Experimental Study of Thermal Performance of Nanofluid-Filled and Nanoparticles-Coated Mesh Wick Heat Pipes

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Naveen Kumar Gupta ◽  
Arun Kumar Tiwari ◽  
Subrata Kumar Ghosh
Keyword(s):  
Thermal Resistance ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Physical Vapor Deposition ◽  
Power Input ◽  
Working Fluid ◽  
Physical Vapor Deposition Method ◽  
The Stability ◽  
Stability Issues ◽  
Time Of Operation

The enhancements in thermal performance of mesh wick heat pipe (HP) using TiO2/H2O nanofluid (0.5, 1.0, and 1.5 vol %) as working fluid for different (50, 100, and 150 W) power input were investigated. Results showed maximum 17.2% reduction in thermal resistance and maximum 13.4% enhancement in thermal efficiency of HP using 1.0 vol % nanofluid as compared to water. The wick surface of the HP was then coated with TiO2 nanoparticles by physical vapor deposition method. The experimental investigation had been also carried out on coated wick HP using water as working fluid. Results showed 12.1% reduction in thermal resistance and 11.9% enhancement in thermal efficiency of the HP as compared to uncoated wick HP using water. Temporal deteriorations in thermal performance during prolonged working (2, 4, and 6 months) of HP were also studied. Temporal deterioration in thermal performance of HP filled with nanofluid depends upon the deterioration in thermophysical properties of nanofluids. The deterioration is due to the agglomeration and sedimentation of nanoparticles with respect to the time. Comparative study shows that after a certain time of operation, thermal performance of HP with nanoparticle coated wick superseded that of the HP filled with nanofluid. Therefore, nanoparticle coating might be a good substitute for nanofluid to avoid the stability issues. The present paper provides incentives for further research to develop nanofluids that avoid the encountered sedimentation or agglomeration.

Thermal Performance of an Open Loop Pulsating Heat Pipe With Ferrofluid (Magnetic Nano-Fluid)

2012 ◽  
Author(s):  
Mehdi Taslimifar ◽  
Maziar Mohammadi ◽  
Mohammad Hassan Saidi ◽  
Hossein Afshin ◽  
Mohammad Behshad Shafii ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Inclination Angle ◽  
Open Loop ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Degree Relative ◽  
Nano Fluid ◽  
Transfer Capability

In the present research an experimental investigation is performed to explore the effects of working fluid, heat input, ferrofluid concentration, magnets location, and inclination angle on the thermal performance of an Open Loop Pulsating Heat Pipe (OLPHP). Obtained results show that using ferrofluid can improve the thermal performance and applying a magnetic field on the water based ferrofluid decreases the thermal resistance. It shows that at an inclination angle of the OLPHP to be zero, the thermal performance of the present OLPHP reduces. Best heat transfer capability was achieved at 67.5 degree relative to horizontal axis for all of working fluids. Variation of the magnets location leads to a different thermal resistance in the OLPHP charged with ferrofluid.

A Comprehensive Experimental Investigation of the Performance of Closed-Loop Pulsating Heat Pipes

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
M. Halimi ◽  
A. Abbas Nejad ◽  
M. Norouzi
Keyword(s):  
Thermal Resistance ◽  
Flow Regime ◽  
Thermal Performance ◽  
Closed Loop ◽  
Heat Pipes ◽  
Filling Ratio ◽  
Working Fluid ◽  
Physical Parameters ◽  
Two Phase ◽  
Laboratory Conditions

Closed-loop pulsating heat pipes (CLPHPs) are a new type of two-phase heat transfer devices that can transfer considerable heat in a small space via two-phase vapor and liquid pulsating flow and work with various types of two-phase instabilities so the operating mechanism of CLPHP is not well understood. In this work, two CLPHPs, made of Pyrex, were manufactured to observe and investigate the flow regime that occurs during the operation of CLPHP and thermal performance of the device under different laboratory conditions. In general, various working fluids were used in filling ratios of 40%, 50%, and 60% in horizontal and vertical modes to investigate the effect of thermo-physical parameters, filling ratio, nanoparticles, gravity, CLPHP structure, and input heat flux on the thermal performance of CLPHP. The results indicate that three types of flow regime may be observed given laboratory conditions. Each flow regime exerts a different effect on the thermal performance of the device. There is an optimal filling ratio for each working fluid. The increased number of turns in CLPHP generally improves the thermal performance of the system reducing the effect of the type of the working fluid on the aforementioned performance. The adoption of copper nanoparticles, which positively affect fluid motion, decreases the thermal resistance of the system as much as 6.06–42.76% depending on laboratory conditions. Moreover, gravity brings about positive changes in the flow regime decreasing thermal resistance as much as 32.13–52.58%.

