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.

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.

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.

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.

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.

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 on the Effects of Inclination Angle on Heat Transfer Performance of a Liquid Metal High-Temperature Oscillating Heat Pipe

2021 ◽  
Author(s):  
Mengke Wu ◽  
Yulong Ji ◽  
Yanmin Feng ◽  
Xin Yang ◽  
Yadong Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Inclination Angle ◽  
Heat Transfer Performance ◽  
Input Power ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Inclination Angles

Abstract The liquid metal high-temperature oscillating heat pipe (LMHOHP) is a kind of high efficiency heat transfer device, which can function in high-temperature environments above 500°C. In this paper, the effects of inclination angle on the startup and heat transfer performance of a LMHOHP were investigated experimentally. The sodium-potassium alloy (potassium 78%) was used as the working fluid of the LMHOHP and the filling ratio was 50%. The start-up characteristics and heat transfer performance of the LMHOHP at four inclination angles of 0°, 30°, 60° and 90° were tested when the operating temperatures were 150°C and 400°C, respectively. Experimental results show that (1) The LMHOHP can start-up and function at all the tested inclination angles, the maximum temperatures of the evaporator and condenser can exceed 1000°C and 700°C, respectively. (2) The thermal resistance of the LMHOHP decreases with inclination angle increases, the thermal resistance at the inclination angle of 90° decreases by up to 32.9%, 41.6% and 55.9% compared with that at the inclination angle of 60°, 30° and 0°, respectively. (3) When the input power exceeds 3000W, the flow patterns of LMHOHP at the inclination angle of 90°, 60° and 30° can be changed from the oscillating motion to the unidirectional circulating flow. (4) Compared with the operating temperature of 150°C, the heat transfer performance of the LMHOHP improves at the operating temperature of 400°C, at the input power of 3457W and the inclination angle of 90°, the minimum thermal resistance of LMHOHP is 0.075°C/W. The results shown that the LMHOHP has a good adaptability to working conditions which further extends the application range of oscillating heat pipe.

Experimental Study on Oscillating Heat Pipe With Hydraulic Diameter Far Exceeding the Maximum Hydraulic Diameter

2019 ◽  
Author(s):  
Lilin Chu ◽  
Yulong Ji ◽  
Chunrong Yu ◽  
Yantao Li ◽  
Hongbin Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Transfer Performance ◽  
Vertical Orientation ◽  
Oscillating Heat Pipe ◽  
Horizontal Orientation ◽  
Small Bubbles

Abstract In order to understand the heat transfer performance, startup and fluid flow condition of oscillating heat pipe (OHP) with hydraulic diameter far exceeding the maximum hydraulic diameter (MHD), an experimental investigation on heat transfer performance and visualization was conducted. From the experimental performance, it is found that the OHP can still work well with ethanol as the working fluid when the tube diameter has exceeded the MHD of 91.6%. In addition, the detailed flow patterns of the OHP were recorded by a highspeed camera for vertical and horizontal orientation to understand its physical mechanism. In the vertical orientation, initially working fluid generates small bubbles, and then the small bubbles coalesce and grow to vapor plugs, the vapor plugs finally pushes the liquid slugs to oscillate in the tube. In the horizontal orientation, the working fluid surface fluctuates due to the vapors flow from the evaporator to the condenser and bubbles burst in the evaporator. When the peak of liquid wave reaches the upper surface of tube, a liquid slug has been formed, and then the steam flow pushes the liquid slugs to oscillate in the tube.

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