Effect of Operational Parameters on the Thermal Performance of Flat Plate Oscillating Heat Pipe

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Kamlesh K. Mehta ◽  
Nirvesh Mehta ◽  
Vivek Patel
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Charge Ratio ◽  
Working Fluid ◽  
Operational Parameters ◽  
Oscillating Heat Pipe ◽  
Transfer Device

Abstract Flat plate oscillating heat pipe (FP-OHP) is a unique heat transfer device and considered as a promising candidate for effective heat transfer device in electronics industries. A number of theoretical studies and experimental investigations have been carried out on FP-OHP in the past decades after its invention. However, due to the operational characteristics of FP-OHP, the effect of various parameters on the thermal performance of FP-OHP has not been completely revealed so far. This paper attempts to discuss the effect of operational parameters on the thermal performance of FP-OHP. In this study, the FP-OHP was investigated with different charge ratios, orientations, working fluids, and heat loads from 10 W to 150 W. In order to investigate the effect, 18 parallel square channels of 2 × 2 mm2 are machined onto pure copper plate (93 × 70 × 8 mm3) to form FP-OHP. DI water, ethanol, methanol, acetone, and FC-72 are investigated. The measured thermal resistance was strongly dependent on operational parameters. The optimum performance was observed with acetone with a charge ratio of 70% in the vertical orientation. The lowest thermal resistance of 0.39 °C/W is achieved using acetone as a working fluid at 100 W. A Kutateladze number (Ku) was used to compare the experimental data and found to be suitable for prediction of the thermal performance of FP-OHP with standard deviation of 15%.

Effect of Filling Ratio on an Uneven Turn Oscillating Heat Pipe

2011 ◽  
Author(s):  
Aaron A. Hathaway ◽  
Hongbin Ma
Keyword(s):  
Experimental Investigation ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Input Power ◽  
Filling Ratio ◽  
Inverted Position ◽  
Oscillating Heat Pipe ◽  
Test Conditions

An experimental investigation of the effect of filling ratio on the thermal performance for a flat plate oscillating heat pipe with uneven turns was conducted. The OHP was designed to have 14 long turns running from the evaporator to the condenser and 6 short turn occurring only in the evaporator. The factors varied for this experimental investigation were the input power, condensing temperature, and charging ratio. Experimental results show that for all test conditions, the OHP functioned very well and could operate with an input power of up to 1200 W and could reach a thermal resistance of 0.028 °C/W in the inverted position with a filling ratio of 70%.

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.

Experimental Investigation of a Flat-Plate Oscillating Heat Pipe With Modified Evaporator and Condenser

2014 ◽  
Author(s):  
M. J. Rhodes ◽  
M. R. Taylor ◽  
J. G. Monroe ◽  
S. M. Thompson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Thermal Performance ◽  
High Heat ◽  
Working Fluid ◽  
High Heat Flux ◽  
Oscillating Heat Pipe ◽  
Lower Heat ◽  
Operating Temperatures

The thermal performance of a flat-plate oscillating heat pipe (FP-OHP) - with modified evaporator and condenser was experimentally investigated during high heat flux conditions. The copper FP-OHP (101.6 × 101.6 × 3.18 mm3) possessed two inter-connected layers of 1.02 mm2 square channels with the evaporator and condenser possessing two parallel, 0.25 × 0.51 mm2 square microchannels. The microchannels were integrated to enhance evaporation and condensation heat transfer to improve the FP-OHP’s ability to transport high heat flux. The FP-OHP was oriented vertically and locally heated with a 14.52 cm2 heating block at its base and cooled with a water block that provided either: 20 °C, 40 °C, or 60 °C operating temperatures. A FP-OHP without embedded microchannels was also investigated for baseline performance comparison. Both FP-OHPs were filled with Novec HFE-7200 (3M) working fluid at a filling ratio of approximately 80% by volume. The maximum temperature of each FP-OHP was recorded versus time for various heat inputs for the investigated operating temperatures. The results indicate that the integrated microchannels enhance the FP-OHP’s thermal performance for all operating temperatures. At 20 °C, 40 °C, and 60 °C, the microchannel-embedded evaporator and condenser dissipated 80 W, 65 W, and 55 W more than the baseline control with a minimum thermal resistance of 0.219 °C/W, 0.205 °C/W, and 0.170 °C/W, respectively — corresponding to a percent enhancement on-the-order of 25%. This percent enhancement increased with operating temperature. It has also been shown that Novec HFE-7200 allows the FP-OHP to start at relatively lower heat inputs — as low as 35 W, demonstrating that this working fluid can enhance heat transfer even at lower heat flux applications.

