Heat Transfer Characteristics of a 3-D Printed Pulsating Heat Pipe: Fundamental Experiments Using Water As a Working Fluid

2017 ◽  
Author(s):  
Yasushi Koito ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Cooling Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transient Temperature ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Condenser Section ◽  
Heater Power ◽  
Cooling Water Temperature

This paper describes extended experiments on a pulsating heat pipe (PHP) fabricated by using a 3-D printer and a graphene-laden PLA (PolyLactic Acid) filament. Water was used as a working fluid. To maintain airtightness, the 3-D printed PHP was electroplated by copper since the graphene in the filament allows electric currents to pass through. The PHP had ten square channels. A cross section and a length of the square channel were 1.5 mm × 1.5 mm and 80 mm, respectively. Ends of each channel were connected to form a single serpentine channel. A filling ratio of the working fluid was 50%. In experiments, an evaporator section of the PHP was heated by a heater and a condenser section was cooled using a water-cooling jacket. The heater power was increased stepwise from 2.0 W to 7.0 W while the cooling water temperature and its flow rate were maintained at 4.0 °C and 0.25 LPM, respectively. Transient temperature distributions of the PHP were measured by K-type thermocouples. From the experimental results, steady-state two-phase heat transport operation of the PHP was confirmed for the heater power between 3.0 W and 6.0 W. Moreover, the present experimental results were compared with the previous ones, where ethanol was used as the working fluid. It was also confirmed that the thermal resistance of the PHP with ethanol was slightly smaller than that with water.

Performance of a Pulsating Heat Pipe Fabricated With a 3-D Printer

2017 ◽  
Author(s):  
Yasushi Koito ◽  
Masahiro Kawaji
Keyword(s):  
Heat Pipe ◽  
Two Phase Flow ◽  
Imaging System ◽  
Cooling Water ◽  
Working Fluid ◽  
Transient Temperature ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Condenser Section

A pulsating heat pipe (PHP) was fabricated by a 3-D printer, and its heat transfer characteristics were investigated by experiments. A graphene-laden PLA (PolyLactic Acid) filament was used as a 3-D printing material. Ten square channels having a cross section of 1.5 mm × 1.5 mm and a length of 80 mm were made inside the PHP and the ends of channels were connected. Since the graphene-laden PLA filament allows electric currents to pass through, the 3-D printed PHP was electroplated by copper to maintain its airtightness. Ethanol was used as the working fluid. The filling ratio of the working fluid was 50 %. In experiments, an evaporator section of the PHP was heated by a heater and a condenser section was cooled using a water-cooling jacket. The heater power was changed from 2.0 W to 8.0 W while the cooling water temperature and its flow rate were kept at 4.0 °C and 0.25 LPM, respectively. The transient temperature distribution of the PHP was measured by thermocouples. Moreover, because the graphene-laden PLA is nontransparent, an X-ray imaging system was also employed to observe the two-phase flow phenomena occurring in channels of the PHP. From the experimental results, the continuous heat transport from the evaporator to the condenser section of the PHP was confirmed with vapor-liquid two-phase flow characteristics observed inside the channels.

scholarly journals Experimental Investigation of the Thermal Performance of a Wickless Heat Pipe Operating with Different Fluids: Water, Ethanol, and SES36. Analysis of Influences of Instability Processes at Working Operation Parameters

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 80 ◽  
Author(s):  
Rafal Andrzejczyk
Keyword(s):  
Heat Pipe ◽  
Input Power ◽  
Liquid Pool ◽  
Filling Ratio ◽  
Working Fluid ◽  
Operating Pressure ◽  
Two Phase ◽  
Condenser Section ◽  
Transfer Resistance ◽  
Working Fluids

In this study, the influences of different parameters on performance of a wickless heat pipe have been presented. Experiments have been carried out for an input power range from 50 W to 300 W, constant cooling water mass flow rate of 0.01 kg/s, and constant temperature at the inlet to condenser of 10 °C. Three working fluids have been tested: water, ethanol, and SES36 (1,1,1,3,3-Pentafluorobutane) with different filling ratios (0.32, 0.51, 1.0). The wall temperature in different locations (evaporation section, adiabatic section, and condenser section), as well as operating pressure inside two phase closed thermosyphon have been monitored. The wickless heat pipe was made of 0.01 m diameter copper tube, which consists of an evaporator, adiabatic, and condensation sections with the same length (0.4 m). For all working fluids, a dynamic start-up effect caused by heat conduction towards the liquid pool was observed. Only the thermosyphon filled with SES36 was observed to have operation limitation caused by achieving the boiling limit in TPCTs (two-phase closed thermosyphons). The geyser boiling effect has been observed only for thermosyphon filled with ethanol and for a high filling ratio. The performance of the thermosyphon determined the form of the heat transfer resistance of the TPCT and it was found to be dependent of input power and filling ratio, as well as the type of working fluid and AR (aspect ratio). Comparison with other authors would seem to indicate that lower AR results in higher resistance; however, the ratio of condenser section length to inside diameter of pipe is also a very important parameter. Generally, performance of the presented thermosyphon is comparable to other constructions.