Enhanced Miniature Loop Heat Pipe Cooling System for High Power Density Electronics

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
J. H. Choi ◽  
B. H. Sung ◽  
J. H. Yoo ◽  
C. J. Kim ◽  
D.-A. Borca-Tasciuc
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Power Density ◽  
Thermal Performance ◽  
High Power ◽  
Design Stage ◽  
Working Fluid ◽  
High Power Density ◽  
Graphic Processing Units ◽  
Maximum Heat

The implementation of high power density, multicore central and graphic processing units (CPUs and GPUs) coupled with higher clock rates of the high-end computing hardware requires enhanced cooling technologies able to attend high heat fluxes while meeting strict design constrains associated with system volume and weight. Miniature loop heat pipes (mLHP) emerge as one of the technologies best suited to meet all these demands. Nonetheless, operational problems, such as instable behavior during startup on evaporator side, have stunted the advent of commercialization. This paper investigates experimentally two types of mLHP systems designed for workstation CPUs employing disk shaped and rectangular evaporators, respectively. Since there is a strong demand for miniaturization in commercial applications, emphasis was also placed on physical size during the design stage of the new systems. One of the mLHP system investigated here is demonstrated to have an increased thermal performance at a reduced system weight. Specifically, it is shown that the system can reach a maximum heat transfer rate of 170 W with an overall thermal resistance of 0.12 K/W. The corresponding heat flux is 18.9 W/cm2, approximately 30% higher than that of larger size commercial systems. The studies carried out here also suggest that decreasing the thermal resistance between the heat source and the working fluid and maximizing the area for heat transfer are keys for obtaining an enhanced thermal performance.

scholarly journals Thermal Performance of Micro-Pulsating Heat Pipe

2019 ◽  
Vol 8 (6) ◽  
pp. 2786-2791
Keyword(s):  
Thermal Resistance ◽  
Temperature Profile ◽  
Thermal Performance ◽  
Heat Input ◽  
Computational Study ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Ansys Fluent ◽  
Vof Model ◽  
Flow Circulation

In this study, thermal performance of MPHP is investigated computationally. A case with 0.7mm hydraulic diameter with 7 turns is considered for the study. Simulation is carried out using ANSYS-FLUENT® software by considering water as working fluid with the help of VOF model. Computational study shows the oscillation of fluid inside and formation of new vapor slugs. The heat input is varied from 1.2 W to 4.8 W in the step of 1.2. Flow circulation inside the MPHP is not unidirectional and frequently changes with the pressure disturbance created in the channels. The temperature profile from computational study shows the startup condition is changing with heat input. Thermal resistance of the MPHP decreases with increase in heat input and the corresponding thermal resistance found to be varied from 3.94 to 3.65 K/W.

The Effect of Material Properties on the Thermal Efficiency of the Minto Solar Wheel

1980 ◽  
Vol 102 (2) ◽  
pp. 504-507 ◽  
Author(s):  
S. Lin ◽  
R. Bhardwaj
Keyword(s):  
Thermal Performance ◽  
Thermal Efficiency ◽  
Material Properties ◽  
Working Fluid ◽  
Working Fluids ◽  
Mean Diameter ◽  
The Mean ◽  
The Ideal

The characteristic of the thermal performance of the Minto solar wheel is that its thermal efficiency is strongly dependent on the material properties of the working fluid. For a specified working fluid, the thermal efficiency of the ideal cycle of the Minto solar wheel is dependent only on the mean diameter of the wheel. To study the effect of the material properties of the working fluid on the ideal thermal efficiency, 14 working fluids are selected, and their thermal efficiencies as functions of the mean diameter of the wheel are calculated and compared with each other. Among these fluids, R-12, R-115, R-500, R-22 and R-13B1 achieve better thermal performance than the others.

Experimental Investigation on Thermal Performance of Flat Plate Heat Pipe with Intersected Micro-Grooves

2013 ◽  
Vol 772 ◽  
pp. 480-486 ◽  
Author(s):  
Chen Wang ◽  
Zhong Liang Liu ◽  
Guang Meng Zhang
Keyword(s):  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Radial Direction ◽  
Filling Ratio ◽  
Working Fluid ◽  
Plate Heat ◽  
Inclination Angles ◽  
Flat Plate Heat Pipe

A copper-water flat plate heat pipe with intersected micro-grooves was developed for cooling electronic devices in this paper. The effects of heat flux, working fluid filling ratio and inclination angles on thermal performance of the flat plate heat pipe was tested and investigated. The laboratory tests show the optimal filling ratio of the heat pipe is about 65%. Excellent thermal performance is also observed in unfavorable titled positions including vertical and anti-gravity orientation at 65%. The smallest overall thermal resistance is obtained in horizontal position and the maximal thermal resistance is observed in vertical position. The influence of inclination angles on thermal performance of the heat pipe in both axial direction and radial direction is also investigated. As the heat pipe is tilted, the ability of temperature leveling in radial direction is enhanced, nevertheless, the capacity of heat transfer in radial direction decreased at the same time.

