Numerical Investigation of Forced Convection of Nanofluids in Circular Tubes

2007 ◽  
Author(s):  
Fabio Chiacchio ◽  
Oronzio Manca ◽  
Sergio Nardini
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Convective Heat Transfer Coefficient ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Particle Volume ◽  
Two Phase ◽  
Liquid Heat ◽  
Temperature Dependent Properties ◽  
Laminar Forced Convection

In this paper developing laminar forced convection flow of a water–γAl2O3 nanofluid in a circular tube submitted to a constant and uniform heat flux at the wall is numerically investigated. A single and two-phase model (discrete particles model) is employed with either constant or temperature-dependent properties. The investigation is accomplished for a size particles equal to 100 nm. Convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement is increasing with the particle volume concentration but it is accompanied by increasing wall shear stress values. The effect of Reynolds number is greater when properties depend on temperature and for higher concentrations.

Numerical Investigation of Turbulent Convection in Al2O3/Water Nanofluid With Temperature Dependent Properties

2009 ◽  
Author(s):  
Vincenzo Bianco ◽  
Oronzio Manca ◽  
Sergio Nardini
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer Coefficient ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Particle Volume ◽  
Two Phase ◽  
Commercial Code ◽  
Particle Dimension ◽  
Liquid Heat ◽  
Temperature Dependent Properties

In this paper turbulent forced convection flow of a water–Al2O3 nanofluid in a circular tube subjected to a constant and uniform heat flux at the wall is numerically analyzed. Two different approach are taken into account: single and two-phase models, with particle dimension equal to 38 nm. Temperature dependant thermophysical properties are considered for both the approaches. The CFD commercial code Fluent is employed to solve the problem by means of finite volume method. It is found that convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement is increasing with the particle volume concentration and Reynolds number. A good agreement is found with the correlation of Xuan and Li.

Numerical Investigation of Forced Convection of Nanofluids in Channels

2008 ◽  
Author(s):  
Vincenzo Bianco ◽  
Oronzio Manca ◽  
Ferdinando Marzano ◽  
Sergio Nardini ◽  
Salvatore Tamburrino ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Convective Heat Transfer Coefficient ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Particle Volume ◽  
Two Phase ◽  
Square Channel

In this paper developing turbulent forced convection flow of a water–Al2O3 nanofluid in a square channel submitted to a constant and uniform heat flux at the wall is numerically investigated. A single model and two-phase models (discrete particles model and mixture model) are employed with constant temperature properties. The investigation is accomplished for a size particles equal to 38 nm. The CFD commercial code Fluent is employed to solve the problem by means of finite volume method. Convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement is increasing with the particle volume concentration but it is accompanied by increasing wall shear stress values. The effect of Reynolds number is great for higher concentrations. The results obtained by tree different models are presented in terms of temperatures and velocity distributions, relative increasing of heat transfer coefficient, hr, and Nusselt number profile.

scholarly journals Numerical Study of Laminar Forced Convection of Water/Al2o3 Nanofluid in an Annulus with Constant Wall Temperature

2013 ◽  
Vol 14 (1) ◽  
Author(s):  
Amin Kashani ◽  
Davood Jalali-vahid ◽  
Siamak Hossainpour
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Volume Concentration ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Behavior ◽  
Convective Heat Transfer Coefficient ◽  
Two Phase ◽  
Constant Wall Temperature ◽  
Laminar Forced Convection

Laminar forced convection of a nanofluid consisting of water and Al2O3 in a horizontal annulus has been studied numerically. Two-phase mixture model has been used to investigate thermal behaviors of the nanofluid over constant temperature thermal boundary condition and with different volume concentration of nanoparticles. Comparisons with previously published experimental and analytical works on flow behavior in horizontal annulus show good agreements between the results as volume fraction is zero. In general convective heat transfer coefficient increases with nanoparticle concentration. ABSTRAK: Kertaskerja ini mengkaji secara numerik olakan paksa bendalir lamina yang menganduangi air dan Al2O3 didalam anulus mendatar. Model campuran dua fasa digunakan bagi mengkaji tingkah laku haba bendalir nano pada keadaan suhu malar dengan kepekatan nanopartikel berbeza. Perbandingan dengan karya eksperimen dan analitikal yang telah diterbitkan menunjukkan bahawa kelakuan aliran didalm anulus mendatar adalah baik apabila pecahan isipadu adalah sifar. Pada amnya, pekali pemindahan haba olakan meningkat dengan kepekatan nanopartikel. KEYWORDS: nanofluid; volume concentration; heat transfer enhancement; laminar flow convection; annulus

