scholarly journals Dimensionless Correlations for Natural Convection Heat Transfer from a Pair of Vertical Staggered Plates Suspended in Free Air

2021 ◽  
Vol 11 (14) ◽  
pp. 6511
Author(s):  
Alessandro Quintino ◽  
Marta Cianfrini ◽  
Ivano Petracci ◽  
Vincenzo Andrea Spena ◽  
Massimo Corcione
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Convection Heat Transfer ◽  
Separation Distance ◽  
Vertical Alignment ◽  
Maximum Heat ◽  
Plate Length ◽  
Optimal Separation ◽  
Maximum Heat Transfer ◽  
Free Air

Buoyancy-induced convection from a pair of staggered heated vertical plates suspended in free air is studied numerically with the main scope to investigate the basic heat and momentum transfer features and to determine in what measure any independent variable affects the thermal performance of each plate and both plates. A computational code based on the SIMPLE-C algorithm for pressure-velocity coupling is used to solve the system of the governing conservation equations of mass, momentum and energy. Numerical simulations are carried out for different values of the Rayleigh number based on the plate length, as well as of the horizontal separation distance between the plates and their vertical alignment, which are both normalized by the plate length. It is observed that an optimal separation distance between the plates for the maximum heat transfer rate related to the Rayleigh number and the vertical alignment of the plates does exist. Based on the results obtained, suitable dimensionless heat transfer correlations are developed for each plate and for the entire system.

Enhancement of Natural Convection Heat Transfer by a Staggered Array of Discrete Vertical Plates

1980 ◽  
Vol 102 (2) ◽  
pp. 215-220 ◽  
Author(s):  
E. M. Sparrow ◽  
C. Prakash
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Parallel Plate ◽  
Convection Heat Transfer ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Parameter Ranges

An analysis has been performed to determine whether, in natural convection, a staggered array of discrete vertical plates yields enhanced heat transfer compared with an array of continuous parallel vertical plates having the same surface area. The heat transfer results were obtained by numerically solving the equations of mass, momentum, and energy for the two types of configurations. It was found that the use of discrete plates gives rise to heat transfer enhancement when the parameter (Dh/H)Ra > ∼2 × 103 (Dh = hydraulic diameter of flow passage, H = overall system height). The extent of the enhancement is increased by use of numerous shorter plates, by larger transverse interplate spacing, and by relatively short system heights. For the parameter ranges investigated, the maximum heat transfer enhancement, relative to the parallel plate case, was a factor of two. The general degree of enhancement compares favorably with that which has been obtained in forced convection systems.

Optimum Arrangement of Rectangular Fins on Horizontal Surfaces for Free-Convection Heat Transfer

1970 ◽  
Vol 92 (1) ◽  
pp. 6-10 ◽  
Author(s):  
Charles D. Jones ◽  
Lester F. Smith
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Design Method ◽  
Convection Heat Transfer ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Maximum Heat Transfer ◽  
Optimum Arrangement ◽  
Free Convection Heat

Experimental average heat-transfer coefficients for free-convection cooling of arrays of isothermal fins on horizontal surfaces over a wider range of spacings than previously available are reported. A simplified correlation is presented and a previously available correlation is questioned. An optimum arrangement for maximum heat transfer and a preliminary design method are suggested, including weight considerations.

Optimum Geometry of Plate Fins

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
R. Karvinen ◽  
T. Karvinen
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Geometrical Properties ◽  
Heat Transfer Coefficients ◽  
Fixed Volume ◽  
Maximum Heat Transfer ◽  
Heat Transfer Theory ◽  
Approximate Analytical Solutions

A method and practical results are presented for finding the geometries of fixed volume plate fins for maximizing dissipated heat flux. The heat transfer theory used in optimization is based on approximate analytical solutions of conjugated heat transfer, which couple conduction in the fin and convection from the fluid. Nondimensional variables have been found that contain thermal and geometrical properties of the fins and the flow, and these variables have a fixed value at the optimum point. The values are given for rectangular, convex parabolic, triangular, and concave parabolic fin shapes for natural and forced convection including laminar and turbulent boundary layers. An essential conclusion is that it is not necessary to evaluate the convection heat transfer coefficients because convection is already included in these variables when the flow type is specified. Easy-to-use design rules are presented for finding the geometries of fixed volume fins that give the maximum heat transfer. A comparison between the heat transfer capacities of different fins is also discussed.

