scholarly journals Research on convective heat transfer characteristics of Fe3O4magnetic nanofluids under vertical magnetic field

2021 ◽  
pp. 151-151
Author(s):  
Ruihao Zhang ◽  
Sixian Wang ◽  
Shan Qing ◽  
Zhumei Luo ◽  
Zhang Xiaohui
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Reynolds Number ◽  
Field Strength ◽  
Convective Heat Transfer ◽  
Magnetic Field Strength ◽  
Convective Heat ◽  
Heat Transfer Characteristics ◽  
Magnetic Nanofluids ◽  
The Magnetic Field

This paper focuses on the convective heat transfer characteristics of Fe3O4 /Water magnetic nanofluids under laminar and turbulent conditions. After verifying the accuracy of the experimental apparatus, the effects of magnetic field strength, concentration, Reynolds number and temperature on the convective heat transfer coefficient have been studied. The convective heat transfer characteristics of nanofluids under laminar and turbulent flow conditions were studied in depth, and the influence of each factor on the heat transfer coefficient was analyzed by orthogonal experimental design method. Under the laminar flow conditions, the convective heat transfer of magnetic nanofluids performed best when the Reynolds number was 2000, the magnetic field strength was 600, the temperature was 30? and the concentration was 2%. And the convective heat transfer coefficient (h) increased by 3.96% than the distilled water in the same conditions. In turbulent state, the convective heat transfer of magnetic nanofluids performed the best when the Re was 6000, the magnetic field strength was 600, the temperature was 40? and the concentration was 2%. The h increased by 11.31% than the distilled water in the same Reynolds number and the magnetic field strength conditions.

scholarly journals Effect of Magnetic Field on the Forced Convective Heat Transfer of Water–Ethylene Glycol-Based Fe3O4 and Fe3O4–MWCNT Nanofluids

2021 ◽  
Vol 11 (10) ◽  
pp. 4683
Author(s):  
Areum Lee ◽  
Chinnasamy Veerakumar ◽  
Honghyun Cho
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Field Strength ◽  
Ethylene Glycol ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Hybrid Nanofluid ◽  
Forced Convective Heat Transfer ◽  
The Magnetic Field

This paper discusses the forced convective heat transfer characteristics of water–ethylene glycol (EG)-based Fe3O4 nanofluid and Fe3O4–MWCNT hybrid nanofluid under the effect of a magnetic field. The results indicated that the convective heat transfer coefficient of magnetic nanofluids increased with an increase in the strength of the magnetic field. When the magnetic field strength was varied from 0 to 750 G, the maximum convective heat transfer coefficients were observed for the 0.2 wt% Fe3O4 and 0.1 wt% Fe3O4–MWNCT nanofluids, and the improvements were approximately 2.78% and 3.23%, respectively. The average pressure drops for 0.2 wt% Fe3O4 and 0.2 wt% Fe3O4–MWNCT nanofluids increased by about 4.73% and 5.23%, respectively. Owing to the extensive aggregation of nanoparticles by the external magnetic field, the heat transfer coefficient of the 0.1 wt% Fe3O4–MWNCT hybrid nanofluid was 5% higher than that of the 0.2 wt% Fe3O4 nanofluid. Therefore, the convective heat transfer can be enhanced by the dispersion stability of the nanoparticles and optimization of the magnetic field strength.

Heat Transfer Characteristics of an Array of Impinging Gaseous Slot Jets

2011 ◽  
Vol 396-398 ◽  
pp. 2234-2239
Author(s):  
Zu Ling Liu ◽  
Cheng Bo Wu ◽  
Xian Jun Wang ◽  
Zheng Rong Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Nozzle Exit ◽  
Convective Heat Transfer Coefficient ◽  
Heat Transfer Characteristics ◽  
Forced Convective Heat Transfer

A comprehensive experiment was conducted for heat transfer characteristics for an array of impinging gaseous slot jets to a flat plate with strong turbulence (nozzle exit Reynolds number Re=22500~64700).Find that turbulence intensity of flow has an important influence on local forced convective heat transfer coefficient. Meanwhile, the nozzle-to-plate spacing and nozzle exit Reynolds number Re would affect the mean forced convective heat transfer coefficient of the slot jets. And heat transfer efficiency of slot jets has been set to show the relation between ability of the jets and energy consumption of gas supply.

scholarly journals LBM Analysis of Micro-Convection in MHD Nanofluid Flow

2017 ◽  
Vol 63 (7-8) ◽  
pp. 426 ◽  
Author(s):  
Arjun Kozhikkatil Sunil ◽  
Rakesh Kumar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Slip Coefficient

