scholarly journals CFD Simulation of Natural Convection Flow and Heat Transfer Process in Rectangular Cavity

2019 ◽  
Vol 9 (1) ◽  
pp. 6121-6124
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Heat Source ◽  
Transfer Process ◽  
Flow Behavior ◽  
Heat Transfer Process ◽  
Rectangular Cavity ◽  
Flow And Heat Transfer ◽  
Source Block

In this paper we investigate the natural convective heat transfer process inside a ventilated rectangular cavity with a projected heat source. The heat source block is mounted on the bottom wall and a horizontal vent is provided on the top wall of the rectangular cavity. The flow is induced due to the density difference which arises due to the variations in temperature between the heat source block and the surrounding ambient fluid. A FORTRAN 90 CFD solver is developed to simulate the natural convection phenomena by solving the Navier-stokes equation, energy equation coupled with Realizable k-ε turbulence model. The transient flow behavior inside the cavity is simulated by varying the heat source aspect ratios, Grashof number and the heat source locations. It is found that the heat source aspect ratio and its locations significantly influences the flow and heat transfer characteristics inside the cavity. The bidirectional exchange rate across the horizontal opening increases linearly with Grashof number and heat source aspect ratio. A chaotic flow behavior pattern is observed across the opening and the strength of the instabilities increases linearly with heat source aspect ratio. It is identified that by varying the aspect ratio 0.1 ≤ β ≤ 3, the average Nusselt number and mass flow rates are increased by 28% and 43% respectively.

scholarly journals Effect of Heat Source Placement on Natural Convection from Cylindrical Surfaces

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4334
Author(s):  
Andrej Kapjor ◽  
Peter Durcansky ◽  
Martin Vantuch
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Theoretical Models ◽  
Heat Transfer Process ◽  
Heat Output ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Thermal Fields ◽  
Horizontal Cylinders

Placement of heat source can play a significant role in final heat output, or heat source effectivity. Because of this, there is a need to analyze thermal fields of the heat exchange system by natural convection, where the description by criterion equations is desired, as the net heat output from tubes can be quantified. Based on known theoretical models, numerical methods were adapted to calculate the heat output with natural air flow around tubes, where mathematical models were used to describe the heat transfer more precisely. After validation of heat transfer coefficients, the effect of wall and heat source placement was studied, and the Coanda effect was also observed. The heat source placement also has an effect at the boundary layer, which can change and therefore affect the overall heat transfer process. The optimal wall-to-cylinder distance for an array of horizontal cylinders near a wall was also expressed as a function of the Rayleigh number and number of cylinders in the array.

Numerical Simulation of Natural Convection in a Two-Dimensional Enclosure Filled with Nanofluids

2012 ◽  
Vol 560-561 ◽  
pp. 1184-1187
Author(s):  
Su Fen Zhao ◽  
Xin Fang Li
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Process ◽  
Transfer Rate ◽  
Mass Fraction ◽  
Heat Transfer Process ◽  
Two Dimensional ◽  
Grashof Number ◽  
Transfer Properties

The natural convection of nanofluids in a two-dimensional enclosure is numerically simulated with Fluent software. The effect of copper particle concentration and Grashof number on heat transfer properties is investigated. The results indicate that the suspended copper nanoparticles substantially increase the heat transfer rate at any given Grashof number, and the heat transfer rate of the nanofluid increases remarkably with the mass fraction of nanoparticles. For a given initial Grashof number, as the mass fraction increases, the velocity components of nanofluid increase as a result of an increase in the energy transport through the fluid. In addition, the intensity of the streamline increase with the increases of the Grashof number, which indicate the heat transfer properties are enhanced. The heat transfer process is dominant with the heat exchange at low Gr, while the heat transfer process is dominant with the natural convection at high Gr.

