Comparative thermal power efficiency of methods to improve convective heat transfer in heat exchangers

1991 ◽  
Vol 27 (12) ◽  
pp. 681-683
Author(s):  
G. Sh. Polishchuk ◽  
V. M. Gurovich ◽  
Ya. S. Teplitskii ◽  
O. A. Vartevanyan
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Power Efficiency ◽  
Thermal Power

An Experimental Investigation of Convective Heat Transfer From Wire-On-Tube Heat Exchangers

1997 ◽  
Vol 119 (2) ◽  
pp. 348-356 ◽  
Author(s):  
J. L. Hoke ◽  
A. M. Clausing ◽  
T. D. Swofford
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Steel Wire ◽  
Convective Heat Transfer Coefficient ◽  
Wire Diameter ◽  
Forced Flow ◽  
Geometrical Parameters

An experimental investigation of the air-side convective heat transfer from wire-on-tube heat exchangers is described. The study is motivated by the desire to predict the performance, in a forced flow, of the steel wire-on-tube condensers used in most refrigerators. Previous investigations of wire-on-tube heat exchangers in a forced flow have not been reported in the literature. The many geometrical parameters (wire diameter, tube diameter, wire pitch, tube pitch, etc.), the complex conductive paths in the heat exchanger, and the importance of buoyant forces in a portion of the velocity regime of interest make the study a formidable one. A key to the successful correlation of the experimental results is a definition of the convective heat transfer coefficient, hw, that accounts for the temperature gradients in the wires as well as the vast difference in the two key characteristic lengths—the tube and wire diameters. Although this definition results in the need to solve a transcendental equation in order to obtain hw from the experimental data, the use of the resulting empirical correlation is straightforward. The complex influence of the mixed convection regime on the heat transfer from wire-on-tube heat exchangers is shown, as well as the effects of air velocity and the angle of attack. The study covers a velocity range of 0 to 2 m/s (the Reynolds number based on wire diameter extends to 200) and angles of attack varying from 0 deg (horizontal coils) to ±90 deg. Heat transfer data from seven different wire-on-tube heat exchangers are correlated so that 95 percent of the data below a Richardson number of 0.004, based on the wire diameter, lie within ±16.7 percent of the proposed correlation.

Compact Miniature Heat Exchangers With Advanced Foam-Like Structure

2005 ◽  
Author(s):  
Eugene M. Wexler ◽  
Lev J. Tuchinsky ◽  
Sharly Ibrahim ◽  
Lance J. Milligan
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Convective Heat Transfer ◽  
Hydraulic Resistance ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Transfer Properties

Experimental study has been carried out to investigate convective heat transfer properties of air-cooled foam-like miniature heat exchangers, fabricated using innovative polycapillary materials technology. Practically important results with regard to heat transfer and hydraulic resistance were established and compared for heat exchangers with different structure.

Heat Transfer Coefficient in Helical Heat Exchangers under Turbulent Flow Conditions

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
Pablo Coronel ◽  
K.P. Sandeep
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Convective Heat Transfer Coefficient ◽  
Flow Conditions ◽  
Overall Heat Transfer Coefficient ◽  
Turbulent Flow Conditions

This study involved the determination of convective heat transfer coefficient in both helical and straight tubular heat exchangers under turbulent flow conditions. The experiments were conducted in helical heat exchangers, with coils of two different curvature ratios (d/D = 0.114 and 0.078), and in straight tubular heat exchangers at various flow rates (1.89 x 10-4 - 6.31 x 10-4 m3/s) and for different end-point temperatures (92 - 149 °C). The results show that the overall heat transfer coefficient (U) in the helical heat exchanger is much higher than that in straight tubular heat exchangers. In addition, U was found to be larger in the coil of larger curvature ratio (d/D = 0.114) than in the coil of smaller curvature ratio (d/D = 0.078). The inside (hi) and outside (ho) convective heat transfer coefficients were determined based on the overall heat transfer coefficient and a correlation to compute the inside convective heat transfer coefficient (hi) as a function of NRe, NPr, and d/D was developed.

A Review of Forced Convective Heat Transfer in Stationary and Rotating Annuli

1996 ◽  
Vol 210 (2) ◽  
pp. 123-134 ◽  
Author(s):  
P R N Childs ◽  
C A Long
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Forced Convection ◽  
Turbulent Flows ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Outer Cylinder ◽  
Forced Convective Heat Transfer ◽  
Analytical Research ◽  
Laminar And Turbulent Flows

The study of heat transfer by forced convection in annular passages is of interest across the range of process and aeronautical industries, for example from annular heat exchangers to the various configurations of annuli found in turbomachinery. The aim of this paper is to review relevant experimental, numerical and analytical research of heat transfer in both stationary and rotating annuli, with an emphasis on presenting useful information for designers. The geometries considered are the stationary annulus with superposed axial throughflow and the rotating annulus with rotation of either the inner or outer cylinder (both with and without throughflow). The work presented covers laminar and turbulent flows as well as flow regimes where transition occurs or vortex flows are present.

scholarly journals Convective Heat Transfer Enhancement through Laser-Etched Heat Sinks: Elliptic Scale-Roughened and Cones Patterns

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1360 ◽  
Author(s):  
Luigi Ventola ◽  
Matteo Fasano ◽  
Roberta Cappabianca ◽  
Luca Bergamasco ◽  
Francesca Clerici ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Exchangers ◽  
Heat Transfer Process ◽  
Heat Sinks ◽  
Turbulent Regime ◽  
Thermal Transmittance ◽  
Microstructured Surface ◽  
Surface Patterns

The efficient dissipation of localized heat flux by convection is a key request in several engineering applications, especially electronic ones. The recent advancements in manufacturing processes are unlocking the design and industrialization of heat exchangers with unprecedented geometric characteristics and, thus, performance. In this work, laser etching manufacturing technique is employed to develop metal surfaces with designed microstructured surface patterns. Such precise control of the solid-air interface (artificial roughness) allows to manufacture metal heat sinks with enhanced thermal transmittance with respect to traditional flat surfaces. Here, the thermal performance of these laser-etched devices is experimentally assessed by means of a wind tunnel in a fully turbulent regime. At the highest Reynolds number tested in the experiments ( R e L ≈ 16 , 500 ), elliptic scale-roughened surfaces show thermal transmittances improved by up to 81% with respect to heat sinks with flat surface. At similar testing conditions, cones patterns provide an enhancement in Nusselt number and thermal transmittance of up to 102% and 357%, respectively. The latter results are correlated with the main geometric and thermal fluid dynamics descriptors of the convective heat transfer process in order to achieve a predictive model of their performance. The experimental evidence shown in this work may encourage and guide a broader use of micro-patterned surfaces for enhancing convective heat transfer in heat exchangers.

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