A Heat Transfer in Iso-Thermal Triangular Channel Filled With Porous Media

2012 ◽  
Author(s):  
S. Negin Mortazavi ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Forced Convection ◽  
Constant Temperature ◽  
Analytical Solutions ◽  
Apex Angle ◽  
Triangular Channel

This study presents an analysis of forced convection in a porous triangular channel. The flow is laminar, fully developed and assumed to have constant properties. The porous channel has an isotropic matrix and the boundary conditions are fixed with a constant temperature. In this paper, accurate analytical solutions are presented to determine the effects of apex angle and porous media properties on the temperature distribution in a triangular channel along with the Nusselt number NuT.

Effect of Porous Media Properties on Heat Transfer in Triangular Porous Duct

2012 ◽  
Author(s):  
S. Negin Mortazavi ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Analytical Solutions ◽  
Series Solution ◽  
Apex Angle ◽  
Average Temperature ◽  
Triangular Channel

This study presents an analysis of forced convection in a porous triangular channel. The flow is laminar, fully developed and assumed to have constant properties. The porous channel has an isotropic matrix and the boundary conditions are fixed with constant temperature. In this paper, accurate analytical solutions are presented to determine the effects of apex angle and porous media properties on the velocity and temperature distribution in a triangular channel along with the friction factor fRe, and Nusselt number NuT. The presentaion includes numerical features of the exact series solution using Brinkman’s model. Numerical results for dimensionless average temperature and velocity are presented for various porosities, permeabilities and apex angles.

Effect of Porous Media Properties on Heat Transfer in Triangular Porous Ducts With Iso-Flux Walls

2011 ◽  
Author(s):  
S. Negin Mortazavi ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Constant Heat Flux ◽  
Triangular Channel ◽  
Wall Boundary Conditions ◽  
Porosity And Permeability ◽  
The Galerkin Method ◽  
Energy Equations

This study presents an analysis of forced convection in a porous triangular channel. The flow is assumed to have constant properties and the porous channel is an isotropic matrix. The flow is laminar and fully developed and the boundary conditions are fixed with a constant heat flux. In this paper, the accurate analytical solutions are presented to obtain the effects of porosity and permeability on the velocity and temperature distribution in a triangular channel along with the friction factor fRe, and Nusselt number NuH. The momentum and energy equations include the term of Darcy, effective viscosity and apex angel. So, the flow velocity and temperature distribution have been investigated in porous media with different properties. The Galerkin method has been applied to solve the equations accurately by considering a weight function for no slippery and isothermal wall boundary conditions. Temperature and velocity distribution and heat transfer coefficient have been obtained and compared with the same flow situation in rectangular channels.

Effect of Apex Angle on the Flow and Heat Transfer in Triangular Porous Ducts With Iso-Flux Boundary Conditions

2011 ◽  
Author(s):  
S. Negin Mortazavi ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Boundary Conditions ◽  
Integral Method ◽  
Apex Angle ◽  
Triangular Channel ◽  
Flow And Heat Transfer ◽  
Temperature Distributions ◽  
Flux Boundary Conditions

This study presents an analysis of fully developed laminar flow in a porous triangular channel. The flow is assumed to have constant properties and the porous channel is an isotropic matrix. Very accurate analytical solutions are presented by Galerkin Integral method for iso-flux boundary conditions. In this paper, the effect of apex angle in the triangular channel is shown on the velocity and temperature distributions along with the friction factor fRe, and the Nusselt number NuH.

Experimental Study of Internal Forced Convection of Ferrofluid Flow in Porous Media

2014 ◽  
Vol 348 ◽  
pp. 139-146 ◽  
Author(s):  
Ashkan Sehat ◽  
Hani Sadrhosseini ◽  
M. Behshad Shafii
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Experimental Study ◽  
Porous Media ◽  
Temperature Distribution ◽  
Pressure Drop ◽  
Forced Convection ◽  
Volume Fraction ◽  
Flow In Porous Media ◽  
Tetra Methyl Ammonium Hydroxide

This work presents an experimental study of the effect of a magnetic field on laminar forced convection of a ferrofluid flowing in a tube filled with permeable material. The walls of the tube are subjected to a uniform heat flux and the permeable bed consists of uniform spheres of 3-mm diameter. The ferrofluid synthesis is based on reacting iron (II) and iron (III) in an aqueous ammonia solution to form magnetite, Fe3O4. The magnetite is mixed with aqueous tetra methyl ammonium hydroxide, (CH3)4NOH, solution. The dependency of the pressure drop on the volume fraction, and comparison of the pressure drop and the temperature distribution of the tube wall is studied. Also comparison of the wall temperature distribution, convection heat transfer coefficient and the Nusselt numbers of ferrofluids with different volume fractions is investigated for various Reynolds numbers (147 < Re < 205 ). It is observed that the heat transfer is enhanced by using a porous media, increasing the volume fraction had a similar effect. The pressure coefficient decreases for higher Reynolds number. The effect of magnetic field in four strategies, named modes, on ferrofluid flow through the porous media is presented.