A Numerical Investigation of Nanofluids Forced Convection Flow in a Horizontal Smooth Tube

2010 ◽  
Author(s):  
Hakan Demir ◽  
Ahmet Selim Dalkılıc¸ ◽  
Nuri Alpay Ku¨rekci ◽  
Bu¨lent Keles¸og˘lu ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Forced Convection ◽  
Smooth Tube ◽  
Convection Flow ◽  
Transfer Coefficients ◽  
Particle Volume ◽  
Constant Wall Temperature ◽  
Nusselt Numbers ◽  
Temperature Dependent Properties

In this study, laminar and turbulent forced convection flows of a nanofluid consisting of water and Al2O3 in a horizontal smooth tube with constant wall temperature are investigated numerically. Studies that are related to the subject in the literature are reviewed. The determination of the nanofluid properties is calculated by means of the correlations of Palm et al. Two-dimensional elliptical governing equations are used to study the hydrodynamics and thermal behaviors of the nanofluid flow. A single-phase model is employed with either constant or temperature dependent properties. The investigation is performed for a constant particle size. The velocity and temperature vectors are presented in the entrance and fully developed region. Effects of nanoparticles concentration and Reynolds number on shear stress and pressure drop are presented. The Nusselt numbers and heat transfer coefficients of nanofluids are obtained for different nanoparticle concentrations. Numerical results show the heat transfer enhancement due to presence of the nanoparticles in the fluid. Heat transfer coefficient increases with increasing the particle volume concentration and also increasing wall shear stress values.

Numerical Analysis on Nanofluid Forced Convection in Ducts With Triangular Cross Sections

2011 ◽  
Author(s):  
O. Manca ◽  
S. Nardini ◽  
D. Ricci ◽  
S. Tamburrino
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Forced Convection ◽  
Cross Sections ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Surface Shear Stress ◽  
Surface Shear

Heat transfer of fluids is very important to many industrial heating or cooling equipments. Convective heat transfer can be enhanced passively by changing flow geometry, boundary conditions or by enhancing the thermal conductivity of the working fluids. An innovative way of improving the fluid thermal conductivity is to introduce suspended small solid nanoparticles in the base fluids. In this paper a numerical investigation on laminar forced convection flow of a water–Al2O3 nanofluid in a duct having an equilateral triangular cross section is performed. The hydraulic diameter is set equal to 1.0×10−2 m. A constant and uniform heat flux on the external surfaces has been applied and the single-phase model approach has been employed. The analysis has been run in steady state regime for a nanoparticle size equal to 38 nm, considering different volume particle concentrations. The CFD code Fluent has been employed in order to solve the tri-dimensional numerical model. Results are presented in terms of temperature and velocity distributions, surface shear stress and heat transfer convective coefficient, Nusselt number and required pumping power profiles. Comparison with results related to the fluid dynamic and thermal behaviors in pure water are carried out in order to evaluate the enhancement due to the presence of nanoparticles in terms of volumetric concentration.

Effects of Particle Shape on Nanofluids Laminar Forced Convection in Helically Coiled Tubes

2017 ◽  
Author(s):  
Fang Liu ◽  
Yang Cai
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Particle Shape ◽  
Spherical Nanoparticles ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Laminar Forced Convection ◽  
Shape And Size

In this study, effects of particle morphology (shape and size) on nanofluids laminar forced convection in helically coiled tubes are investigated numerically using Eulerian-Lagrangian two-phase approach. The laminar forced convective heat transfer and pressure drop of Al2O3-water nanofluids containing nanoparticles with various particle shapes (sphere, platelet, blade, cylinder and brick) and sizes at different volume fractions in the developing and fully developed regions are investigated using the validated two-phase model. It is found that the nanofluids containing platelet particle shape has the highest heat transfer enhancement, which is followed by nanofluids containing cylinder, blade, sphere and brick nanoparticle shapes, respectively. Non-spherical nanoparticles with larger aspect ratio, small particle size and a suitable particle volume concentration are beneficial for heat transfer enhancement of forced convection. Heat transfer efficiency reaches minima at Re of 1250 for laminar forced convection with 1% volume fraction. The correlations of Nusselt number and pressure drop with nanoparticle shape and size were developed to predict convective heat transfer of nanofluids containing spherical nanoparticles and non-spherical nanoparticles.

