scholarly journals FLAT PLATE PULSATING HEAT PIPES WITH DIFFERENT CHANNEL GEOMETRIES FOR HIGH HEAT FLUX APPLICATIONS

2021 ◽  
Vol 20 (1) ◽  
pp. 12
Author(s):  
L. Krambeck ◽  
K. G. Domiciano ◽  
L. A. Betancur-Arboleda ◽  
M. B. H. Mantelli
Keyword(s):  
Flat Plate ◽  
Low Cost ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
The Novel ◽  
Heat Loads ◽  
Round Channel

The thermal performance of flat plate pulsating heat pipes with differentchannel geometries was performed in this experimental work. The testswere accomplished with two channel profiles, round and grooved. One ofthe channel geometries, located on the evaporator, can be considered novel,consisting of a round channel with two lateral grooves. Diffusion bondingtechnology was used to manufacture the PHPs made of two copper flatplates. Distilled water was used as the working fluid with a filling ratio of50% (17.9 ml) of the total volume. The pulsating heat pipes were tested atone position (vertical) under heat loads from 20 up to 2000 W. Theexperimental results showed that both flat plate pulsating heat pipesoperates successfully for high heat fluxes. The lateral grooves reduced thethermal resistance, being principally efficient in lower loads. Besides that,the novel channel considerably anticipated the operation startup. Therefore,a much better performance was obtained by the grooved channel PHP,which was constructed from a simple, low cost modification of thefabrication process.

FLAT PLATE PULSATING HEAT PIPES WITH DIFFERENT CHANNEL GEOMETRIES FOR HIGH HEAT FLUX APPLICATIONS

2020 ◽  
Author(s):  
Larissa Krambeck ◽  
Kelvin Guessi Domiciano ◽  
Luis Alonso Betancur Arboleda ◽  
Marcia Mantelli
Keyword(s):  
Heat Flux ◽  
Flat Plate ◽  
Heat Pipes ◽  
High Heat ◽  
High Heat Flux

Thermal Management of a Heat-Pipe Drill: A FEM Analysis

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Rajendra Jadhav
Keyword(s):  
Finite Element ◽  
Heat Pipe ◽  
Thermal Management ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Drilling Process ◽  
Generation Process ◽  
Finite Element Software

Thermal management using heat pipes is gaining significant attention in past decades. This is because of the fact that it can be used as an effective heat sink in very intricate and space constrained applications such as in electronics cooling or turbine blade cooling where high heat fluxes are involved. Extensive research has been done in exploring various possible applications for the use of heat pipes as well as understanding and modeling the behavior of heat pipe under those applications. One of the possible applications of heat pipe technology is in machining operations, which involves a very high heat flux being generated during the chip generation process. Present study focuses on the thermal management of using a heat pipe in a drill for a drilling process. To check the feasibility and effectiveness of the heat pipe drill, structural and thermal analyses are performed using Finite Element Analysis. Finite Element Software ANSYS was used for this purpose. It is important for any conceptual design to be made practical and hence a parametric study was carried out to determine the optimum geometry size for the heat pipe for a specific standard drill.

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.

Forced Convection Boiling in Microchannels for Improved Heat Transfer

2006 ◽  
Author(s):  
Thomas B. Baummer ◽  
Ebrahim Al-Hajri ◽  
Michael M. Ohadi ◽  
Serguei V. Dessiatoun
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Surface Areas ◽  
Feed Pressure ◽  
Wide Range

This paper presents experimental results from research investigating the heat transfer capabilities of microchannel surfaces using a novel force-fed boiling and evaporation technique. The evaporative surfaces being investigated consist of a series of parallel, high-aspect ratio, open topped microchannels. The different sample surfaces vary in channel density, channel aspect ratio, and channel width and have heat transfer surface areas up to ten times their nominal surface areas. Liquid enters the channels of the evaporative surface from above through a developed system of feed channels. This method organizes a liquid-vapor circulation at the boiling surface that results in dissipation of very high heat fluxes in the boiling/thin film evaporation mode. By using the force-fed boiling technique, nominal area heat transfer rates of 100,000 W/m2-K have been achieved with HFE-7100 as the working fluid [1]. In force-fed boiling, the many very short microchannels are working in parallel; therefore the feed pressure and pumping power are very low. This technique may prove valuable to a wide range of heat transfer applications, particularly for heat removal at high heat flux surfaces.

