Experimental Study on Start-up Characteristics of Pulsating Heat Pipe

2011 ◽  
Vol 354-355 ◽  
pp. 87-91 ◽  
Author(s):  
Xun Wang ◽  
Tong Han ◽  
Lei Wang ◽  
Xin Xin Mao ◽  
Cheng Si Yang
Keyword(s):  
Experimental Study ◽  
Heat Pipe ◽  
Filling Ratio ◽  
Heating Power ◽  
Working Fluid ◽  
Incline Angle ◽  
Distilled Water ◽  
Pulsating Heat Pipe ◽  
Start Up ◽  
Time Required

Pulsating heat pipe (PHP) with distilled water and acetone as working fluids was experimentally investigated. It is found that the PHP required a certain range of heating power to be started, within which the time required to start the PHP became shorter when the heating power was higher. There was a certain incline angle which is 45°in this experiment to start the PHP more quickly than other angles performed. The minimum power to start the PHP became higher when the filling ratio was higher. Compared with distilled water, the PHP was more readily to be started with acetone as working fluid.

scholarly journals Experiment Study on Improved Closed Loop Pulsating Heat Pipe with Silver/Water Nanofluid

2013 ◽  
Vol 732-733 ◽  
pp. 462-466
Author(s):  
Wei Xiu Shi ◽  
Wei Yi Li ◽  
Li Sheng Pan
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Filling Ratio ◽  
Pulsating Heat Pipe ◽  
Start Up ◽  
High Heating ◽  
Operation Stability ◽  
Heat Transfer Limit

Start up and heat transfer performances of improved closed loop pulsating heat pipe (ICLPHP) charged with water and silver/water nanofluid, respectively, were investigated experimentally with angles of 90° and 60°. Both the average evaporator wall temperature and the overall thermal resistance of the ICLPHP with different working fluids and at the volume filling ratio of 35% were tested and compared. Experimental results showed that nanofluid caused different thermal performances of ICLPHP. Within the experiment range, silver/water nanofluid can improve operation stability and heat transfer limit and reduce starting power compared with water. With high heating power, thermal resistance of nanofluid was lower than that of water. With inclination of 60°, ICLPHP with nanofluid operated better and reduced sensitivity of inclination.

Experimental Investigation of Heat Transfer of Refrigerant Fluid Pulsating Heat Pipe

2017 ◽  
Vol 865 ◽  
pp. 137-142
Author(s):  
Somchai Maneewan ◽  
Chantana Punlek ◽  
Hoy Yen Chan ◽  
Atthakorn Thongtha
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Heat Input ◽  
Filling Ratio ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Filling Volume ◽  
Volume Filling

Heat transfer performances of a pulsating heat pipe (PHP) having internal and external diameter with 4.5 mm and 6 mm with various contents of refrigerant are experimentally investigated. The working fluid as R404A refrigerant was filled in the volume ratios from 0% to 80% and the heat input was controlled in the range from 10 W to 80 W. Obtained results exhibited the ability of R404A refrigerant can enhance the thermal performance in steady state condition. The average temperature difference of the evaporating section and condensing section in the 80% filling volume ratio decreased from 9.5 °C to 2.5 °C when the heating power increase from 10 W to 80 W. The thermal resistance of evaporator and condenser decreased with an increase of the heat input as well. For other filling volume ratios, the trend of temperature difference and thermal resistance was similar to that of the 80% volume filling ratio. Considering the same heat input, the highest heat transfer performance was found at the 80% volume filling ratio. Refrigerant with a relatively low dynamic consistency can lead to relatively high velocity in the PHP that can reduce the temperature difference between the evaporating section and condensing section.

scholarly journals Effect of Filling Ratio on Thermal Characteristics and Performance of a Pulsating Heat Pipe

2019 ◽  
Vol 9 (2) ◽  
pp. 3341-3345
Keyword(s):  
Heat Pipe ◽  
Thermal Characteristics ◽  
Filling Ratio ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Key Factors ◽  
Condenser Section ◽  
Oscillating Heat Pipe ◽  
Bottom Heat ◽  
And Performance

Pulsating heat pipes are complex devices for heat transfer and their optimal thermal performance depends mainly on different parameters. This work is about the thermal efficiency of a closed-loop oscillating heat pipe with a diameter of 2.0 mm and 3.0 copper tube inner and outer. For all experiments, the filling ratio (FR) was used 40%, 50 %,70%,80% and heat inputs of 20W, 40W, 60W, and 80W was provided to PHP. The position of the PHP was vertical bottom heat type. The length of evaporator, adiabatic and condenser section was maintained 52 mm,170mm,60mm. Water and benzene were selected as working fluids. From the available literature it is observed that working fluid and filling ratio are key factors in PHP's performance. The results show that the thermal resistance decreases rapidly with the increase in the heat input to 20 to 40 W., while it decreases gradually over 40 to 80W.Simulation is done in CFD and experimental data were equated to the results.

scholarly journals A Novel Thermal Module with 3-D Configuration Pulsating Heat Pipe for High-Flux Applications

