Capillary and thermal performance enhancement of rectangular grooved micro heat pipe with micro pillars

Hamidnia, Mohammad; Luo, Yi; Li, Zhixin; Wang, Xiaodong

doi:10.1016/j.ijheatmasstransfer.2020.119581

Cited by 24 publications

(7 citation statements)

References 39 publications

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“…Ignoring the effects of hydrostatic pressure and air pressure, the Laplace pressure produced by the meniscus can be expressed as while the hydraulic resistance is where η is the dimensionless geometrical correction factor, l is the capillary rising height, μ is the dynamic viscosity of the liquid, and A = ∫ Ω d x d y is the cross-sectional area. The flow rate q m can thereby be calculated using the following formula 27 Finally, we can obtain an equation that describes the relationship between liquid transport distance and time by substituting eqs 7 and 8 into eq 9 According to the above analysis, the capillary driving pressure (Laplace pressure) increases with the decrease of the width of the microgrooves ( Figure 4 a–c), thus resulting in fast capillary rising in microgrooves with a small width. However, an interesting phenomenon is that the average capillary rising velocity V average slows in the microgrooves with a width smaller than 100 μm ( Figure 4 d).…”

Section: Resultsmentioning

confidence: 99%

“…The capillary of the wicks is very important for enhanced phase change heat transfer as it determines the capacity of rewetting and liquid replenishing to the hot spot, thus dominates the heat transfer limit. , Microgroove wicks have strong capillary pressure and weak viscous resistance; in addition, the liquid replenishing direction can be easily manipulated for heat dissipation application on both 1-D and 2-D regions.…”

Section: Resultsmentioning

confidence: 99%

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Capillary-Driven Boiling Heat Transfer on Superwetting Microgrooves

Yang

Tian

et al. 2022

ACS Omega

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Boiling can transfer a vast amount of heat and thereby is widely used for cooling advanced systems with high power density. However, the capillary force of most existing wicks is insufficient to surpass the liquid replenishing resistance for high-efficient boiling. Herein, we report a new microgroove wick on high-conductive copper substrates that was constructed via ultraviolet nanosecond pulsed laser milling. The phase explosion, combined with melting and resolidification effects of laser milling induces dense microcavities with sizes around several micrometers on the microgroove surface. The hierarchical microstructures significantly improve the wettability of the microgroove wicks to obtain strong capillary and meanwhile provide abundant effective nucleation sites. The boiling heat transfer in a visualized flat heat pipe shows that the new wicks enable sustainable liquid replenishing even under antigravity conditions, thus resulting in maximum 33-fold improvement of equivalent thermal conductivity when compared with the copper base. This research provides both scientific and technical bases for the design and manufacture of high-performance phase change cooling devices.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Capillary-Driven Boiling Heat Transfer on Superwetting Microgrooves

Yang

Tian

et al. 2022

ACS Omega

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“…where K denotes the permeability of trapezoidal grooved wick calculated by Eq. (10) in which ε represents the void ratio of trapezoidal grooved wick calculated by Eq. (11) and r hl is hydraulic radius defined by Eq.…”

Section: The Working Principle Of Micro-groove Heat Pipementioning

confidence: 99%

“…Flat-plate micro heat pipes with different geometries were designed and fabricated to determine the best geometries of wicking structures to improve efficiency [9]. Micro-pillars added inside the microgrooves have been proven not only to improve the wettability of micro-grooves but also increase the heat transfer capability of two-phase flow inside the micro heat pipe [10]. Nanofluids are shown to be effective means for enhancing heat transfer of heat pipes [11].…”

Section: Introductionmentioning

confidence: 99%

Plough-extrusion Forming for Making Micro-groove Heat Pipes on Hydrostatic Thrust Bearings of Heavy Machinery

Zhe

Li³

et al. 2020

SV-JME

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The present paper focuses on the manufacturing of micro-groove heat pipes on hydrostatic thrust bearings of heavy machinery. Special multitooth tools were designed for plough-extrusion forming heat pipes on flat copper. Experimental results were conducted to determine whether the plough-extrusion forming could achieve better performance than traditional wire electrical discharge. Furthermore, the processing using multi-tooth tool with 10 mm length, 55 tooth number, 0.25 mm tooth depth and 0.22 tooth top width was found to achieve the best performance among the six optional tools. The 50 mm/min forming speed was determined to acquire the best surface quality of the microgroove structure. Through heat transfer testing, the theoretical model for a micro-groove heat pipe made by plough-extrusion forming was also verified.

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“…Hence, if the nucleation and growth stages of the vapor bubbles are controlled by microtexturing the interface, the boiling curve in Figure 1 is significantly modified in the boiling heat transfer regime. In addition to the studies on controlling the boiling transfer by micro-/nano-texturing [8][9][10][11][12], MEMS (microelectronicmechanical system) technique was utilized to develop the cooling system by impinging the droplets [14] and to investigate the effect of micro-pillared micro-pipe on its thermal performance [15]. Those micro-/nano-texturing methods are useful to demonstrate the improvement of boiling heat transfer in the laboratory scale, but most of them are difficult to be used in the industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Boiling Heat Transfer on the Micro-Textured Interfaces

Aizawa¹,

Nakata²

2023

Heat Transfer - Fundamentals, Enhancement and Applications

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Higher heat flux than its normal criticality from high-power transistors, LIDAR (Laser Imaging Detection and Ranging), stacked CPUs, high-power transistors, and lasers must be efficiently transferred to cooling media through the metallic interface. The micro-/nano-textured aluminum and copper devices were highlighted among several approaches and fabricated to enhance the boiling heat transfer process to the subcooled water. The plasma printing was proposed to fabricate a pure aluminum device with concave micro-textures and to describe the boiling heat transfer behavior with comparison to the bare aluminum plate. A copper device was wet-plated to have convex micro-textures and to discuss the effect of micro-textures on the heat transfer characteristics under the forced water cooling by varying the Reynolds number. The boiling curve on the micro-textured interfaces was newly constructed by improving the boiling heat transfer process by micro-/nano-texturing.

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Capillary and thermal performance enhancement of rectangular grooved micro heat pipe with micro pillars

Cited by 24 publications

References 39 publications

Capillary-Driven Boiling Heat Transfer on Superwetting Microgrooves

Capillary-Driven Boiling Heat Transfer on Superwetting Microgrooves

Plough-extrusion Forming for Making Micro-groove Heat Pipes on Hydrostatic Thrust Bearings of Heavy Machinery

Boiling Heat Transfer on the Micro-Textured Interfaces

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