A Paradox of Heat Conduction in Porous Media Subject to Lack of Local Thermal Equilibrium

2006 ◽  
Author(s):  
Peter Vadasz
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Conduction ◽  
Boundary Conditions ◽  
Constant Temperature ◽  
Thermal Equilibrium ◽  
Local Thermal Equilibrium ◽  
Apparent Paradox

Based on the traditional formulation of heat transfer in porous media it is demonstrated that Local Thermal Equilibrium (Lotheq) applies generally for any boundary conditions that are a combination of constant temperature and insulation. The resulting consequences raising an apparent paradox are being analyzed and discussed.

Analysis of two approaches for an adiabatic boundary condition in porous media

2016 ◽  
Vol 26 (3/4) ◽  
pp. 977-998 ◽  
Author(s):  
Kun Yang ◽  
Xingwang You ◽  
Jiabing Wang ◽  
Kambiz Vafai
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Media ◽  
Nusselt Number ◽  
Analytical Solutions ◽  
Channel Wall ◽  
Flux Distribution ◽  
Heat Flux Distribution ◽  
Content Type ◽  
Adiabatic Boundary Condition

Purpose – The purpose of this paper is to analyze two different approaches (Models A and B) for an adiabatic boundary condition at the wall of a channel filled with a porous medium. The analytical solutions for the velocity distribution, the fluid and solid phase temperature distributions are derived and compared with numerical solutions. The phenomenon of heat flux bifurcation for Model A is demonstrated. The effects of pertinent parameter C on the applicability of the Models A and B are discussed. Analytical solutions for the overall Nusselt number and the heat flux distribution at the channel wall are derived and the influence of pertinent parameters Da and k on the overall Nusselt number and the heat flux distribution is discussed. Design/methodology/approach – Two approaches (Models A and B) for an adiabatic boundary condition in porous media under local thermal non-equilibrium (LTNE) conditions are analyzed in this work. The analysis is applied to a microchannel which is modeled as a porous medium. Findings – The phenomenon of heat flux bifurcation at the wall for Model A is demonstrated. The effect of pertinent parameter C on the applicability of each model is discussed. Model A is applicable when C is relatively large and Model B is applicable when C is small. The heat flux distribution is obtained and the influence of Da and k is discussed. For Model A, ϕAfin increases and ϕAsub, ϕAcover decrease as Da decreases and k is held constant, ϕAsub increases and ϕAfin, ϕAcover decrease as k increases while Da is held constant; for Model B, ϕBfin increases and ϕBsub decreases either as Da decreases or k decreases. The overall Nusselt number is also obtained and the effect of Da and k is discussed: Nu increases as either Da or k decrease for both models. The overall Nusselt number for Model A is larger than that for Model B when Da is large, the overall Nusselt numbers for Models A and B are equivalent when Da is small. Research limitations/implications – Proper representation of the energy equation and the boundary conditions for heat transfer in porous media is very important. There are two different models for representing energy transfer in porous media: local thermal equilibrium (LTE) and LTNE. Although LTE model is more convenient to use, the LTE assumption is not valid when a substantial temperature difference exists between the solid and fluid phases. Practical implications – Fluid flow and convective heat transfer in porous media have many important applications such as thermal energy storage, nuclear waste repository, electronic cooling, geothermal energy extraction, petroleum processing and heat transfer enhancement. Social implications – This work has important fundamental implications. Originality/value – In this work the microchannel is modeled as an equivalent porous medium. The analytical solutions for the velocity distribution, the fluid and solid phase temperature distributions are obtained and compared with numerical solutions. The first type of heat flux bifurcation phenomenon, which indicates that the direction of the temperature gradient for the fluid and solid phases is different at the channel wall, occurs when Model A is utilized. The effect of pertinent parameter C on the applicability of the models is also discussed. The analytical solutions for the overall Nusselt number and the heat flux distribution at the channel wall are derived, and the effects of pertinent parameters Da and k on the overall Nusselt number and the heat flux distribution are discussed.

Unsteady and porous media flow of reactive non-Newtonian fluids subjected to buoyancy and suction/injection

2015 ◽  
Vol 25 (7) ◽  
pp. 1682-1704 ◽  
Author(s):  
Tirivanhu Chinyoka ◽  
Daniel Oluwole Makinde
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Boundary Conditions ◽  
Flow Velocity ◽  
Flow System ◽  
Finite Difference Methods ◽  
Porous Media Flow ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Content Type

Purpose – The purpose of this paper is to examine the unsteady pressure-driven flow of a reactive third-grade non-Newtonian fluid in a channel filled with a porous medium. The flow is subjected to buoyancy, suction/injection asymmetrical and convective boundary conditions. Design/methodology/approach – The authors assume that exothermic chemical reactions take place within the flow system and that the asymmetric convective heat exchange with the ambient at the surfaces follow Newton’s law of cooling. The authors also assume unidirectional suction injection flow of uniform strength across the channel. The flow system is modeled via coupled non-linear partial differential equations derived from conservation laws of physics. The flow velocity and temperature are obtained by solving the governing equations numerically using semi-implicit finite difference methods. Findings – The authors present the results graphically and draw qualitative and quantitative observations and conclusions with respect to various parameters embedded in the problem. In particular the authors make observations regarding the effects of bouyancy, convective boundary conditions, suction/injection, non-Newtonian character and reaction strength on the flow velocity, temperature, wall shear stress and wall heat transfer. Originality/value – The combined fluid dynamical, porous media and heat transfer effects investigated in this paper have to the authors’ knowledge not been studied. Such fluid dynamical problems find important application in petroleum recovery.

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