Heat transfer of temperature-sensitive magnetic fluids around single heating pipe

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1039-1046
Author(s):  
Yuhiro Iwamoto ◽  
Hayaki Nakasumi ◽  
Yasushi Ido ◽  
Xiao-Dong Niu
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transport ◽  
Thermal Boundary Layer ◽  
High Heat ◽  
Temperature Sensitive ◽  
Long Distance ◽  
Nanoparticle Suspension ◽  
Single Heating

Temperature-sensitive magnetic fluid (TSMF) is a magnetic nanoparticle suspension with strong temperature-dependent magnetization even at room temperature. TSMF is a refrigerant that enables high heat transport capability and pumpless long-distance heat transport. To enhance the heat transport capacity of the magnetically-driven heat transport device using TSMF, it is effective to use a heating body with a very large heat exchange surface such as a heat sink or a porous medium. In the present study, the thermal flow of TSMF around a single heating pipe under a magnetic field was investigated. Visualization of the temperature field by infrared thermography showed that the application of the magnetic field dramatically developed the thermal boundary layer and improved heat transfer. It was clarified by numerical analysis that this dramatic variation in the thermal boundary layer was associated with several vortexes generated by magnetic force in the vicinity of the heating pipe.

Long Distance Heat Transfer of Pump-Less Heat Transport Device Using Temperature-Sensitive Magnetic Fluids

2018 ◽  
Vol 2018 (0) ◽  
pp. GS3-1
Author(s):  
Yuhiro IWAMOTO ◽  
Hayaki NAKASUMI ◽  
Keita ODAI ◽  
Yasushi IDO ◽  
Hiroshi YAMAGUCHI
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Magnetic Fluids ◽  
Temperature Sensitive ◽  
Long Distance ◽  
Transport Device

Magnetic bubbles dynamics and heat transfer characteristics under influence of non-uniform magnetic fields

2021 ◽  
pp. 095440622110358
Author(s):  
MM Larimi ◽  
A Ramiar ◽  
H Ramyar ◽  
Hamid Kazemi Moghadam
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
External Magnetic Field ◽  
Flow Field ◽  
Thermal Boundary Layer ◽  
Computational Study ◽  
Two Phase ◽  
Navier Stokes Equation ◽  
Vof Model

The computational study of transient immiscible and incompressible two-phase flows is one of the most common and desirable way for investigation of engineering phenomena and physics science. In the previous studies, generally bubbles current have been used as an active method for increasing heat transfer, however, due to existence of hydraulic boundary layers, the bubbles were not able to cross over this layer to thinning the thermal boundary layer and consequently the efficiency of this method was not very considerable. In this study, by considering potential of magnetic field, the effect of co-applying of external non uniform magnetic field and magnetic bubbles in enhancing the heat transfer efficiency in a 3-D tube has been investigated. The computational model consisted of the Navier–Stokes equation for liquid phase and VOF model for interface tracking are carried out by OpenFOAM. The external magnetic field has been considered non-uniform and time dependent. The results predicted that magnetic bubbles and external magnetic field due to their effect on thermal boundary layer increased significantly heat transfer and Nusselt number. Furthermore, results indicated magnetic bubbles can act as an active torbulators in the flow field and can be applied for increasing recirculation and secondary flow in the flow field. The average temperature and magnetic field over times for different cases have been discussed in the results.

A Study on Heat Transport Phenomena in a Developed Thermal Boundary Layer of Drag Reducing Channel Flow

2016 ◽  
Author(s):  
K. Watanabe ◽  
Y. Kaiho ◽  
S. Hara ◽  
T. Tsukahara ◽  
Y. Kawaguchi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transport ◽  
Thermal Boundary Layer ◽  
Transport Phenomena ◽  
Surfactant Solution ◽  
Temperature Fluctuations ◽  
Large Temperature ◽  
Wall Region ◽  
Solution Flow

