Factors affecting oscillating motion and heat transfer in an oscillating heat pipe

2013 ◽  
Author(s):  
Christopher Smoot
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Oscillating Heat Pipe ◽  
Factors Affecting ◽  
Oscillating Motion

Experimental Investigation of Ultrasonic Effect on an Acetone Oscillating Heat Pipe

2013 ◽  
Author(s):  
Nannan Zhao ◽  
Benwei Fu ◽  
Dianli Zhao ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Power Input ◽  
Input Power ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Ultrasonic Effect ◽  
Ultrasonic Sound ◽  
Oscillating Motion

The ultrasonic effect on the oscillating motion and heat transfer in an oscillating heat pipe (OHP) containing acetone was investigated experimentally. The ultrasonic sound was applied to the evaporating section of the OHP by using electrically-controlled piezoelectric ceramics. The ultrasonic sound is used to generate and maintain the oscillating motion, and, thereby, heat transfer is enhanced. The heat pipe was tested with or without the ultrasonic sound. In addition, the effects of heat load, filling ratio, orientation, operating temperature, and input power from 15 W to 200 W were investigated. The experimental results demonstrate that ultrasonic sound can affect the oscillating motions and enhance the heat transfer performance of the acetone OHP. In particular, the application of the ultrasonic sound on an acetone OHP can significantly reduce the thermal resistance of the acetone OHP and enhance the heat transfer performance in a low power input region. The investigation will provide an insight into the oscillating mechanism of the acetone OHP influenced by ultrasonic sound and provide a new way to enhance the heat transfer performance of the OHP.

Heat Transport Capability in an Oscillating Heat Pipe

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
H. B. Ma ◽  
B. Borgmeyer ◽  
P. Cheng ◽  
Y. Zhang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Convection Heat Transfer ◽  
Power Input ◽  
Film Condensation ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion

A mathematical model predicting the oscillating motion in an oscillating heat pipe is developed. The model considers the vapor bubble as the gas spring for the oscillating motions including effects of operating temperature, nonlinear vapor bulk modulus, and temperature difference between the evaporator and the condenser. Combining the oscillating motion predicted by the model, a mathematical model predicting the temperature difference between the evaporator and the condenser is developed including the effects of the forced convection heat transfer due to the oscillating motion, the confined evaporating heat transfer in the evaporating section, and the thin film condensation in the condensing section. In order to verify the mathematical model, an experimental investigation was conducted on a copper oscillating heat pipe with eight turns. Experimental results indicate that there exists an onset power input for the excitation of oscillating motions in an oscillating heat pipe, i.e., when the input power or the temperature difference from the evaporating section to the condensing section was higher than this onset value the oscillating motion started, resulting in an enhancement of the heat transfer in the oscillating heat pipe. Results of the combined theoretical and experimental investigation will assist in optimizing the heat transfer performance and provide a better understanding of heat transfer mechanisms occurring in the oscillating heat pipe.

Ultrasonic Effect on the Startup of an Oscillating Heat Pipe

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Nannan Zhao ◽  
Dianli Zhao ◽  
H. B. Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pipe ◽  
Electric Power ◽  
Input Power ◽  
Enhance Heat Transfer ◽  
Sound Effect ◽  
Oscillating Heat Pipe ◽  
Ultrasonic Sound ◽  
Oscillating Motion

This paper investigates the ultrasonic sound effect on oscillating motion and heat transfer in an oscillating heat pipe (OHP). The ultrasonic sound produced by electrically controlled piezoelectric ceramics is used to generate and maintain the oscillating motion and thereby enhance heat transfer. The results demonstrate that when an ultrasonic sound with a total electric power of 4.48 mW is added, the input power needed to start the oscillating motion can be reduced from 30 W to 18 W and the effective thermal conductivity is increased from 672.8 W/mK to 1254.7 W/mK.

Wavelet Analysis of Oscillating Motions in an Oscillating Heat Pipe

2011 ◽  
Author(s):  
Nannan Zhao ◽  
Hongbin Ma ◽  
Xinxiang Pan
Keyword(s):  
Heat Transfer ◽  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Heat Pipe ◽  
Electronic Components ◽  
Enhance Heat Transfer ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion

The heat to be removed from the electronic components or systems can be used to excite the oscillating motion of a train of liquid plugs and bubbles in the oscillating heat pipe (OHP). The oscillating motion in the OHP can significantly enhance heat transfer. The wavelet transform (WT) analysis is used to analyze the oscillating motions occurring in the OHP. It is found that a number of waveforms exist, which indicates that the oscillating motions in an OHP are resulted from a number of sources. Results of the investigation will provide a better understanding of oscillating motion mechanisms occurring in the OHP.