Natural Convection Cooling of Multiple Heat Sources in Parallel Open-Top Cavities Filled With a Fluorinert Liquid

1998 ◽  
Vol 120 (1) ◽  
pp. 73-81 ◽  
Author(s):  
M. Behnia ◽  
A. A. Dehghan ◽  
H. Mishima ◽  
W. Nakayama
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Alumina Ceramic ◽  
Heat Sources ◽  
Flow And Heat Transfer ◽  
Discrete Heat Sources ◽  
Vertical Walls ◽  
Convection Cooling ◽  
Lower Heat

Natural convection immersion cooling of discrete heat sources in a series of parallel interacting open-top cavities filled with a fluorinert liquid (FC–72) has been numerically studied. A series of open-top slots which are confined by conductive vertical walls with two heat sources on one side are considered. One of the slots is modeled and simulated. The effect of the separation between the heat sources on the flow and heat transfer characteristics of the wall and the effect of strength of the lower heat source (which location is upstream of the other one) on the flow and heat transfer of the upper heat source are considered. The wall thermal conductivity considered ranges from adiabatic to alumina-ceramic. The results of bakelite and alumina-ceramic are shown, which are commonly used as wiring boards in electronic equipment. It is found that conduction in the wall is very important and enhances the heat transfer performance.

Melting in Rectangular Enclosures: Experiments and Numerical Simulations

1985 ◽  
Vol 107 (4) ◽  
pp. 794-803 ◽  
Author(s):  
C. Be´nard ◽  
D. Gobin ◽  
F. Martinez
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Transfer Process ◽  
Solid Phase ◽  
Solid Material ◽  
Melting Process ◽  
Heat Transfer Process ◽  
Numerical Code ◽  
Melting Front ◽  
Kinetics Of

This paper presents a numerical and experimental analysis of the heat transfer process that takes place while melting a solid material, in a rectangular enclosure. Natural convection is present in the melt layer, and the solid phase is assumed to be isothermal. Very detailed and precise experimental results are given that are used to validate a particularly rapid numerical code. Some insights into the kinetics of the melting process lead to a deeper understanding of the coupling between convection and phase change and allow us to propose a simple algebraic correlation that predicts the time evolution of the melting front to within 5 percent.

Natural convection in a rectangular cavity filled with nanofluids

2018 ◽  
Vol 28 (6) ◽  
pp. 1410-1432 ◽  
Author(s):  
Cornelia Revnic ◽  
Eiyad Abu-Nada ◽  
Teodor Grosan ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Design Methodology ◽  
Volume Fraction ◽  
Numerical Study ◽  
Rectangular Cavity ◽  
Heat Transfer Characteristics ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Comprehensive Survey

Purpose This paper aims to develop a numerical study of the steady natural convection in a rectangular cavity filled with the CuO–water-based nanofluid. It is assumed that the viscosity of nanofluids depends on the temperature and on the nanofluids volume fraction. Design/methodology/approach The mathematical nanofluid model has been formulated on the basis of the model proposed by Buongiorno (2006). The system of partial differential equations is written in terms of a dimensionless stream function, vorticity, temperature and the volume fraction of the nanoparticles, and is solved numerically using the finite difference method for different values of the governing parameters. Findings It is found that both fluid flow and heat transfer coefficient are affected by the considered parameters. Thus, the Nusselt number is slowly increasing with increasing volume fraction from 2 per cent to 5 per cent and it is more pronounced increasing with increasing Rayleigh number from 103 to 105. Originality/value Buongiorno’s (2006) nanofluid model has been applied for the flow with the characteristics as mentioned in the paper. A comprehensive survey on the behavior of flow and heat transfer characteristics has been presented. All plots presented in the paper are new and are not reported in any other study.

scholarly journals Intensification of Heat Transfer in Cavity Partially Heated and Filled with Nanofluid (Cu-Water)

2015 ◽  
Vol 55 ◽  
pp. 173-179
Author(s):  
Ridha Jmai ◽  
Brahim Ben Beya ◽  
Taieb Lili
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Heat Transfer Rate ◽  
Finite Volume ◽  
Transfer Rate ◽  
Heat Sources ◽  
Flow And Heat Transfer ◽  
Vertical Walls

Natural convection in a rectangular cavity with aspect ratio (Ax), partially heated and filled with a nanofluid (Cu-Water) has been studied numerically. Two heat sources with length (B) are placed on the opposite vertical walls; the remainder of the walls is maintained adiabatic while the horizontal walls are brought to a cold temperature. The equations governing the flow are solved using a finite volume home code using a multigrid technique. Among the parameters governing the flow, a detailed study on the effects of the aspect ratio (Ax) and the length of the source (B) on flow and heat transfer rate is given. The results are shown in terms of streamlines and isotherms. It was found that the transfer of heat significantly increases with the aspect ratio (Ax) and the length of the source (B). A correlation expressing the Nusselt number as a function of (Ax) and d is established.

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