The heat transport phenomena in a developed thermal boundary layer of surfactant solution flow were investigated experimentally. The experiment was conducted under different surfactant additive concentrations. The temperature fluctuations in a thermal boundary layer in a smooth channel flow were measured by fine-wire thermocouple probe. Heat transfer reducing rate and temperature fluctuation characteristics including mean temperature distribution, intensity, wave form, spectral density function, and skewness factor were studied. The results showed that the turbulent transport is obstructed by additives, and the temperature field shows dramatic changes. High frequency component of temperature fluctuation of surfactant solution flow was decreased due to suppression of turbulence and viscoelasticity. Large temperature fluctuations occur in the thermal boundary layer because the development of the thermal boundary layer is obstructed, and large temperature fluctuations appear to concentrate the temperature gradient in the near-wall region (10 < y+ < 60). In contrast, viscous sublayer expands due to viscoelasticity, and the temperature gradient and turbulence fluctuation are small in the near-wall region of y+ < 10. As a result, two layers having significantly different characteristics seem to coexist. The heat transfer reduction is constant with variation of additive concentration condition, but heat transport phenomena were microscopically influenced by viscoelasticity.

Effect of Nanofluid on Heat Transfer Enhancement for Mixed Convection Flow Over a Corrugated Surface

2020 ◽  
Vol 45 (4) ◽  
pp. 373-383
Author(s):  
Nepal Chandra Roy ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Thermal Boundary Layer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Mixed Convection Flow

AbstractA mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of \mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

Vortex-Induced Vibration for Heat Transfer Enhancement

2014 ◽  
Author(s):  
Junxiang Shi ◽  
Steven R. Schafer ◽  
Chung-Lung (C. L. ) Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Enhancement ◽  
Natural Frequency ◽  
Vortex Shedding ◽  
Pressure Loss ◽  
Thermal Boundary Layer ◽  
Transfer Enhancement ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

A passive, self-agitating method which takes advantage of vortex-induced vibration (VIV) is presented to disrupt the thermal boundary layer and thereby enhance the convective heat transfer performance of a channel. A flexible cylinder is placed at centerline of a channel. The vortex shedding due to the presence of the cylinder generates a periodic lift force and the consequent vibration of the cylinder. The fluid-structure-interaction (FSI) due to the vibration strengthens the disruption of the thermal boundary layer by reinforcing vortex interaction with the walls, and improves the mixing process. This novel concept is demonstrated by a three-dimensional modeling study in different channels. The fluid dynamics and thermal performance are discussed in terms of the vortex dynamics, disruption of the thermal boundary layer, local and average Nusselt numbers (Nu), and pressure loss. At different conditions (Reynolds numbers, channel geometries, material properties), the channel with the VIV is seen to significantly increase the convective heat transfer coefficient. When the Reynolds number is 168, the channel with the VIV improves the average Nu by 234.8% and 51.4% in comparison with a clean channel and a channel with a stationary cylinder, respectively. The cylinder with the natural frequency close to the vortex shedding frequency is proved to have the maximum heat transfer enhancement. When the natural frequency is different from the vortex shedding frequency, the lower natural frequency shows a higher heat transfer rate and lower pressure loss than the larger one.

Investigation of Enhancement in Pool Boiling Heat Transfer of a Binary Temperature Sensitive Magnetic Fluid

2013 ◽  
Author(s):  
Giti Karimi-Moghaddam ◽  
Richard D. Gould ◽  
Subhashish Bhattacharya
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Fluid ◽  
Boiling Heat Transfer ◽  
Magnetic Particles ◽  
Pool Boiling ◽  
Simulation Software ◽  
Temperature Sensitive ◽  
Magnetic Field Effects ◽  
Pool Boiling Heat Transfer

In this paper, the performance of pool boiling heat transfer using a binary temperature sensitive magnetic fluid in the presence of a non-uniform magnetic field is investigated numerically. By using a binary magnetic fluid, enhanced boiling heat transfer is obtained by thermomagnetic convection without deterioration of properties of the fluid. This work is aimed at gaining a qualitative understanding the magnetic field effects on boiling heat transfer enhancement of magnetic fluids. In order to accomplish this, the boiling process and the effects of position of the external magnetic field on flow pattern and heat transfer are investigated in a 2D rectangular domain using COMSOL Multiphysics simulation software. Finally, the boiling curves for a binary temperature sensitive magnetic fluid and its base fluid (without magnetic particles) are compared for various applied heat flux magnitudes.

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