One-Dimensional Model for the Combined Heat Transfer in Open-Cell Metal Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones ◽  
Carolina Briano ◽  
Jessica Fontanez
Keyword(s):  
Heat Transfer ◽  
Metal Foam ◽  
Dimensional Model ◽  
Open Cell ◽  
One Dimensional ◽  
Combined Heat Transfer

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

One-dimensional model for the Rijke tube

1989 ◽  
Vol 202 ◽  
pp. 83-96 ◽  
Author(s):  
C. Nicoli ◽  
P. Pelcé
Keyword(s):  
Heat Transfer ◽  
Transfer Function ◽  
Dimensional Model ◽  
Unsteady Heat Transfer ◽  
Order Unity ◽  
Rijke Tube ◽  
Thermoacoustic Instability ◽  
One Dimensional ◽  
The Stability ◽  
Stability Limits

We develop a simple model in which longitudinal, compressible, unsteady heat transfer between heater and gas is computed in the small-Mach-number limit. This calculation is used to determine the transfer function of the heater, which plays an important role in the stability limits of the thermoacoustic instability of the Rijke tube. The transfer function is determined analytically in the limit of small expansion parameter γ, and numerically for γ of order unity. In the case ρμ/cp = constant, an analytical solution can be found.

One Dimensional Model for Rotating Channels in the Turbine System: Part 2 — Formulation and Validation for Film Condensation

2013 ◽  
Author(s):  
Murali Krishnan R. ◽  
Zain Dweik ◽  
Deoras Prabhudharwadkar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Steam Turbine ◽  
Compressible Flow ◽  
Saturation Temperature ◽  
Film Condensation ◽  
Bulk Temperature ◽  
Dimensional Model ◽  
One Dimensional

This paper provides an extension of the previously described [1] formulation of a one-dimensional model for steady, compressible flow inside a channel, to the steam turbine application. The major challenge faced in the network simulation of the steam turbine secondary system is the prediction of the condensation that occurs during the engine start-up on the cold parts that are below the saturation temperature. Neglecting condensation effects may result in large errors in the engine temperatures since they are calculated based on the boundary conditions (heat transfer coefficient and bulk temperature) which depend on the solution of the network analysis. This paper provides a detailed formulation of a one-dimensional model for steady, compressible flow inside a channel which is based on the solution of two equations for a coupled system of mass, momentum and energy equations with wall condensation. The model also accounts for channel area variation, inclination with respect to the engine axis, rotation, wall friction and external heating. The formulation was first validated against existing 1D correlation for an idealized case. The wall condensation is modeled using the best-suited film condensation models for pressure and heat transfer coefficient available in the literature and has been validated against the experimental data with satisfactory predictions.

Experimental studies of the propagation of combustion in solids

1992 ◽  
Vol 339 (1654) ◽  
pp. 387-394 ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Steady State ◽  
Chemical Kinetics ◽  
Profile Analysis ◽  
Numerical Models ◽  
Experimental Studies ◽  
Dimensional Model ◽  
Thermal Methods ◽  
One Dimensional

The application of thermal methods to the study of steady-state combustion is described. Such methods provide a route to information on heat transfer and chemical kinetics which forms a basis for the implementation of numerical models. The experimental results from thermal analysis and temperature profile analysis have been examined within the context of a simple pseudo one-dimensional model of propagation offering some confirmation of the validity of the approach.

A One-Dimensional Model for Heat Transfer in Engine Exhaust Systems

2005 ◽  
Author(s):  
Huiyu Fu ◽  
Xiangdong Chen ◽  
Ian Shilling ◽  
Steve Richardson
Keyword(s):  
Heat Transfer ◽  
Dimensional Model ◽  
Engine Exhaust ◽  
One Dimensional ◽  
Exhaust Systems

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.

Numerical Study of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite at Pore Scale

2016 ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Foam Cell ◽  
High Porosity ◽  
Pore Scale ◽  
Thermal Equilibrium State ◽  
Foam Structure ◽  
Open Cell

In this paper, a numerical model employing 3D foam structure represented by Weaire-Phelan foam cell is developed to study the steady heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. Two conduction problems are considered in the cubic representative computation unit of the composite material: one with constant temperature difference between opposite sides of the cubic unit (that can be used to determine the effective thermal conductivity (ETC)) and the second with constant heat flux at the interface between metal foam and paraffin (that can be used to determine the interstitial conduction heat transfer coefficient (ICHTC)). The effects of foam pore structure parameters (pore size and porosity) on heat conduction are investigated for the above two problems. Results show that for the first conduction problem, the effect of foam structure on heat conduction (i.e. the ETC) is related to porosity rather than pore size. The essential reason is due to the thermal equilibrium state between metal foam and paraffin indicated by the negligible interstitial heat transfer. While for the second conduction problem with inherent thermal non-equilibrium effect, it shows that both porosity and pore size significantly influence the interstitial heat conduction (i.e. the ICHTC). Furthermore, the present ETC and ICHTC data are compared to the results in the published literature. It shows that our ETC data agree well with the reported experimental results, and are more accurate than the numerical predications based on body-centered-cubic foam cell in literature. And our ICHTC data are in qualitative agreement with the published numerical results, but the present results are based on a more realistic foam structure.

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.

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