scholarly journals Effect of Filling Ratio on Thermal Characteristics and Performance of a Pulsating Heat Pipe

2019 ◽  
Vol 9 (2) ◽  
pp. 3341-3345
Keyword(s):  
Heat Pipe ◽  
Thermal Characteristics ◽  
Filling Ratio ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Key Factors ◽  
Condenser Section ◽  
Oscillating Heat Pipe ◽  
Bottom Heat ◽  
And Performance

Pulsating heat pipes are complex devices for heat transfer and their optimal thermal performance depends mainly on different parameters. This work is about the thermal efficiency of a closed-loop oscillating heat pipe with a diameter of 2.0 mm and 3.0 copper tube inner and outer. For all experiments, the filling ratio (FR) was used 40%, 50 %,70%,80% and heat inputs of 20W, 40W, 60W, and 80W was provided to PHP. The position of the PHP was vertical bottom heat type. The length of evaporator, adiabatic and condenser section was maintained 52 mm,170mm,60mm. Water and benzene were selected as working fluids. From the available literature it is observed that working fluid and filling ratio are key factors in PHP's performance. The results show that the thermal resistance decreases rapidly with the increase in the heat input to 20 to 40 W., while it decreases gradually over 40 to 80W.Simulation is done in CFD and experimental data were equated to the results.

Thermal Resistance of a Rotating Closed-Loop Pulsating Heat Pipe: Effect of Centrifugal Accelerations

2016 ◽  
Vol 851 ◽  
pp. 292-298
Author(s):  
Niti Kammuang-Lue ◽  
Deuansavanh Phommavongsa ◽  
Kritsada On-Ai ◽  
Phrut Sakulchangsatjatai ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Working Fluid ◽  
Outer Side ◽  
Gravitational Acceleration ◽  
Pulsating Heat Pipe ◽  
Centrifugal Acceleration ◽  
Condenser Section ◽  
Evaporator Section

Objective of this study is to experimentally investigate the effect of centrifugal accelerations on thermal resistance of the rotating closed-loop pulsating heat pipe (RCLPHP). The RCLPHPs were made of a copper tube with internal diameter of 1.50 and 1.78 mm and bent into flower’s petal-shape and arranged into a circle with 11 turns. The evaporator section located at the outer end of the bundle while the condenser section placed around the center of the RCLPHP with no adiabatic section. Both sections had an identical length of 50 mm. R123, and ethanol was filled as working fluid respectively. The RCLPHP was installed on the test rig and it was rotated by the DC motor at the centrifugal acceleration of 0.5, 1, 3, 5, 10, and 20 times of the gravitational acceleration considering at the connection between the evaporator and condenser section. Heat input was generated by electrical annular-plate heaters and varied from 30 to 50, 100, 150, and 200 W. Ceramic papers, wooden plate, and insulation sheet were consecutively attached on the outer side of the heaters in order to prevent the heat loss from the heater. It can be concluded that when the centrifugal acceleration increases, the thermal resistance continuously decreases since the condensate flows back to the evaporator section more rapidly.

Thermal Characteristics of a Three-Dimensional Coil Type Pulsating Heat Pipe at Different Heating Modes

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Satyanand Abraham ◽  
Anand Takawale ◽  
Peter Stephan ◽  
Arvind Pattamatta
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Input ◽  
3D Structure ◽  
Three Dimensional ◽  
Working Fluid ◽  
Coolant Temperature ◽  
Pulsating Heat Pipe ◽  
Condenser Section ◽  
Maximum Heat

