An Open Loop Pulsating Heat Pipe for Integrated Electronic Cooling Applications

2013 ◽  
Author(s):  
Daniel Kearney ◽  
Justin Griffin
Keyword(s):  
Heat Pipe ◽  
Open Loop ◽  
Organic Substrate ◽  
Heat Fluxes ◽  
Electronic Cooling ◽  
Electronic Systems ◽  
Pulsating Heat Pipe ◽  
Fill Ratio ◽  
Lower Heat ◽  
Increasing Trends

Increasing trends towards integrated power electronic systems demand advancements in novel, efficient thermal management solutions to cope with the increasing the power density. This paper investigates the performance of a novel open loop pulsating heat pipe embedded in an FR4 organic substrate. The heat pipe and is comprised of 26 parallel minichannels with 13 turns, an average hydraulic diameter of 1.9mm and maximum surface roughness of 2.5μm. The bulk thermal performance of three saturated working fluids — Novec 649, Novec 7200 and Ethanol (99.8%) — is investigated in terms of fill ratio, three angles of orientation, and applied heat fluxes ranging from 0.4 to 2.5W/cm2 at sub-ambient pressures. Novec 649 achieved quasi-stable pulsations at lower heat fluxes due to lower (dp/dT)sat. In addition, the dielectric Novec 649 fluid showed significant potential for integrated heat spreading applications demonstrating heat transfer of up to 176W and thermal resistances as low as 0.25°C/W for a filling ratio of 30% — a 16× improvement to that of a standard dry FR4 substrate.

An Open Loop Pulsating Heat Pipe for Integrated Electronic Cooling Applications

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Daniel Kearney ◽  
Justin Griffin
Keyword(s):  
Heat Pipe ◽  
Open Loop ◽  
Organic Substrate ◽  
Heat Fluxes ◽  
Electronic Cooling ◽  
Electronic Systems ◽  
Pulsating Heat Pipe ◽  
Fill Ratio ◽  
Lower Heat ◽  
Increasing Trends

Increasing trends toward integrated power electronic systems demand advancements in novel, efficient thermal management solutions to cope with the increasing the power density. This paper investigates the performance of a novel open loop pulsating heat pipe embedded in an FR4 organic substrate. The heat pipe is comprised of 26 parallel minichannels, 13 turns with an average hydraulic diameter of 1.7 mm and maximum surface roughness of 2.5 μm. The bulk thermal performance of three saturated working fluids—Novec 649, Novec 7200 and Ethanol (99.8%)—is investigated in terms of fill ratio, three angles of orientation, and applied heat fluxes ranging from 0.4 to 2.5 W/cm2 at subambient pressures. Novec 649 achieved quasi-stable pulsations at lower heat fluxes compared to Novec 7200 and Ethanol (99.8%). In addition, the dielectric Novec 649 fluid showed significant potential for integrated heat spreading applications demonstrating heat transfer of up to 176 W and thermal resistances as low as 0.25 °C/W for a filling ratio of 30%—16 times greater than that of a standard dry FR4 substrate

Effects of Working Fluid, Fill Ratio and Orientation on Looped and Unlooped Pulsating Heat Pipes

2005 ◽  
Author(s):  
Kathryn Nikkanen ◽  
Christian G. Lu ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Rectangular Channel ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Fill Ratio ◽  
Triangular Channel ◽  
Horizontal Orientation

