Investigations on Convective Heat Transfer Enhancement in Circular Tube Radiator Using Al2O3 and CuO Nanofluids

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Sobin Alosious ◽  
S. R. Sarath ◽  
Anjan R. Nair ◽  
K. Krishnakumar
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Concentration ◽  
Circular Tube ◽  
Convective Heat Transfer Coefficient ◽  
Maximum Enhancement ◽  
Study Results

In this study, forced convective heat transfer inside a circular tube automobile radiator is experimentally and numerically investigated. The investigation is carried out using Al2O3 and CuO nanofluids with water as their base fluid. A single radiator circular tube with the same dimensions is numerically modeled. Numerical model is validated using the experimental study results. In the experimental study, Al2O3 and CuO nanofluids of 0.05% volume concentrations (ϕ) were recirculated through the radiator for the Reynolds number (Re) between 260 and 1560. The numerical investigation is conducted for the nanoparticle volume concentration from 0% to 6.0% and 260 < Re < 1560. The investigation shows an enhancement of convective heat transfer coefficient (h) with the increase in nanoparticle volume concentration and with the Reynolds number. A maximum enhancement of 38% and 33% were found for Al2O3 and CuO nanofluids of ϕ = 1% and Re = 1560. For the same cooling load of the radiator, the pumping power can be reduced by 8% and 10%, when Al2O3 and CuO nanofluids (ϕ = 0.8%) were used. Enhancement in convective heat transfer can be utilized to reduce the radiator surface area required. However, the addition of nanofluid results in an enhancement of density (ρ) and viscosity (μ) along with a reduction in specific heat capacity (Cp). Hence, the selection of nanoparticle volume concentration should consider its effect on the thermophysical properties mentioned earlier. It is found that the preferred concentration is between 0.4% and 0.8% for both Al2O3 and CuO nanofluids. In our investigations, it is observed that the convective heat transfer performance of Al2O3 nanofluid is better than the CuO nanofluid.

Numerical Investigation of Convective Heat Transfer of Refined Kerosene-Alumina Nanofluid Under Laminar and Turbulent Regime

2018 ◽  
Vol 24 (8) ◽  
pp. 5543-5547
Author(s):  
Aldin Justin Sundararaj ◽  
B. C Pillai ◽  
Austin Lord Tennyson ◽  
Allison Edward ◽  
Bhaskar Gupta
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Computational Models ◽  
Volume Concentration ◽  
Convective Heat Transfer Coefficient ◽  
Nano Particles ◽  
Phase Model ◽  
Turbulent Regime

The study reports Computational Fluid Dynamics (CFD) investigations of the convective heat transfer coefficient of Al2O3/refined kerosene nanofluids. The study was carried out under laminar and turbulent regime in a circular tube under uniform and constant heat flux on the wall. The study was carried out for Re 500 to 5500 for base refined kerosene and with alumina added with 0.01% and 0.05% volume concentration in the base refined kerosene. The size of the alumina nanoparticle was 35 nm. Different computational models of Ansys-Fluent were used for the study. For laminar flows, laminar viscous models and K-Epsilon model for turbulence modelling was used. Energy model was used to define convective heat transfer and a discrete phase model to study particle behaviour and flow pattern in the tube. Multi-phase model with two phase refined kerosene suspended with alumina nano particles were used for the study. Experimental and simulation results showed that as the Reynolds number and the particle concentration increased there was an enhancement in the thermal performance of nanofluids which was found to be higher than that of the base fluid. The convective heat transfer increased by 14% for volume concentration of 0.05% and Reynolds number of 5500.

An Experimental Study of Convective Heat Transfer in Radially Rotating Rectangular Ducts

1991 ◽  
Vol 113 (3) ◽  
pp. 604-611 ◽  
Author(s):  
C. Y. Soong ◽  
S. T. Lin ◽  
G. J. Hwang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Rotational Speed ◽  
Main Flow ◽  
Buoyancy Flow ◽  
Aspect Ratios

The paper presents an experimental study of convective heat transfer in radially rotating isothermal rectangular ducts with various height and width aspect ratios. The convective heat transfer is affected by secondary flows resulting from Coriolis force and the buoyancy flow, which is in turn due to the centrifugal force in the duct. The growth and strength of the secondary flow depend on the rotational Reynolds number; the effect of the buoyancy flow is characterized by the rotational Rayleigh number. The aspect ratio of the duct may affect the secondary flow and the buoyancy flow, and therefore is also a critical parameter in the heat transfer mechanism. In the present work the effects of the main flow, the rotational speed, and the aspect ratio γ on heat transfer are subjects of major interest. Ducts of aspect ratios γ=5, 2, 1, 0.5, and 0.2 at rotational speed up to 3000 rpm are studied. The main flow Reynolds number ranges from 700 to 20,000 to cover the laminar, transitional, and turbulent flow regimes in the duct flow. Test data and discussion are presented.

