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过程工程学报 ›› 2021, Vol. 21 ›› Issue (11): 1364-1372.DOI: 10.12034/j.issn.1009-606X.220349

• 环境与能源 • 上一篇    

圆柱系统中石蜡/纳米银复合相变材料热特性分析

张润洁,罗博,李中杰,杨国均,林一歆*   

  1. 华中科技大学能源与动力工程学院，湖北 武汉 430074
  • 收稿日期:2020-10-26 修回日期:2021-01-07 出版日期:2021-11-28 发布日期:2021-11-29
  • 通讯作者: 林一歆 yixinlin@hust.edu.cn
  • 作者简介:张润洁(1996-)，女，硕士研究生，研究方向为锂离子电池热管理，E-mail: 1798912641@qq.com；林一歆，通讯联系人，E-mail: yixinlin@hust.edu.cn.

Analysis of thermal properties of paraffin/silver nanoparticle CPCM in cylindrical system

Runjie ZHANG, Bo LUO, Zhongjie LI, Guojun YANG, Yixin LIN*   

  1. Academy of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
  • Received:2020-10-26 Revised:2021-01-07 Online:2021-11-28 Published:2021-11-29

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摘要： 相变材料由于具有相变潜热，被应用于各领域的热管理。锂离子动力电池作为一种新能源，近年来广泛应用于电动汽车，相变冷却作为一种有效的被动冷却方式，能够有效减缓锂电池的热聚集。为将相变材料应用于减缓锂电池热失控，本工作建立了石蜡/纳米银复合相变材料(CPCM)的圆柱系统，使用相变模型及流体体积(VOF)模型研究了相变材料的融化过程，得到了初始时期空气/石蜡气液交界面的变化以及石蜡的液相分布，与实验结果具有很好的一致性。在此基础上分析了相变过程的吸热及储热情况。同时，针对不同质量分数的石蜡/纳米银复合相变材料进行模拟，结果表明，添加0.5wt%~2wt%的纳米银颗粒能够改善石蜡的导热性能，但潜热会有所降低。相变结束后，材料吸收的热量将转化为显热，底面传热减小，主要是通过壁面传热。另外分析了融化过程中液相的流动情况，相变材料液态层增厚，Nu数下降并趋于稳定，增加纳米银浓度也会降低Nu数。

关键词: 复合相变材料（CPCM）, 潜热, 导热增强, 纳米银颗粒, 热能存储

Abstract: Because of the latent heat of phase change, phase change materials (PCM) are used in thermal management in various fields. As a new energy source, lithium power batteries have been widely used in electric vehicles in recent years. As an effective passive cooling method, phase change cooling can effectively slow down the heat accumulation of lithium batteries. To apply phase change materials to alleviate the thermal runaway of lithium batteries, a paraffin/silver nanoparticle composite phase change material (CPCM) cylindrical system was established, and the phase change model and the volume of fluid (VOF) model were used to study the melting process of phase change materials. The change of the air/paraffin gas-liquid interface and the liquid phase distribution of the paraffin was obtained during the initial period, which was in good agreement with the experimental results. On this basis, the heat absorption and heat storage of the phase change process were analyzed. In the initial stage of melting, the bottom solid-phase heat storage was higher than the wall heat flux. As the liquid phase area expanded, the melting rate decreased, and the wall heat flux was basically the same as the solid phase heat storage of the PCM. After 360 s, the heat flux on the top wall and the solid-phase heat storage continued to decrease to zero. Simultaneously, simulations of paraffin/silver nanoparticle CPCM with different mass fractions showed that adding 0.5wt%~2wt% of silver nanoparticles can improve the thermal conductivity of paraffin, but the latent heat reduced. When the phase change process was over, the heat absorbed by the material was converted into sensible heat. The heat transfer on the bottom surface was reduced and energy mainly carried out through the vertical wall. Besides, the flow of the liquid phase during the melting process was analyzed. The liquid layer of the phase change material thickened, and the Nusselt number decreased and tended to stabilize. Increasing the silver nanoparticle concentration reduced the Nusselt number.

Key words: Composite phase change material (CPCM), latent heat, enhanced thermal conductivity, silver nanoparticles, thermal energy storage