Performance of Circular Oscillating Heat Pipe for Highly Adaptable Heat Transfer Layout

2021 ◽  
pp. 117497
Author(s):  
Shun Okazaki ◽  
Hideyuki Fuke ◽  
Hiroyuki Ogawa
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Oscillating Heat Pipe

Experimental Investigation of Ultrasonic Frequency Effect on an Oscillating Heat Pipe

2016 ◽  
Author(s):  
Nannan Zhao ◽  
Benwei Fu ◽  
Hongbin Ma ◽  
Fengmin Su
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transport ◽  
Frequency Effect ◽  
Ultrasonic Frequency ◽  
Sound Effect ◽  
Oscillating Heat Pipe ◽  
Ultrasonic Sound ◽  
Heat Transfer Capacity ◽  
Heat Transport Capability

The heat transport capability in an oscillating heat pipe (OHP) significantly depends on the oscillating frequency. An external frequency directly affects the natural frequency in the system. In this investigation, the ultrasound sound effect on the heat transport capability in an OHP was conducted with focus on the ultrasonic frequency effect on the oscillating motion and heat transfer capacity in an OHP. The ultrasonic sound was applied to the evaporating section of the OHP by using the electrically-controlled piezoelectric ceramics. The heat pipe was tested with or without the ultrasonic sound with different frequencies. In addition, the effects of operating temperature, heat load from 25 W to 150 W were investigated. The experimental results demonstrate that the heat transfer capacity enhancement of the OHP depends on the frequency of the ultrasound field, and there exists an optimum combination of the frequencies which will lead to the largest enhancement of the heat transfer capacity of the OHP.

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.

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.

Experimental Investigation of Oscillating Heat Pipe With Hybrid Fluids of Liquid Metal and Water

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Tingting Hao ◽  
Hongbin Ma ◽  
Xuehu Ma
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Heat Pipe ◽  
Heat Input ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe

A new oscillating heat pipe (OHP) charged with hybrid fluids can improve thermal performance. The key difference in this OHP is that it uses room temperature liquid metal (Galinstan consisting of gallium, indium, and tin) and water as the working fluid. The OHP was fabricated on a copper plate with six turns and a 3 × 3 mm2 cross section. The OHP with hybrid fluids as the working fluid was investigated through visual observation and thermal measurement. Liquid metal was successfully driven to flow through the OHP by the pressure difference between the evaporator and the condenser without external force. Experimental results show that while added liquid metal can increase the heat transport capability, liquid metal oscillation amplitude decreases as the filling ratio of liquid metal increases. Visualization of experimental results show that liquid metal oscillation position and velocity increase as the heat input increases. Oscillating motion of liquid metal in the OHP significantly increases the heat transfer performance at high heat input. The lowest thermal resistance of 0.076 °C/W was achieved in the hybrid fluids-filled OHP with a heat input of 420 W. We experimentally demonstrated a 13% higher heat transfer performance using liquid metal as the working fluid compared to an OHP charged with pure water.

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.

A study on the heat transfer characteristics of a self-oscillating heat pipe

2002 ◽  
Vol 16 (3) ◽  
pp. 354-362 ◽  
Author(s):  
Seok Hun Yoon ◽  
Cheol Oh ◽  
Jae Hyuk Choi
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Oscillating Heat Pipe ◽  
Transfer Characteristics
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