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.

scholarly journals PERFORMANCE OF HEAT PIPE FOR DIFFERENT WORKING FLUIDS AND FILL RATIOS

2011 ◽  
Vol 41 (2) ◽  
pp. 96-102 ◽  
Author(s):  
A. K. Mozumder ◽  
A. F. Akon ◽  
M. S. H. Chowdhury ◽  
S. C. Banik
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Capacity ◽  
Working Fluid ◽  
Working Fluids ◽  
Overall Heat Transfer Coefficient ◽  
Lower Temperature

An attempt is made to design, fabricate and test a miniature heat pipe with 5 mm diameter and 150 mm length with a thermal capacity of 10 W. Experiments were conducted with and without working fluid for different thermal loads to assess the performance of heat pipe. The working fluids chosen for the study were same as those commonly used namely, water, methanol and acetone. The temperature distribution across the heat pipe was measured and recorded using thermocouples. The performance of the heat pipe was quantified in terms of thermal resistance and overall heat transfer coefficient. The amount of liquid filled was varied and the variation of the performance parameters for varying liquid inventory is observed. Finally, optimum liquid fill ratio is identified in terms of lower temperature difference and thermal resistance and higher heat transfer coefficient. The data reported in this study will serve as a good database for the researchers in this field. Overall heat transfer coefficient of the Miniature heat pipe is found to be the maximum for the Acetone as working fluid.DOI: http://dx.doi.org/10.3329/jme.v41i2.7473

Experimental Investigation on Performance of Pulsating Heat Pipe

2015 ◽  
Author(s):  
Tarigonda Hari Prasad ◽  
Pol Reddy Kukutla ◽  
P. Mallikarjuna Rao ◽  
R. Meenakshi Reddy
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
The Given ◽  
Liquid Vapor

Pulsating heat pipes (PHP) receives heat from the working fluid distributes itself naturally in the form of liquid–vapor system, i.e., receiving heat from one end and transferring it to other end by a pulsating action of the liquid–vapor system. Pulsating heat pipes have more advantages than other heat pipes. The problem identified is, to calculate the performance of the pulsating heat pipes with respect to different inclinations using various parameters. In this paper, experiment on performance of closed single loop pulsating heat pipe (CLPHP) using water as a working fluid is considered. The parameters such as thermal resistance (Rth), heat transfer coefficient (h), and variation of temperature with respect to time for the given input at different inclinations such as 0°, 45°, and 90° are taken for the present work. Water is used as the working fluid and is subjected to 50% filling ratio and vacuumed at a pressure of 2300Pa. The performance is calculated at different inclinations of the CLPHP with single turn/loop. The factors such as heat transfer coefficient, thermal resistance, time taken for heating the pulsating heat pipe with the given input are calculated. Finally, it has been concluded that is preferable orientation for PHP and it was found be at vertical orientation i.e., at 90° inclination, because more pulsating action is taken place at this inclination and henceforth, heat transfer rate is faster at this inclination.

Thermal Characteristics of a Cylindrical Heat Pipe using Multi-Layer Screen Mesh Wick

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
R. Sankar Rao ◽  
S. Bhanu Prakash
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Characteristics ◽  
Wire Mesh ◽  
Working Fluid ◽  
Wick Structure ◽  
Screen Mesh

Heat pipe is the most widely used heat exchanging device in removal of heat from any given system at a faster rate. The thermal characteristics of heat pipe with single and multi-layered screen mesh wicks have been observed with two working fluids water and acetone. Heat pipe of length 250 mm and 12.7 mm outer diameter, made of copper material is used in all the trials of with and without wick structure. A 100 mesh stainless steel screen wire mesh is chosen as wick structure. Experiments were conducted at different heat loads and various inclinations with 100% fill ratio in evaporator. The performance is measured based on total thermal resistance and overall heat transfer coefficient. The heat pipe is found effective at 60o inclination with acetone as a working fluid and with four layered screen mesh wick. Uncertainty in thermal resistance and heat transfer coefficient is calculated for a heat input of 10W at 0 and 60 inclinations.