scholarly journals Determination of Heat Transfer Coefficients Over Ribbed Surfaces With Infrared Thermography

1997 ◽  
Author(s):  
Francisco P. Brójo ◽  
Luís C. Gonçalves ◽  
Pedro D. Silva
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Stanton Number ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The scope of the present work is to characterize the heat transfer between a ribbed surface and an air flow. The convective heat transfer coefficients, the Stanton number and the Nusselt number were calculated in the Reynolds number range, 5.13 × 105 to 1.02 × 106. The tests were performed inside a turbulent wind tunnel with one roughness height (e/Dh = 0.07). The ribs had triangular section with an attack angle of 60°. The surface temperatures were measured using an infrared (IR) thermographic equipment, which allows the measurement of the temperature with a good spatial definition (10.24 × 10−6 m2) and a resolution of 0.1°C. The experimental measures allowed the calculation of the convective heat transfer coefficient, the Stanton number and the Nusselt number. The results obtained suggested a flow pattern that includes both reattachment and recirculation. Low values of the dimensionless Stanton number, i.e. Stx*, are obtained at the recirculation zones and very high values of Stx* at the zones of reattachment. The reattachment is located at a dimensionless distance of 0.38 from the top of the rib. That distance seems to be independent of the Reynolds number. The local dimensionless Stanton number remains constant as the Reynolds number varies. The convective heat transfer coefficient presents an uncertainty in the range of 3 to 6%.

scholarly journals Experimental study of the convective heat transfer coefficient in a packed bed at low Reynolds numbers

2014 ◽  
Vol 18 (2) ◽  
pp. 443-450 ◽  
Author(s):  
Souad Messai ◽  
Ganaoui El ◽  
Jalila Sghaier ◽  
Ali Belghith
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Packed Bed ◽  
Bed Temperature ◽  
Proposed Model

An experimental study to evaluate the convective heat transfer coefficient in a cylindrical packed bed of spherical porous alumina particles is investigated. The task consists in proposing a semi-empirical model to avoid excessive instrumentation and time consumption. The measurement of the bed temperature associated to a simple energy balances led to calculate the gas to particle heat transfer coefficient using a logarithmic mean temperature difference method. These experiments were performed at atmospheric pressure. The operating fluid is humid air. The gas velocity and temperature ranged from 1.7-3 m/s and 120-158?C, respectively. The data obtained was compared with the correlations reported in the literature. It is shown that the proposed model is in reasonable agreement with the correlation of Ranz and Marshall. Despite, many researches on experimental investigations of heat transfer coefficient in packed beds at low and average temperature are proposed, few studies presented calculation of convective heat transfer coefficient at high temperature (above 120?C). A possible application of the proposed model is drying and combustion.

scholarly journals Statistical Analysis of the Effect of Nanoparticles Volume Fraction on Turbulent Forced Convective Heat Transfer Coefficient of Nanofluid in a Circular Tube

2015 ◽  
Vol 37 ◽  
pp. 141
Author(s):  
Farhad Vahidinia ◽  
Behrooz Keshtegar ◽  
Mohadeseh Miri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Probability Distribution ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Circular Tube ◽  
Convective Heat Transfer Coefficient ◽  
Nanoparticles Volume Fraction

In this paper, the statistical analysis of the effect of nanoparticles volume fraction on one of the most important thermal characteristics turbulent flow of nanofluid i.e. convection heat transfer coefficient, inside a circular tube with uniform wall heat flux is investigated numerically. Also, water as a base fluid and Al2O3 as suspended particles with a diameter of 36 nm are considered. Heat transfer characteristics are computed using the solution of elliptic equations based on discrete the finite volume method and the second order upwind. The relationship between pressure and velocity using SIMPLEC algorithm is established. In this study, the variation of volume fraction of nanoparticles is assumed in the range of 0 to 6%. The best probability distribution function of the heat transfer parameters are selected using chi square test that various probability distribution such as: Gamma, Normal, Lognormal, Gumbel, and Frechet are evaluated based on numerical analysis of tube flow. After reviewing the results, it was found that with increasing volume fraction of nanoparticles, the convective heat transfer coefficient increases. On the other hand, the convective heat transfer coefficients with regard to variation of volume fraction of nanoparticles follow Gumbel Max probability distribution function.