Abstract The heat transfer performance of a pulsating heat pipe (PHP) configured as a three-dimensional (3D) structure is reported in the present study. The PHP structure resembles an elongated coil and termed “coil type PHP.” Five different heating modes were created by positioning the evaporator at different locations and placing the PHP device in vertical and horizontal orientations. Studies were conducted primarily with de-ionized water as the working fluid. Limited number of experiments were also performed using binary fluids. The filling ratio was varied from 40% to 80%, while the heat input was varied from 20 W to 240 W. The vertical and horizontal orientations show almost 30 and 10 times reduction in the thermal resistance, respectively, compared with bare PHP tubes without the working fluid. This results in an effective thermal conductivity of more than 3000 W/(m K) and 12,000 W/(m K) for horizontal and vertical orientations, respectively. The use of the binary fluid (10 wt% and 20 wt% of ethanol aqueous solution) results in an increase in the maximum heat input at different heating modes. The temperature of the coolant supplied to the condenser section of the PHP was also varied, and the thermal resistance of the system was observed to reduce with an increase in the coolant temperature.

Fabrication of a Vapor Chamber on a Plastic Board

2015 ◽  
Author(s):  
Fumihiko Hideyama ◽  
Shuto Nonoshita ◽  
Yasushi Koito ◽  
Toshio Tomimura
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Low Cost ◽  
Cooling Water ◽  
Working Fluid ◽  
Liquid Volume ◽  
Transient Temperature ◽  
Vapor Chamber ◽  
Condenser Section ◽  
Phase Change Heat Transfer

A vapor chamber is a flat-plate heat pipe, where a cooled (condenser) section is much larger than a heated (evaporator) section, and has been used as a heat spreader to enhance the cooling of electronic devices. An objective of this study is to integrate the vapor chamber into a polycarbonate board. Plastic materials are easy to manufacturing, light weight, low cost, flexible, and then the present study aims at performing a phase-change heat transfer and a heat spreading inside the polycarbonate board. A sintered copper powder and water are used as a wick structure and a working fluid, respectively. In experiments, the heat is applied by a heater while the cooling water is circulated between a thermostatic bath and a cooling jacket. The experiments are conducted changing a liquid volume and a heat input, and the transient temperature distribution of the vapor chamber is measured by thermocouples. For comparison, the experiment is also conducted where the working fluid is not charged into the vapor chamber. Moreover, based on a thermal resistance network, an analytical model of the vapor chamber is made and the analysis is performed on the phase-change heat transfer inside the vapor chamber. From the experimental and analytical results, the heat transfer characteristics of the polymer-based vapor chamber and the effectiveness of the phase-change heat transfer are confirmed.

Visualization of Two-Phase Flow in 3D Printed Polycarbonate Pulsating Heat Pipe With Aluminum Substrate

2018 ◽  
Author(s):  
Takahiro Arai ◽  
Masahiro Kawaji ◽  
Yasushi Koito
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Two Phase Flow ◽  
Aluminum Plate ◽  
Working Fluid ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Flow Channels ◽  
Heat Transport Capability

A pulsating heat pipe (PHP) is a passive device with a good heat transport capability compared to other heat pipes. This paper describes an experimental investigation of a PHP with a serpentine channel fabricated by using a 3-D printer. The configuration of the flow channels in the PHP was close to that of commercially available PHPs made entirely of aluminum. To improve the heat transport capability and enable flow visualization, an aluminum plate was used on one side as the heat-transfer surface, on which transparent flow channels were fabricated by a 3-D printer and a polycarbonate filament. The interface between the aluminum plate and polycarbonate flow channel was cemented with a heat-resistant glue to ensure long term sealing. HFE-7000 was used as a working fluid. Oscillating two-phase flow in the PHP was observed with a high-speed digital video camera and transient surface temperatures at evaporator, insulator and condenser sections were measured by fine diameter thermocouples. The two-phase flow and thermal characteristics of the PHP at different heater power levels are presented.

scholarly journals Effect of Working Fluid on Thermal Performance of Closed Loop Pulsating Heat Pipe

2019 ◽  
Vol 9 (2) ◽  
pp. 953-956
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Filling Ratio ◽  
Working Fluid ◽  
External Diameter ◽  
Pulsating Heat Pipe ◽  
Condenser Section ◽  
Heat Transfer Efficiency ◽  
Bottom Heat

