INFLUENCE OF THE POROUS MEDIA ON HEAT EXCHANGE AT FILM BOILING LIQUID

The present work focuses on a study of heat transfer during film boiling of a liquid on a vertical heated wall immersed in a porous medium subject to variation of different parameters of the porous medium and heating conditions at the wall. An analytical solution was obtained for the problem using Darcy-Brinkman-Forchheimer model. It was shown that heat transfer intensity during film boiling in a porous medium is weaker than in a free fluid (without porosity) and decreases with the decreasing permeability of the porous medium. The use of a porous medium model in the Darcy-Brinkman-Forchheimer approximation showed the effect of the Forchheimer parameter on heat transfer during film boiling in a porous medium. An increase in the Forchheimer parameter leads to heat transfer deterioration, which is more significant at small values of the Darcy number. Effects of different thermal boundary conditions on the heated wall on the heat transfer are insignificant.

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HEAT TRANSFER FOR FILN BOILING OF A LIQUID ON A VERTICAL HEATED WALL IN A POROUS MEDIUM

Thermophysics and Thermal Power Engineering ◽

10.31472/ttpe.1.2021.3 ◽

2021 ◽

Vol 43 (1) ◽

pp. 20-29

Author(s):

A.A. Avramenko ◽

M.M. Kovetskaya ◽

E.A. Kondratieva ◽

T.V. Sorokina

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Porous Medium ◽

Fluid Flow ◽

Wall Temperature ◽

Heated Wall ◽

Film Boiling ◽

Transfer Coefficients ◽

Constant Wall Temperature ◽

Heat Transfer Coefficients

The paper presents results of the modelling of heat transfer at film boiling of a liquid in a porous medium on a vertical heated wall. Such processes are observed at cooling of high-temperature surfaces of heat pipes, microstructural radiators etc. Heating conditions at the wall were the constant wall temperature or heat flux. An analytical solution was obtained for the problem of fluid flow and heat transfer using the porous medium model in the Darcy-Brinkman. It was shown that heat transfer at film boiling in a porous medium was less intensive than in the absence of a porous medium (free fluid flow) and further decreased with the decreasing permeability of the porous medium. A sharp decrease in heat transfer was observed for the Darcy numbers lower than five. The analytical predictions of heat transfer coefficients qualitatively agreed with the data [14] though demonstrated lower values of heat transfer coefficients for the conditions of the constant wall temperature and constant wall heat flux.

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Darcy-Brinkman free convection about a wedge and a cone subjected to a mixed thermal boundary condition

International Journal of Mathematics and Mathematical Sciences ◽

10.1155/s0161171292001029 ◽

1992 ◽

Vol 15 (4) ◽

pp. 789-794 ◽

Cited By ~ 3

Author(s):

G. Ramanaiah ◽

V. Kumaran

Keyword(s):

Heat Transfer ◽

Boundary Condition ◽

Heat Flux ◽

Porous Medium ◽

Heat Transfer Coefficient ◽

Free Convection ◽

Transformation Group ◽

Darcy Number ◽

Thermal Boundary Condition ◽

High Porosity

The Darcy-Brinkman free convection near a wedge and a cone in a porous medium with high porosity has been considered. The surfaces are subjected to a mixed thermal boundary condition characterized by a parameterm;m=0,1,∞correspond to the cases of prescribed temperature, prescribed heat flux and prescribed heat transfer coefficient respectively. It is shown that the solutions for differentmare dependent and a transformation group has been found, through which one can get solution for anymprovided solution for a particular value ofmis known. The effects of Darcy number on skin friction and rate of heat transfer are analyzed.