Improved miniaturization and a trend towards increasingly dense and compact architectures have led to unmanageably high heat fluxes in electronic components. In order to keep temperatures at operational levels more advanced cooling solutions are being required that go beyond the solid heat sink and forced convection. Pulsating heat pipes made out of multi port extrusion tubing are a proposed solution. Typically, gas-liquid slug flow occurs in the serpentine channel imbedded in the pulsating heat pipe. Vapour is produced in the heated section and condensed in the cooled section located at opposite ends of the heat pipe. In this work, experiments were conducted on four Multi-Port Extruded (MPE) aluminum tubing heat pipes with different internal structures: rectangular channel looped, rectangular channel unlooped, triangular channel looped, and triangular channel unlooped. The effect of changing the working fluid (ethanol or de-ionized water), fill ratio, and orientation were measured and compared for the different heat pipes. It was found that most of the heat pipes performed better with ethanol than de-ionized water. Only the looped rectangular channel heat pipe performed satisfactorily with de-ionized water, which is attributed both to the larger channel size and the looped architecture. The unlooped heat pipes performed best at the lowest fill ratios (10%) while the looped heat pipes showed their best performances between 30 and 50% with marked decrease at the lower and higher fill ratios. Both looped heat pipes performed poorly in horizontal orientation as compared to vertical, however, the unlooped heat pipes performed quite well in both orientations. This may be more the effect of the fill ratio on horizontal performance as literature suggests that horizontal orientation requires a lower fill ratio to perform satisfactorily.

scholarly journals Effect of Fin and Insert on the Performance Characteristics of Open Loop Pulsating Heat Pipe (OLPHP)

2015 ◽  
Vol 105 ◽  
pp. 105-112 ◽  
Author(s):  
M. Lutfor Rahman ◽  
Fariha Mir ◽  
Sumaiya Nawrin ◽  
R.A. Sultan ◽  
Mohammad Ali
Keyword(s):  
Heat Pipe ◽  
Open Loop ◽  
Performance Characteristics ◽  
Pulsating Heat Pipe

Effects of Surface Coating of Nanoparticles on Thermal Performance of Open Loop Pulsating Heat Pipes

2012 ◽  
Author(s):  
Mehdi Taslimifar ◽  
Maziar Mohammadi ◽  
Ali Adibnia ◽  
Hossein Afshin ◽  
Mohammad Hassan Saidi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Surface Coating ◽  
Heat Pipes ◽  
Open Loop ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Performance Of Heat Transfer

Homogenous dispersing of nanoparticles in a base fluid is an excellent way to increase the thermal performance of heat transfer devices especially Heat Pipes (HPs). As a wickless, cheap and efficient heat pipe, Pulsating Heat Pipes (PHPs) are important candidates for thermal application considerations. In the present research an Open Loop Pulsating Heat Pipe (OLPHP) is fabricated and tested experimentally. The effects of working fluid namely, water, Silica Coated ferrofluid (SC ferrofluid), and ferrofluid without surface coating of nanoparticles (ferrofluid), charging ratio, heat input, and application of magnetic field on the overall thermal performance of the OLPHPs are investigated. Experimental results show that ferrofluid has better heat transport capability relative to SC ferrofluid. Furthermore, application of magnetic field improves the heat transfer performance of OLPHPs charged with both ferrofluids.

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.

Experimental Characterization of an Open Loop Pulsating Heat Pipe Cooler

2014 ◽  
Author(s):  
Daniele Torresin ◽  
Mathieu Habert ◽  
Francesco Agostini ◽  
Bruno Agostini ◽  
Violette Mounier
Keyword(s):  
Heat Pipe ◽  
Heat Load ◽  
Low Cost ◽  
Fluid Pressure ◽  
Electronics Cooling ◽  
Open Loop ◽  
Air Cooling ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Term Operation

Pulsating heat pipes (PHP) have emerged in the last years as suitable cooling devices for dissipating the high heat loads generated by electronic devices since they allow to extend the applicability of air cooling in area nowadays covered by water cooling. Two-phase cooling technologies based on the two phase pulsating heat pipe principle are promising solutions because, being entirely passive they can comply with long term operation without maintenance. The main advantage of a PHP compared to conventional thermosyphon technologies for electronics cooling is that a PHP is orientation independent. The authors has developed a novel, compact, and low cost PHP based on automotive technology. The present paper presents the experimental results of an air cooled open loop pulsating heat pipe with optimized manifold design to minimize fluid pressure drops in the fluid turns. The effect of several parameters including filling ratio and heat load are presented. Tests have been done with the refrigerant fluid R245fa in vertical and horizontal orientations. The measurements showed a maximum thermal resistance ranging between 40 and 48 K/kW in vertical and horizontal position respectively for a heat load of 2 kW and air temperature of 20 °C.