Heat Transfer and Hydraulic Characteristics of Cooling Water in a Flat Plate Heat Sink for High Heat Flux IGBT

2016 ◽  
Author(s):  
Chang-Nian Chen ◽  
Ji-Tian Han ◽  
Wei-Ping Gong ◽  
Tien-Chien Jen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Heat Sink ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Plate Heat

High heat flux is very dangerous for electronic heat transfer, such as IGBT (Insulated Gate Bipolar Transistor) cooling. In order to explore and master the heat transfer and hydraulic characteristics for IGBT cooling, experiments have been carried out to study the situation mentioned above in a flat plate heat sink, which was designed for high heat flux IGBT cooling. The geometrical parameters of the test section are as follows: outline dimension 229 mm × 124 mm × 30 mm; flow channels of 229 mm × 3 mm × 4 mm in total of 20. The experiments performed at atmospheric pressure and with inlet temperatures of 25–35°C, heat fluxes of 3.5–18.9 kW/m2. The influence of temperatures, heat fluxes on IGBT surface temperature and the cooling effect of the liquid cold plate have been investigated under a range of flow rates of 280–2300 kg/m2s. It was found that the heat transfer enhancement was very obvious using this kind of small sized channel for IGBT cooling, which was tens of times of the effect than air cooling or triple of the effect than that in normal sized channels. And the heat transfer enhancement increases with increasing heat fluxes and flow rates, while it decreases with increasing inlet temperatures. Most of the experimental results show good cooling effect as expected. However, it is dangerous for the cooling system under high heat fluxes when the system starts or stops suddenly, when the Respond Time (RT) is less than 5 seconds to cut off heated power. Also, the cooling performance is bad when the heat fluxes increased greatly, which is considered as abnormal situation in operating. The effect on IGBT surface temperature of heat flux is more obvious when the average Nusselt Number is smaller. For hydraulic characteristics observed, it was found that the flow friction increased with flow rates increasing, but the pressure drops of heated flow channels ahead were slightly larger than those back, especially under large flow rates conditions. That is because the temperatures of flow heated in channels ahead are lower than those back, which causes the fluid viscosity to be higher. At last, this paper suggested a series of method for enhancing heat transfer in flat plate heat sink, and also gave some ways to avoid heat transfer dangerous situations for IGBT cooling, which can provide a basis for thermodynamic and hydraulic calculation of flat plate heat sink design and lectotype.

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.

Integrated Flat Plate Heat Pipe-Pulsation Heat Pipe for the High-Flux Electronics Cooling

2014 ◽  
Vol 960-961 ◽  
pp. 389-393
Author(s):  
Ya Ping Zhang ◽  
J.G. Wang
Keyword(s):  
Flat Plate ◽  
Heat Pipe ◽  
Electronics Cooling ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Electronic Components ◽  
Plate Heat ◽  
Effective Combination ◽  
Flat Plate Heat Pipe

A trend towards increasingly dense and compact architectures has led to unmanageably high heat fluxes in electronic components. A novel heat pipe will be developed. Heat pipe designed is based on the flat plate heat pipe and pulsation heat pipe effective combination. Channel quantity is greatly increased ,as well as compact and homogeneous red copper pulsation plank is severed as the wick，dense and connected channels are served as the passage of the working fluid.

