The Study of Convective Heat Transfer Behavior of Polymer Melt in Micro Injection Molding

The laminar convective heat transfer behavior of CuO nanoparticle dispersions in water with three different particle sizes (23 nm, 51 nm, and 76 nm) is investigated experimentally in a flow loop with constant heat flux. The main purpose of this study is to evaluate the effect of particle size on convective heat transfer in laminar region. The experimental results show that the suspended nanoparticles remarkably increase the convective heat transfer coefficient of the base fluid, and the nanofluid with 23nm particles shows higher heat transfer coefficient than nanofluids containing the other two particle sizes about 10% under the same Re. Based on the effective medium approximation and the fractal theory, the effective thermal conductivity of suspension is obtained. It is shown that if the new effective thermal conductivity correlation of the nanofluids is used in calculating the Prandtl and Nusselt numbers, the new correlation accurately reproduces the convective heat transfer behavior in tubes.

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The Influence of a Horseshoe Vortex on Local Convective Heat Transfer

Journal of Heat Transfer ◽

10.1115/1.2910381 ◽

1990 ◽

Vol 112 (2) ◽

pp. 329-335 ◽

Cited By ~ 21

Author(s):

E. M. Fisher ◽

P. A. Eibeck

Keyword(s):

Heat Transfer ◽

Flat Plate ◽

Convective Heat Transfer ◽

Convective Heat ◽

Research Program ◽

Cylindrical Body ◽

Horseshoe Vortex ◽

Stanton Number ◽

Horseshoe Vortices ◽

Transfer Behavior

The objective of this research program has been to determine experimentally the extent to which horseshoe vortices modify turbulent convective heat transfer along a flat plate downstream of an appendage. The importance of appendage shape on the heat transfer behavior was evaluated by taking Stanton-number measurements downstream of both a cylindrical body and a streamlined body. The results indicate that a region of augmented heat transfer occurs near the centerline downstream of both obstacles, with Stanton numbers 10 to 50 percent over the undisturbed values. The streamlined cylinder produces the strongest modifications in heat transfer.

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Effect of Thermophysical Properties Models on the Predicting of Convective Heat Transfer of Nanofluids With Considering Nanoparticles Migration

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 5 ◽

10.1115/esda2010-24044 ◽

2010 ◽

Author(s):

Mohammad Mahdi Heyhat ◽

Farshad Kowsary ◽

Saeed Alem

Keyword(s):

Heat Transfer ◽

Physical Properties ◽

Convective Heat Transfer ◽

Convective Heat ◽

Thermophysical Properties ◽

Numerical Study ◽

Brownian Diffusion ◽

Al2o3 Nanoparticles ◽

Constant Wall Temperature ◽

Transfer Behavior

In order to study the heat transfer behavior of the nanofluids, precise values of thermal and physical properties such as specific heat, viscosity and thermal conductivity of the nanofluids are required. There are a few well-known correlations for predicting the thermal and physical properties of nanofluids which are often cited by researchers to calculate the convective heat transfer behaviors of the nanofluids. Each researcher has used different models of the thermophysical properties in their works. The aim of the present paper is to study the convective heat transfer of nanofluids containing low volume concentration of Al2O3 nanoparticles with a regard to the migration of nanoparticles due to Brownian diffusion and thermophoresis. To do this, a two-component model has been used and a numerical study on laminar flow of alumina-water nanofluid through a constant wall temperature tube has been performed. Two different models have been adopted for predicting the thermophysical properties of nanofluids. All of the properties are assumed to be temperature as well as particle concentration dependent. The effects of these models on the predicted value of the convective heat transfer of nanofluid and the migration of nanoparticles have been discussed in detail.

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