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3425 ◽  
Author(s):  
Chih-Yung Tseng ◽  
Ho-Meng Wu ◽  
Shwin-Chung Wong ◽  
Kai-Shing Yang ◽  
Chi-Chuan Wang
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Simple Structure ◽  
Filling Ratio ◽  
Working Fluid ◽  
High Flux ◽  
Test Results ◽  
Pulsating Heat Pipe ◽  
Effective Contact ◽  
Tube Condenser

A pulsating heat pipe (PHP) contains a wickless design with aligned serpentine tube configuration whose simple structure offers a comparatively easy manufacturing capability. The bends with large curvature are often used for serpentine PHPs. This eventually results in a decline in effective contact surface area between evaporator/condenser and PHP circuitry, thereby impairing the benefit of the wickless design of a PHP. A novel thermal module featuring a 3-D configuration pulsating heat pipe, an evaporator, and a fin-and-tube condenser is proposed to tackle the high-flux application. Methanol is used as the working fluid with a filling ratio of around 60%. Test results indicate the thermal resistance of the proposed module varies from 0.148 K/W to 0.0595 K/W when the supplied power changes from 100 to 1000 W. The proposed thermal module can handle a supplied power up to 1 kW and the corresponding power or heat flux is much higher than any existing literatures.

scholarly journals Experimental Study on the Starting-Up and Heat Transfer Characteristics of Pulsating Heat Pipe Under Local Low-Frequency Vibrations

2021 ◽  
Author(s):  
Jing Chen ◽  
Junbiao Dong ◽  
Ye Yao
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Low Frequency ◽  
Heating Power ◽  
Pulsating Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Condensation Section ◽  
Adiabatic Section

This study mainly experimentally investigates and explores the effects of local low-frequency vibrations on the starting-up and heat transfer characteristics of the pulsating heat pipe. A micro motors with the vibration frequency of 200 Hz were imposed on the external surface of evaporation, condensation and adiabatic section of the pulsating heat pipe, respectively, and the starting-up temperature and the average temperatures along the evaporation section as well as the thermal performances of the vibrating heat pipe were experimentally scrutinized under the local vibrations of different positions. The following important conclusions can be achieved by the experimental study: 1) The effect of vibrations at the evaporation section and at the adiabatic section on the starting-up time of pulsating heat pipe is more significant than that at the condensation section. 2) The vibrations at different positions can reduce the starting-up temperature of the pulsating heat pipe. The effect of the vibrations at the evaporation section is the best as the heating power is lower, and the effect of the vibration at the adiabatic section is the best as the heating power is higher. 3) The vibrations at the evaporation section and at the adiabatic section can reduce the thermal resistance of the pulsating heat pipe. However, the vibrations at the condensation section have little effect on the thermal resistance of the pulsating heat pipe. 4) The vibrations at the evaporation section and at the adiabatic section can effectively reduce the temperature of evaporation section of the pulsating heat pipe, but the vibrations at the condensation section have no effect on the temperature of evaporation section of the pulsating heat pipe.

Visualization Experiment on the Start-up Performance of the Close Loop Pulsating Heat Pipe

2012 ◽  
Vol 550-553 ◽  
pp. 3150-3154 ◽  
Author(s):  
Xun Wang ◽  
Cheng Si Yang ◽  
Xin Xin Mao ◽  
Tong Han
Keyword(s):  
Heat Pipe ◽  
Heat Load ◽  
Early Stage ◽  
Flow Direction ◽  
High Heat ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Optical Visualization ◽  
Start Up ◽  
Visualization Experiment

Through the visualization experiment, the behavior evolution of the vapor and liquid slugs in the pulsating heat pipe (PHP) was investigated in the start-up process. Optical visualization results indicate that the flow pattern mainly is slug flow in the start-up process. In the early stage of the start-up process, the distribution of vapor and liquid slugs was random at the beginning, and then gradually develops to the other form which can easily pulsate in the PHP. In the later stage, pulsation stagnation in short time and reversing of the flow direction of the working fluid could be found at low heat load, when there exists the circulation flow in the PHP. Circulation was formed along a certain direction at high heat load. In addition, the PHP can be started up with less time and lower minimum start load by using working fluid which has lower latent heat.

The Start-Up Performance of Pulsating Heat Pipe With Communicating Pipe at Different Inclination Angles

2019 ◽  
Author(s):  
Fu-Min Shang ◽  
Shi-Long Fan ◽  
Jian-Hong Liu
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Pulsating Heat Pipe ◽  
High Heat Transfer ◽  
Start Up ◽  
Inclination Angles

Abstract The pulsating heat pipe (PHP) is a passive cooling device, which has the advantages of simple structure, high heat transfer performance and low production cost. The complex vapor-liquid phase change occurs in the in the initial stage of PHP. In this work, we explore the start-up performance of PHP at different inclination angles and the experiment shows that start-up performance is respectively different when the angles are 0°, 45°, 90°, 135° and 180°. Since the gravitational auxiliary function, the working fluid in the communicating pipe which takes longer time to vaporize change phase earlier than that in PHP’s loop when the angles are 0° and 45°. Nevertheless, when the angle is 90°, the phase change of working fluid in communicating pipe and in the loop occurs at the same time. Meanwhile, the oscillating mode affects the stability of the starting and heat transfer performance of the PHP.

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