The pulsing heat pipe (PHP) is an technology that is increasingly capable of applying many manufacturing areas, but a thorough knowledge of its thermo-hydrodynamic There's far from enough system. This research explored the features of oscillation and the heat transfer efficiency of a closed-loop PHP using an internal and external diameter copper tube with 2.0 and 3.0 mm respectively. For all experimentation, filling ratio (FR) was 40%, five turns and different heat inputs of 20 to 80 W was supplied to PHP. The position of the PHP was vertical bottom heat type. 52 mm, 170 mm,60 mm was retained for the duration of the evaporator, adiabatic and condenser section. Water, Ethanol are chosen as working liquids. To understand, thermal resistance features and median evaporator pressures for multiple operating liquids at distinct heat inputs. An significant consideration for the results of PHPs is the research on PHP stated operating fluid. The result demonstrates that, with the rise of the heating output from 20 to 80 W, where as steadily increases above 80W, the thermal resistance reduces faster. By comparing Water , Ethanol working fluids, Ethanol provides the highest heat performance . The simulation is performed in Mat lab and the results have been contrasted

Gravitational effects on electroosmotic flow in micro heat pipes

2019 ◽  
Vol 30 (2) ◽  
pp. 535-556
Author(s):  
Fun Liang Chang ◽  
Yew Mun Hung
Keyword(s):  
Heat Pipe ◽  
Electroosmotic Flow ◽  
Temperature Drop ◽  
Working Fluid ◽  
Vapor Flow ◽  
Two Phase ◽  
Condenser Section ◽  
Content Type ◽  
Micro Heat Pipe ◽  
Gravity Forces

Purpose This paper aims to investigate the coupled effects of electrohydrodynamic and gravity forces on the circulation effectiveness of working fluid in an inclined micro heat pipe driven by electroosmotic flow. The effects of the three competing forces, namely, the capillary, the gravitational and the electrohydrodyanamic forces, on the circulation effectiveness of a micro heat pipe are compared and delineated. Design/methodology/approach The numerical model is developed based on the conservations of mass, momentum and energy with the incorporation of the Young–Laplace equation for electroosmotic flow in an inclined micro heat pipe incorporating the gravity effects. Findings By inducing electroosmotic flow in a micro heat pipe, a significant increase in heat transport capacity can be attained at a reasonably low applied voltage, leading to a small temperature drop and a high thermal conductance. However, the favorably applied gravity forces pull the liquid toward the evaporator section where the onset of flooding occurs within the condenser section, generating a throat that shrinks the vapor flow passage and may lead to a complete failure on the operation of micro heat pipe. Therefore, the balance between the electrohydrodyanamic and the gravitational forces is of vital importance. Originality/value This study provides a detailed insight into the gravitational and electroosmotic effects on the thermal performance of an inclined micro heat pipe driven by electroosmotic flow and paves the way for the feasible practical application of electrohydrodynamic forces in a micro-scale two-phase cooling device.

Developing the Coaxial Dual-Pipe Heat Pipe for Applications on Heat Pipe Cooler

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Chen-Ching Ting ◽  
Chien-Chih Chen
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling Water ◽  
Working Fluid ◽  
Observation Window ◽  
Condenser Section ◽  
Transfer Property ◽  
Heat Transfer Property ◽  
Adiabatic Section ◽  
Pipe Heat

This article presents significant experimental data about the coaxial dual-pipe heat pipe which is invented by our CCT laboratory. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe. A common heat pipe is composed of three sections: the evaporator section at the one end; the condenser section at the other end; and the adiabatic section in between. The vapor and the liquid phases of the working fluid flow in opposite directions through the core and the wick, respectively. This special heat transfer behavior causes a common heat pipe to yield the discrete heat transfer property. In process, the vapor directly brings large amounts of heat from heat source and rapidly flows through the adiabatic section to the condenser section. This intelligent heat transfer technique lets the heat pipe yield extremely large thermal conductivity. Unfortunately, a heat pipe integrated with cooling fin in the adiabatic section has changed its original heat transfer property. The integrated cooling fin in the adiabatic section has in advance taken heat of the vapor away and caused the vapor to be condensed in the adiabatic section. Therefore, the vapor cannot reach the condenser section and the condenser section hence loses its cooling capability. In other words, the effective cooling length of a common heat pipe which is integrated with cooling fin in the adiabatic section is shortened. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe to avoid heat of the vapor to be earlier taken away and even condensed in the adiabatic section. Experimental study in this work first built a home-made square coaxial dual-pipe heat pipe integrated with outside isothermal cycling cooling water as the coaxial dual-pipe heat pipe cooler. The home-made square coaxial dual-pipe heat pipe has an observation window. It is convenient to observe change of the two-phase flow inside the heat pipe influenced by the outside cooling water. The results show that the new developed coaxial dual-pipe heat pipe cooler has kept the original heat transfer property of the bare heat pipe. The vapor has reached the condenser section.

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