A Novel Thermal Solution for Electronics: Alumina Flat-Plate Oscillating Heat Pipe

2019 ◽  
Author(s):  
Bohan Tian ◽  
Hongbin Ma ◽  
Yang Deming ◽  
Jiujun Xu ◽  
Zhiyong Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Pipe ◽  
Printed Circuit Boards ◽  
Ct Scanning ◽  
Working Fluid ◽  
Micro Computed Tomography ◽  
Two Phase ◽  
Oscillating Heat Pipe ◽  
Two Phase Cooling

Abstract The heat flux in electronics requires the thermal management of printed circuit boards (PCBs) using two-phase cooling methods. In this study, an integrated ceramic heat transfer device, the alumina flat-plate oscillating heat pipe, is developed. The device was fabricated by pressing and sintering procedures, and the inner serpentine channels were simultaneously formed during sintering without brazing or separated caps. This novel manufacturing process simplifies the fabrication of the macrochannels inside ceramic devices and provides a new method for fabricating ceramic two-phase cooling devices. This paper presents an analysis of the internal channel’s formation mechanism and illustrates the major factors of densification. Micro-computed tomography (Micro-CT) scanning was adopted to assess the macrostructure, and SEM was used to characterize the microstructure of the alumina OHP. Water was charged inside the device as the working fluid. The effects of the power input, orientation, operating temperature and filling ratio on the heat transfer performance were investigated. The experimental results show that the alumina OHP has a high heat transport capability. When the OHP structure is embedded inside the alumina and charged with water, the thermal resistance can be reduced by 97%.

Experimental Investigation of a Three-Phase Oscillating Heat Pipe

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Tingting Hao ◽  
Hongbin Ma ◽  
Xuehu Ma
Keyword(s):  
Heat Transfer ◽  
Liquid Phase ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Solid Phase ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Three Phase

This paper presents an investigation of a three-phase oscillating heat pipe (3P OHP). The working fluid in the OHP consists of phase change material (PCM) and water. During the operation, the PCM changes the phase between solid and liquid, and water changes phase between liquid and vapor. The OHP investigated herein contains three phases: solid, liquid, and vapor. Erythritol was selected as the PCM with an instant cooling effect when dissolved in water due to the high fusion heat of 340 J/g. When the working fluid flows into the evaporator section, the PCM solid phase of the working fluid can become liquid phase in the evaporator, and the PCM liquid phase of the working fluid become solid phase in the condenser. The effects of heat input ranging from 100 to 420 W, and the erythritol concentration ranging from 1 to 50 wt % on the slug oscillations, and the OHP thermal performance was investigated. Experimental results show that while the erythritol can help to increase the heat transfer performance of an OHP, the heat transfer performance depends on the erythritol concentration. With a range of 1–5 wt % concentration of erythritol/water mixtures, a maximum 10% increase in the thermal performance was observed. When the erythritol concentration of erythritol/water mixtures was increased to a range of 10–50 wt %, the thermal performance of OHPs was lower than pure water-filled OHP, and the thermal performance decreased as the erythritol concentration was further increased. In addition, visualization results showed that slug oscillation amplitudes and velocities were reduced in the OHPs with erythritol solution compared with water-filled OHP.

Experimental Investigation of a Flat-Plate Oscillating Heat Pipe With Groove-Enhanced Minichannels

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Matthew J. Rhodes ◽  
Scott M. Thompson
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Heat Pipe ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Working Fluid ◽  
Oscillating Heat Pipe ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Wide Range