An Experimental Study of Closed Loop Two-Phase Thermosyphon for Spent Fuel Pool Passive Cooling

2016 ◽  
Author(s):  
Minglu Wang ◽  
Mingguang Zheng ◽  
Cheng Ye ◽  
Zhongming Qiu ◽  
Zhenqin Xiong
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Closed Loop ◽  
Working Fluid ◽  
Spent Fuel ◽  
Two Phase ◽  
Spent Fuel Pool

The study reported here examined a closed loop two-phase thermosyphon (CLTPT) of evaporator length 7.6m and internal diameter 65mm used to cool the spent fuel pool. This experimental study investigates the thermal performances and heat and mass transfer characteristic of CLTPT by examining the thermodynamic cycles and overall thermal resistances with ammonia, R134a and water as the working fluid. Measurements of temperature and pressure distributions of the fluid around the loop were made under various conditions. Results show that this loop operates with low filling ratio, low mass flow rate, and high heat-transfer coefficient and the CLTPT has the ability to cool the spent fuel pool. The working fluid flowing through the heat pipe evaporator section generally experienced a subcooled zone, pool boiling zone and high gas quality two-phase region. The average heat transfer coefficient of evaporator reaches 450 W/m2•°C using R134a as working fluid. The thermal resistance of R134a is always smaller than ammonia but the thermal resistance of water is largest at small temperature difference while is smallest when temperature difference is large.

scholarly journals Effect of Pure and Binary Fluids on Thermal Performance of Closed Loop Pulsating Heat Pipe

2020 ◽  
Vol 9 (3) ◽  
pp. 1716-1721
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Outer Diameter ◽  
Pulsating Heat Pipe ◽  
Binary Fluids ◽  
Working Fluids ◽  
Source To Sink ◽  
Acetone Water

Pulsating heat pipe is the raising methodology of cooling systems in many areas. CLPHP is a passive mode of phase change heat transfer device having potential to transfer heat from source to sink in less span. Heat transfer performance of this method is improving day by day as giving less thermal resistance. Number of experimentations are conducting to increase the efficiency of pulsating heat pipes in many aspects i.e. varying lengths, working fluids, number of turns, different fill ratios, heat inputs and orientation. As taking part of these research a five turn closed loop pulsating heat pipe (of tube inner diameter 2mm, outer diameter 3mm; adiabatic section length 170mm, condensation section length is50mm, evaporation section length is 42mm) working with pure and binary fluids (water-acetone, water-ethanol) compared with water, Acetone, Ethanol with heat inputs 20w, 40w, 60w, 80w, and fill ratio 50%, also the orientations are horizontal and vertical. The analysis from the results obtained was the thermal resistance of all working fluids is drastically diminishing from 20w to 40w heat input and slowly from 40w to 80w.

Experimental and theoretical investigation of heat transfer characteristics of cylindrical heat pipe using Al2O3–SiO2/W-EG hybrid nanofluids by RSM modeling approach

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
R. Vidhya ◽  
T. Balakrishnan ◽  
B. Suresh Kumar
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Diffraction Spectrum ◽  
Step Method ◽  
Ceramic Nanoparticles ◽  
Transfer Mechanisms

AbstractNanofluids are emerging two-phase thermal fluids that play a vital part in heat exchangers owing to its heat transfer features. Ceramic nanoparticles aluminium oxide (Al2O3) and silicon dioxide (SiO2) were produced by the sol-gel technique. Characterizations have been done through powder X-ray diffraction spectrum and scanning electron microscopy analysis. Subsequently, few volume concentrations (0.0125–0.1%) of hybrid Al2O3–SiO2 nanofluids were formulated via dispersing both ceramic nanoparticles considered at 50:50 ratio into base fluid combination of 60% distilled water (W) with 40% ethylene glycol (EG) using an ultrasonic-assisted two-step method. Thermal resistance besides heat transfer coefficient have been examined with cylindrical mesh heat pipe reveals that the rise of power input decreases the thermal resistance and inversely increases heat transfer coefficient about 5.54% and 43.16% respectively. Response surface methodology (RSM) has been employed for the investigation of heat pipe experimental data. The significant factors on the various convective heat transfer mechanisms have been identified using the analysis of variance (ANOVA) tool. Finally, the empirical models were developed to forecast the heat transfer mechanisms by regression analysis and validated with experimental data which exposed the models have the best agreement with experimental results.

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.

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.

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.

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