Effect of Hydrophilic Nanostructured Cupric Oxide Surfaces on the Heat Transport Capability of a Flat-Plate Oscillating Heat Pipe

With a surface treatment of hydrophilic cupric oxide (CuO) nanostructures on the channels inside a flat-plate oscillating heat pipe (FP-OHP), the wetting effect on the thermal performance of an FP-OHP was experimentally investigated. Three FP-OHP configurations were tested: (1) evaporator treated, (2) condenser treated, and (3) untreated. Both evaporator- and condenser-treated FP-OHPs show significantly enhanced performance. The greatest improvement was seen in the condenser-treated FP-OHP, a 60% increase in thermal performance. Neutron imaging provided insight into the fluid dynamics inside the FP-OHPs. These findings show that hydrophilic nanostructures and their placement play a key role in an OHP's performance.

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An Experimental Investigation of an Oscillating Heat Pipe Heat Spreader

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4026815 ◽

2015 ◽

Vol 7 (2) ◽

Cited By ~ 6

Author(s):

F. F. Laun ◽

H. Lu ◽

H. B. Ma

Keyword(s):

Flat Plate ◽

Heat Pipe ◽

Heat Transport ◽

Power Input ◽

Heat Spreader ◽

Oscillating Heat Pipe ◽

Test Configuration ◽

Central Heating ◽

Center Section ◽

Heat Transport Capability

With ever increasing technological advances in electronics, modern computer components continue to produce higher power densities that present a challenge to thermal management. A radial flat-plate oscillating heat pipe (RFP-OHP) heat spreader is investigated to study the effect of central heating on the heat transport capability in an OHP. The investigated OHP has dimensions of 100 mm × 100 mm × 2.5 mm with central heating using a 30 mm × 30 mm heater. Experimental results show that when heat is added to the center section of one side of the radial flat-plate OHP, and when heat is removed from the whole surface of another side of the heat pipe, the startup power for the oscillating motion increases. In addition, the spacer effect on the heat transport capability including the startup is investigated experimentally. The spacer added between the cooling block and OHP could lower the startup power for oscillatory motion. When compared to a copper slab of the same dimensions in the same test configuration, the temperature difference for the OHP with and without the additional copper spacer was reduced by a maximum of 46% and 25%, respectively, at a power input of 525 W and a heat flux of 58 W/cm2.

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Experimental Investigation of Ultrasonic Frequency Effect on an Oscillating Heat Pipe

Volume 2: Micro/Nano-Thermal Manufacturing and Materials Processing; Boiling, Quenching and Condensation Heat Transfer on Engineered Surfaces; Computational Methods in Micro/Nanoscale Transport; Heat and Mass Transfer in Small Scale; Micro/Miniature Multi-Phase Devices; Biomedical Applications of Micro/Nanoscale Transport; Measurement Techniques and Thermophysical Properties in Micro/Nanoscale; Posters ◽

10.1115/mnhmt2016-6497 ◽

2016 ◽

Author(s):

Nannan Zhao ◽

Benwei Fu ◽

Hongbin Ma ◽

Fengmin Su

Keyword(s):

Heat Transfer ◽

Heat Pipe ◽

Heat Transport ◽

Frequency Effect ◽

Ultrasonic Frequency ◽

Sound Effect ◽

Oscillating Heat Pipe ◽

Ultrasonic Sound ◽

Heat Transfer Capacity ◽

Heat Transport Capability

The heat transport capability in an oscillating heat pipe (OHP) significantly depends on the oscillating frequency. An external frequency directly affects the natural frequency in the system. In this investigation, the ultrasound sound effect on the heat transport capability in an OHP was conducted with focus on the ultrasonic frequency effect on the oscillating motion and heat transfer capacity in an OHP. The ultrasonic sound was applied to the evaporating section of the OHP by using the electrically-controlled piezoelectric ceramics. The heat pipe was tested with or without the ultrasonic sound with different frequencies. In addition, the effects of operating temperature, heat load from 25 W to 150 W were investigated. The experimental results demonstrate that the heat transfer capacity enhancement of the OHP depends on the frequency of the ultrasound field, and there exists an optimum combination of the frequencies which will lead to the largest enhancement of the heat transfer capacity of the OHP.

