scholarly journals Numerical investigation for convective heat transfer and friction factor under pulsating flow conditions

2018 ◽  
Vol 240 ◽  
pp. 01003
Author(s):  
Erman Aslan ◽  
Mert Ozsaban ◽  
Guven Ozcelik ◽  
Hasan Riza Guven
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Numerical Study ◽  
Pulsating Flow ◽  
Channel Height ◽  
Corrugated Channel ◽  
Sst Model

For pulsating flow, the behaviours of the convective heat transfer and friction factor for a periodic corrugated channel are investigated numerically. The finite volume method is used in the numerical study. Three different Reynolds Averaged Numerical Simulation based turbulence models, namely the k-ω model, the Shear Stress Transport (SST) model and the transition SST model are used and compared. The results are also compared with the previous experiments for non-pulsating flow. Analyses are conducted for air flow through a corrugated channel which has sharp corrugation peaks with an inclination angle of 30° and a 5mm minimum channel height. Reynolds number is changed in the range 6294 to 7380, while keeping the Prandtl number constant at 0.70. A sinusoidal pulsatile flow condition which is F=400 and uA*=0.5 is used. Variations of the Nusselt number and the friction factor with the Reynolds number are studied. Non-pulsating flow results and pulsating flow results are compared with each other.

scholarly journals Astray State-Laminar Forced Convective Heat Transfer of Al2O3 – H2O Nanofluid through 3D-Rectangular Cross- Sectional Duct

2019 ◽  
Vol 8 (2S3) ◽  
pp. 899-907
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Flow Rate ◽  
Base Fluid ◽  
Volume Fraction ◽  
Phase Model ◽  
Forced Convective Heat Transfer

A Steady state-laminar forced convective heat transfer has been simulated by Computational Fluid Dynamics (CFD) with a Single Phase Model (SPM), Multi Phase model & Diameter effects and also determined the effects of nanoparticles concentration and nanofluid flow rate through 3D rectangular duct under certain boundary condition (constant heat flux). The nanofluid contains Alumina nanoparticles of size 60nm diameter used for MPM which is mixed with base fluid (water) with volume fraction of 0% ≤ ȼ ≤ 5% and Reynolds number (Re) ranges from 250 ≤ Re ≤ 1000. ANSYS 18.0 has been used for simulation. Three cases of analysis have been carried out in which the thermal conductivity (k) and dynamic viscosity (µ) of nanofluids are determined using two sets of theoretical models and one set of experimental k & µ data from literature respectively. The nanoparticles which stay more dispersed in the base fluid due to increase in Reynolds number which improves HTC and also decreases the friction factor accordingly. Particular attention has been paid to the variation of heat transfer characteristics when the modeling approach is switched from SPM to MPM. It is revealed that higher heat transfer rates are observed in MPM. The results shows that the friction factor decreases and Nusselt number (Nu) increases when there is an increase in the flow rate and also increase in the volume concentration of the nanofluid, while the pressure drop increases only slightly. The increase in HTC is one of the most important aims for industry and researchers.

Effect of Volume Fraction of Nanoparticles to the Convective Heat Transfer of Nanofluids

2011 ◽  
Vol 464 ◽  
pp. 528-531 ◽  
Author(s):  
Zhi Yong Ling ◽  
Tao Zou ◽  
Jian Ning Ding ◽  
Guang Gui Cheng ◽  
Peng Fei Fu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Small Difference ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Full Development ◽  
Significant Difference

A numerical study on the convective heat transfer characteristics of Cu-water nanofluid under the laminar flow condition was performed. The results show that the convective heat transfer coefficient increases with the increase of the volume fraction of the nanoparticles and the Reynolds number. There is a significant difference between the numerical simulation result and the result calculated from the Shah equation in the entrance region, but a small difference in full development areas. The numerical results agree well with that obtained from the Xuan equation when the Reynolds number and the volume fraction of the nanoparticles are small, but the errors between them increase as the increase of the Reynolds number and the volume fraction of nanoparticles.

scholarly journals Forced convective heat transfer and thermal efficiency assessment in square channel equipped with 10° wavy thin rib

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098526
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Efficiency ◽  
Efficiency Factor ◽  
Channel Height ◽  
Forced Convective Heat Transfer ◽  
Square Channel ◽  
Flow And Heat Transfer