Thermal Characteristics of a Circular Finned Thermosyphon Using Different Working Fluids

2014 ◽  
Vol 575 ◽  
pp. 322-328 ◽  
Author(s):  
Narayanan Alagappan ◽  
Narayanan Karunakaran
Keyword(s):  
Experimental Study ◽  
Ethylene Glycol ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Input ◽  
Base Fluid ◽  
Thermal Characteristics ◽  
Working Fluid ◽  
Two Phase ◽  
Evaporation And Condensation

The two-phase closed thermosyphon (TPCT), which is essentially a gravity-assisted wickless heat pipe, utilizes the evaporation and condensation of the working fluid inside the TPCT to transport heat. This experimental study was carried out to understand the thermal performance of circular finned thermosyphon using nanofluid with alcohol and was analyzed, compared with alcohol and base fluid DI water. The concentration of nanoparticle used in this setup was 110mg/lit of TiO2combined with 0.2 ml of ethylene glycol. The heat input (Q) were 10W, 12W, 14 W and 16 W and the orientation 30°, 45°, 60° and 90°.The results demonstrate that TiO2nanofluid with 0.2 ml of ethylene glycol improves the performance through reduction in thermal resistance by 85.86%.

scholarly journals Analysis on thermal and hydraulic performance of a T-shaped vapor chamber designed for motorcycle led lights

2019 ◽  
Vol 23 (1) ◽  
pp. 137-148 ◽  
Author(s):  
Qifei Jian ◽  
Cong Li ◽  
Li Wang
Keyword(s):  
Thermal Resistance ◽  
Thermal Performance ◽  
Working Fluid ◽  
Large Temperature ◽  
Vapor Chamber ◽  
Cooling Conditions ◽  
Circulation Characteristic ◽  
Large Pressure ◽  
Led Lights ◽  
Heat Loads

Experiment and numerical analyses were conducted to study the thermal performance and circulation characteristic of the working fluid of a T-shaped vapor chamber special designed for the motorcycle LED light. The influences of heat loads and cooling magnitude were experimentally investigated. Results show that both the heat loads and cooling conditions have strong influences on the thermal performance of the vapor chamber, and the thermal resistance in the extended section occupies over 75.8% of the overall thermal resistance of the vapor chamber. Simulation results indicate that large pressure drop occurs along the extended section of the vapor chamber, and causes large temperature difference along the extended section.

scholarly journals Augmentation of the Thermal Efficiency of PTC using CeO2 Nanofluid

2019 ◽  
Vol 9 (1) ◽  
pp. 6268-6272
Keyword(s):  
Thermal Analysis ◽  
Energy Efficiency ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Good Choice ◽  
Working Fluid ◽  
Synthetic Oil ◽  
Smooth Flow ◽  
Heating Water ◽  
Current Scenario

In the current scenario, experts largely focused on mi niaturizing devices and energy efficiency during the development of solar system.In the present study, nanofluid is used as a working fluid to see its effect on the thermal performance of PTC. The Thermal analysis of PTC heating water using CeO2 nanofluids as a working fluid is presented. The experimentation were carried out using cerium oxide nanofluid, water and synthetic oilThe result shows hat CeO2 nanofluid can be a good choice as a working fluid for smooth flow condition to use in PTC rather than water or any other synthetic oil. Experiment result shows, CeO2 - water can increase thermal efficiency by 2.66 times w.r.t water and 1.7 times w.r.t. synthetic oil.

Thermal Performance of Steam Receiver in Tower-Type Solar Power Plants

2017 ◽  
Author(s):  
Kai Yan ◽  
Xiaojiang Wu ◽  
Jianbin Liu
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Solar Power ◽  
Working Fluid ◽  
Receiver Design ◽  
Solar Power Plants ◽  
Performance Calculation

In this paper, the thermal performance of steam receiver in tower-type solar power plants has been performed using the tower-type solar receiver design program developed by Shanghai boiler works Co Ltd. In the program, the integrated effect of three types of heat transfer, i.e. heat conduction, convection and radiation, in the process of heat transfer of receivers has been considered. With integrating the characteristics and the working conditions of receivers of both steam and molten salt, the developed program can be used to perform the thermal performance calculations for the receivers of both working fluids. The proposed program was validated through Solar Two project and the satisfactory results achieve. A steam receiver in a tower-type solar power plant with double superheats is selected as an example for thermal performance calculation. In view of the receiver operating in subcritical status, the thermal performance calculation is carried out for two sections, the one for evaporation and that for superheat. In evaporation section, the working fluid is circulated with a circulating pump at a very high circulating ratio. At the outlet of panels, the qualities of working fluid can reach to maximum about 0.35. Besides, the great difference of qualities of working fluid at the outlet of panels is observed. Even for some pipes of some panels, the working fluid at the outlet is in liquid phase. The distribution of metal temperature at fin end of panels in the evaporation region varies dramatically from place to place and reaches to over 520 °C. In superheat region, the temperature of the outer front crown of tubes is concerned. The highest front point temperature of pipe, which reaches to maximum over 660 °C, is in the middle region of the last parts of the primary superheat pass. The thermal efficiency distribution of the receiver, including the evaporation and the superheat regions, are also performed. The results show that the averaged efficiency is about 86%. Besides, the phenomenon of negative thermal efficiency happens in both two regions. That is because the solar incidence cannot compensate the natural heat loss due to incident radiation reflection, the pipe wall infrared radiation and convective heat loss.

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