Thermal Assessment of Forced Convection Through Metal Foam Heat Exchangers

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
A. Tamayol ◽  
K. Hooman
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Forced Convection ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Metal Foam ◽  
Convection Heat Transfer ◽  
Geometrical Parameters ◽  
Convection Heat

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.

Boundary-Layer Treatment of Forced Convection Heat Transfer From a Semi-infinite Flat Plate Embedded in Porous Media

1987 ◽  
Vol 109 (2) ◽  
pp. 345-349 ◽  
Author(s):  
M. Kaviany
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Forced Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Finite Difference Approximation ◽  
Solid Matrix ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

The effect of the presence of an isotropic solid matrix on the forced convection heat transfer rate from a flat plate is studied using the integral method. The closed-form solutions found are in good agreement with the available numerical results and also with the results obtained using a finite difference approximation and the expansion method. For large values of the flow resistance (due to the presence of the solid matrix), the asymptotic value for the heat transfer rate shows a Prandtl number dependency of 1/2 power, while the results for the intermediate values of the resistances show a 1/3 power dependency. The effect of the presence of the solid matrix on the heat transfer rate is shown through a regime diagram marking the boundaries of the regime of no significant alteration, the non-Darcian regime, and the Darcian regime.

Forced Convection Heat Transfer from a Pair of Circular Cylinders Confined in Ventilated Enclosure

2020 ◽  
Vol 26 ◽  
pp. 104-111 ◽  
Author(s):  
Mustapha Helmaoui ◽  
Houssem Laidoudi ◽  
Azzedine Belbachir ◽  
Adel Ayad ◽  
Abedallah Ghaniam
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Forced Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Vertical Wall ◽  
Convection Heat Transfer ◽  
Circular Cylinders ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

This paper deals with a numerical simulation of laminar forced convection heat transfer from a pair of identical circular cylinders placed at the center of square cavity in the line array, the cavity is ventilated with single inlet and outlet ports, the inlet port is located at the middle of left vertical wall and the outlet port is located at the middle of right vertical wall. The work represents the effects of the distance between cylinders and Reynolds number on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy are solved by using finite-volume method. The obtained results are represented and discussed for following conditions: Reynolds number Re = 1 to 40, Prandtl number Pr = 7.01 and the gap distance S = 0.3L to 0.7L, where L is the cavity length. The main results are potted under the streamline and isotherm contours, the total drag coefficient and average Nusselt number of each cylinder is plotted versus studied parameters. It is found that the increase in the gap space distance between cylinders increases the heat transfer rate.

scholarly journals An experimentally investigate the fin thermal performance to the different fin spaces by natural convections

2018 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
Hazim Mohammed Al-Jewaree
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Environmental Condition ◽  
Convection Heat

In oil and gas industries there are a lot off heat transfer devices used for different purposes. These devices are widely used in various industrial, transportation, or domestic applications such as heat exchangers thermal power plants, means of transport, heating and air conditioning systems, electronic equipments and space vehicles. In all these applications, improvements in the efficiency of heat exchangers can lead to substantial cost, space and materials savings. The research work summarized in this articles presents an experimental investigation on the effect of fin space (s)  and aluminum materials on the fin performance using rectangular  fins. The steady-state natural convection heat transfer from vertical rectangular fins extending perpendicularly from horizontal square base was investigated experimentally at new range not found in the previous works, this range of temperatures from 50 to 150 Co  . The effects of fin space parameter and base-to-ambient temperature difference on the heat transfer performance of fin arrays were observed and the environmental condition were determined. Five fin space settings,( 22, 27, 30, 35 and 38 mm) with a constant fin height is 50mm for all types of configuration are presented in this work  were employed under free convection heat transfer conditions. This range of fin space not found on previous study or research. The heat transfer area was kept the same. The performance of the fin expressed in terms of fin efficiency, effectiveness and thermal resistance as a function of the ambient temperature and fin space parameters has been study in this work. The dimensionless parameter Biot no. on the locally variable environmental condition is examined for different fin spaces to the fin heat transfer rate. Also, the effect of environmental condition is study.  Experimental results show that the effect fin space on fin performance is more significant.. The maximum increase in convection heat transfer coefficient value obtained is about 22 percent. The increase in heat transfer coefficient value is also manifested by a corresponding decrease in the fin base temperature. Also, it is concluded from the experimental results that the performance of heat transfer rate increase with decreasing the fin space  in respect of heat transfer coefficient, thermal resistance ,overall efficiency and effectiveness.

Heat Transfer Investigation of a Tube Partially Wrapped by Metal Porous Layer as a Potential Novel Tube for Air Cooled Heat Exchangers

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
M. Mohammadpour-Ghadikolaie ◽  
M. Saffar-Avval ◽  
Z. Mansoori ◽  
N. Alvandifar ◽  
N. Rahmati
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Rate ◽  
Porous Layer ◽  
Transfer Rate ◽  
Metal Foam ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
High Heat Transfer

Laminar forced convection heat transfer from a constant temperature tube wrapped fully or partially by a metal porous layer and subjected to a uniform air cross-flow is studied numerically. The main aim of this study is to consider the thermal performance of some innovative arrangements in which only certain parts of the tube are covered by metal foam. The combination of Navier–Stokes and Darcy–Brinkman–Forchheimer equations is applied to evaluate the flow field. Governing equations are solved using the finite volume SIMPLEC algorithm and the effects of key parameters such as Reynolds number, metal foam thermophysical properties, and porous layer thickness on the Nusselt number are investigated. The results show that using a tube which is fully wrapped by an external porous layer with high thermal conductivity, high Darcy number, and low drag coefficient, can provide a high heat transfer rate in the high Reynolds number laminar flow, increasing the Nusselt number almost as high as 16 times compared to a bare tube. The most important result of thisstudy is that by using some novel arrangements in which the tube is partially covered by the foam layer, the heat transfer rate can be increased at least 20% in comparison to the fully wrapped tube, while the weight and material usage can be considerably reduced.