Forced convective heat transfer and thermo-hydraulic efficiency in the heat exchanger square channel (HESC) inserted with 10° wavy thin rib (WTR) are reported numerically. The effects of rib height, pitch distance and flow velocity on flow and heat transfer profiles are considered. The rib height to the channel height; e/H or HR, is varied in the range 0.05–0.30, while the rib pitch to the channel height; P/H or PR, is varied in the range 0.50–1.25. The air velocity in the HESC inserted with the WTR is considered in terms of Reynolds number. The Reynolds numbers (Re = 100–2000) for the present investigation is analyzed at the inlet condition. The finite volume method (commercial code) with SIMPLE algorithm is picked to solve the present problem. The numerical model of the HESC inserted with the WTR is validated for both grid independence and verification of the smooth HESC. The numerical results of the HESC inserted with the WTR are printed in terms of flow and heat transfer profiles. The values of Nusselt number, friction factor and thermal efficiency factor in the HESC inserted with the WTR are also plotted. As the numerical result, it is found that the WTR in the HESC can produce the vortex flow that the reason for the enhancements of heat transfer and efficiency. The increment of the heat transfer ability in the HESC is detected when increasing rib height and Reynolds number. In addition, the greatest thermal efficiency factor in the HESC inserted with the WTR is around 3.43 at HR = 0.20, PR = 1, and Re = 2000.

scholarly journals Convective Heat Transfer of Al2O3 and CuO Nanofluids Using Various Mixtures of Water-Ethylene Glycol as Base Fluids

2017 ◽  
Vol 7 (2) ◽  
pp. 1496-1503
Author(s):  
K. Boukerma ◽  
M. Kadja
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Ethylene Glycol ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Volume Fraction ◽  
Numerical Study ◽  
Constant Heat Flux ◽  
Volume Fractions

In this work, a numerical study has been performed on the convective heat transfer of Al2O3/Water-Ethylene Glycol (EG) and CuO/(W-EG) nanofluids flowing through a circular tube with circumferentially non-uniform heating (constant heat flux) under the laminar flow condition. We focus on the study of the effect of EG-water mixtures as base fluids with mass concentration ranging from 0% up to 100% ethylene glycol on forced convection. The effect on the flow and the convective heat transfer behavior of nanoparticle types, their volume fractions (φ=1-5%) and Reynolds number are also investigated. The results obtained show that the highest values of the average heat transfer coefficient is observed between 40% and 50% of EG concentration. The average Nusselt number increases with the increase in EG concentration in the base fluid, and the increase in the Reynolds number and volume fraction. For concentrations of EG above 60%, and for all volume fractions, the increase of thermal performance of nanofluids became inversely proportional to the increase of Reynolds number. In addition, CuO/(W-EG) nanofluids show the best thermal performance compared with Al2O3/ (W-EG) nanofluids.

scholarly journals Numerical Study of Turbulent Flows and Convective Heat Transfer of Al2O3-Water Nanofluids In A Circular Tube

2020 ◽  
Vol 77 (2) ◽  
pp. 1-12
Author(s):  
Abdelkader Mahammedi ◽  
Houari Ameur ◽  
Younes Menni ◽  
Driss Meddah Medjahed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Turbulent Flows ◽  
Convective Heat ◽  
Circular Tube ◽  
Numerical Study ◽  
Constant Heat Flux ◽  
Flux Boundary Condition ◽  
Pressure Losses

The convective heat transfer of Al2O3-water nanofluids through a circular tube with a constant heat flux boundary condition is studied numerically. Turbulent flow conditions are considered with a Reynolds number ranging from 3500 to 20000. The numerical method used is based on the single-phase model. Four volume concentrations of Al2O3-water nanoparticles (0.1, 0.5, 1, and 2%) are used with a diameter of nanoparticle of 40 nm. A considerable increase in Nusselt number, axial velocity, and turbulent kinetic energy was found with increasing Reynolds number and volume fractions. However, the pressure losses were also increased with the raise of Re and nanoparticles concentration.

Experimental and Numerical Study of Convective Heat Transfer in an Array of Slot Jets

2002 ◽  
Author(s):  
Jean-Marie Buchlin ◽  
Jean-Baptiste Gouriet ◽  
Philipe Planquart ◽  
Jeroen van Beeck ◽  
Michel Renard
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Cooling System ◽  
Numerical Study ◽  
Three Dimensional ◽  
Small Width ◽  
Moving Strip ◽  
Experimental Findings

The paper describes a study of convective heat transfer in a multiple-jet systems composed of straight and inclined slot nozzles. The application concerned is the fast cooling of moving strip. The experimental approach involves the application of infrared thermography associated with the steady-state heated foil technique. Three-dimensional numerical simulations performed with the code FLUENT compare agreeably with the IR data. The study aims to determine the effect on the average heat transfer coefficient of the slot Reynolds number up to the value of 100000, the nozzle spacing normalised by the slot hydraulic diameter in the range 6 ≤ W/S ≤ 18, the normalised nozzle emergence length, E/S, from 5 to 17 and the normalised nozzle to strip standoff distance Z/S from 3 to 10. The geometrical arrangements tested include perpendicular (90°) and tilted (60°) nozzles. A thermal entrainment phenomenon is found for cooling system of small width. A corrective factor is derived to account for this effect. The experimental findings are compared with existing correlation; deviations, which are observed at high values of the Reynolds number may reach 25%. The numerical simulation emphasises the benefit to use H2/N2 gas mixture to enhance significantly the cooling rate.

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