Prandtl Number Effect on the Laminar Convective Heat Transfer From a Rotating Disk

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Christian Helcig ◽  
Stefan aus der Wiesche ◽  
Igor V. Shevchuk
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Rotating Disk ◽  
Ratio Method ◽  
Experimental Investigations ◽  
Wide Range ◽  
Experimental Apparatus ◽  
Similar Solutions

Convective heat transfer in rotating disk systems is of great importance in many engineering applications. Despite the high practical relevance, there have been only a small number of experimental investigations regarding the influence of the Prandtl number larger than unity. Ever since Dorfman's pioneering work more than 50 years ago, various analytical works about the heat transfer of a rotating disk have been published. However, this study is a novelty because measurements of the laminar convective heat transfer over a free rotating disk for a wide range of Prandtl number up to Pr=5000 are presented. The accuracy of the employed experimental apparatus was assessed by heat transfer measurements in air, for which reliable literature data are widely available. Natural convection effects and temperature-dependent physical properties have been taken into consideration using the property-ratio method. The experimental results are in excellent agreement with analytical self-similar solutions and the theoretical correlation of Lin and Lin. The applicability of frequently used heat transfer correlations is assessed by the means of the new experimental data.

Effect of Prandtl Number on Convective Heat Transfer in the Separated and Reattached Flow Region on a Blunt Flat Plate

2016 ◽  
Author(s):  
Christian Helcig ◽  
Stefan aus der Wiesche
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Flat Plate ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Working Fluid ◽  
Present Contribution ◽  
Starting Point ◽  
Wide Range ◽  
Separated And Reattached Flow

The understanding of the heat transfer in separated and reattached flows is essential for a wide range of engineering applications. The majority of the literature uses air as a working fluid for experimental and numerical investigations. The blunt flat plate configuration offers a generic starting point for flow and heat transfer investigations in separated and reattached flow regions. The present contribution is dealing with experimental measurements of the flow and convective heat transfer within the separated and reattached flow on a blunt flat plate. The blunt plate was placed inside a closed circuit water tunnel. By this approach, in comparison with reliable literature data for air, it was possible to investigate the effect of the Prandtl number on the convective heat transfer of blunt flat plate.

scholarly journals A Critical Review of Experimental Investigations about Convective Heat Transfer Characteristics of Nanofluids under Turbulent and Laminar Regimes with a Focus on the Experimental Setup

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 6004
Author(s):  
Gianpiero Colangelo ◽  
Noemi Francesca Diamante ◽  
Marco Milanese ◽  
Giuseppe Starace ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Research Field ◽  
Experimental Investigations ◽  
Experimental Setup ◽  
Increase Energy Efficiency

In this study, several experimental investigations on the effects of nanofluids on the convective heat transfer coefficient in laminar and turbulent conditions were analyzed. The aim of this work is to provide an overview of the thermal performance achieved with the use of nanofluids in various experimental systems. This review covers both forced and natural convection phenomena, with a focus on the different experimental setups used to carry out the experimental campaigns. When possible, a comparison was performed between different experimental campaigns to provide an analysis of the possible common points and differences. A significant increase in the convective heat transfer coefficient was found by using nanofluids instead of traditional heat transfer fluids, in general, even with big data dispersion from one case to another that depended on boundary conditions and the particular experimental setup. In particular, a general trend shows that once a critic value of the Reynolds number or nanoparticle concentrations is reached, the heat transfer performance of the nanofluid decreases or has no appreciable improvement. As a research field still under development, nanofluids are expected to achieve even higher performance and their use will be crucial in many industrial and civil sectors to increase energy efficiency and, thus, mitigate the environmental impact.

Development and validation of an incompressible Navier-Stokes solver including convective heat transfer

2015 ◽  
Vol 25 (4) ◽  
pp. 861-886 ◽  
Author(s):  
Konstantinos Stokos ◽  
Socrates Vrahliotis ◽  
Theodora Pappou ◽  
Sokrates Tsangaris
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Content Type ◽  
Strongly Coupled ◽  
Loosely Coupled ◽  
Wide Range ◽  
Coupled Solution

Purpose – The purpose of this paper is to present a numerical method for the simulation of steady and unsteady incompressible laminar flows, including convective heat transfer. Design/methodology/approach – A node centered, finite volume discretization technique is applied on hybrid meshes. The developed solver, is based on the artificial compressibility approach. Findings – A sufficient number of representative test cases have been examined for the validation of this numerical solver. A wide range of the various dimensionless parameters were applied for different working fluids, in order to estimate the general applicability of our solver. The obtained results agree well with those published by other researchers. The strongly coupled solution of the governing equations showed superiority compared to the loosely coupled solution as inviscid effects increase. Practical implications – Convective heat transfer is dominant in a wide variety of practical engineering problems, such as cooling of electronic chips, design of heat exchangers and fire simulation and suspension in tunnels. Originality/value – A comparison between the strongly coupled solution and the loosely coupled solution of the Navier-Stokes and energy equations is presented. A robust upwind scheme based on Roe’s approximate Riemann solver is proposed.

Numerical and Experimental Study of Flow and Convective Heat Transfer on a Rotor of a Discoidal Machine with Eccentric Impinging Jet

2019 ◽  
pp. 1-29
Author(s):  
Chadia Haidar ◽  
Rachid Boutarfa ◽  
Mohamed Sennoune ◽  
Souad Harmand
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Steady State ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Flow ◽  
Impinging Jet ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Air Jet

This work focuses on the numerical and experimental study of convective heat transfer in a rotor of a discoidal the machine with an eccentric impinging jet. Convective heat transfers are determined experimentally in steady state on the surface of a single rotating disk. The experimental technique is based on the use of infrared thermography to access surface temperature measurement, and on the numerical resolution of the energy equation in steady-state, to evaluate local convective coefficients. The results from the numerical simulation are compared with heat transfer experiments for rotational Reynolds numbers between 2.38×105 and 5.44×105 and for the jet's Reynolds numbers ranging from 16.5×103 to 49.6 ×103. A good agreement between the two approaches was obtained in the case of a single rotating disk, which confirms us in the choice of our numerical model. On the other hand, a numerical study of the flow and convective heat transfer in the case of an unconfined rotor-stator system with an eccentric air jet impinging and for a dimensionless spacing G=0.02, was carried out. The results obtained revealed the presence of different heat transfer zones dominated either by rotation only, by the air flow only or by the dynamics of the rotation flow superimposed on that of the air flow. Critical radii on the rotor surface have been identified

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