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.

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 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.

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.

Experimental Investigation on Nanofluids Effectiveness on Heat Transfer in Oscillating Heat Pipe

2013 ◽  
Vol 856 ◽  
pp. 98-102 ◽  
Author(s):  
Hamid R. Goshayeshi ◽  
Ali Khosravi ◽  
Mehdi Abedpour Karizaki
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
High Speed ◽  
Oscillatory Flow ◽  
Glass Tube ◽  
Heat Pipes ◽  
Oscillating Heat Pipe ◽  
Flow And Heat Transfer ◽  
Heat Loads

An experimental investigation of the oscillatory flow and heat transfer in a vertical oscillating heat pipe (OHP) was conducted. The oscillating heat pipe was made of a copper-glass tube. Flow inside the oscillating heat pipe at different heat loads was recorded by a high speed camera. Through this research, the authors investigated the effect of utilizing nanofluids on heat transfer amount in heat pipes. The employed nanofluids in this study were water-Fe2O3, water-SiO2and water-TiO2with various volumetric concentrations. The results show that after adding nanoparticles in the base fluid (here water) heat transfer rate increases significantly. It's also noteworthy, of the all applied nanofluids, water-TiO2mixture presents the best enhancement in heat transfer amount.

scholarly journals MATHEMATICAL MODEL OF HEAT TRANSFER IN A MICROCHANNEL HEAT PIPE WITH CIRCULATING TWO-PHASE FLOW

2020 ◽  
Vol 55 ◽  
pp. 62-67
Author(s):  
Rufat Sh. Abiev ◽  
◽  
Ritunesh Kumar ◽  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Pipe ◽  
Two Phase Flow ◽  
Experimental Studies ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Proof ◽  
Oscillating Heat Pipe ◽  
Taylor Flow

In addition to the previously created hydrodynamics model, a mathematical model describing the heat transfer parameters of two-phase flow is constructed. Particular role of longitudinal convection in the heat transport is shown. The experimental studies confirmed a microchannel heat pipe operability with a two-phase flow in a circulating mode. A circulating two-phase Taylor flow in microchannel was considered to be more efficient for overall heat transfer in a heat pipe compared to the pulsating (oscillating) heat pipe. The advantages of circulating two-phase Taylor flow related to the pulsating heat pipes are discussed on the proposed mathematical model basis. The conditions of experimental proof of the proposed mathematical model were elaborated.

An Experimental Investigation of the Heat Transfer Performance of an Oscillating Heat Pipe With Copper Oxide (CuO) Microstructure Layer on the Inner Surface

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Yulong Ji ◽  
Chen Xu ◽  
Hongbin Ma ◽  
Pan Xinxiang
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Copper Oxide ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Inner Surface ◽  
Copper Tubing

This paper presents an experimental investigation of whether heat transfer performance in an oscillating heat pipe (OHP) would improve if the inner surface of the heat pipe was coated with a layer of copper oxide (CuO). The OHP had six turns and three sections, i.e., evaporator, condenser, and adiabatic section with lengths of 40 mm, 64 mm, and 51 mm, respectively. The cleaned copper tubing was chemically treated with a chemical solution and heated in a furnace. A microstructure layer of CuO was formed in the inner surface of the OHP with K2S2O8 and KOH. The working fluid in this study was water with filling ratios ranging from 40% to 70%. The experimental results show that the CuO microstructure layer is superhydrophilic and can enhance the OHP heat transfer performance. The investigation results in a new way to enhance the heat transfer performance of an OHP.

Effects of Film Evaporation and Condensation on Oscillatory Flow and Heat Transfer in an Oscillating Heat Pipe

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Wei Shao ◽  
Yuwen Zhang
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Liquid Flow ◽  
Oscillatory Flow ◽  
Film Condensation ◽  
Evaporator Temperature ◽  
Oscillating Heat Pipe ◽  
Film Evaporation ◽  
Flow And Heat Transfer

An advanced theoretical model of a U-shaped minichannel, a building block of a closed-end oscillating heat pipe, has been developed. Thin film evaporation in the evaporator and thin film condensation in the condenser, axial variation of surface temperature, and pressure loss at the bend are incorporated in this model. The sensible heat transfer coefficients between the liquid slug and the wall are obtained by analytical solution for laminar liquid flow and by empirical correlations for turbulent liquid flow. The effects of the inner diameter, evaporator temperature on the thermally induced oscillatory flow and heat transfer performance, and the mechanism of film condensation and evaporation are investigated.

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