Utilization of Advanced Working Fluids With Biporous Evaporators

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Sean W. Reilly ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Operating Temperature ◽  
Temperature Drop ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Inorganic Aqueous Solution ◽  
Operating Temperature Range

A novel fluid for use as a working fluid in a heat pipe has been tested at UCLA. The fluid was discovered originally in use with a device consisting of a metal tube charged with the patented inorganic aqueous solution (IAS), which is evaporated when the tube is evacuated before use. According to the patent, this evaporation leaves a thin film that allows the tube to carry high heat flux loads with low temperature drop across the tube in a solid state mode. However, various experiments with these tubes have produced inconsistent results, and there are some questions as to whether the fluid is completely evaporated. The research on which this work is based is focused on testing whether the charging fluid will operate as the working fluid in a heat pipe, in order to determine the nature of the IAS fluid. A heat pipe apparatus was charged with a biporous wick in order to investigate if the fluid plays a role in heat transfer. There are extensive data for this experiment using water as the working fluid, which will be used to compare the two sets of results. Testing has shown a reduction of the superheat required to drive heat fluxes through a wick compared to water by approximately 40%. Some experiments have shown that the operating (temperature) range of the IAS is much larger than a standard heat pipe. It is theorized that the increase in performance of the IAS is due to an increased thermal conductivity of the wick and increased capillarity. If this fluid is proven to be effective, it would lead to more effective and tunable heat transfer devices.

Utilization of Advanced Working Fluids in Heat Pipes

2011 ◽  
Author(s):  
Sean W. Reilly ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Temperature Drop ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Inorganic Aqueous Solution ◽  
Positive Results ◽  
Operating Temperature Range

A novel fluid for use as a working fluid in a heat pipe has been tested at UCLA. The fluid was discovered originally in use with a device consisting of a metal tube charged with the patented inorganic aqueous solution (IAS) which is evaporated when the tube is evacuated before use. According to the patent, this evaporation leaves a thin film which allows the tube to carry high heat flux loads with low temperature drop across the tube in a solid state mode. However, various experiments with these tubes have produced inconsistent results and there is some question as to whether the fluid is completely evaporated. The research on which this work is based, is focused on testing whether the charging fluid will operate as the working fluid in a heat pipe, in order to determine the nature of the IAS fluid. We charged a heat pipe apparatus with a biporous wick in order to investigate if the fluid plays a role in heat transfer. We have extensive data for this experiment using water as the working fluid which will use to compare the two sets of results. Testing has shown positive results in the reduction of the superheat required to drive heat fluxes through a wick compared to water. Some experiments have shown that the operating (temperature) range of the IAS is much larger than a standard heat pipe. It is theorized that the increase in performance of the IAS is due to an increased heat of vaporization. If this fluid is proven to be effective, it would lead to more effective and tunable heat transfer devices.

Loop Thermosyphon Design for Cooling of Large Area, High Heat Flux Sources

2007 ◽  
Author(s):  
John R. Hartenstine ◽  
Richard W. Bonner ◽  
Jared R. Montgomery ◽  
Tadej Semenic
Keyword(s):  
Saturation Temperature ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Working Fluid ◽  
High Heat Flux ◽  
Flow Loop ◽  
Large Area ◽  
Two Phase ◽  
Porous Wick

Two-phase flow loop technologies capable of acquiring high heat fluxes (>1kW/cm2) from large area heat sources (10cm2) are being considered for the next generation naval thermal requirements. A loop thermosyphon device (∼1 meter tall) was fabricated and tested that included several copper porous wick structures in cylindrical evaporators. The first two were standard annular monoporous and biporous wick designs. The third wick consists of an annular evaporator wick and an integral secondary slab wick for improved liquid transport. In this configuration a circular array of cylindrical vapor vents are formed integral to the primary and secondary transport wick composite. Critical heat fluxes using these wick structures were measured between 240W/cm2 and 465W/cm2 over a 10cm2 area with water as the working fluid at 70°C saturation temperature. A thermosyphon model capable of predicting flow rate at various operating conditions based on a separated flow model is presented.

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