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Natural Convection Inside a Bidisperse Porous Medium Enclosure

Journal of Heat Transfer ◽

10.1115/1.3192134 ◽

2009 ◽

Vol 132 (1) ◽

Cited By ~ 21

Author(s):

Arunn Narasimhan ◽

B. V. K. Reddy

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Natural Convection ◽

Volume Fraction ◽

Solid Phase ◽

Darcy Number ◽

The Core ◽

Side Walls ◽

Porous Blocks ◽

Rayleigh Numbers

Bidisperse porous medium (BDPM) consists of a macroporous medium whose solid phase is replaced with a microporous medium. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the microporous medium. The side walls are subjected to differential heating, while the top and bottom ones are kept adiabatic. The bidispersion effect is generated by varying the number of blocks (N2), macropore volume fraction (ϕE), and internal Darcy number (DaI) for several enclosure Rayleigh numbers (Ra). Their effect on the BDPM heat transfer (Nu) is investigated. When Ra is fixed, the Nu increases with an increase in both DaI and DaE. At low Ra values, Nu is strongly affected by both DaI and ϕE. When N2 is fixed, at high Ra values, the porous blocks in the core region have negligible effect on the Nu. A correlation is proposed to evaluate the heat transfer from the BDPM enclosure, Nu, as a function of Raϕ, DaE, DaI, and N2. It predicts the numerical results of Nu within ±15% and ±9% in two successive ranges of modified Rayleigh number, RaϕDaE.

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Numerical Investigation of Heat Transfer in Forced Convection in a Helical Pipe Filled With a Porous Medium

Heat Transfer: Volume 1 ◽

10.1115/ht2005-72059 ◽

2005 ◽

Author(s):

Liping Cheng ◽

Andrey V. Kuznetsov

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Saturated Porous Medium ◽

Axial Flow ◽

Darcy Number ◽

Momentum Equation ◽

Darcy Law ◽

Helical Pipe ◽

Fluid Saturated Porous Medium ◽

Flow Inertia

This paper investigates numerically heat transfer in a helical pipe filled with a fluid saturated porous medium. The analysis is based on the full momentum equation for porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Numerical computations are performed in an orthogonal helical coordinate system. The effects of the Darcy number, the Forchheimer coefficient as well as the Dean and Germano numbers on the axial flow velocity, secondary flow, temperature distribution, and the Nusselt number are analyzed.

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Natural Convection in a Cavity Partially Filled with a Vertical Porous Medium

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.321.15 ◽

2011 ◽

Vol 321 ◽

pp. 15-18 ◽

Cited By ~ 1

Author(s):

Fang Liu ◽

Bao Ming Chen

Keyword(s):

Heat Transfer ◽

Finite Element Method ◽

Boundary Condition ◽

Porous Medium ◽

Nusselt Number ◽

Free Fluid ◽

Stress Jump ◽

Convection And Heat Transfer ◽

Flow And Heat Transfer ◽

Stress Jump Boundary Condition

The shear stress jump boundary condition that must be imposed at an interface between a porous medium and a free fluid in an enclosure is investigated. Two-domain approach is founded and finite element method is used to solve the problem. Three stress jump coefficients 0, 1, -1 are analyzed for different Rayleigh number, permeability and thickness of porous layer. Variation of Maximum stream function and Nusselt number show stronger convection and heat transfer when the stress jump coefficient is positive. There is little distinctive in flow and heat transfer when the value of coefficient is equal to 0 and -1.

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Numerical Simulation of Transient Free Convection Flow and Heat Transfer in a Porous Medium

Mathematical Problems in Engineering ◽

10.1155/2013/371971 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Rajesh Sharma ◽

Anuar Ishak

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Differential Equations ◽

Darcy Number ◽

Convection Flow ◽

Force Model ◽

Moving Plate ◽

Drag Forces ◽

Flow And Heat Transfer ◽

Momentum And Heat Transfer

The coupled momentum and heat transfer in unsteady, incompressible flow along a semi-infinite vertical porous moving plate adjacent to an isotropic porous medium with viscous dissipation effect are investigated. The Darcy-Forchheimer nonlinear drag force model which includes the effects of inertia drag forces is employed. The governing differential equations of the problem are transformed into a system of nondimensional differential equations which are solved numerically by the finite element method (FEM). The non-dimensional velocity and temperature profiles are presented for the influence of Darcy number, Forchheimer number, Grashof number, Eckert number, Prandtl number, plate velocity, and time. The Nusselt number is also evaluated and compared with finite difference method (FDM), which shows excellent agreement.