Abstract The thermal and capillary performance of a groove-enhanced, or “microchannel-embedded,” flat-plate oscillating heat pipe (MC FP-OHP) was experimentally investigated while varying heating width, orientation, working fluid and operating temperature. The copper MC FP-OHP possessed two layers of 1.02 × 1.02 mm2 square channels, with the center 14 channels possessing two embedded microchannels (0.25 × 0.13 mm2) aligned coaxially with the primary minichannels. A FP-OHP without embedded microchannels, but with deeper minichannels (DC FP-OHP), was also tested for comparison. The FP-OHPs were filled with Novec 7200 or water (both at 80% ± 2% by volume), and the heating widths were varied between full-width and localized configurations: 38.71 cm2 and 14.52 cm2, respectively. Experimental results demonstrate that the MC FP-OHP is significantly less sensitive to operating orientation and can perform with less detriment as heat flux increases. The MC FP-OHP has a lower startup heating requirement and provides more fluid wetting along the FP-OHP structure—which is advantageous for pumping liquid from the evaporator to the condenser. The MC FP-OHP has enhanced convective heat transfer during operation, as it was observed to have similar or lower thermal resistances to that of the DC FP-OHP for a wide range of operating conditions. The groove-enhanced minichannel within the MC FP-OHP also provides for enhanced heat transfer because there being more thin-film evaporation sites and vapor–liquid mixing between the minichannel and microchannels.

scholarly journals Thermal Performance Improvement of the Heat Pipe by Employing Dolomite/Ethylene Glycol Nanofluid

2020 ◽  
Vol 9 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Duygu Yilmaz Aydin ◽  
Metin Gürü ◽  
Adnan Sözen ◽  
Erdem Çiftçi
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Sodium Dodecyl ◽  
Active Agent ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Working Fluid ◽  
Maintenance Cost

In heat transfer applications, heat pipes are widely- preferred because of some characteristics such as low cost, being able to be produced in any size and low maintenance cost make them superior. Moreover, the working fluid to be employed substantially affects the heat transfer characteristics of a heat pipe. In this paper, effects of nanoparticle addition into the ethylene glycol on heat pipe’s thermal performance were analysed experimentally. Every test was done using two variant working fluids, ethylene glycol and dolomite nanoparticles-doped ethylene glycol, respectively. Dolomite nanoparticles (2% by weight) and Sodium Dodecyl Benzene Sulfonate (0.5% by weight) were doped into the ethylene glycol while preparing the dolomite/ethylene glycol nanofluid. After filling in the heat pipe, experiments were realized under changing working conditions. Using experimental data, efficiency and thermal resistance of the heat pipe were examined. Viscosity of the each working fluid was determined. The contact angle –wettability measurements were also performed to specify the effects of surface active agent addition. The obtained findings revealed that nanoparticle inclusion inside the base fluid, i.e. ethylene glycol, improved the thermal performance (efficiency) and decreased the heat pipe’s thermal resistance substantially. ©2020. CBIORE-IJRED. All rights reserved

Experimental and Numerical Simulation for Thermal Investigation of Oscillating Heat Pipe Using VOF Model

2020 ◽  
Vol 38 (1A) ◽  
pp. 88-104
Author(s):  
Anwar S. Barrak ◽  
Ahmed A. M. Saleh ◽  
Zainab H. Naji
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Input ◽  
Cfd Simulation ◽  
Working Fluid ◽  
Maximum Deviation ◽  
Inlet Temperature ◽  
Maximum Heat ◽  
Oscillating Heat Pipe ◽  
Vof Model

This study is investigated the thermal performance of seven turns of the oscillating heat pipe (OHP) by an experimental investigation and CFD simulation. The OHP is designed and made from a copper tube with an inner diameter 3.5 mm and thickness 0.6 mm and the condenser, evaporator, and adiabatic lengths are 300, 300, and 210 mm respectively.  Water is used as a working fluid with a filling ratio of 50% of the total volume. The evaporator part is heated by hot air (35, 40, 45, and 50) oC with various face velocity (0.5, 1, and 1.5) m/s. The condenser section is cold by air at temperature 15 oC. The CFD simulation is done by using the volume of fluid (VOF) method to model two-phase flow by conjugating a user-defined function code (UDF) to the FLUENT code. Results showed that the maximum heat input is 107.75 W while the minimum heat is 13.75 W at air inlet temperature 35 oC with air velocity 0.5m/s. The thermal resistance decreased with increasing of heat input. The results were recorded minimum thermal resistance 0.2312 oC/W at 107.75 W and maximum thermal resistance 1.036 oC/W at 13.75W. In addition, the effective thermal conductivity increased due to increasing heat input.  The numerical results showed a good agreement with experimental results with a maximum deviation of 15%.

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