Experimental study of heat transfer capacity for loop heat pipe with flat disk evaporator

Zhang, Zikang; Zhang, Hao; Ma, Zhenyuan; Liu, Zhichun; Liu, Wei

doi:10.1016/j.applthermaleng.2020.115183

Cited by 26 publications

(7 citation statements)

References 32 publications

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“…This is attributed to the increase in thermal resistance with applied heat loads as the vapor zone under the heated fin enlarges with an increase in heat loads [20]. presented LHP with a bi-porous wick and a flat disk evaporator that can transport heat for a distance to up to 1.6 m. The author presented that the LHP can start up successfully also at very low power (2.5 W) [21]. Table 1 presents a comparison between recent works related to bi-porous wick LHPs.…”

Section: Bi-porous Wicksmentioning

confidence: 99%

Recent Advances in Loop Heat Pipes with Flat Evaporator

Szymański

Law

McGlen

et al. 2021

Entropy

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The focus of this review is to present the current advances in Loop Heat Pipes (LHP) with flat evaporators, which address the current challenges to the wide implementation of the technology. A recent advance in LHP is the design of flat-shaped evaporators, which is better suited to the geometry of discretely mounted electronics components (microprocessors) and therefore negate the need for an additional transfer surface (saddle) between component and evaporator. However, various challenges exist in the implementation of flat-evaporator, including (1) deformation of the evaporator due to high internal pressure and uneven stress distribution in the non-circular casing; (2) heat leak from evaporator heating zone and sidewall into the compensation chamber; (3) poor performance at start-up; (4) reverse flow through the wick; or (5) difficulties in sealing, and hence frequent leakage. This paper presents and reviews state-of-the-art LHP technologies; this includes an (a) review of novel manufacturing methods; (b) LHP evaporator designs; (c) working fluids; and (d) construction materials. The work presents solutions that are used to develop or improve the LHP construction, overall thermal performance, heat transfer distance, start-up time (especially at low heat loads), manufacturing cost, weight, possibilities of miniaturization and how they affect the solution on the above-presented problems and challenges in flat shape LHP development to take advantage in the passive cooling systems for electronic devices in multiple applications.

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Section: Bi-porous Wicksmentioning

confidence: 99%

Recent Advances in Loop Heat Pipes with Flat Evaporator

Szymański

Law

McGlen

et al. 2021

Entropy

View full text Add to dashboard Cite

show abstract

“…The thermal resistance represents the resistance of heat transfer within the LHP, which quantifies the effectiveness of the LHP in transferring heat from the evaporator to the condenser. The expression of the thermal resistance is as follows: R LHP = T evap − T ̅ cond Q where T̅ cond is the average temperature of the condenser, that is, the average value of T cond‑in and T cond‑out , and Q is the heat load of the electric heating sheet, which can be recorded by a power meter.…”

Section: Results and Discussionmentioning

confidence: 99%

Superior Heat and Mass Transfer Performance of Bionic Wick with Finger-like Pores Inspired by the Stomatal Array of Natural Leaf

Xu,

Long,

Chen

et al. 2024

Langmuir

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The thermal management of electronics has gained significant attention, with loop heat pipes (LHPs) emerging as an attractive solution for heat dissipation. The heat transfer performance of LHPs is influenced by the heat and mass transfer processes within the wick. However, designing the pore diameter of the wick is challenging due to the different requirements of flow resistance and capillary force. Specifically, the working fluid needs large pores to reduce resistance, while the liquid suction requires small pores to provide a large capillary force. To address this issue, we drew inspiration from the stomatal array of natural leaves used for transpiration and developed an alumina ceramic bionic wick with finger-like pores using the phase-inversion tape casting method. The finger-like pores in the wick resemble the straight hole structure of stomata, which increases the gas−liquid interface area within the wick. This design allows for timely discharge of water vapor generated by boiling, thereby reducing mass transfer resistance. Additionally, numerous micrometer-sized small pores surrounding the finger-like pores provide sufficient capillary force to replenish liquid for the gas−liquid evaporation interface. Experimental results demonstrate that the introduction of finger-like pores in the wick increases gas and water permeabilities by 2.4 and 5.2 times, respectively. Furthermore, the superior heat and mass transfer performance of the bionic wick was demonstrated with an LHP. This work effectively addresses the conflicting demands of capillary force and flow resistance, enhancing the heat transfer performance of LHPs, which holds great promise for addressing heat dissipation challenges in high power density electronic chips and has potential applications in aviation, aerospace, and microelectronics for efficient thermal management.

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“…First, evaporation can be applied to prepare some refined industrial materials that are difficult to produce directly . Then, evaporation can also be combined with solar energy for seawater purification or desalination. , Due to its efficient heat dissipation ability, evaporation is often used in various heat pipes, − evaporative coolers, − and even the cooling of specific electronic systems. Many researchers have studied the evaporation heat transfer deeply at the macroscale.…”

Section: Introductionmentioning

confidence: 99%

Atomistic Insight into the Effects of Depositional Nanoparticle on Nanoscale Liquid Film Evaporation

Shao

Cao

et al. 2021

Langmuir

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Nanoscale liquid film evaporation plays an essential role in many engineering applications. This study carries out molecular dynamics simulations on the effects of the depositional nanoparticle’s wettability and volume in base fluid on the evaporation process to understand how the depositional nanoparticle affects the evaporation heat transfer. Increasing the nanoparticle’s wettability can enhance the evaporation heat transfer process, and the enhancement effect of the hydrophobic surface is more remarkable than that of the hydrophilic surface. This because the increasing wettability causes more significant solid–liquid interaction. However, the potential energy of argon atoms at the liquid–vapor interface is almost unaffected by wettability. Moreover, when the depositional nanoparticle locates below the free liquid film, increasing the nanoparticle volume has a better heat transfer performance. As the volume increases, the heat transfer through the nanoparticle becomes more obvious, which effectively enhances the heat transfer at the solid–liquid interface and the liquid–vapor interface. The latent heat of phase change at the liquid–vapor interface is almost unchanged so that the evaporation can be enhanced. This research provides an understanding of the effects of depositional nanoparticles on nanoscale evaporation, which can impact several engineering applications, including devices’ cooling and fluid transport.

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Experimental study of heat transfer capacity for loop heat pipe with flat disk evaporator

Cited by 26 publications

References 32 publications

Recent Advances in Loop Heat Pipes with Flat Evaporator

Recent Advances in Loop Heat Pipes with Flat Evaporator

Superior Heat and Mass Transfer Performance of Bionic Wick with Finger-like Pores Inspired by the Stomatal Array of Natural Leaf

Atomistic Insight into the Effects of Depositional Nanoparticle on Nanoscale Liquid Film Evaporation

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