scholarly journals Quantitative Visualization of Heat Transfer in Oscillatory and Pulsatile Flows

10.5772/14460 ◽  
2011 ◽  
Author(s):  
Cila Herman
Keyword(s):  
Heat Transfer ◽  
Quantitative Visualization ◽  
Pulsatile Flows

Viscous dissipation and heat transfer in pulsatile flows of a yield-stress fluid

1996 ◽  
Vol 23 (5) ◽  
pp. 599-612 ◽  
Author(s):  
Khaled J. Hammad ◽  
George C. Vradis
Keyword(s):  
Heat Transfer ◽  
Yield Stress ◽  
Viscous Dissipation ◽  
Yield Stress Fluid ◽  
Pulsatile Flows

Heat Transfer Enhancement in an Electrically Heated Horizontal Pipe Due to Flow Pulsation

2003 ◽  
Author(s):  
Mir-Akbar Hessami ◽  
Andrew Berryman ◽  
Pratish Bandopdhayay
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Industrial Applications ◽  
Pulsation Frequency ◽  
Flow Pulsation ◽  
Transfer Enhancement ◽  
Horizontal Pipe ◽  
Published Evidence ◽  
Experimental Apparatus ◽  
Pulsatile Flows

The concept of applying a periodic pulse to a fluid flow has been widely used in industrial applications for many years. One would expect flow pulsation to have a significantly positive effect on the efficiency of heat transfer. However, several decades of research into this type of flow (mainly for a gas such as air flowing in a pipe) has brought conflicting conclusions as to the advantages or disadvantages of pulsation on heat transfer. In order to study the published evidence in a more objective manner, this research project was initiated. The approach used was experimental, involving laboratory experiments with water flowing in a heated horizontal pipe. For this purpose, a special experimental apparatus was designed and built, and a large number of experiments were performed for different values of pulsation frequency and amplitude, superimposed over a varying main flow rate through the pipe. For the range of variables considered in this study (ie, 5,000 < Re < 23,000, 0.1 Hz ≤ f ≤ 1.0 Hz and various pulsation amplitudes), it was found that (a) increasing pulsation frequency improved the heat transfer by as much as 15%, (b) increasing pulsation amplitude reduced the heat transfer by as much as 25% and (c) up to 50% heat transfer enhancement was obtained for pulsatile flows with flow reversal.

scholarly journals Assessment of Measurement Accuracy of a Micro-PIV Technique for Quantitative Visualization of Al2O3 and MWCNT Nanofluid Flows

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2777
Author(s):  
Hanwook Park ◽  
Jeonggyun Ham ◽  
Honghyun Cho ◽  
Sung Yong Jung
Keyword(s):  
Heat Transfer ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Velocity Profiles ◽  
Velocity Fields ◽  
Measured Velocity ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Quantitative Visualization ◽  
Static Images

Nanofluids, which are liquids containing nanoparticles, are used to modify heat transfer performance in various systems. To explain the mechanism of heat transfer modification with nanofluids, many theories have been suggested based on numerical simulations without experimental validation because there is no suitable experimental method for measuring the velocity fields of nanofluid flows. In this study, the measurement accuracy of micro-particle image velocimetry (μ-PIV) is systemically quantified with Al2O3 and multi-walled carbon nanotube (MWCNT) nanofluids. Image quality, cross-correlation signal-to-noise ratio, displacement difference, and spurious vector ratio are investigated with static images obtained at various focal plane positions along the beam pathway. Applicable depth is enough to investigate micro-scale flows when the concentrations of Al2O3 and MWCNT nanofluids are lower than 0.01% and 0.005%, respectively. The velocity fields of Hagen–Poiseuille flow are measured and compared with theoretical velocity profiles. The measured velocity profiles present good agreement with the theoretical profiles throughout. This study provides the criteria for μ-PIV application and demonstrates that μ-PIV is a promising technique for measuring the velocity field information of nanofluids.

Heat Transfer Physics

2008 ◽  
Author(s):  
Massoud Kaviany
Keyword(s):  
Heat Transfer

Heat Transfer in Nuclear Reacter Safety

1997 ◽  
Keyword(s):  
Heat Transfer
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