Natural Convection at Different Prandtl Numbers in Rectangular Cavities with a Fin on the Cold Wall (original) (raw)
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Thermal Science, 2014
In the present paper, natural convection fluid flow and heat transfer in a square cavity heated from below and cooled from sides and the ceiling with a thin fin attached to its hot bottom wall is investigated numerically. The right and the left walls of the cavity, as well as its horizontal top wall are maintained at a constant temperature T c , while the bottom wall is kept at a constant temperature T h ,with T h > T c. The governing equations are solved numerically using the finite volume method and the couple between the velocity and pressure fields is done using the SIMPLER algorithm. A parametric study is performed and the effects of the Rayleigh number and the length of the fin on the flow pattern and heat transfer inside the cavity are investigated. Two competing mechanisms that are responsible for the flow and thermal modifications are observed. One is the resistance effect of the fin due to the friction losses which directly depends on the length of the fin, whereas the other is due to the extra heating of the fluid that is offered by the fin. It is shown that for high Rayleigh numbers, placing a hot fin at the middle of the bottom wall has more remarkable effect on the flow field and heat transfer inside the cavity.
Heat Transfer Research, 2011
Fluid flow and natural convection heat transfer in a differentially heated square cavity with a fin attached to its cold wall is investigated numerically. The top and the bottom horizontal walls of the cavity are insulated while the left and right vertical walls of the cavity are maintained at a constant temperature T h and T c , with T h > T c , respectively. The governing equations written in terms of the primitive variables are solved numerically using the finite volume method and the SIMPLER algorithm. Using the developed code, a parametric study is performed, and the effects of the Rayleigh number, length of the fin and its position on the flow pattern and heat transfer inside the enclosure are investigated. The results show that for high Rayleigh numbers, a longer fin placing at the middle of the right wall has a more remarkable effect on the flow field and heat transfer inside the cavity.
Effect of inclined thick fin on natural convection in a cavity heated from bottom
Progress in Computational Fluid Dynamics, An International Journal, 2015
In this study, natural convection heat transfer in a square cavity with an adiabatic fin mounted on a vertical wall was investigated numerically. Vertical boundaries were adiabatic and horizontal boundaries were isothermal at different constant temperature. Two-dimensional equations of conservation of mass, momentum and energy were solved using finite difference method. Successive under relaxation (SUR) method was used to solve linear algebraic equations. Results were obtained for various geometrical parameters as the thermal conductivity ratio (RK = 0.1, 1.0 and 10), inclination angle of the fin (30° ≤ φ ≤ 150°), thickness of the fin (0.033 ≤ t ≤ 0.2), and Rayleigh numbers (10 3 ≤ Ra ≤ 10 6). Location and length of fin was fixed as h = w = 0.5. Results were presented with streamlines, isotherms, local and mean Nusselt numbers. It was found that Rayleigh number and the fin mounted on the wall had significant effect on natural convection heat transfer and flow field. The thick fin can be used as control parameter of heat and fluid flow.
Heat and Mass Transfer, 2011
Natural convection heat transfer in an inclined fin attached square enclosure is studied both experimentally and numerically. Bottom wall of enclosure has higher temperature than that of top wall while vertical walls are adiabatic. Inclined fin has also adiabatic boundary conditions. Numerical solutions have been done by writing a computer code in Fortran platform and results are compared with Fluent commercial code and experimental method. Governing parameters are Rayleigh numbers (8.105 ≤ Ra ≤ 4 × 106) and inclination angle (30° ≤ and ≤ 120°). The temperature measurements are done by using thermocouples distributed uniformly at the wall of the enclosure. Remarkably good agreement is obtained between the predicted results and experimental data. A correlation is also developed including all effective parameters on heat transfer and fluid flow. It was observed that heat transfer can be controlled by attaching an inclined fin onto wall.
Natural Convection in a Square Cavity with Discrete Heating at the Bottom with Different Fin Shapes
Heat Transfer Engineering, 2017
Numerical study is carried out to investigate the effect of different fin shapes on heating a square cavity by small heating strip located at the bottom wall. The natural convection of air is considered with constant heat flux from heat source which is located at the centre of the bottom wall. The width of the heating strip is assumed to be 20% of the total width of the bottom wall. The remaining (non-heated) part of the bottom wall and the top wall are adiabatic and the side walls are maintained at constant temperature. The investigation considered four shapes of
Effects of fin on mixed convection heat transfer in a vented square cavity: A numerical study
Mağallaẗ al-qādisiyyaẗ li-l-ʻulūm al-handasiyyaẗ, 2023
Numerical investigation of mixed convective in a vented square cavity with fin. The horizontal walls are adiabatic, while the left and right walls are hot (ℎ) and cold () temperatures, respectively. The fluid inlet to the cavity from the lower left open area(), and exits from the upper right open area (). In this study, a finite element scheme is employed. The analysis is done for specific Prandtl number (= 7), Reynolds number (50 ≤ ≤ 200), fin length (0.2 ≤ ≤ 0.6), Richardson number (0.1 ≤ ≤ 1), and the location of the fin (0.2 ≤ ℎ ≤ 0.6). The finding indicates that the increases when high the location of the fin increases at the maximum height of this fin location is estimated to be 17% due to an increase in the fluid flow area on the hot wall caused by rising convective. The highest heat transfer occurs when the fin length equals 0.6 at the location(ℎ = 0.2).
2014
In this article an experimental investigation is made to predict the performance of heated triangular fin array within a vertically oriented and air filled rectangular enclosure. The experimental analysis is done to analyze the effects of several influencing parameters for their wide ranges; Rayleigh number 295214 ≤ Ra ≤ 773410, fin spacing 25 mm ≤ S ≤ 100 mm and fin height 12.5 mm ≤ L ≤ 37.5 mm for constant heat flux boundary conditions at the heated and cooled walls of the enclosure. An empirical correlation is also developed relating Nusselt number to several influencing parameters.
Purpose – The purpose of this paper is to optimize the heat transfer rate in square cavity by attaching fin at the bottom wall. Design/methodology/approach – The problem is formulated and solved using finite element method. Accuracy of the method is validated by comparisons with previously published work. Findings – It was found that attaching fin reduces heat transfer rate in the cavity. Originality/value – Although the problem is not very original it is important in that many applications have heating on adjacent walls.
Effect of length and inclination of a thin fin on natural convection in a square enclosure
2006
A numerical investigation of steady, laminar, natural convective fluid flow in a square enclosure with an inclined heated thin fin of arbitrary length attached to the hot wall is considered. A transverse temperature gradient is applied on two opposing walls of the enclosure, while the other two walls are adiabatic. Attachment of highly conductive inclined thin fins with lengths equal to 20%, 35%, and 50% of the side, positioned in the middle of the hot left wall of the enclosure, is examined. The problem is formulated in terms of the vorticity-stream function procedure. A numerical solution based on the finite-volume method is obtained. Representative results illustrating the effects of the thin-fin inclination angle and length on the streamlines and temperature contours within the enclosure are reported. In addition, results for the local and average Nusselt numbers at the heated wall of the enclosure are presented and discussed for various parametric conditions. It is found that the Rayleigh number and the thin-fin inclination angle and length have significant effects on the average Nusselt number of the heated wall including the fin of the enclosure.