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.

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.

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.

Liquid Film Thickness of Oscillating Flow in a Micro Tube

2011 ◽  
Author(s):  
Youngbae Han ◽  
Naoki Shikazono ◽  
Nobuhide Kasagi
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Two Phase Flow ◽  
Liquid Film Thickness ◽  
Working Fluid ◽  
Oscillating Flow ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Flow Systems

Oscillating flow is encountered frequently in many two-phase flow systems such as pulsating heat pipe, refrigerator with reciprocating compressor, etc. Thickness of liquid film formed between the tube wall and the vapor bubble is one of the crucial parameters to develop two-phase flow systems using micro tubes. However, liquid film formation and variation of oscillating flows are very complicated phenomena coupled with acceleration, deceleration, evaporation, condensation, etc. In the previous research, liquid film thickness in accelerating flow under adiabatic conditions was measured and compared with the correlation developed under steady condition [5]. In the present study, liquid film thickness in decelerating flow in a micro tube is investigated under adiabatic condition. Circular tubes with diameter, D = 1.0 mm, is used. Laser focus displacement meter is used to measure the liquid film thickness. Two-phase flow is obtained by introducing air from the open end of the test tube. Ethanol is used as a working fluid. At small capillary numbers, the effect of deceleration is negligible similar to the trend under accelerated condition. As capillary number increases, liquid film thicknesses in decelerated conditions become larger than the predictions of adiabatic steady correlation. However, liquid film thickness does not exceed the critical thickness at Re > Recrit. It is considered that liquid film thickness is affected by the altered velocity profiles in the liquid slug ahead of air-liquid interface according to accelerated or decelerated condition.

scholarly journals Infrared analysis of the two phase flow in a single closed loop pulsating heat pipe

2018 ◽  
Vol 97 ◽  
pp. 304-312 ◽  
Author(s):  
Daniele Mangini ◽  
Marco Marengo ◽  
Lucio Araneo ◽  
Mauro Mameli ◽  
Davide Fioriti ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Closed Loop ◽  
Two Phase Flow ◽  
Infrared Analysis ◽  
Phase Flow ◽  
Pulsating Heat Pipe ◽  
Two Phase

Flow and heat transfer in a closed loop thermosyphon. Part I – theoretical simulation

2007 ◽  
Vol 18 (4) ◽  
pp. 32-40 ◽  
Author(s):  
R.T. Dobson ◽  
J.C. Ruppersberg
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Closed Loop ◽  
Two Phase Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Operating Modes ◽  
Flow And Heat Transfer ◽  
Control Volumes

A natural circulation, closed loop thermosyphon can transfer heat over relatively large distances without any moving parts such as pumps and active controls. Such loops are thus considered suitable for nuclear reactor cooling applications where safety and high reliability are of paramount importance. A theoretical basis from which to predict the flow and heat transfer performance of such a loop is present-ed. A literature survey of the background theory is undertaken and the theoretical equations describing the single and two-phase flow as well as heat trans-fer behaviour are given. The major assumptions made in deriving these equations are that the work-ing fluid flow is quasi-static and that its single, two-phase flow and heat transfer behaviour may be cap-tured by dividing the working fluid in the loop into a number of one dimensional control volumes and then applying the equations of change to each of these control volumes. Theoretical simulations are conducted for single phase, single and two-phase and heat pipe operating modes, and a sensitivity analysis of the various variables is undertaken. It is seen that the theoretical results capture the single and two-phase flow operating modes well for a loop that includes an expansion tank, but not for the heat pipe operating mode. It is concluded that the theo-retical model may be used to study transient and dynamic non-linear effects for single and two-phase modes of operation. To more accurately predict the heat transfer rate of the loop however, loop specific heat transfer coefficients need to be determined experimentally and incorporated into the theoretical model.

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