scholarly journals Effect of Fin Number and Position on Non-linear Characteristics of Natural Convection Heat Transfer in Internally Finned Horizontal Annulus

2021 ◽  
Vol 9 ◽  
Author(s):  
Kun Zhang ◽  
Yu Zhang ◽  
Xiaoyu Wang ◽  
Liangbi Wang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stokes Equations ◽  
Convection Heat Transfer ◽  
The Self ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Simpler Algorithm

Detailed numerical calculations are performed for investigating the effect of fin number and position on unsteady natural convection heat transfer in internally finned horizontal annulus. The SIMPLER algorithm with Quick scheme is applied for solving the Navier Stokes equations of flow and heat transfer. The results show that the heat transfer rate in annulus with fins increases with the increasing numbers of fin and Rayleigh numbers. For Ra = 2 × 105, the effect of numbers of fins and fins position at the bottom part on the unsteady solutions can be neglected, because the self-oscillation phenomenon is mainly affected by natural convection at the upper part of annulus. Although the fin positions cannot increase heat transfer rate significantly in the case of four fins, the self-oscillated solutions can be suppressed by altering fins position.

Experimental Study of Free Convection Heat Transfer From a Fin Attached Cylinder Confined Between Tilt and Low Conductive Plates

2010 ◽  
Author(s):  
Amir Abbas Rezaei ◽  
Masoud Ziabasharhagh ◽  
Tooraj Yousefi ◽  
Mehran Ahmadi
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Cylinder Surface ◽  
Convection Heat ◽  
Number Range ◽  
Rayleigh Numbers ◽  
Chimney Effect

Steady state and two-dimensional natural convection heat transfer flow around a horizontal and isothermal cylinder with a longitudinal fin attached to it that is located between two tilt and very low conductive plates is studied experimentally by using a Mach-Zehnder interferometer. Effects of the plates slope angel (θ) on heat transfer from the tube is investigated for Rayleigh number ranging from 1000 to 15500. Experiments are done for a fin attached cylinder placed between two low conductive plates. Two different diameter tubes with diameters of D=10 and 20mm are utilized for broad Rayleigh number range. Results specify that, heat transfer experience differs for special Rayleigh numbers. For Rayleigh numbers ranging less than 5500, rate of heat transfer amount from the cylinder surface is less than that of a lone cylinder and it’s the result of no slip boundary condition on the fin surface. For this range of Rayleigh number by the use of plates, heat transfer from the cylinder surface decreases slightly and plates leaning does not alter heat transfer speed from the cylinder surface. For Rayleigh number ranging from 5500 to 15500, heat transfer rate from the cylinder surface is lower than the heat transfer rate from the surface of an individual cylinder. Though, by adding placing the low conductive plates as plates to experimental model, heat transfer system differs and chimney effect between fin and the plates increases the heat transfer from the cylinder surface. By increasing the plates slope angel from 0° to 20°, the chimney effect between plates and fin weakens and heat transfer rate from the tube surface is going to the amount of heat transfer rate from a fin attached cylinder which is not placed between plates.

scholarly journals Numerical Study of Natural Convection Heat Transfer in a Porous Annulus Filled with a Cu-Nanofluid

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 990
Author(s):  
Lingyun Zhang ◽  
Yupeng Hu ◽  
Minghai Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
Radius Ratio ◽  
Natural Convection Heat Transfer ◽  
Nanoparticle Volume Fraction ◽  
Convection Heat

Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the isotherms, streamlines, and heat transfer rate are obtained under the following parameters: Brownian motion, Rayleigh number (103–105), Darcy number (10−4–10−2), nanoparticle volume fraction (0.01–0.09), nanoparticle diameter (10–90 nm), porosity (0.1–0.9), and radius ratio (1.1–10). Results show that Brownian motion should be considered. The nanoparticle volume fraction has a positive effect on the heat transfer rate, especially with high Rayleigh number and Darcy number, while the nanoparticle diameter has an inverse influence. The heat transfer rate is enhanced with the increase of porosity. The radius ratio has a significant influence on the isotherms, streamlines, and heat transfer rate, and the rate is greatly enhanced with the increase of radius ratio.

scholarly journals Enhancement of natural convection heat transfer in concentric annular space using inclined elliptical cylinder

2020 ◽  
Vol 17 (2) ◽  
pp. 89-99
Author(s):  
Houssem Laidoudi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Elliptical Cross

The governing equations of continuity, momentum and energy are numerically solved to study the laminar natural convection heat transfer of Newtonian fluid confined within two concentric cylinders. The inner cylinder is elliptical cross-section with different aspect ratio E = 0.1 to 0.5 and it is considered to be hot, whereas the outer cylinder is circular and it is supposed to be cold.    The annular spacing between the cylinders is defined based on radii ratio (RR = 2.5). Also, the inner cylinder is inclined with an inclination angle (θ = 0 to 90). The main purpose of this study is to determine the effects of inclination angle (θ = 0° to 90°), aspect ratio of inner cylinder (E = 0.1 to 0.5), Prandtl number (Pr = 0.71 and 7.01) and Rayleigh number (Ra = 103 to 105) on fluid flow and heat transfer rate. The flow patterns and temperature distributions are potted in terms of streamlines and isotherms respectively. The obtained results showed that increase in inclination angle enhances the heat transfer rate of inner cylinder for all values of aspect ratio. Also, for the inclination angle          (θ = 90°), the decrease in aspect ratio (E) improves the heat transfer rate of inner cylinder.

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