scholarly journals CFD Simulation of Convective Heat Transfer on Vernacular Sustainable Architecture: Validation and Application of Methodology

2019 ◽  
Vol 11 (15) ◽  
pp. 4231
Author(s):  
Wenzhou Zhong ◽  
Tong Zhang ◽  
Tetsuro Tamura
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Flow Field ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Vernacular Architecture ◽  
Building Design ◽  
Building Model

The global background of energy shortages and climate deterioration demands bioclimatic sustainable buildings. Vernacular architecture can provide a useful resource of passive strategies and techniques for creating inner comfort conditions with minimum heating, ventilation, and air conditioning (HVAC) assistance. The identification and verification of such knowledge are essential for climate responsive or energy passive building design. Among the methods, computational fluid dynamics (CFD) is a useful tool for simulating convective heat transfer of vernacular architecture and predicting the convective heat transfer coefficient (CHTC) and flow field. Geometric complexity and diversity of building samples are crucial in the development of an effective simulation methodology in terms of computational cost and accuracy. Therefore, this paper presents high-resolution 3D steady Reynolds-averaged Navier–Stokes (RANS) CFD simulations of convective heat transfer on Japanese vernacular architecture, namely, “machiya.” A CFD validation study on the CHTC is performed based on wind-tunnel experiments on a cube heated by constant heat flux and placed in a turbulent channel flow with a Reynolds number of 3.3 × 104. Three steady RANS models and two boundary layer modeling approaches are compared and discussed. Results show that the SST k-ω model applied with low Reynolds number modeling approach is suitable for CHTC simulations on a simplified building model. The RNG k-ε model applied with wall functions is an appropriate choice for simulating flow field of a complicated building model. Overall, this study develops a methodology involving RANS model selection, boundary layer modeling, and target model fitting to predict the convective heat transfer on vernacular architecture.

Gas Solids Suspension Convective Heat Transfer at a Reynolds Number of 130,000

1968 ◽  
Vol 90 (4) ◽  
pp. 464-468 ◽  
Author(s):  
R. Briller ◽  
R. L. Peskin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Particle Temperature ◽  
Convective Heat Transfer Coefficient ◽  
Loading Ratio ◽  
High Reynolds

An experiment was performed to determine the convective heat-transfer coefficient to heated and cooled gas solids suspensions at a Reynolds number of 130,000. Measurements of the heat transfer were performed by traversing the stream at various locations along the pipe with specially designed probes which measured air and particle temperature locally. The results showed that for a high Reynolds number, the heat-transfer coefficient for the suspension appears to be equal to that of the pure gas at the same Reynolds number, and independent of solids loading ratio, heating or cooling, and particle size (between 0.0011 and 0.0058 in. dia).

scholarly journals AN EXPERIMENTAL STUDY OF THE CONVECTIVE HEAT TRANSFER ENHANCEMENT: APPLICATION OF TURBULENCE PROMOTERS

2013 ◽  
Vol 12 (2) ◽  
pp. 03
Author(s):  
P. S. B. Zdanski ◽  
A. E. Bublitz ◽  
C. N. Correa
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Cylinder ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Experimental Methodology ◽  
Transfer Enhancement ◽  
Convective Heat Transfer Enhancement

This work presents an experimental study addressing the effects of turbulence promoters on heat transfer rate at circular cylinder in external cross flow. Within this framework, the work focuses on assessing the effects of three kind of turbulence promoters (with circular, square and hexagonal cross sections) on convective heat transfer enhancement. The distance from turbulence promoters to the circular cylinder (50, 100 and 150mm upstream), as well as the free stream velocity inside the wind tunnel (Reynolds number) were the parameters investigated. The validation of the experimental methodology was performed by comparing the present results with empiric correlations available in the literature. The main results indicate that the convective heat transfer coefficient was enhanced when using turbulence promoters. The highest heat transfer enhancement obtained was around 25% correponding to the case of square turbulence promoter placed closely (50mm) to the circular cylinder. Finally, it is worth mentioning that all the experimental results for the convective coefficient were condensed in a new empirical correlation with good accuracy.

Sign in / Sign up

Export Citation Format

Share Document