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 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.

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.

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.

scholarly journals Characteristics of Heat Transfer for Heat Pipe and Its Correlation

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Aloke Kumar Mozumder ◽  
Mohammed Shafiul Hasib Chowdhury ◽  
Abul Fahad Akon
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Cooling System ◽  
Thermal Capacity ◽  
Input Power ◽  
Working Fluid ◽  
Fill Ratio ◽  
The Heat Transfer Coefficient

In spite of wide application of heat pipe in microelectronics cooling system, a complete understanding of heat pipe mechanism has not yet been completed. An experimental investigation of heat transfer performance of a heat pipe for dry condition and with three different liquids as acetone, methanol, and water having four fill ratios, for each liquid has been conducted in the present study. The heat pipe was 5 mm in diameter and 150 mm long with a thermal capacity of 10 W. The evaporator and condenser's temperatures were measured with varying input power to estimate the heat transfer coefficient. This study reveals that the dominating parameters for the heat transfer coefficient are evaporator surface temperature, saturated boiling temperature of working fluid, latent heat of vaporization, and fill ratio. The investigation also shows that 85% fill ratio can be regarded as an optimum value for a heat pipe. A new correlation for the heat transfer coefficient has been proposed here which fairly agrees with the experimental results.

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 Thermal performance prediction of heat pipe with TiO2 nanofluids using RSM

2021 ◽  
pp. 199-199
Author(s):  
Lakshmi Reddy ◽  
Srinivasa Bayyapureddy Reddy ◽  
Kakumani Govindarajulu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Tilt Angle ◽  
Heat Load ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Heat pipe is a two phase heat transfer device with high effective thermal conductivity and transfer huge amount of heat with minimum temperature gradient in between evaporator and condenser section. This paper objective is to predict the thermal performance in terms of thermal resistance (R) and heat transfer coefficient (h) of screen mesh wick heat pipe with DI water-TiO2 as working fluid. The input process parameters of heat pipe such as heat load (Q), tilt angle (?) and concentration of nanofluid (?) were modeled and optimized by utilizing Response Surface Methodology (RSM) with MiniTab-17 software to attain minimum thermal resistance and maximum heat transfer coefficient. The minimum thermal resistance of 0.1764 0C/W and maximum heat transfer coefficient of 1411.52 W/m2 0C was obtained under the optimized conditions of 200 W heat load, 57.20 tilt angle and 0.159 vol. % concentration of nano-fluid.

Simulation and experimental analysis of heat transfer characteristics in the plate type heat exchangers using TiO2/water nanofluid

2019 ◽  
Vol 29 (4) ◽  
pp. 1343-1362 ◽  
Author(s):  
Ataollah Khanlari ◽  
Adnan Sözen ◽  
Halil İbrahim Variyenli
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Working Fluid ◽  
Heat Transfer Characteristics ◽  
Content Type ◽  
Plate Heat ◽  
Overall Heat Transfer Coefficient ◽  
Transfer Characteristics

PurposeThe plate heat exchangers (PHE) with small size but large efficiency are compact types of heat exchangers formed by corrugated thin pressed plates, operating at higher pressures when compared to most other traditional exchangers. This paper aims to analyze heat transfer characteristics in the PHE experimentally and numerically.Design/methodology/approachComputational fluid dynamics analysis has been used to simulate the problem by using the ANSYS fluent 16 software. Also, the effect of using TiO2/water nanofluid as working fluid was investigated. TiO2/water nanofluid had 2% (Wt/Wt) nanoparticle content. To improve solubility of the TiO2nanoparticles, Triton X-100 was added to the mixture. The results have been achieved in different working condition with changes in fluid flow rate and its temperature.FindingsThe obtained results showed that using TiO2/water nanofluid improved the overall heat transfer coefficient averagely as 6%, whereas maximum improvement in overall heat transfer coefficient was 10%. Also, theoretical and experimental results are in line with each other.Originality/valueThe most important feature which separates the present study from the literature is that nanofluid is prepared by using TiO2nanoparticles in optimum size and mixing ratio with surfactant usage to prevent sedimentation and flocculation problems. This process also prevents particle accumulation that may occur inside the PHE. The main aim of the present study is to predict heat transfer characteristics of nanofluids in a plate heat exchanger. Therefore, it will be possible to analyze thermal performance of the nanofluids without any experiment.

