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.

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.

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.

Spatial Variation of Heat Transfer to Pistons and Liners of Some Medium Speed Diesel Engines

1970 ◽  
Vol 185 (1) ◽  
pp. 203-218 ◽  
Author(s):  
W. J. Seale ◽  
D. H. C. Taylor
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling Water ◽  
Radial Variation ◽  
Transfer Coefficients ◽  
Air Concentration ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Maximum Heat Transfer

Heat transfer coefficients have been measured on the gas side of pistons and liners, the water side of liners, and the oil side of pistons. A significant radial variation in heat transfer across the piston crown has been found. The position of the maximum heat transfer coefficient appears to be coincident with the maximum air concentration, or the position the tips of the fuel sprays have reached at the time of ignition, and the radial variation of heat transfer is possibly related to the amount of fuel burnt at each radius. For four-stroke engines, equations are presented to describe this variation. Heat transfer coefficients at the exposed section of the liner have been found to be similar to the values at the outer edge of the piston. Heat transfer between piston undercrown and cooling oil has been measured for various types of cooling arrangement and, for jet cooling, an expression has been suggested for the heat transfer coefficient. Equations have also been derived to enable coefficients to be predicted for heat transfer from liner to cooling water.

scholarly journals Heat transfer through the regular polyhedrons with asymmetric boundary conditions

2012 ◽  
Vol 33 (3) ◽  
pp. 117-125
Author(s):  
Ewa Pelińska-Olko
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Extreme Values ◽  
Regular Polyhedron ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Heat Transfer Coefficients ◽  
Maximum Heat Transfer

Abstract During heat transport through the walls of a hollow sphere, the heat stream can achieve extreme values. The same processes occur in regular polyhedrons. We can calculate the maximum heat transfer rate, the so-called critical heat transfer rate. We must assume here identical conditions of heat exchange on all internal and external walls of a regular polyhedron. The transfer rate of heat penetrating through the regular polyhedron with different heat transfer coefficients on the walls is called the heat transfer rate with asymmetric boundary conditions. We show that the heat transfer rate in this case will grow up if we replace those coefficients with their average values.

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.

scholarly journals OPTIMALLY STAGGERED FINNED CIRCULAR AND ELLIPTIC TUBES IN FORCED CONVECTION

2003 ◽  
Vol 2 (2) ◽  
pp. 65 ◽  
Author(s):  
R. S. Matos ◽  
T. A. Laursen ◽  
J. V. C. Vargas ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Total Heat ◽  
Cross Sectional ◽  
Maximum Heat ◽  
Pressure Drops ◽  
Tube Cross Section ◽  
Fixed Volume ◽  
Maximum Heat Transfer

This work presents a three-dimensional (3-D) numerical and experimental geometric optimization study to maximize the total heat transfer rate between a bundle of finned tubes in a given volume and a given external flow both for circular and elliptic arrangements, for general staggered configurations. The optimization procedure started by recognizing the design limited space availability as a fixed volume constraint. The experimental results were obtained for circular and elliptic configurations with a fixed number of tubes (12), starting with an equilateral triangle configuration, which fitted uniformly into the fixed volume with a resulting maximum dimensionless tube-to-tube spacing S/2b = 1.5, where S is the actual spacing and b is the smaller ellipse semi-axis. Several experimental configurations were built by reducing the tube-to-tube spacings, identifying the optimal spacing for maximum heat transfer. Similarly, it was possible to investigate the existence of optima with respect to other two geometric degrees of freedom, i.e., tube eccentricity and fin-to-fin spacing. The results are reported for air as the external fluid in the laminar regime, for 125 and 100 Re 2b , where 2b is the ellipses smaller axis length. Circular and elliptic arrangements with the same flow obstruction cross-sectional area were compared on the basis of maximum total heat transfer. This criterion allows one to quantify the heat transfer gain in the most isolated way possible, by studying arrangements with equivalent total pressure drops independently of the tube cross section shape. This paper reports three-dimensional (3- D) numerical optimization results for finned circular and elliptic tubes arrangements, which are validated by direct comparison with experimental measurements with good agreement. Global optima with respect to tube-to-tube spacing, eccentricity and fin-tofin spacing ( 0.5 e 0.5, S/2b and 06 . 0 f for 125 and 100 Re 2b , respectively) were found and reported in general dimensionless variables. A relative heat transfer gain of up to 19% is observed in the optimal elliptic arrangement, as compared to the optimal circular one. The heat transfer gain, combined with the relative material mass reduction of up to 32% observed in the optimal elliptic arrangement in comparison to the circular one, show the elliptical arrangement has the potential for a considerably better overall performance and lower cost than the traditional circular geometry.

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.

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