Experimental Investigations on Thermal Performance of a Multi-Turn Closed Loop Pulsating Heat Pipe

2012 ◽  
Vol 433-440 ◽  
pp. 5854-5860 ◽  
Author(s):  
Yu Wang ◽  
Wei Yi Li
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Input ◽  
Closed Loop ◽  
Research Work ◽  
Design Parameters ◽  
Working Fluid ◽  
High Heat Flux ◽  
Pulsating Heat Pipe

Closed loop pulsating heat pipe (CLPHP) is a relatively new two-phase passive heat transfer device to suit present requirement of high heat flux dissipation in modern electronic components. The operating mechanism of CLPHP is not well understood and the present state of the technology cannot predict required design parameters for a given task. The aim of research work presented in this paper is to better understand thermal performance of CLPHP. A series of experimental investigation were conducted on a multi-turn CLPHP made of copper capillary tube of 2-mm inner diameter. Two kinds of working fluids viz. ethanol and acetone were employed. The influence characterization has been studied for the variation of heat input and filling ratio (FR) of the tested CLPHP. Thermal performance of the CLPHP is evaluated by heat transfer and thermal resistance. The results strongly demonstrate the effect of heat input and FR of the working fluid on thermal performance of the device.

Operating Activity Visualization and Thermal Performance Measurement of Pulsating Heat Pipe

2016 ◽  
Vol 369 ◽  
pp. 42-47 ◽  
Author(s):  
Patrik Nemec ◽  
Zuzana Kolková ◽  
Milan Malcho
Keyword(s):  
Heat Transfer ◽  
Performance Measurement ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Vapour Phase ◽  
Working Fluid ◽  
Internal Diameter ◽  
Pulsating Heat Pipe ◽  
Inner Diameter ◽  
Thermo Physical Properties

Heat pipe is well known device which is used to heat transfer phase-change of working fluid. Pulsating heat pipe (PHP) is special type of heat pipe which heat transfer by pulsating movement of working fluid. Article deals about operating activity and thermal performance measurement of this special heat pipe. Operating activity visualization of PHP was performed with PHP made from glass. The two types of PHPs were made. The first PHP has internal diameter of tube 1 mm, second PHP has internal diameter of tube 1.5 mm and both PHPs have eleven meanders. The working fluids used in PHP were water and Fluorinert FC-72. These fluids were chose for their different thermo-physical properties and the visualization observe formation of liquid and vapour phase working fluid during filling process and working operation.Next, the article describes thermal performance measurement of PHP depending on working fluid amount and heat source temperature. Measurement was performed with PHP made from copper tube with inner diameter 1.5 mm curved to the twenty one meanders and filled with water. The results give us image about formation and distribution of working fluid in pulsating heat pipe and about influence of working fluid amount on the heat transfer ability of pulsating heat pipe.

Effect of Inclination Angle on the Closed Loop Pulsating Heat Pipe Thermal Performance

2013 ◽  
Author(s):  
Pramod R. Pachghare ◽  
Ashish M. Mahalle
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Inclination Angle ◽  
Heat Input ◽  
Closed Loop ◽  
Pulsating Heat Pipe ◽  
Working Fluids ◽  
Inclination Angles ◽  
R 134A

The closed loop pulsating heat pipe (CLPHP) is a passive two-phase heat transfer device, patented by Akachi (1990). Due to its excellent features, PHP has been considered as one of the promising technologies for electronic cooling, heat exchanger, etc. This paper presents an experimental study shows the effect of inclination angle on the thermal performance of CLPHP, which consist of 10 turns of copper tubes having inner and outer diameter 2 mm and 3.6 mm respectively. The equal lengths of evaporator, condenser and adiabatic sections are 50 mm each. Different working fluids are used as R-134a, Methanol and Water. For all experimentations, an optimum filling ratio was maintained 50% by volume. The thermal performance have been investigated with different inclination angles (viz. 0°, 20°, 40°, 60° and 90°) at various heat input from 5 to 50W in the steps of 5W. The thermal resistance (which is inversely proportional to thermal performance) of CLPHP at various heat input are plotted for different working fluids. The result shows that, the thermal resistance decreases as heat input increases. But at low heat input i.e. upto 25W, the thermal resistance decreases rapidly and the PHP performance is more sensitive to the inclination angle whereas high heat input i.e. above 25W, the thermal resistance decreases smoothly and less independent to the inclination angle. In all inclination angles, vertical bottom heat position (at 90°) of CLPHP gives best thermal performance due to presence of gravity force. At all inclination angles, the working fluid R-134a show best thermal performance followed by methanol and water.

Effects of Surface Coating of Nanoparticles on Thermal Performance of Open Loop Pulsating Heat Pipes

2012 ◽  
Author(s):  
Mehdi Taslimifar ◽  
Maziar Mohammadi ◽  
Ali Adibnia ◽  
Hossein Afshin ◽  
Mohammad Hassan Saidi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Surface Coating ◽  
Heat Pipes ◽  
Open Loop ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Performance Of Heat Transfer

Homogenous dispersing of nanoparticles in a base fluid is an excellent way to increase the thermal performance of heat transfer devices especially Heat Pipes (HPs). As a wickless, cheap and efficient heat pipe, Pulsating Heat Pipes (PHPs) are important candidates for thermal application considerations. In the present research an Open Loop Pulsating Heat Pipe (OLPHP) is fabricated and tested experimentally. The effects of working fluid namely, water, Silica Coated ferrofluid (SC ferrofluid), and ferrofluid without surface coating of nanoparticles (ferrofluid), charging ratio, heat input, and application of magnetic field on the overall thermal performance of the OLPHPs are investigated. Experimental results show that ferrofluid has better heat transport capability relative to SC ferrofluid. Furthermore, application of magnetic field improves the heat transfer performance of OLPHPs charged with both ferrofluids.