Experimental Investigation on the Performance of Naphthalene Heat Pipe in Half-Circumferential Heating Method

2010 ◽  
Author(s):  
Yun Liu ◽  
Hong Zhang ◽  
Dongdong Zhan ◽  
Caixia Yin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Carbon Steel ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Filling Ratio ◽  
Circumferential Direction ◽  
Temperature Uniformity ◽  
Heating Method

Based on the characteristics of a carbon steel-naphthalene heat pipe, a new type of medium temperature heat pipe solar receiver has been developed. According to Direct Steam Generation (DSG) with solar parabolic trough concentrators, a simulation experiment is founded which used a new half-circumferential heating method. At the working dip angles 4° and 8°, the working temperature of heat pipe is stabilized at 250°C, 300°C, 350°C, 380°C, respectively. In this article, the temperature uniformity in circumferential direction, thermal resistance and heat transfer coefficient of the carbon steel-naphthalene has been analyzed and studied. The results indicate: the temperature uniformity in circumferential direction is below 20°C. The optimum filling ratio is 30% and when used this filling ratio, the total thermal resistance basically maintained below 0.23°C/W. Heat transfer coefficient increased with the increase of the transfer power. This article serves as a reference to understanding the heat transfer performance of the carbon steel-naphthalene heat pipe in medium soar receiver.

Effect of Wick Characteristics on the Thermal Performance of the Miniature Loop Heat Pipe

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Randeep Singh ◽  
Aliakbar Akbarzadeh ◽  
Masataka Mochizuki
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Working Fluid ◽  
Vapor Flow ◽  
Loop Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Two phase heat transfer devices based on the miniature version of loop heat pipe (LHP) can provide very promising cooling solutions for the compact electronic devices due to their high heat flux management capability and long distance heat transfer with minimal temperature losses. This paper discusses the effect of the wick properties on the heat transfer characteristics of the miniature LHP. The miniature model of the LHP with disk-shaped evaporator, 10 mm thick and 30 mm disk diameter, was designed using copper containment vessel and water as the working fluid, which is the most acceptable combination in electronic cooling applications. In the investigation, wick structures with different physical properties including thermal conductivity, pore radius, porosity, and permeability and with different structural topology including monoporous or biporous evaporating face were used. It was experimentally observed that copper wicks are able to provide superior thermal performance than nickel wicks, particularly for low to moderate heat loads due to their low heat conducting resistance. With monoporous copper wick, maximum evaporator heat transfer coefficient (hev) of 26,270 W/m2 K and evaporator thermal resistance (Rev) of 0.06–0.10°C/W were achieved. For monoporous nickel wick, the corresponding values were 20,700 W/m2 K for hev and 0.08–0.21°C/W for Rev. Capillary structure with smaller pore size, high porosity, and high permeability showed better heat transfer characteristics due to sufficient capillary pumping capability, low heat leaks from evaporator to compensation chamber and larger surface area to volume ratio for heat exchange. In addition to this, biporous copper wick structure showed much higher heat transfer coefficient of 83,787 W/m2 K than monoporous copper wick due to improved evaporative heat transfer at wick wall interface and separated liquid and vapor flow pores. The present work was able to classify the importance of the wick properties in the improvement of the thermal characteristics for miniature loop heat pipes.

scholarly journals Experimental investigation of two-phase thermosyphon heat exchanger charged with acetone

2018 ◽  
Vol 70 ◽  
pp. 02003
Author(s):  
Janusz T. Cieśliński ◽  
Maciej Fabrykiewicz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Thermal Characteristics ◽  
Working Fluid ◽  
Shell Side ◽  
Two Phase ◽  
Overall Heat Transfer Coefficient ◽  
Working Liquid

This paper presents thermal characteristics of prototype of a two-phase thermosyphon heat exchanger (TPTHEx) charged with acetone as a working fluid. The TPTHEx consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. The tested TPTHEx operates in a vacuum. Therefore, the working liquid is boiled in temperatures ranging from 33°C to 62°C. The overall heat transfer coefficient (OHTC) of the tested TPTHEx was estimated by the use of the Wilson method and the modified Peclet equation. The results obtained indicate a superiority of water over acetone as a working fluid. Moreover, it was shown that having a lower pressure in the shell-side of TPTHEx results in a higher overall heat transfer coefficient. The Wilson method and the modified Peclet equation predict OHTC with satisfactory agreement.

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