带有石墨烯涂层的微流体封装相变光纤，用于被动热管理

摘要：本文，东南大学Yongping Chen等研究人员在《Small》期刊发表名为“Microfluidic-Encapsulated Phase Change Fibers with Graphene Coating for Passive Thermal Ma

1成果简介

本文，东南大学Yongping Chen等研究人员在《Small》期刊发表名为“Microfluidic-Encapsulated Phase Change Fibers with Graphene Coating for Passive Thermal Management”的论文，研究介绍了一种利用微流体技术将相变材料（PCM）封装到无毒、柔性纤维中的新方法，并通过石墨烯涂层增强了被动热管理功能。相变纤维具有均匀的核壳结构，外壳轻盈多孔且致密，可防止 PCM 泄漏。纤维的尺寸和 PCM 与外壳材料的比例可根据需要进行精确控制。

相变纤维表面涂有石墨烯涂层，可增强其导热性和发射率，从而提高被动冷却性能，而不会影响纤维的结构完整性或密封稳定性。特别是在周期性热负荷下对间歇运行的电子元件进行的热管理实验表明，石墨烯涂层相变纤维（GPCF）的热管理可以有效降低电子设备的峰值温度和平均温度。值得注意的是，基于GPCF的无功耗纯被动冷却相当于0.8m s−1风速下的强制空气冷却性能，从而节省了大量能源。GPCF 在对周期性、短期高负荷的电子设备进行热管理方面显示出巨大的潜力，有可能显著节省与冷却相关的能耗。

2图文导读

图1、Fabrication and morphological characteristics of phase change fiber (PCF) and graphene-coated phase change fiber (GPCF). a) The fabrication process initially employs microfluidic techniques to encapsulate liquid PCM RT25 into fibers, followed by the application of a graphene coating layer through two-step pneumatic spraying. b,c) Morphological characteristics of fabricated b) PCF and c) GPCF: i) Macroscopic morphology, indicating the fibers' flexibility; ii) SEM images of the cross-sections of the PCF and the GPCF, showing that the outer rings of the fibers are porous media, with density increasing radially toward a denser exterior surface; iii) SEM images of the fiber surface, demonstrating a dense outer surface that prevents the leakage of the liquid PCM.

图2、Compositions and properties of PCF and GPCF. a) Thermogravimetric analysis results of the PCM RT25, fiber shell material PVB, PCF, and GPCF. b) Differential scanning calorimetry test results for RT25, PVB shell, PCF, and GPCF during the heating process. c) Differential scanning calorimetry test results for RT25, PVB shell, PCF, and GPCF during the cooling process. d) Thermal conductivities of paraffin RT25, PVB, PCF, and GPCF. e) Infrared spectra of RT25, PVB shell, and graphene-coated PVB shell. f) Comparison of the emissivity of GPCF and PCF in the mid-infrared and far-infrared bands. g) Emissivity comparison of GPCF and PCF in the UV–vis, and near-infrared bands. h) Flexibility and durability test of GPCF: i) a Chinese knot knitted with GPCF, indicating the good flexibility of the fiber; ii) morphological comparison of GPCF after one month of water soaking and air drying; iii) morphological comparison of GPCF after one month of exposure to sunlight and natural air; iv) morphological comparison of GPCF after 50 cycles of solid-liquid phase transition. i) Tensile strain curves of GPCF and PCF.

图3、Thermal management capability testing experiment of the prepared fibers. a) Test units: unit A is not wrapped with any fibers; unit B is wrapped with PCF; and unit C is wrapped with GPCF. b) Photo of the test experiment system. c) Schematic diagram of the test experiment system. d) Schematic diagram of the test unit structure and the arrangement of thermocouples.

图4、Thermal response of the test units under passive thermal management with a duty cycle of 1:9. Each test unit undergoes five phase change cycles. No forced air cooling (FAC) is applied. a) Temperature variation of the three units: i) temperature change during the fifth phase change cycle; ii) temperature variation over all phase change cycles. b) Infrared thermographs of the test units: i) heating process; ii) cooling process.

图5、Thermal characteristics of unit C under passive thermal management and of unit A subjected to different intensities of forced air cooling (FAC). The duty cycle is 1:9. Each test unit undergoes five phase change cycles. a) Temperature variation of the three units: i) temperature change during the fifth phase change cycle; ii) temperature variation over all phase change cycles. b) Infrared thermographs of the test units: i) heating process; ii) cooling process.

图6、Summarize the a) maximum and b) average temperatures of the heating rod across all cycles.

3小结

本文介绍了一种利用微流体技术将相变材料（PCM）封装到无毒柔性纤维中的新方法，特别是结合石墨烯涂层来提高其辐射冷却能力。制成的相变纤维具有均匀的核壳结构和表面致密的轻质多孔外壳，可防止液态 PCM 泄漏。微流体方法可以通过调节流速精确控制纤维尺寸和 PCM 与外壳材料的比例。此外，相变纤维保留了纯芯 PCM ≈ 90% 的熔化/凝固焓。相变纤维表面涂有石墨烯涂层，可增强其导热性和红外发射率，从而促进有效的热传递，并增强自然对流和辐射冷却。在模拟电子设备上进行的热管理实验表明，石墨烯涂层相变纤维（GPCF）的热管理可以有效降低电子设备在间歇性周期热负荷运行时的峰值温度和平均温度。特别是，基于石墨烯涂层相变纤维的无功耗纯被动冷却相当于 0.8 m s-1 风速下的强制空气冷却性能，从而实现了显著的节能效果。

结合其结构的自适应灵活性以及固液 PCM 和石墨烯涂层的协同优势，制造出的 GPCF 有望应用于周期性、短期高负载电子设备的热管理。这种协同作用可实现高效的被动冷却，保护电子元件免受热应力的影响，同时降低能耗。除电子热管理外，其表面温度调节能力使其在热伪装和可穿戴体温调节等应用中大有可为，在这些应用中，精确和自适应的热控制至关重要。

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