Vapor chambers offer high thermal conductivity and compact configuration, making them suitable for high heat-flux dissipation; however, their sealed and non-transparent structure prevents direct observation of internal two-phase flow and phase-change mechanisms. To address this issue, a dual-shape hybrid groove (DSHG) structure with excellent capillary performance is fabricated on an aluminum substrate by laser etching-sputtering. Under fixed laser-processing parameters, including pulse energy, scanning speed, scan spacing, and number of scans, the structure shows good reproducibility and can be stably formed with a dual-scale composite surface morphology characterized by high surface roughness and open porous features. The DSHG achieves a capillary rise height of 200 mm within 85 s, with an average rise velocity of 24 mm/s during the first 2 s. A vapor chamber is then assembled with deionized water as the working fluid. With the optimized wick structure, a dedicated visualization platform is established to enable real-time observation of liquid return, vapor generation, and vapor-liquid interface evolution inside the chamber, while systematically evaluating its heat-transfer performance.
Based on this platform, the effects of orientation, filling ratio, and wick structure on liquid evaporation behavior and liquid-level evolution are investigated and compared with the overall thermal-performance results to verify the reliability of the visualization method. The results further show that under the 90° anti-gravity orientation, the liquid level decreases markedly, and the condensed droplets at the evaporation section are significantly reduced, indicating that liquid replenishment gradually becomes restricted. For samples with filling ratios of 30% and 45%, condensed droplets can still be continuously generated at the evaporation section when the heating power reaches 15.8 W, demonstrating good liquid replenishment capability. Under the horizontal orientation, the liquid amount at a 15% filling ratio decreases noticeably, and the maximum sustainable heating power is 15.8 W, beyond which dry-out readily occurs. At a filling ratio of 30%, the liquid distribution remains sufficient at 19.2 W, with liquid reserves retained along the peripheral regions to replenish evaporation loss in a timely manner. In contrast, at a filling ratio of 45%, excessive retained liquid reduces the vapor-space volume and weakens the phase-change process. Under the 90° gravity-assisted orientation, the vapor chamber with a 15% filling ratio sustains a maximum heating power of 19.2 W, and a large number of condensed droplets are generated at the evaporation section, indicating the best evaporation performance. For the sample with a 30% filling ratio, when the heating power reaches 22.8 W, approximately half of the evaporation section is immersed in liquid, resulting in slightly inferior evaporation performance. For the sample with a 45% filling ratio, excessive liquid causes the liquid level to flood the heating region, leading to boiling at the evaporation section and the generation of numerous bubbles, while the amounts of vapor and condensed droplets are reduced, indicating poor phase-change performance. The optimal filling ratio of the vapor chamber varies with orientation. Under the corresponding operating conditions, the minimum thermal resistances are 1.25, 1.27, and 1.09 ℃/W, while the maximum effective thermal conductivity reaches 2 142.85, 2 109.11, and 2 457.4 W/(m·K), respectively. Compared with the vapor chamber using an unetched aluminum plate, the DSHG vapor chamber exhibits a more uniform liquid distribution along the periphery of the chamber, whereas the liquid in the unetched aluminum plate chamber is mainly concentrated on one side, indicating that the DSHG structure possesses stronger liquid-transport capability. In the vapor chamber with the unetched aluminum plate, only a small amount of condensate forms, while pronounced boiling and extensive bubble adhesion appear at the evaporation section, indicating that vapor generation and phase-change heat transfer are restricted. By contrast, the liquid distribution in the copper-mesh wick vapor chamber is also nonuniform, and a large number of isolated bubbles readily form inside the chamber and further evolve into local vapor regions, thereby impairing the heat-transfer performance.
Overall, the optimal filling ratio under different orientations is governed by the combined effects of liquid-level distribution and vapor-region formation. The good agreement between the thermal-performance measurements and visualization observations confirms the accuracy and applicability of the visualization platform, providing a powerful tool and new insight for investigating the internal phase-change mechanisms of grooved vapor chambers.
Key words
dual-shape hybrid groove /
wick /
laser etch-sputtering /
visualization /
vapor chamber /
thermal performance
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References
[1] ZHOU F, ZHOU J Z, HUAI X L.Advancements and Challenges in Ultra-Thin Vapor Chambers for High-Efficiency Electronic Thermal Management: A Comprehensive Review[J]. International Journal of Heat and Mass Transfer, 2023, 214: 124453.