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Laminar Filmwise Condensation on Horizontal Disk Embedded in Porous Medium With Suction at Wall

Journal of Heat Transfer ◽

10.1115/1.2909075 ◽

2008 ◽

Vol 130 (7) ◽

Cited By ~ 5

Author(s):

Tong-Bou Chang

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Liquid Film ◽

Mechanical Energy ◽

Disk Surface ◽

Darcy Number ◽

Nonlinear Ordinary Differential Equation ◽

Phase Zone ◽

Two Phase ◽

Suction Parameter

This study performs a theoretical investigation into the problem of two-dimensional steady filmwise condensation flow on a horizontal disk embedded in a porous medium layer with suction at the disk surface. The analysis considers the case of a water-vapor system and is based on typical values of the relevant dimensional and dimensionless parameters. Due to the effects of capillary forces, a two-phase zone is formed between the liquid film and the vapor zone. The minimum mechanical energy concept is employed to establish the boundary condition at the edge of the horizontal disk and the Runge–Kutta shooting method is used to solve the second-order nonlinear ordinary differential equation of the liquid film. It is found that the capillary force and wall suction effects have a significant influence on the heat transfer performance. Specifically, the results show that the dimensionless heat transfer coefficient depend on the Darcy number Da, the Jacob number Ja, the effective Rayleigh number Rae, the effective Prandtl number Pre, the suction parameter Sw, and the capillary parameter Boc.

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A Parametric Experimental Study on the Heat Transfer Characteristics of Supercritical Kerosene in Active Cooling Channels of Scramjets

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.774-776.252 ◽

2013 ◽

Vol 774-776 ◽

pp. 252-257

Author(s):

Ning Wang ◽

Jin Zhou ◽

Yu Pan ◽

Hui Wang

Keyword(s):

Heat Transfer ◽

Wall Temperature ◽

Sharp Increase ◽

Film Boiling ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Heat Transfer Deterioration ◽

Cooling Channels ◽

Transfer Characteristics ◽

The Heat Transfer Coefficient

Heat transfer characteristics of China RP-3 kerosene under supercritical state were experimentally investigated. Results showed that at sub-critical pressures, heat transfer deterioration happens, and the wall temperature rises from approximately 350°C to 750°C. This is thought to be resulted from film boiling when kerosene begins to transfer from liquid to gas. At supercritical pressures, heat transfer enhancement was observed. And it is mainly caused by the sharp increase of specific heat of kerosene when the wall temperature is approaching the critical temperature of kerosene. The heat transfer coefficient doesnt increase with velocity for kerosene, because the thermal properties and residence time of kerosene have changed when velocity is changed.

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Analysis of combined radiation and convection heat transfer inside a porous medium with heat source electronic devices

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211046791 ◽

2022 ◽

pp. 095440622110467

Author(s):

Ali Mokhtari Nahal ◽

Mohammad Hassan Nobakhti ◽

Cyrus Aghanajafi ◽

Morteza Khayat

Keyword(s):

Heat Transfer ◽

Porous Medium ◽

Heat Source ◽

Cooling Rate ◽

Numerical Study ◽

Electronic Devices ◽

Convection Heat Transfer ◽

Darcy Number ◽

Flow Lines ◽

Rayleigh Numbers

In this study, a numerical study is performed on the cooling phenomenon of three heat source electronic devices. The electronic devices are cooled in the form of natural heat transfer by the airflow in a porous medium. Electronic devices are installed on the boundary walls of a square environment. Cooling simulations are performed by drawing flow lines and constant temperature lines. Our main goal is to find the highest cooling rate in different Darcy numbers and different Rayleigh numbers in our investigation. The range of Darcy numbers and Rayleigh numbers is between 0.0001 to 0.01 and 1000 to 100,000, respectively. Our investigation showed the maximum cooling is obtained at the Darcy number of about 0.01. And also, by decreasing the value of Darcy number, a higher cooling rate for the hot boundary walls is achieved.

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