Simplified Heat Transfer Analysis in Metal Foam With Low-Conductivity Fluid

2005 ◽  
Author(s):  
Nihad Dukhan ◽  
Rube´n Pico´n-Feliciano
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Equilibrium ◽  
Metal Foam ◽  
Flow Direction ◽  
Reynolds Numbers ◽  
Heat Transfer Analysis ◽  
Local Thermal Equilibrium ◽  
Open Cell ◽  
Simplifying Assumptions

The use of open-cell metal foam in contemporary technologies is increasing rapidly. Certain simplifying assumptions for the combined conduction/convection heat transfer analysis in metal foam have not been exploited. Solving the complete, and coupled, fluid flow and heat transfer governing equations numerically is time consuming. A simplified analytical model for the heat transfer in open-cell metal foam cooled by a low-conductivity fluid is presented. The model assumes local thermal equilibrium between the solid and fluid phases in the foam, and neglects the conduction in the fluid. The local thermal equilibrium assumption is supported by previous studies performed by other workers. The velocity profile in the foam is taken as non-Darcean slug flow. An approximate solution for the temperature profile in the foam is obtained using a similarity transform. The solution for the temperature profile is represented by the error function, which decays in what looks like an exponential fashion as the distance from the heat base increases. The model along with the simplifying assumptions were verified by direct experiment using air and two aluminum foam samples heated from below, for a range of Reynolds numbers. Each foam sample was 5.08 cm-thick in the flow direction. One sample had a pore density of ten pores per inch while the other had twenty pores per inch. Very good agreement was found between the analytical and the experimental results for a considerable range of Reynolds number, with the agreement being generally better for higher Reynolds numbers, and for foam with higher surface area density.

Heat Transfer Analysis in Metal Foams With Low-Conductivity Fluids

2006 ◽  
Vol 128 (8) ◽  
pp. 784-792 ◽  
Author(s):  
Nihad Dukhan ◽  
Rubén Picón-Feliciano ◽  
Ángel R. Álvarez-Hernández
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Equilibrium ◽  
Metal Foam ◽  
Flow Direction ◽  
Reynolds Numbers ◽  
Heat Transfer Analysis ◽  
Local Thermal Equilibrium ◽  
Open Cell ◽  
Simplifying Assumptions

The use of open-cell metal foam in contemporary technologies is increasing rapidly. Certain simplifying assumptions for the combined conduction∕convection heat transfer analysis in metal foam have not been exploited. Solving the complete, and coupled, fluid flow and heat transfer governing equations numerically is time consuming. A simplified analytical model for the heat transfer in open-cell metal foam cooled by a low-conductivity fluid is presented. The model assumes local thermal equilibrium between the solid and fluid phases in the foam, and neglects the conduction in the fluid. The local thermal equilibrium assumption is supported by previous studies performed by other workers. The velocity profile in the foam is taken as non-Darcean slug flow. An approximate solution for the temperature profile in the foam is obtained using a similarity transform. The solution for the temperature profile is represented by the error function, which decays in what looks like an exponential fashion as the distance from the heat base increases. The model along with the simplifying assumptions were verified by direct experiment using air and several aluminum foam samples heated from below, for a range of Reynolds numbers and pore densities. The foam samples were either 5.08- or 20.32‐cm-thick in the flow direction. Reasonably good agreement was found between the analytical and the experimental results for a considerable range of Reynolds numbers, with the agreement being generally better for higher Reynolds numbers, and for foam with higher surface area density.

Analysis of Constant-Heat-Flux Heat Transfer in Metal Foam

2007 ◽  
Author(s):  
Nihad Dukhan ◽  
Kuan-Chin Chen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Profile ◽  
Thermal Equilibrium ◽  
Metal Foam ◽  
Constant Heat Flux ◽  
Local Thermal Equilibrium ◽  
Constant Heat ◽  
Open Cell ◽  
Simplifying Assumptions

The use of open-cell metal foam in contemporary heat exchange technologies is increasing rapidly. The high surface area density of metal foam places them among the best options for heat exchanger core materials. Certain simplifying assumptions for the combined conduction/convection heat transfer analysis in metal foam have not been exploited. Solving the complete, and coupled, fluid flow and heat transfer governing equations numerically is time consuming. A simplified two-dimensional analytical model for the heat transfer in open-cell metal foam block subjected to constant heat flux, and cooled by a low-conductivity fluid, is presented. The model assumes local thermal equilibrium between the solid and fluid phases in the foam, and neglects the conduction in the fluid. The local thermal equilibrium assumption is supported by previous studies performed by other workers. The velocity profile in the foam is taken as non-Darcean slug flow. An approximate solution for the temperature profile in the foam is obtained analytically. The temperature profile decays in what looks like an exponential fashion as the distance from the heat base increases, and increases in the flow direction. The model along with the simplifying assumptions were verified by direct experiment using air and an aluminum foam block heated from above by constant heat flux, for a range of Reynolds numbers. Very good agreement was found between the analytical and the experimental results.

Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters

Solar Energy ◽  
2003 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Aluminum Foams ◽  
Maximum Heat ◽  
Open Cell ◽  
Maximum Heat Transfer

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.

One-dimensional heat transfer analysis in open-cell 10-ppi metal foam

2005 ◽  
Vol 48 (25-26) ◽  
pp. 5112-5120 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quiñones-Ramos ◽  
Edmundo Cruz-Ruiz ◽  
Miguel Vélez-Reyes ◽  
Elaine P. Scott
Keyword(s):  
Heat Transfer ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Open Cell ◽  
One Dimensional

Heat transfer analysis of a ventilated room with a porous partition: LB-MRT simulations

2020 ◽  
Vol 91 (2) ◽  
pp. 20904
Author(s):  
Zouhira Hireche ◽  
Lyes Nasseri ◽  
Djamel Eddine Ameziani
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Natural Convection ◽  
Reynolds Numbers ◽  
Darcy Number ◽  
The Other ◽  
Flow In Porous Media ◽  
Heat Transfer Analysis ◽  
Maximum Deviation ◽  
Important Conclusion

This article presents the hydrodynamic and thermal characteristics of transfers by forced, mixed and natural convection in a room ventilated by air displacement. The main objective is to study the effect of a porous partition on the heat transfer and therefore the thermal comfort in the room. The fluid flow future in the cavity and the heat transfer rate on the active wall have been analyzed for different permeabilities: 10−6 ≤ Da ≤ 10. The other control parameters are obviously, the Rayleigh number and the Reynolds number varied in the rows: 10 ≤ Ra ≤ 106 and 50 ≤ Re ≤ 500 respectively. The transfer equations write were solved by the Lattice Boltzmann Multiple Relaxation Time method. For flow in porous media an additional term is added in the standard LB equations, to consider the effect of the porous media, based on the generalized model, the Brinkman-Forchheimer-extended Darcy model. The most important conclusion is that the Darcian regime start for small Darcy number Da < 10−4. Spatial competition between natural convection cell and forced convection movement is observed as Ra and Re rise. The effect of Darcy number values and the height of the porous layer is barely visible with a maximum deviation less than 7% over the ranges considered. Note that the natural convection regime is never reached for low Reynolds numbers. For this Re values the cooperating natural convection only improves transfers by around 10% while, for the other Reynolds numbers the improvement in transfers due to natural and forced convections cooperation is more significant.

Optimized Multi-Floor Throughflow Micro Heat Exchangers

2013 ◽  
Author(s):  
Abas Abdoli ◽  
George S. Dulikravich
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Stokes Equations ◽  
Flow Direction ◽  
Computing Time ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Fluid Analysis ◽  
Response Surface Approximations ◽  
Hot Surface

Multi-floor networks of straight-through liquid cooled microchannels have been investigated by performing conjugate heat transfer in a silicon substrate of size 15×15×1 mm. Two-floor and three-floor cooling configurations were analyzed with different numbers of microchannels on each floor, different diameters of the channels, and different clustering among the floors. Thickness of substrate was calculated based on number of floors, diameter of floors and vertical clustering. Direction of microchannels on each floor changes by 90 degrees from the previous floor. Direction of flow in each microchannel is opposite of the flow direction in its neighbor channels. Conjugate heat transfer analysis was performed by developing a software package which uses quasi-1D thermo-fluid analysis and a 3D steady heat conduction analysis. These two solvers are coupled through their common boundaries representing surfaces of the cooling microchannels. Using quasi-1D solver significantly decreases overall computing time and its results are in good agreement with 3D Navier-Stokes equations solver for these types of application. Multi-objective optimization with modeFRONTIER software was performed using response surface approximations and genetic algorithm. Maximizing total amount of heat removed, minimizing coolant pressure drop, minimizing maximum temperature on the hot surface, and minimizing non-uniformity of temperature on the hot surface were four simultaneous objectives of the optimization. Pareto-optimal solutions demonstrate that thermal loads of 800 W cm−2 can be effectively managed with such multi-floor microchannel cooling networks. Two-floor microchannel configuration was also simulated with 1,000 W cm−2 uniform thermal load and shown to be feasible.

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