Modelling and performance of heat pipes with long evaporator sections

Wits, Wessel W.; Riele, Gert Jan te

doi:10.1007/s00231-017-2040-5

Cited by 11 publications

(4 citation statements)

References 11 publications

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“…A geyser boiling effect was observed and there was an operation limit for heat inputs larger than 160 W for all FRs. During operation, the TPCT could encounter various limitations such as the viscous limit, sonic limit, entrainment limit, boiling limit, and capillary limit [9]. As can be seen in Figure 21, boiling limit is encountered in this case.…”

Section: Effect Of Geyser Boiling Influences and Boiling Limit On Opementioning

confidence: 93%

“…Experiments have been performed for distilled water as a working fluid with an FR equal to 0.75 and for various power inputs from 71 W to 960 W. It has been confirmed that a new type of condenser section in a TPCT could enhance the performance from 10% to 17% compared to the unmodified version of a thermosyphon. W. Wits and G. Riele [9] have worked on a cooling strategy for advanced electronic applications using heat pipe technology. The authors' idea was based on using an array of relatively long heat pipes, whereby heat was disposed to a long section of the pipes.…”

Section: Introductionmentioning

confidence: 99%

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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

Andrzejczyk

2018

Energies

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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.

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Section: Effect Of Geyser Boiling Influences and Boiling Limit On Opementioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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

Andrzejczyk

2018

Energies

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“…The phase-change heat transfer performance here, to a large extend, determine the thermosyphon's overall heat transfer performance. In contrast, heat pipes use a wick structure to 978-1-6654-1896-6/21/$31.00 ©2021 IEEE return the working fluid by capillary force [2]. Although wick structures help to return the working fluid and improve evaporation and boiling heat transfer, they generally increase the system's thermal resistance [3].…”

Section: A Background and Literature Reviewmentioning

confidence: 99%

Utilizing Additive Manufacturing to Enhance Two-Phase Heat Transfer Devices

Winkelhorst

Jafari

Wits

2021

2021 27th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)

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Two-phase heat transfer devices are among the most popular devices in thermal management systems due to their superior thermal characteristics. This paper investigates a thermosyphon for electronics cooling applications into which a freeform wick structure is inserted to enhance thermal performance. Additive manufacturing is employed to fabricate the wick structure tailored to the thermosyphon at hand using a conductive thermoplastic material. The goal of this study is to investigate how the freeform wick structure inserted into a thermosyphon affects the local liquid and vapor distributions and thus improving the thermal performance. Experiments were carried out with various heat loads and inclination angles, while the temperature distribution was recorded along the length of the thermosyphon. Thermal resistances were determined for both a conventional thermosyphon and an adapted version with an inserted wick structure in order to quantify the enhancement. The obtained experimental data demonstrate that the additively manufactured wick structure gives benefits at higher heat loads due to enhanced evaporation and boiling modes. The evaporation thermal resistance improves by 7% to 13% at heat loads above 55 W for the vertical orientation. Likewise, an improvement of about 7% to 9% was found at a heat load of 105 W for inclination angles of 30° and 60°. Both results exemplify the advantages additive manufacturing may bring to thermal management systems and in particular to two-phase heat transfer devices.

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“…The condenser capacity will be reduced due to overcharging, whilst the artery may be dried out due to undercharging. Providing an extra fluid reservoir that will absorb surplus fluid while also being non-required by the primary wick structure [11], [12] is the research topic at hand. Calculation of operating limits and parameters limit, entrainment limit, sonic limit, boiling limit and viscous.…”

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confidence: 99%

Experimental Analysis of Single and Three-Stage Heat Pipe With Three Fluids for Cooling of Electronic Devices

2022

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An electronic device and energy storage device such as a super and ultra-capacitor are kept cool by a single or three-stage cascade heat pipe: selected heat pipe materials, primary and secondary fluids. Cascade heat pipes designed, built, and tested single and three fluid cascade heat pipes with heat inputs ranging from 100 to 200 W. The axial temperature difference is studied, and the evaporator and condenser temperatures are measured using a thermocouple and connected to an Agilent Data Logger. In multistage heat pipe experiments, each stage reached a steady state after 35 seconds. Heat pipe temperature, thermal resistance, and heat transfer were predicted. The primary fluid (water) merit number 4.26x10 9 is 25 times higher than ethanol merit number 166.3x10 6 and acetone merit number, but ethanol had a higher latent heat of evaporation than water. The operating range (100 to 220 deg C) was suitable for energy storage devices.

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Modelling and performance of heat pipes with long evaporator sections

Cited by 11 publications

References 11 publications

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

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

Utilizing Additive Manufacturing to Enhance Two-Phase Heat Transfer Devices

Experimental Analysis of Single and Three-Stage Heat Pipe With Three Fluids for Cooling of Electronic Devices

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