The lattice Boltzmann-Bhatnagar-Gross-Krook method was used to simulate Al2O3-water nanofluid to find the effects of Reynolds, Rayleigh and Hartmann numbers, slip coefficient, nanoparticle volume fraction and axial distance on forced convection heat transfer in MATLAB. The ranges of studied Reynolds number, Rayleigh number, magnetic field strength, nanoparticle volume concentration and slip coefficient include 200 ≤ Re ≤ 4000; 103 ≤ Ra ≤ 106; 0 ≤ Ha 90; 0 ≤ φ ≤ 2%; 0.005 ≤ B ≤ 0.02, respectively. The results show that increasing Reynolds number and nanoparticle volume fractions improve heat transfer in the 2D microtube under laminar, turbulent, slip and temperature jump boundary conditions. Decreasing the values of slip coefficient decreases the temperature jump and enhances the Nusselt number. A critical value for the Rayleigh number (105) and magnetic field strength (Ha 10) exists, at which the impacts of the solid volume fraction and slip coefficient effects are the most pronounced. The pressure drop shows a similar type of enhancement in magnitude, as observed in the case of the Nusselt number. However, application of nanofluids for low Reynolds numbers is more beneficial, and the effect of volume fractions are more pronounced in comparison to slip coefficient, though the effects are marginal.

scholarly journals CONVECTIVE HEAT TRANSFER ON STENOSED BLOOD FLOW THROUGH PERMEABLE MICROCIRCULATION IN THE PRESENCE OF A MAGNETIC FIELD

2020 ◽  
Author(s):  
Alana Sankar ◽  
Sreedhara Rao Gunakala ◽  
Donna Comissiong
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Reynolds Number ◽  
Blood Flow ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Hartmann Number ◽  
Darcy Number ◽  
Flow Through

Blood flow through permeable microcirculation in the presence of a composite stenosis, an external magnetic field and convective heat transfer was examined. A two-layered model for the blood consisting of a fluid-particle suspension in the core region with a peripheral cell-free plasma layer was used. The proposed system of equations was solved and plots were generated. In the presence of permeable walls, an external magnetic field and convective heat transfer, the temperature of the blood, friction-factor Reynolds number and Nusselt number were investigated. The temperature of the blood increased when the Hartmann number increased, Darcy number increased, haematocrit level increased or the peripheral layer thinned. The friction-factor Reynolds number product increased as the haematocrit, Hartmann number, stenosis height or Darcy number increased. The Nusselt number decreased as the Hartmann number, haematocrit, stenosis height or Darcy number increased. These results were interpreted in terms of the physical situation. This study aids in understanding the effects of wall permeability, a magnetic field and the presence of heat transfer on different diseased arterial systems in the future.

Investigation on Heat Transfer Characteristics of Water Through Narrow Annulus

2006 ◽  
Author(s):  
Guangyao Lu ◽  
Jing Wang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Removal ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Transfer Characteristics ◽  
Lower Reynolds Number ◽  
Axial Heat

A study is carried out to investigate the forced convective heat transfer characteristics of water through narrow annulus. For most works undertaken before were mainly concerned with the heat transfer characteristics of heat removal systems, the experiments herein are conducted to detect the heat transfer characteristics of heated fluid, as well as cooled fluid, flowing through narrow annulus. In the experiments, directions of flow include horizontal, upstream and downstream. The Reynolds number range, based on the annular hydraulic diameter, of 10 to 30,000 is covered in the experiments. During the experiments, the transitions from laminar to turbulent convective heat transfer are carefully observed. It is found that fully turbulent convective heat transfer is achieved at a lower Reynolds number in narrow annulus than that in larger tubes. When the Reynolds number is lower than 150, the heat transfer is degraded attributed to the slow flow rate and axial heat conduction. The experimental results indicate that the heat transfer characteristics of narrow annular flow are different from that of lager, more conventionally sized pipe flow. A convective heat transfer correlation is developed and the comparisons are made with the correlations of other works.

The Heat Transfer Characteristics of Rolling Wheel and the Characteristic Length Determining Them

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Liangbi Wang ◽  
Yongheng Zhang ◽  
Yuan Wu ◽  
Qiuwang Wang ◽  
Zhihui Yin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Characteristic Length ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Rolling Wheel ◽  
Wheel Radius

The convective heat transfer characteristics on the surface of a rolling wheel are investigated using the naphthalene sublimation technique. Five sizes of rolling wheel are selected in the experiments. The local and average Nusselt numbers are obtained. The results reveal that if the wheel radius is used as the characteristic length, the relationship between Nusselt number and Reynolds number is dependent on the wheel radius. This indicates that the wheel radius is not the characteristic length to determine the dimensionless convective heat transfer characteristics of the rolling wheel. Thus, a newly defined characteristic length is provided. For different radii of the wheel, the relationships between Nusselt number and Reynolds number based on this length collapse into one reasonable correlation. The correlation not only enriches the insight of convective heat transfer on rolling wheel but also extends the applicability of the present experimental data.

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