[2] 郝洛西, 杨秀. 基于LED光源特性的半导体照明应用创新与发展[J]. 照明工程学报, 2012, 23(1): 1-6.
HAO L X, YANG X.Innovation and Tendency of LED Lighting Based on LED's Feature[J]. China Illuminating Engineering Journal, 2012, 23(1): 1-6.
[3] YIN S B, ZHAO W, TANG Y, et al.Ultra-Thin Vapour Chamber Based Heat Dissipation Technology for Lithium- Ion Battery[J]. Applied Energy, 2024, 358: 122591.
[4] TANG H, TANG Y, WAN Z P, et al.Review of Applications and Developments of Ultra-Thin Micro Heat Pipes for Electronic Cooling[J]. Applied Energy, 2018, 223: 383-400.
[5] 刘腾庆, 张尧康, 汪双凤. 强化超薄均热板传热性能的研究进展[J]. 化工进展, 2024, 43(12): 6592-6607.
LIU T Q, ZHANG Y K, WANG S F.Research Progress of Enhanced Heat Transfer Performance of Ultrathin Vapor Chamber[J]. Chemical Industry and Engineering Progress, 2024, 43(12): 6592-6607.
[6] 王志威. 超薄均热板设计制造及气液两相流可视化研究[D]. 广州: 华南理工大学, 2022: 14-16.
WANG Z W.Design, Fabrication and Gas-Liquid Two- Phase Flow Visualization for Ultra-Thin Vapor Chamber [D]. Guangzhou: South China University of Technology, 2022: 14-16.
[7] EGBO M.A Review of the Thermal Performance of Vapor Chambers and Heat Sinks: Critical Heat Flux, Thermal Resistances, and Surface Temperatures[J]. International Journal of Heat and Mass Transfer, 2022, 183: 122108.
[8] JAFARI GUKEH M, BAO C B, MUKHOPADHYAY A, et al.Air-Cooled Hybrid Vapor Chamber for Thermal Management of Power Electronics[J]. Applied Thermal Engineering, 2023, 224: 120081.
[9] HE H D, LI J P, HE Z Y, et al.Preparation of Hierarchical Microgroove Textures on the Surface of Al-Based Wicks by Roller Pressing and Laser Scanning Irradiation[J]. Surface and Coatings Technology, 2024, 487: 131008.
[10] XU J Y, WANG D C, HU Z H, et al.Effect of the Working Fluid Transportation in the Copper Composite Wick on the Evaporation Efficiency of a Flat Loop Heat Pipe[J]. Applied Thermal Engineering, 2020, 178: 115515.
[11] LI X B, TANG Y, LI Y, et al.Sintering Technology for Micro Heat Pipe with Sintered Wick[J]. Journal of Central South University of Technology, 2010, 17(1): 102-109.
[12] LIU X L, LI X, MENG X, et al.Manufacturing of Sintered Aluminum Powder Wicks by the Liquid Phase Enhance Sintering Method for Aluminum Heat Pipes[J]. Physics of Fluids, 2024, 36(12): 122022.
[13] WANG H W, TANG Y F, BAI P F, et al.A Multiscale Composite Silicon Carbide Wick with Excellent Capillary Performance[J]. International Communications in Heat and Mass Transfer, 2022, 139: 106478.
[14] JIANG G C, TIAN Z, LUO X, et al.Ultrathin Aluminum Wick with Dual-Scale Microgrooves for Enhanced Capillary Performance[J]. International Journal of Heat and Mass Transfer, 2022, 190: 122762.
[15] JIANG H P, SUN X Y, WANG X L, et al.A Dual-Height Wick to Improve Capillary Performance of Vapor Chambers[J]. Applied Thermal Engineering, 2024, 241: 122371.
[16] XIE X Z, ZHENG Y M, LIAO H Q, et al.Ultrafast Laser Preparation of Gas-Liquid Partitioned Microgroove Wicks to Enhance Heat Transfer in Ultrathin Vapor Chambers[J]. International Journal of Heat and Mass Transfer, 2024, 224: 125317.