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Experimental investigation of the thermal performance of closed loop flat plate oscillating heat pipe

Experimental Heat Transfer ◽

10.1080/08916152.2020.1718802 ◽

2020 ◽

Vol 34 (1) ◽

pp. 85-103 ◽

Cited By ~ 3

Author(s):

Kamlesh Mehta ◽

Nirvesh Mehta ◽

Vivek Patel

Keyword(s):

Experimental Investigation ◽

Flat Plate ◽

Heat Pipe ◽

Thermal Performance ◽

Closed Loop ◽

Oscillating Heat Pipe

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An Experimental Investigation of Three-Dimensional Flat-Plate Oscillating Heat Pipe

Volume 3: Combustion, Fire and Reacting Flow; Heat Transfer in Multiphase Systems; Heat Transfer in Transport Phenomena in Manufacturing and Materials Processing; Heat and Mass Transfer in Biotechnology; Low Temperature Heat Transfer; Environmental Heat Transfer; Heat Transfer Education; Visualization of Heat Transfer ◽

10.1115/ht2009-88180 ◽

2009 ◽

Author(s):

Scott M. Thompson ◽

Hongbin Ma ◽

Robert A. Winholtz ◽

Corey Wilson

Keyword(s):

Experimental Investigation ◽

Flat Plate ◽

Heat Pipe ◽

Three Dimensional ◽

Neutron Imaging ◽

Heat Fluxes ◽

Working Fluid ◽

Oscillating Heat Pipe ◽

Oscillatory Pattern ◽

Thermal Oscillations

An experimental investigation on the effects of condenser temperatures, heating modes and heat inputs on a miniature, three dimensional flat-plate oscillating heat pipe (3D FP-OHP) was conducted visually and thermally. The 3D FP-OHP was charged with acetone at a filling ratio of 0.80, had dimensions of 101.60 × 63.50 × 2.54 mm3, possessed 30 total turns, and had square channels on both sides of the device with a hydraulic diameter of 0.762 mm. Unlike traditional flat-plate designs, this new three-dimensional, compact design allows for multiple heating arrangements and higher heat fluxes. Transient and steady-state temperature measurements were collected at various heat inputs and the activation/start-up was clearly observed for both bottom and side heating modes during reception of its excitation power for this miniature 3D FP-OHP. The neutron imaging technology was simultaneously employed to observe the internal working fluid flow for all tests directly through the heat pipe’s copper wall. The activation was accompanied with a pronounced temperature field relaxation and the onset of chaotic thermal oscillations — all occurring with the same general oscillatory pattern at locations all around the 3D FP-OHP. Qualitative and quantitative analysis of these thermal oscillations, along with the presentation of the average temperature difference and thermal resistance, for all experimental conditions are provided. The novelty of the three-dimensional OHP design is its ability to still produce the oscillating motions of liquid plugs and vapor bubbles and, more importantly, its ability to remove higher heat fluxes.

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Experimental Investigation of a Three-Layer Oscillating Heat Pipe

Journal of Heat Transfer ◽

10.1115/1.4026217 ◽

2014 ◽

Vol 136 (5) ◽

Cited By ~ 17

Author(s):

C. D. Smoot ◽

H. B. Ma

Keyword(s):

Thermal Conductivity ◽

Experimental Investigation ◽

Heat Pipe ◽

Effective Thermal Conductivity ◽

Heat Transport ◽

Total Power ◽

Oscillating Heat Pipe ◽

Layer Effect ◽

Layering Effect ◽

Heat Transport Capability

An experimental investigation of a compact, triple-layer oscillating heat pipe (OHP) has been conducted to determine the channel layer effect on the heat transport capability in an OHP. The OHP has dimensions 13 mm thick, 229 mm long, and 76 mm wide embedded with two-independent closed loops forming three layers of channels. The unique design of the investigated OHP can be readily used to explore the channel layering effect on the heat transport capability in the OHP. The experimental results show that the addition of channel layers can increase the total power and at the same time, it can increase the effective thermal conductivity of the OHP. When the OHP switches from one layer of channels to two layers of channels, the highest effective thermal conductivity can be increased from 5760 W/mK to 26,560 W/mK. At the same time, the dryout limit can be increased. With three layers of channels, the OHP investigated herein can transport a power up to 8 kW with a heat flux level of 103 W/cm2 achieving an effective thermal conductivity of 33,170 W/mK.

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Effect of Filling Ratio on an Uneven Turn Oscillating Heat Pipe

Volume 10: Heat and Mass Transport Processes, Parts A and B ◽

10.1115/imece2011-63614 ◽

2011 ◽

Cited By ~ 1

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%.

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