新型聚乙烯醇/聚乙二醇水凝胶热沉性能研究

为研究水凝胶作为热管理技术的可行性和潜力，采用物理循环冷冻法制备一种力学和经济性良好的新型聚乙烯醇（PVA）/聚乙二醇（PEG）复合水凝胶热沉，热沉尺寸为60 mm×60 mm×2 mm,通过表面的水分蒸发来实现自冷。在2 712 W/m2热流下进行散热性能探究实验，得到了升温特性、蒸发对流强度变化关系和溶胀变化规律。发现加入2.5%质量分数的PEG减小了随循环冷冻次数增加造成的制备变形，减小了75.53%的含水量衰减，同时使芯片表面控温下降7.53%。根据实验结果计算得到了蒸发换热系数，并研究了热流、厚度和湿度对蒸发散热的影响。通过对水凝胶不同温度和使用情况（4 h连续使用及120 d常温储存）下溶胀率的测定，证明水凝胶具备一定的短时使用可靠性，但对温度的敏感响应并不显著。

Performance of a novel polyvinyl alcohol/polyethylene glycol hydrogel for heat sink

To study the feasibility and potential of hydrogels for thermal management, a novel polyvinyl alcohol (PVA) /polyethylene glycol (PEG) composite hydrogel heat sink with good mechanics and economy was prepared by freezing-thaw method. The size of the sink is 60 mm×60 mm×2 mm, and self-cooling is realized by water evaporation on the surface. A heat dissipation experiment was carried out with a heat flow of 2712 W/m2, and the heating characteristics, the relationship of the evaporative convection intensity change and the swelling change law were obtained. It was found that the addition of 2.5% PEG reduced the preparation deformation caused by the increase in the number of freezing cycles, with the water content attenuation being decreased by 75.53%, and the chip surface temperature 7.53%. Based on the experimental results, the evaporation heat transfer coefficient was calculated, and the effects of heat flow, thickness, and humidity on evaporative heat dissipation were studied. The swelling rates of the hydrogel with different temperatures and usage conditions (4 h continuous use and 120-day storage at room temperature) were then measured, showing that the hydrogel has a certain short-term reliability in spite of the insignificant sensitive response to temperature.