Heat Transfer Enhancement Using Ferromagnetic Particle Laden Fluid and Oscillating Magnetic Fields

2007 ◽  
Author(s):  
Mark M. Murray
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Pipe Wall ◽  
Transfer Enhancement ◽  
Bulk Fluid ◽  
Enhancement Technique ◽  
Internally Cooled ◽  
Ferromagnetic Particles

A convective heat transfer enhancement technique and the experimental method used to quantify the improvement in heat transfer are introduced. The enhancement technique employs time varying magnetic fields produced in a pipe to cause the ferromagnetic particles of a particle laden fluid (mineral oil and iron filings) to be attracted to and released from the pipe wall. The magnetic field remains energized long enough to attract particles to the wall and allow the heat to be quickly transferred to the highly thermally conductive particles. The released particles utilize their large surface area when dispersed to efficiently transfer heat to the bulk fluid. The ferromagnetic particles act not only to advect heat into the bulk fluid, but they also disrupt the boundary layer, allowing cooler fluid to reach the high temperature pipe wall, increase thermal energy transfer directly to the fluid and contribute to the overall improvement in heat transfer rate. The experimental method utilized to quantify increased effectiveness of convective heat transfer uses an experimental apparatus designed to replicate an internally cooled fin. The pipe test section acts as an internally cooled fin whose surface temperature is measured with an IR camera. These temperature measurements are then utilized to calculate the convective heat transfer coefficient (h) of the fluid within the pipe. The enhancement technique demonstrated a 250% increases in heat transfer coefficient for the experimental parameters tested.

Demonstration of Heat Transfer Enhancement Using Ferromagnetic Particle Laden Fluid and Switched Magnetic Fields

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Mark M. Murray
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Pipe Wall ◽  
Differential Pressure ◽  
Transfer Enhancement ◽  
Enhancement Technique ◽  
Ferromagnetic Particles

A convective heat transfer enhancement technique and the experimental methods used to quantify the improvement in heat transfer and subsequent differential pressure are introduced. The enhancement technique employed time varying magnetic fields produced in a pipe to cause the ferromagnetic particles of a particle laden fluid (mineral oil and iron filings) to be attracted to and released from a heated pipe wall. The ferromagnetic particles acted not only to advect heat from the pipe wall into the bulk fluid but they also significantly modified the flow field, disrupted the boundary layer, allowed cooler fluid to reach the high temperature pipe wall, increased thermal energy transfer directly to the fluid, and contributed to the overall improvement in heat transfer rate. The experimental method utilized to quantify an increased effectiveness of convective heat transfer used an apparatus designed to replicate an internally cooled fin, whose surface temperature was measured with an IR camera. These temperature measurements were utilized to calculate the convective heat transfer coefficient (h) of the fluid within the pipe. The enhancement technique demonstrated a 267% increase in heat transfer coefficient with only a corresponding 48% increase in flow differential pressure for an electromagnetic switching frequency of 2 Hz. It is also found that there were optimum magnetic field switching frequencies for both enhancement and differential pressure magnitudes.

Numerical Study of Turbulent Convective Heat Transfer of Aviation Kerosene in Coiled Pipes

2021 ◽  
Author(s):  
Wenhui Fan ◽  
Fengquan Zhong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Pipe Wall ◽  
Outer Side ◽  
Inlet Temperature ◽  
Aviation Kerosene ◽  
Helical Pipe

Abstract Turbulent flow and convective heat transfer of kerosene in helical pipes with different wall thermal conditions and curvature radii of pipe were numerically studied with Reynolds Averaged Numerical Method and realizable k-e turbulence model. The fluid media is aviation kerosene with an inlet supercritical pressure of 3MPa and an inlet temperature of 400K. The present results provide temperature and velocity fields as well as distributions of turbulence kinetic energy and streamlines at different axial locations along the flow direction. The non-dimensional heat transfer coefficient, Nusselt number at the inner and the outer sides of the pipe wall are compared and its value of the outer side is higher than that of inner side by 75%. Compared to straight pipe with the same pipe radius of 6mm and inlet flow conditions, the helical pipe with a curvature radius of 192.5mm can increase the averaged heat transfer coefficient by 28.5%. Meanwhile, it is found that when the curvature ratio increases, the effect of secondary flow in helical pipe is more significant and the difference of heat transfer between different locations of the pipe wall is larger. In addition, the present results also reveal that heat transfer deterioration takes place for the kerosene flow in helical pipe with an increased wall heat flux due to the state change of kerosene from liquid to supercritical.

scholarly journals Convective Heat Transfer Enhancement in Nanofluids: Real Anomaly or Analysis Artifact?

2011 ◽  
Author(s):  
Naveen Prabhat ◽  
Jacopo Buongiorno ◽  
Lin-wen Hu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Transfer Coefficient ◽  
Temperature Dependence ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Transfer Enhancement

The nanofluid literature contains many claims of anomalous convective heat transfer enhancement in both turbulent and laminar flow. To put such claims to the test, we have performed a critical detailed analysis of the database reported in 12 nanofluid papers (8 on laminar flow and 4 on turbulent flow). The methodology accounted for both modeling and experimental uncertainties in the following way. The heat transfer coefficient for any given data set was calculated according to the established correlations (Dittus-Boelter’s for turbulent flow and Shah’s for laminar flow). The uncertainty in the correlation input parameters (i.e. nanofluid thermo-physical properties and flow rate) was propagated to get the uncertainty on the predicted heat transfer coefficient. The predicted and measured heat transfer coefficient values were then compared to each other. If they differed by more than their respective uncertainties, we judged the deviation anomalous. According to this methodology, it was found that in nanofluid laminar flow in fact there seems to be anomalous heat transfer enhancement in the entrance region, while the data are in agreement (within uncertainties) with the Shah’s correlation in the fully developed region. On the other hand, the turbulent flow data could be reconciled (within uncertainties) with the Dittus-Boelter’s correlation, once the temperature dependence of viscosity was included in the prediction of the Reynolds number. While this finding is plausible, it could not be conclusively confirmed, because most papers do not report information about the temperature dependence of the viscosity for their nanofluids.

Heat Transfer Enhancement in Split and Recombine Flow Configurations: A Numerical and Experimental Study

2016 ◽  
Author(s):  
Mojtaba Jarrahi ◽  
Jean-Pierre Thermeau ◽  
Hassan Peerhossaini
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Working Fluid ◽  
Transfer Enhancement

Heat transfer enhancement in laminar regime by split and recombine (SAR) mechanism, based on the baker’s transformation, is investigated. Two different heat exchangers, called SAR1 and SAR2, are studied. Their geometries are inspired from the previous studies reported in the literature. The working fluid on both, shell and tube side, is water and the temperature on the shell side is kept constant. Experiments are carried out for the Reynolds number range 100<Re<3000 when the Prandtl number is between 4.5 and 7.5. The results show that the convective heat transfer coefficient in the first element of heat exchanger SAR1 is higher than that in the second one, i.e. SAR2. However, the variation in the convective heat transfer coefficient from the first to the third element along the heat exchanger SAR2 is less significant than that observed for SAR1. Moreover, SAR2 causes a higher pressure drop, especially when Re>1000, and provides a less uniform temperature field at the outlet.

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