Numerical Analysis of Natural Convective Heat Transfer over a Vertical Cylinder Using External Fins

2015 ◽  
Vol 813-814 ◽  
pp. 707-712
Author(s):  
Anwesha Panigrahi ◽  
D.P. Mishra ◽  
Deepak Kumar
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Vertical Cylinder ◽  
Working Fluid ◽  
Natural Convection Heat Transfer ◽  
Maximum Heat ◽  
Optimum Parameters ◽  
Maximum Heat Transfer

The present numerical study deals with the natural convection heat transfer on the surface of a vertical cylinder with external longitudinal fins. The aim of the study was to determine the effects of geometric parameters like fin height, fin number and fin shape on the heat transfer and thus obtain the optimum parameters that will maximize the rate of heat transfer have been discussed. The numerical investigation consists of an aluminium cylinder of length 1m and diameter 0.07m with air as the working fluid. It has been seen from the numerical investigation that the heat transfer increases with fin height. It is also observed that there exists optimum fin number for maximum heat transfer. Keeping the fin number, fin height and volume fixed, it was found that the heat transfer is maximum for rectangular shaped fin.

scholarly journals Heat Transfer in Horizontal Copper Tube Heated by Electric Heating  Process

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Ramesh Chandra Nayak ◽  
Abinash Sahoo ◽  
Manmatha K. Roul ◽  
Saro Ku. Sarangi
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Printed Circuit Boards ◽  
Convection Heat Transfer ◽  
Heating Process ◽  
Internal Diameter ◽  
Convection Heat ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Heat transfer from electrical and electronics component is essential for better performance of that electrical system, The maximum heat transfer from that system results long period durability. In most of the system  base  provided for equipments are very small and placed in a very complicated position. so heat transfer by forced convection is not easy for that  purpose. The heat transfer by natural convection is the familiar technique used in electronics cooling; there is huge group of apparatus that lends itself to natural convection .This category consist of stand-alone correspondence such as modems and small computers having an array of printed circuit boards (PCB) accumulate within an area.Natural convection heat transfer in heated horizontal duct drive away heat from the interior surface is offered. The duct is open-ended and round in cross section. The test section is heated by provision of heating coils, where constant wall heat flux mentioned. Heat transfer experiment is carried out for channel of 50 mm. internal diameter and 4 mm thickness with length 600 mm. Ratios of length to diameter of the channel are taken as L/D = 12. Wall heat fluxes maintained at q// = 300 W/m2 to 3150 W/m2.  A methodical investigational record for the local steady state natural convection heat transfer activities is obtained. The wall heating condition on local steady-state heat transfer phenomena are studied. The present experimental data is compared with the existing theoretical and experimental results for the cases of vertical smooth tubes. 

scholarly journals Development of Forced Convection Heat Transfer Enhancement System by using Mesh Inserts in a Circular Tube

2021 ◽  
Author(s):  
Avinash D. Sapkal ◽  
Akash A Pawar ◽  
Shridhar V Kulkarni ◽  
Umesh B Andh ◽  
Digambar T Kashid ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Test Section ◽  
Circular Tube ◽  
Convection Heat Transfer ◽  
Transfer Enhancement ◽  
Measure Flow Rate ◽  
Maximum Heat ◽  
Maximum Heat Transfer

In the present work, aluminium mesh type inserts flow has been developed. The aluminium meshes are arranged on spokes at the angle of 00, 450, 900 concerning horizontal are inserted in the test section to create turbulence. To carry out an experimental investigation using this mesh inserts, we have developed a forced convection system. In this system, we have wounded three 200 Volt heaters over a 500 mm test section of 25 mm diameter respectively. The input to the heater is controlled by a variable dimmer stat, and the mass flow rate is controlled by an orifice meter with a diameter of 25 mm across which the manometer is connected to measure flow rate. Experiments were carried out at Reynolds number greater than 4000. The experimental setup was validated first and readings with different inserts were taken. This led to the conclusion that the rate of heat transfer was improved by using mesh inserts inclined at an angle 00, 450, and 900. Among these, the inserts inclined at 450 angles showed maximum heat transfer rate i.e., 37.44%, 29.95%, and 38.40% for the manometric reading of 5 mm, 4 mm, and 3 mm respectively.

Correlating Equations for Laminar Free Convection From Misaligned Horizontal Cylinders in Interacting Flow Fields

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Massimo Corcione ◽  
Claudio Cianfrini ◽  
Emanuele Habib ◽  
Gino Moncada Lo Giudice
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Free Convection ◽  
Computer Code ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Maximum Heat Transfer ◽  
Tilting Angle ◽  
Correlating Equations ◽  
Horizontal Cylinders

Steady laminar free convection in air from a pair of misaligned, parallel horizontal cylinders, i.e., a pair of parallel cylinders with their axes set in a plane inclined with respect to the gravity vector, is studied numerically. A specifically developed computer code based on the SIMPLE-C algorithm is used for the solution of the dimensionless mass, momentum, and energy transfer governing equations. Results are presented for different values of the center-to-center cylinder spacing from 1.4 up to 10 diameters, the tilting angle of the two-cylinder array from 0degto90deg, and the Rayleigh number based on the cylinder diameter in the range between 103 and 107. It is found that the heat transfer rates at both cylinder surfaces may in principle be traced back to the combined contributions of the so-called plume effect and chimney effect, which are the mutual interactions occurring in the vertical and horizontal alignments, respectively. In addition, at any misalignment angle, an optimum spacing between the cylinders for the maximum heat transfer rate, which decreases with increasing the Rayleigh number, does exist. Heat transfer dimensionless correlating equations are proposed for any individual cylinder and for the pair of cylinders as a whole.