Experimental Study on Flow Visualizing and Heat Transfer Characteristic of Pulsating Heat Pipe

2007 ◽  
Author(s):  
Li Jia ◽  
Dayan Yin
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Flow Patterns ◽  
Bulk Flow ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Transition Flow ◽  
Fill Ratio

The flow of looped pulsating heat pipe was studied by a visualizing experiment, and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The experimental results indicate that bulk flow, transition flow and annular flow are the major flow patterns in PHP. Under different fill ratios and heat transfer rate, the flow pattern in PHP is transferred form bulk flow to semi-annual flow and annual flow, and the performance of heat transfer is improved. In the experiment, nuclear boiling, the convergence and break up of liquid-plug and vapor-slug were observed. The influence characterization has been done for the variation of fill ration, heat transfer rate, non-condensable gas and inclination angle. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%; the heat resistance is decreased with heat transfer rate, and non-condensable gas also has significant influence on it. The temperature of tubes in heating, condensing and observe sections were recorded, The fluctuation of heat pipe wall temperature was analysed, and the phenomena of suddently increase or decrease of temperature, the unregular fluctuation of temperature were analyzed. Otherwise the response time under different conditions was also analyzed.

Experimental Research on Heat Transfer Characteristics of Pulsating Heat Pipe

2008 ◽  
Author(s):  
Li Jia ◽  
Yan Li
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Experimental Research ◽  
Transfer Rate ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Fill Ratio ◽  
Transfer Characteristics

Experimental research was conducted to understand heat transfer characteristics of pulsating heat pipe in this paper. The PHP is made of high quality glass capillary tube. The heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage under different fill ratio. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appeares in top heating condition. The flow pattern in PHP is transferred form bulk flow to semi-annual flow and annual flow, and the performance of heat transfer is improved for down heating case under different fill ratios and heat transfer rate. The experimental results show that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

Thermal performance of an open loop closed end pulsating heat pipe

2011 ◽  
Vol 48 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Manabendra Saha ◽  
C. M. Feroz ◽  
F. Ahmed ◽  
T. Mujib
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Open Loop ◽  
Pulsating Heat Pipe

Heat Transfer Enhancement of Planar Pulsating Heat Pipe Device

2006 ◽  
Author(s):  
Qingjun Cai ◽  
Chung-Lung Chen ◽  
Julie F. Asfia
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Printed Circuit Boards ◽  
Longitudinal Direction ◽  
High Heat ◽  
Electronic Cooling ◽  
Circuit Boards ◽  
Pulsating Heat Pipe ◽  
Evaporator Temperature ◽  
Key Factor

Heat pipes are widely used heat transfer devices in the electronic cooling area. In this paper, a novel pulsating heat pipe (PHP) design, which combines features of PHP and capillary microstructures, is presented to enhance heat transfer of electronic printed circuit boards (PCB). Test prototype fabrication is initiated by making dual-radius serpentine channels on a 4.0mm thick aluminum plate, followed by compressing 4.67mm diameter copper tube into the grooves, and completed by generating a millimeter sized liquid channel with micro-grooves in the PHP along the longitudinal direction. Because of this design, the planar PHP is able to circulate operating liquid by both capillary pump and oscillation motions, which eliminate the dry state in the evaporator section and supply sufficient coolant at high heat loads. Demonstrations of heat transfer performance indicate that the planar PHP has high effective thermal conductivity and low evaporator temperature fluctuations, and oscillation continuity is the key factor to reduce the temperature difference between the evaporator and condenser.

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