing an expensive experimental setup.

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
A. Tamayol ◽  
K. Hooman

Using a thermal resistance approach, forced convection heat transfer through metal foam heat exchangers is studied theoretically. The complex microstructure of metal foams is modeled as a matrix of interconnected solid ligaments forming simple cubic arrays of cylinders. The geometrical parameters are evaluated from existing correlations in the literature with the exception of ligament diameter which is calculated from a compact relationship offered in the present study. The proposed, simple but accurate, thermal resistance model considers: the conduction inside the solid ligaments, the interfacial convection heat transfer, and convection heat transfer to (or from) the solid bounding walls. The present model makes it possible to conduct a parametric study. Based on the generated results, it is observed that the heat transfer rate from the heated plate has a direct relationship with the foam pore per inch (PPI) and solidity. Furthermore, it is noted that increasing the height of the metal foam layer augments the overall heat transfer rate; however, the increment is not linear. Results obtained from the proposed model were successfully compared with experimental data found in the literature for rectangular and tubular metal foam heat exchangers.


2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Indranil Ghosh

Forced convection heat transfer in high porosity metal foam, either attached to an isothermal surface or confined between two isothermal plates, has been analyzed, assuming a repetitive simple cubic structure for the foam matrix. The model, in the microscopic level takes account of the forced convective heat transfer coupled with heat conduction through the foam fibers. Analytical expressions have been derived for the gas-solid temperature difference, total heat transfer through the foam, and efficiency of foam as an extended surface. The resulting expressions have strong resemblance with those of the conventional finned surface. The effect of porosity and foam density on the heat transfer in metallic foam has been established through parametric studies. Significant heat-transfer augmentation due to cross connections in metal struts has been noticed.


2010 ◽  
Vol 297-301 ◽  
pp. 960-965 ◽  
Author(s):  
Jean Michel Hugo ◽  
Emmanuel Brun ◽  
Frédéric Topin ◽  
Jérôme Vicente

This numerical study focuses on the determination of macroscopic (effective) properties from pore scale calculation. These results will be applied to heat exchangers design. The computational domain -representative of heat exchanger section- is a parallelepiped filled with metallic foam, heated on one face and crossed by a forced fluid flow. Conjugate heat transfer and fluid flow are computed using finite volume approach on the actual solid matrix and pore space topology obtained from X-ray tomograms. Calculated heat transfer coefficient and flow law parameters are in good agreement with literature data. An active foam length is defined and measured in order to provide optimal design characteristic for foamed heat exchanger.


Author(s):  
Srivatsan Madhavan ◽  
Prashant Singh ◽  
Srinath Ekkad

High-porosity metal foams are known for providing high heat transfer rates, as they provide a significant increase in wetted surface area as well as highly tortuous flow paths resulting in enhanced mixing. Further, jet impingement offers high convective cooling, particularly at the jet footprint areas on the target surface due to flow stagnation. In this study, high-porosity thin metal foams were subjected to array jet impingement, for a special crossflow scheme. High porosity (92.65%), high pore density (40 pores per inch (ppi)), and thin foams (3 mm) have been used. In order to reduce the pumping power requirements imposed by full metal foam design, two striped metal foam configurations were also investigated. For that, the jets were arranged in 3 × 6 array (x/dj = 3.42, y/dj = 2), such that the crossflow is dominantly sideways. Steady-state heat transfer experiments have been conducted for varying jet-to-target plate distance z/dj = 0.75, 2, and 4 for Reynolds numbers ranging from 3000 to 12,000. The baseline case was jet impingement onto a smooth target surface. Enhancement in heat transfer due to impingement onto thin metal foams has been evaluated against the pumping power penalty. For the case of z/dj = 0.75 with the base surface fully covered with metal foam, an average heat transfer enhancement of 2.42 times was observed for a concomitant pressure drop penalty of 1.67 times over the flow range tested.


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