Enhancement of Free Convection From Horizontal-Base Straight-Fin Heat Sink by Partial Shrouding

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Dileep V. Nair
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Computational Study ◽  
Light Emitting Diode ◽  
Convection Heat Transfer ◽  
Lower Surface ◽  
Simple Method ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract This work presents a simple method to improve natural convection heat transfer performance of horizontal-base straight-fin heat sink by adding partial shroud plates on top of the heat sink at both ends. Experiments are conducted in conjunction with a detailed three-dimensional (3D) computational study. The numerical model is validated using experimental results. With partial shrouding, the modification and effective utilization of airflow surrounding the heat sink leads to significant heat transfer enhancement. The installation of shroud plates effectively improves the mass flowrate of air admitted into the fin channel. Further, the airflow drawn above the heat sink dissipates heat from the upper surface of the shroud plate. There is also a significant heat dissipation from the lower surface of the shroud plate which is exposed to cold air drawn from the side-end of the heat sink. The heat transfer from the existing optimal conventional heat sink is improved by 17% with the introduction of shroud plates. An optimal width of the shroud plate is identified to exist for the maximum heat transfer. The percentage enhancement in heat transfer achieved by partial shrouding increases with a decrease in the fin height and with an increase in the fin spacing. The proposed compact heat sink design would be of application in enhancing passive heat dissipation from light-emitting diode (LED) lights and other electronic devices, especially when size constraints exist.

Geometry of Plate Fins for Maximizing Heat Transfer

2010 ◽  
Author(s):  
Timo Karvinen ◽  
Reijo Karvinen
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Transfer Coefficients ◽  
Optimal Point ◽  
Maximum Heat ◽  
Geometrical Properties ◽  
Heat Transfer Coefficients ◽  
Maximum Heat Transfer ◽  
Approximate Analytical Solutions ◽  
Need To Evaluate

A method is presented for finding plate fin geometries for maximizing dissipated heat flux. The method is based on approximate analytical solutions of conjugated heat transfer which are utilized in optimization. As a result non-dimensional variables have been found that contain thermal and geometrical properties of the fin and the flow. These variables have a fixed value at the optimal point. The values are given for rectangular, convex parabolic, triangular, and concave parabolic fin shapes for natural and forced convection including laminar and turbulent boundary layers. An essential fact is that there is no need to evaluate convection heat transfer coefficients because they are already included in these variables. Easy-to-use design rules are presented for finding the geometry of fixed volume fins that gives the maximum heat transfer.

scholarly journals Laminar natural convection from a vertical array of horizontal heated cylinders inside a water-filled rectangular enclosure cooled at sides

2019 ◽  
Vol 30 (5) ◽  
pp. 2607-2623 ◽  
Author(s):  
Marta Cianfrini ◽  
Massimo Corcione ◽  
Alessandro Quintino ◽  
Vincenzo Andrea Spena
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Control Volume ◽  
Maximum Heat ◽  
Content Type ◽  
Rectangular Enclosure ◽  
Cylinder Diameter ◽  
Maximum Heat Transfer ◽  
Laminar Natural Convection

Purpose The purpose of this study is to investigate numerically the laminar natural convection from a pair of horizontal heated cylinders, set one above the other, inside a water-filled rectangular enclosure cooled at sides, with perfectly insulated top and bottom walls, through a control-volume formulation of the finite-difference method, with the main aim to evaluate the effects of the center-to-center cylinder spacing, the size of the cavity and the temperature difference imposed between the cylinders and the cavity sides. Design/methodology/approach The system of the conservation equations of the mass, momentum and energy, expressed in dimensionless form, is solved by a specifically developed computer code based on the SIMPLE-C algorithm for the pressure-velocity coupling. Numerical simulations are executed for different values of the Rayleigh number based on the cylinder diameter, as well as the center-to-center cylinder spacing and the width of the cavity normalized by the cylinder diameter. Findings The main results obtained may be summarized as follows: the existence of an optimum cylinder spacing for maximum heat transfer rate is found at any investigated Rayleigh number; as a consequence of the downstream confinement, a periodic flow arises at sufficiently high Rayleigh numbers; the amplitude of oscillation of the periodic heat transfer performance of the cylinder array decreases as the cylinder spacing is increased and the cavity width is decreased, whereas the frequency of oscillations remains almost the same; at very small cavity widths, a transition from the typical two-cell to a four-cell flow pattern occurs. Originality/value The computational code used in the present study incorporates an original composite polar/Cartesian discretization grid scheme.

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