scholarly journals Study of Heat Pipe Thermal Performance with Internal Modified Geometry

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 231
Author(s):  
Alaa A. B. Temimy ◽  
Adnan A. Abdulrasool ◽  
F. A. Hamad
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Transit Time ◽  
Thermal Performance ◽  
Inclination Angle ◽  
Input Power ◽  
Filling Ratio ◽  
Lower Side ◽  
Condenser Section ◽  
Inner Diameter

The aim of this study was to investigate the effect of inserting a new internal tube packing (TP) on the thermal performance of a thermosyphon heat pipe (THP). The THP pipe was made from copper with an inner diameter of 17.4 mm and length of 600 mm. The new internal tube packing (TP) had a central copper disc with two copper tubes soldered onto both sides to transport vapor and condensate. The upper tube or riser had an inner diameter of 8.3 mm and was 300 mm long; it was connected to a hole in the disc from the upper side to transport the steam to the condenser section. The lower tube or downcomer had an inner diameter of 5 mm, was 225 mm long and was connected to the lower side of the disc to collect the condensate and transport it to the evaporator. The TP was inserted inside the THP to complete the design of the improved heat pipe (TPTHP). Experimental results showed that the TPTHP reduces the transit time from 16 to 11 min and the thermal resistance by 17–62% based on the input power and depending on the conditions of the THP. The results also showed that the inclination angle and filling ratio have no effect on the thermal resistance of the TPTHP.

Effect of Filling Ratio on an Uneven Turn Oscillating Heat Pipe

2011 ◽  
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%.

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.

Effect of Inclination Angle on the Closed Loop Pulsating Heat Pipe Thermal Performance

2013 ◽  
Author(s):  
Pramod R. Pachghare ◽  
Ashish M. Mahalle
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Inclination Angle ◽  
Heat Input ◽  
Closed Loop ◽  
Pulsating Heat Pipe ◽  
Working Fluids ◽  
Inclination Angles ◽  
R 134A

The closed loop pulsating heat pipe (CLPHP) is a passive two-phase heat transfer device, patented by Akachi (1990). Due to its excellent features, PHP has been considered as one of the promising technologies for electronic cooling, heat exchanger, etc. This paper presents an experimental study shows the effect of inclination angle on the thermal performance of CLPHP, which consist of 10 turns of copper tubes having inner and outer diameter 2 mm and 3.6 mm respectively. The equal lengths of evaporator, condenser and adiabatic sections are 50 mm each. Different working fluids are used as R-134a, Methanol and Water. For all experimentations, an optimum filling ratio was maintained 50% by volume. The thermal performance have been investigated with different inclination angles (viz. 0°, 20°, 40°, 60° and 90°) at various heat input from 5 to 50W in the steps of 5W. The thermal resistance (which is inversely proportional to thermal performance) of CLPHP at various heat input are plotted for different working fluids. The result shows that, the thermal resistance decreases as heat input increases. But at low heat input i.e. upto 25W, the thermal resistance decreases rapidly and the PHP performance is more sensitive to the inclination angle whereas high heat input i.e. above 25W, the thermal resistance decreases smoothly and less independent to the inclination angle. In all inclination angles, vertical bottom heat position (at 90°) of CLPHP gives best thermal performance due to presence of gravity force. At all inclination angles, the working fluid R-134a show best thermal performance followed by methanol and water.

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 Investigation on Thermal Performance of Flat Plate Heat Pipe with Intersected Micro-Grooves

2013 ◽  
Vol 772 ◽  
pp. 480-486 ◽  
Author(s):  
Chen Wang ◽  
Zhong Liang Liu ◽  
Guang Meng Zhang
Keyword(s):  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Radial Direction ◽  
Filling Ratio ◽  
Working Fluid ◽  
Plate Heat ◽  
Inclination Angles ◽  
Flat Plate Heat Pipe

A copper-water flat plate heat pipe with intersected micro-grooves was developed for cooling electronic devices in this paper. The effects of heat flux, working fluid filling ratio and inclination angles on thermal performance of the flat plate heat pipe was tested and investigated. The laboratory tests show the optimal filling ratio of the heat pipe is about 65%. Excellent thermal performance is also observed in unfavorable titled positions including vertical and anti-gravity orientation at 65%. The smallest overall thermal resistance is obtained in horizontal position and the maximal thermal resistance is observed in vertical position. The influence of inclination angles on thermal performance of the heat pipe in both axial direction and radial direction is also investigated. As the heat pipe is tilted, the ability of temperature leveling in radial direction is enhanced, nevertheless, the capacity of heat transfer in radial direction decreased at the same time.