Simulation of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a duct under bleeding condition

2012 ◽  
Vol 227 (2) ◽  
pp. 332-345 ◽  
Author(s):  
M Atashafrooz ◽  
SA Gandjalikhan Nassab
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Discrete Ordinates ◽  
Convection Flow ◽  
Backward Facing Step ◽  
Forced Convection Flow ◽  
Laminar Forced Convection

This study presents a numerical analysis of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a rectangular duct under bleeding condition. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The three-dimensional Cartesian coordinate system is used to solve the governing equations which are the conservations of mass, momentum, and energy. These equations are solved numerically using the computational fluid dynamic techniques to obtain the temperature and velocity fields, while the blocked-off method is employed to simulate the incline surface. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, besides the convective and conductive terms in the energy equation, the radiative term also presented. For computation of this term, the radiative transfer equation is solved numerically by the discrete ordinates method to find the divergence of radiative heat flux distribution inside the radiating medium. By this numerical procedure, the role of radiation heat transfer on convection flow of a radiating gas which has many engineering applications (for example in heat exchangers and combustion chambers) is studied in detail. Beside, the effects of bleeding coefficient, albedo coefficient, optical thickness, and the radiation–conduction parameter on heat transfer behavior of the system are investigated. Comparison of numerical results with the available data published in the open literature shows a good agreement.

scholarly journals Further Investigation on Laminar Forced Convection of Nanofluid Flows in a Uniformly Heated Pipe Using Direct Numerical Simulations

2016 ◽  
Author(s):  
Ghofrane Sekrani ◽  
Sébastien Poncet
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Numerical Simulations ◽  
Forced Convection ◽  
Direct Numerical Simulations ◽  
Phase Model ◽  
Temperature Dependent ◽  
Two Phase ◽  
Laminar Forced Convection

In the present paper, laminar forced convection nanofluid flows in a uniformly heated horizontal tube were revisited by direct numerical simulations. Single and two-phase models were employed with constant and temperature-dependent properties. Comparisons with experimental data showed that the mixture model performs better than the single-phase model in the all cases studied. Temperature-dependent fluid properties also resulted in a better prediction of the thermal field. A particular attention was paid to the grid arrangement. The two-phase model was used then confidently to investigate the influence of the nanoparticle size on the heat and fluid flow with a particular emphasis on the sedimentation process. Four nanoparticle diameters were considered: 10, 42, 100 and 200 nm for both copper-water and alumina/water nanofluids. For the largest diameter dnp = 200 nm, the Cu nanoparticles were more sedimented by around 80 %, while the Al2O3 nanoparticles sedimented only by 2.5 %. Besides, it was found that increasing the Reynolds number improved the heat transfer rate, while it decreased the friction factor allowing the nanoparticles to stay more dispersed in the base fluid. The effect of nanoparticle type on the heat transfer coefficient was also investigated for six different water-based nanofluids. Results showed that the Cu-water nanofluid achieved the highest heat transfer coefficient, followed by C, Al2O3, CuO, TiO2, and SiO2, respectively. All results were presented and discussed for four different values of the concentration in nanoparticles, namely φ = 0, 0.6, 1 and 1.6%. Empirical correlations for the friction coefficient and the average Nusselt number were also provided summarizing all the presented results.

scholarly journals UNSTEADY LAMINAR CONVECTION FLOW OVER PERIODIC GROOVES BY USING SIO2-WATER NANOFLUID

2013 ◽  
pp. 159-165
Author(s):  
AMIRHOSSEIN HESHMATI ◽  
MOHAMMAD PARSAZADEH ◽  
FARSHID FATHINIA
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Channel Height ◽  
Uniform Heat Flux ◽  
Nanoparticles Volume Fraction ◽  
Laminar Convection ◽  
Volume Method ◽  
Laminar Forced Convection ◽  
Upwind Method

Unsteady laminar forced convection flow in a 2-dimensional channel over periodic grooves is numerically investigated. Finite volume method is used and the equations were discretized by second order upwind method. The ribheight to channel-height ratio (B/H) is 2. The downstream wall is heated by a uniform heat flux while the upstream wall is insulated. Quasi steady point was obtained at τ=10. The heat transfer is analyzed with different nanoparticles volume fraction and diameter of 0-4% and 20nm-50nm for SiO2 respectively at Reynolds number of 400 and τ=10. Water is used as a base fluid of nanoparticles. The results revealed 124% heat transfer enhancement compared to the water in a grooved channel by using SiO2 nanoparticle with volume fraction and nanoparticle diameter of 4% and 20nm respectively.

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