[17] 刘璐琪, 尹玉莹, 黄美茹, 等. 多孔吸液芯的多步电沉积法制备及其结合性能[J]. 中国表面工程, 2024, 37(6): 354-363.
LIU L Q, YIN Y Y, HUANG M R, et al.Bonding Performance and Preparation of Porous Wick via Multistep Electrodeposition[J]. China Surface Engineering, 2024, 37(6): 354-363.
[18] YIN K, WU Y J, ZHAO D H, et al.Methods for Performance Optimization of Ultra-Thin Heat Pipes with Composited Wick[J]. International Journal of Heat and Fluid Flow, 2024, 110: 109635.
[19] LI Y, LI Z X, ZHOU W J, et al.Experimental Investigation of Vapor Chambers with Different Wick Structures at Various Parameters[J]. Experimental Thermal and Fluid Science, 2016, 77: 132-143.
[20] 陈恭, 汤勇, 张仕伟, 等. 超薄均热板的研究现状及发展趋势[J]. 机械工程学报, 2022, 58(12): 197-212.
CHEN G, TANG Y, ZHANG S W, et al.Development Status and Perspective Trend of Ultrathin Vapor Chamber[J]. Journal of Mechanical Engineering, 2022, 58(12): 197-212.
[21] LEE D, BYON C.Fabrication and Characterization of Pure-Metal-Based Submillimeter-Thick Flexible Flat Heat Pipe with Innovative Wick Structures[J]. International Journal of Heat and Mass Transfer, 2018, 122: 306-314.
[22] YUAN X P, YAN C M, HUANG Y X, et al.Fabrication and Capillary Performance of Multi-Scale Microgroove Ceramic Wicks via Nanosecond Laser Irradiation for Ultrathin Ceramic Heat Pipes[J]. Applied Thermal Engineering, 2024, 236: 121927.
[23] LI H, FANG X T, LI G F, et al.Investigation on Fabrication and Capillary Performance of Multi-Scale Composite Porous Wick Made by Alloying-Dealloying Method[J]. International Journal of Heat and Mass Transfer, 2018, 127: 145-153.
[24] ALIJANI H, ÇETIN B, AKKUŞ Y, et al.Effect of Design and Operating Parameters on the Thermal Performance of Aluminum Flat Grooved Heat Pipes[J]. Applied Thermal Engineering, 2018, 132: 174-187.
[25] DUAN L H, WANG Z W, CHEN G, et al.Capillary Wicking in Double-Scale Composite Microgroove Wicks for Copper-Aluminum Composite Vapor Chambers[J]. International Communications in Heat and Mass Transfer, 2021, 126: 105449.
[26] HE J J, WANG Y T, MENG T, et al.Visualized Study and Performance Evaluation on a Micro-Grooved Vapor Chamber[J]. International Journal of Heat and Fluid Flow, 2024, 107: 109416.
[27] 黎小辉, 邓凯江, 罗达强, 等. 均热板热阻性能的研究现状[J]. 材料研究与应用, 2025, 19(3): 439-450.
LI X H, DENG K J, LUO D Q, et al.Research Status of Thermal Resistance Performance of Vapor Chamber[J]. Materials Research and Application, 2025, 19(3): 439-450.
[28] LOU D Y, CHEN P J, JIANG H L, et al.Novel Capillary Rise Enhancement of Dual-Shape Hybrid Groove Made by Laser Etch-Sputtering[J]. Optics & Laser Technology, 2024, 179: 111261.
[29] LI H, FU S J, LI G F, et al.Effect of Fabrication Parameters on Capillary Pumping Performance of Multi-Scale Composite Porous Wicks for Loop Heat Pipe[J]. Applied Thermal Engineering, 2018, 143: 621-629.
[30] WU C X, TANG Y, ZHANG S W, et al.Analytical and Experimental on the Capillary Rise of Aluminum Multi- Scale Microgroove Wick Structures[J]. Physics of Fluids, 2023, 35(5): 052016.
[31] HUANG C K, SU C Y, LEE K Y.The Effects of Vapor Space Height on the Vapor Chamber Performance[J]. Experimental Heat Transfer, 2012, 25(1): 1-11.
Funding
Hubei Province Key Research and Development Project (2025BAB045, 2025BAB108); Open Fund of Hubei Provincial Key Laboratory of Green Materials for Light Industry (202107A03)
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