Experiment Investigation on Heat Transfer Characteristics of a Novel Gravity-Assisted Heat Pipe Heat Exchanger

2011 ◽  
Vol 236-238 ◽  
pp. 689-693
Author(s):  
Xiao Lin Cao ◽  
Shuang Jun Cao ◽  
Xiao Jun Zhu ◽  
Wei Zeng ◽  
Fang Fang Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Inclination Angle ◽  
Filling Ratio ◽  
Heat Transfer Characteristics ◽  
Air Velocity ◽  
Condenser Section ◽  
Transfer Resistance ◽  
Transfer Characteristics ◽  
Minimum Heat

A novel gravity-assisted heat pipe with fins was developed. The influences of filling ratio, inclination angle and air velocity at condenser section on the heat transfer characteristics were investigated experimentally. The results show that heat power has an important effect on heat transfer characteristics while inclination angle has little effect on that. The minimum heat transfer resistance is got at the filling ratio equaling about 20%. The heat transfer thermal resistance decreases gradually as the air velocity at condenser section increases.

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

Characteristics of Thermal Performance in High Power LED Package with Heat Pipe

2007 ◽  
Vol 124-126 ◽  
pp. 85-88 ◽  
Author(s):  
Woong Joon Hwang ◽  
Hwa Jun Yeo ◽  
Moo Whan Shin
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
High Power ◽  
Pure Water ◽  
Input Power ◽  
Junction Temperature ◽  
Working Fluid ◽  
Sintered Metal ◽  
Forced Cooling

This paper discusses about thermal performance of high power light emitted diode (HPLED) implemented with sintered metal wick type heat pipe(SWHP). The HPLED(2.5 W) samples were surface mounted device(SMD) package used in our experiments. The experiments were made for SWHP with diameters of 6.0 mm. The length of the SWHP is 150 mm. The working fluid in the heat pipes is pure water. The electrical-thermal transient technique was employed for the junction temperature measurement. It was found that the SWHP leads to decreased of thermal resistance by 35 % compared with a simple copper bar in oil bath (forced cooling condition). Employment of copper cap as a LED attachment was more advantageous over the phosphor bronze. After the increase of input power, the thermal resistance of HPLED package has decreased with the increase of effective thermal conductivity of SWHP.

scholarly journals Experimental Investigation on the Thermal Performance of Pulsating Heat Pipe Heat Exchangers

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 269 ◽  
Author(s):  
Kai-Shing Yang ◽  
Ming-Yean Jiang ◽  
Chih-Yung Tseng ◽  
Shih-Kuo Wu ◽  
Jin-Cherng Shyu
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Filling Ratio ◽  
Working Fluid ◽  
Pulsating Heat Pipe ◽  
Evaporator Temperature ◽  
Inner Diameter ◽  
Air Streams

In this study, the vertically-oriented pulsating heat pipe (PHP) heat exchangers charged with either water or HFE-7000 in a filling ratio of 35% or 50% were fabricated to exchange the thermal energy between two air streams in a parallel-flow arrangement. Both the effectiveness of the heat exchangers and the thermal resistance of PHP with a size of 132 × 44 × 200 mm, at a specific evaporator temperature ranging from 55 to 100 °C and a specific airflow velocity ranging from 0.5 to 2.0 m/s were estimated. The results show that the heat pipe charged with HFE-7000 in either filling ratio is likely to function as an interconnected array of thermosiphon under all tested conditions because of the unfavorable tube inner diameter, whereas the water-charged PHP possibly creates the pulsating movement of the liquid and vapor slugs once the evaporator temperature is high enough, especially in a filling ratio of 50%. The degradation in the thermal performance of the HFE-7000-charged PHP heat exchanger resulted from the non-condensable gas in the tube became diminished as the evaporator temperature was increased. By examining the effectiveness of the present heat exchangers, it is suggested that water is a suitable working fluid while employing the PHP heat exchanger at an evaporator temperature higher than 70 °C. On the other hand, HFE-7000 is applicable to the PHP used at an evaporator temperature lower than 70 °C.

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