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.

Modeling for Fluid Flow and Heat Transfer in Closed Loop Pulsating Heat Pipe

2020 ◽  
pp. 1-34
Author(s):  
Radhakanta Sarangi ◽  
Satya Prakash Kar ◽  
Abhilas Swain ◽  
Lalit Kumar Pothal
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Vapor Bubble ◽  
Closed Loop ◽  
Working Fluid ◽  
Vapour Bubble ◽  
Pulsating Heat Pipe ◽  
Time Step ◽  
Liquid Plug ◽  
Evaporation And Condensation

Abstract Numerical modelling of multi turn Closed Loop Pulsating Heat Pipe (CLPHP) is presented in this paper for ethanol as working fluid. Modelling is carried out for 1mm and 2mm ID PHP for different number of turns, different orientations and at constant wall temperature boundary conditions. Momentum and heat transfer variations with time are investigated numerically solving the one dimensional governing equations for vapor bubble and liquid plugs. Evaporation and condensation takes place by heat transfer through liquid film present around the vapour bubble. The code takes into account the realistic phenomena such as vapour bubble generation, liquid plug merging and super heating of vapor bubbles above its saturation temperature. During merging of liquid plugs, a time step adaptive scheme is implemented and this minimum time step was found to be 10−7 s. Nature of flow is investigated by momentum variation plot. Model results are compared with the experimental results from literature for nine different cases. Maximum variation in heat transfer for all these cases is found to be below ±34%. Keywords: Closed Loop Pulsating Heat Pipe, Liquid Plug, Plug momentum, Vapor Bubble, Heat Transfer, Thin Film Evaporation and Condensation

Experimental Investigations on the Thermal Performance of a Single Closed Loop Pulsating Heat Pipe Using TiO2 Nanofluid

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
G. V. Pradeep ◽  
K. Rama Narasimha
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Closed Loop ◽  
Experimental Investigations ◽  
Pulsating Heat Pipe ◽  
Vertical Orientation ◽  
Stable Suspension ◽  
Bottom Heating ◽  
Heating Mode

This paper describes the experimental investigations conducted on a closed loop pulsating heat pipe (CLPHP) for assessing the thermal performance. The pulsating heat pipe has a single closed loop made of copper. The working fluids used are water and titanium dioxide nanofluids with varying concentrations of TiO2 nanoparticles (1.5% and 1%) on weight basis. The TiO2 particles are mixed in water to form a stable suspension using a sonicator. The heat input is varied between 40 W and 100 W in steps of 20 W. All experiments are conducted in the bottom heating mode (evaporator at the top) in the vertical and horizontal orientations. The parameters considered for evaluating the thermal performance are the temperature difference between evaporator and condenser, thermal resistance, heat transfer coefficient, and thermal conductivity. The results of the investigation reveal that the vertical orientation and increase in nanoparticle concentration favors better heat transfer performance of the single closed loop pulsating heat pipe.

Circulation Effectiveness of Working Fluid in Inclined Micro Heat Pipes

2015 ◽  
Vol 789-790 ◽  
pp. 422-425
Author(s):  
Fun Liang Chang ◽  
Yew Mun Hung
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Operating Conditions ◽  
Circulation Rate ◽  
Working Fluid ◽  
High Heat Flux ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Micro heat pipe is a two-phase heat transfer device offering effective high heat-flux removal in electronics cooling. Essentially, micro heat pipe relies on the phase change processes, namely evaporation and condensation, and the circulation of working fluid to function as heat transfer equipment. The vast applications of micro heat pipe in portable appliances necessitate its functionality under different orientations with respect to gravity. Therefore, its thermal performance is strongly related to its orientation. By incorporating solid wall conduction, together with the continuity, momentum, and energy equations of the working fluid, a mathematical model is developed to investigate the heat and fluid flow characteristics of inclined micro heat pipes. We investigate both the favorable and adverse effects of gravity on the circulation rate which is intimately related to the thermal performance of micro heat pipes. The effects of gravity, through the angle of inclination, on the circulation strength and heat transport capacity are analysed. This study serves as a useful analytical tool in the micro heat pipe design and performance analysis, associated with different inclinations and operating conditions.

Experimental Investigation and Performance Evaluation of a Multi Turn Closed Loop Pulsating Heat Pipe

2014 ◽  
Vol 592-594 ◽  
pp. 1554-1558 ◽  
Author(s):  
N. Narendra Babu ◽  
Rudra Naik
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Closed Loop ◽  
Experimental Result ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Working Fluids

Pulsating heat pipe (PHP) is a passive heat transfer device, which transfers heat from one region to another with exceptional heat transfer capacity. It utilizes the latent heat of vaporization of the working fluid as well as the sensible heat. As a result, the effective thermal conductivity is higher than that of the conductors. An experimental study on three turn closed loop pulsating heat pipe with three different working fluids viz., Acetone, Methanol, Heptane and distilled water were employed. The PHP is made up of brass material with an inner diameter of 1.95mm, with a total length of 1150 mm for different fill ratios (FR) was employed .The PHP is tested for the thermal resistance and the heat transfer coefficient. The experimental result strongly demonstrates that acetone is a better working fluid among the working fluids considered in terms of higher heat transfer coefficient and lower thermal resistance.

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