A Mathematical Model Predicting Heat Transfer Performance in a Oscillating Heat Pipe

2007 ◽  
Author(s):  
H. B. Ma ◽  
B. Borgmeyer ◽  
P. Cheng ◽  
Y. Zhang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Heat Transfer Performance ◽  
Temperature Drop ◽  
Film Condensation ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion

A mathematical model predicting the oscillating motion in an oscillating heat pipe is developed. The model considers the vapor bubble as the gas spring for the oscillating motions including effects of operating temperature, non-linear vapor bulk modulus, and temperature difference between the evaporator and the condenser. Combining the oscillating motion predicted by the model, a mathematical model predicting the temperature drop between the evaporator and the condenser is developed including the effects of the forced convection heat transfer due to the oscillating motion, the confined evaporating heat transfer in the evaporating section, and the thin film condensation in the condensing section. In order to verify the mathematical model, an experimental investigation was conducted. Experimental results indicate that there exists an onset power input for the excitation of oscillating motions in an oscillating heat pipe, i.e., when the input power or the temperature difference from the evaporating section to the condensing section was higher than this onset value the oscillating motion started, resulting in an enhancement of the heat transfer in the pulsating heat pipe. Results of the investigation will assist in optimizing the heat transfer performance and provide a better understanding of heat transfer mechanisms occurring in the oscillating heat pipe.

Experimental Investigation of Magnetic Field Effect on the Magnetic Nanofluid Oscillating Heat Pipe

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Nannan Zhao ◽  
Dianli Zhao ◽  
Hongbin Ma
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Field Effect ◽  
Heat Transfer Performance ◽  
Magnetic Field Effect ◽  
Magnetic Nanofluid ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion ◽  
The Magnetic Field

The magnetic field effect on oscillating motion and heat transfer in an oscillating heat pipe (OHP) containing magnetic nanofluid was investigated experimentally. The nanofluid consisted of distilled water and dysprosium (III) oxide nanoparticles with an average size of 98 nm. A magnetic field was applied to the evaporating section of the OHP by using a permanent magnet. The heat pipes charged with magnetic nanofluids at mass ratios of 0.1%, 0.05%, and 0.01% were tested. In addition, the effects of orientation and input power ranging from 50 W to 250 W on the heat transport capability of the heat pipe were investigated. The experimental results demonstrate that the magnetic field can affect the oscillating motions and enhance the heat transfer performance of the magnetic nanofluid OHP. The magnetic nanoparticles in a magnetic field can reduce the startup power of oscillating motion and enhance the heat transfer performance.

Hydrophobic Surface Effect on Heat Transfer Performance in an Oscillating Heat Pipe

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Yulong Ji ◽  
Hsiu-hung Chen ◽  
Young Jo Kim ◽  
Qingsong Yu ◽  
Xuehu Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Surface Effect ◽  
Hydrophobic Surface ◽  
Heat Transfer Mechanism ◽  
Self Assembled Monolayer ◽  
Oscillating Heat Pipe ◽  
Inner Surface ◽  
Oscillating Motion

An experimental investigation of an oscillating heat pipe (OHP) with a superhydrophobic inner surface coated with a superhydrophobic self-assembled monolayer (SAM) of n-octadecyl mercaptan was conducted. The experimental results show that the oscillating motion in an OHP with a superhydrophobic surface can be generated and the OHP can function well. This is very different from the conventional wicked heat pipe, which cannot function if the inner surface is hydrophobic. The functionality of a superhydrophobic OHP is not sensitive to the wetting condition of the inner surface of the OHP. The investigation results in a better understating of heat transfer mechanism occurring in an OHP.

Experimental Investigation of Magnetic Field Effect on the Magnetic Nanofluid Oscillating Heat Pipe

2012 ◽  
Author(s):  
Nannan Zhao ◽  
Dianli Zhao ◽  
Hongbin Ma
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Magnetic Field Effect ◽  
Input Power ◽  
Magnetic Nanofluid ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion ◽  
The Magnetic Field

The magnetic field effect on the oscillating motion and heat transfer in an oscillating heat pipe (OHP) containing magnetic nanofluid was investigated experimentally. The nanofluid consists of distilled water and Dysprosium (III) oxide nanoparticles with sizes less than 100 nm. A magnetic field was applied to the evaporating section of the OHP by using the permanent magnet. The heat pipes charged with magnetic nanofluids at mass ratios of 0.1%, 0.05%, and 0.01%, respectively, were tested. In addition, the effects of orientation and input power ranging from 50 W to 250 W on the heat transport capability of the heat pipe were investigated. The experimental results demonstrate that the magnetic field can affect the oscillating motions and enhance the heat transfer performance of the magnetic nanofluid OHP. The magnetic nanoparticles in a magnetic field can reduce the startup power of oscillating motion and enhance the heat transfer performance in a low input power.

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