多孔基定形复合相变材料传热性能提升研究进展

Thermal conductivity enhancement of porous shape-stabilized composite phase change materials for thermal energy storage applications: a review

  • 摘要: 先进的相变储能材料是推动储能技术发展的核心和关键,在促进新能源开发和提高能源利用率中起着至关重要的作用。因在相变过程中具有高储能密度和小体积变化等优势,相变材料中应用最多的是固‒液相变材料。然而在其相变过程中会发生固态向液态的转变,为了避免其在液相状态下的泄露,需要加以定形才能使用。多孔基复合相变材料在有效防止固液相变发生泄露的同时,还需兼顾定形复合相变材料传热性能的提升。本文针对这个问题进行了大量的调研,对近年来国内外在提高多孔基定形复合相变材料传热性能方面的研究进行了综合分析,介绍了三种强化传热的方法,分别是使用高导热多孔材料做载体材料、掺杂高导热纳米材料做添加剂以及构筑高导热多级结构多孔材料,并对提升复合相变材料传热性能研究方法的前景作了展望。

     

    Abstract: How to realize the efficient use of the renewable energy sources is a present-day challenge to the technologists and has become an important issue in their large scale applications. Energy storage not only reduces the mismatch between supply and demand but also improves the performance and reliability of energy systems and plays an important role in conserving the energy. Current energy storage techniques mainly include sensible heat storage, latent heat storage and chemical reaction heat storage. The researchers place emphasis on the latent heat storage due to its advantages of high heat storage density, little temperature fluctuation and easily controllable utility system. In principle, phase change materials (PCMs) are used for the latent heat storage to absorb and release large amounts of latent heat during their phase change process. Therefore, PCMs are the key factor for the development of latent energy storage technology and play the crucial role in exploring new energy and improving energy utilization. The solid-liquid transition is more efficient compared with the other transformations due to its high latent heat density and small volume change. However, the leakage of solid-liquid PCMs above the melting point from the thermal storage system still hinders their practical applications. Considerable efforts have been devoted to introducing the porous support and development of shape-stabilized composite PCMs to address this technical issue. During the melting or solidifying processes, the PCMs store or release latent heat, while the support materials confine the melted phase from leaking and keep the whole system in the solid state. Moreover, low thermal conductivity of PCMs may degrade the performance for energy storage and thermal regulation during the melting and freezing cycles and restrict their final applications. Therefore, the necessity to enhance thermal conductivity of porous shape-stabilized composite PCMs is evident. In this paper, the recent researches on the enhancement of conductivity of porous shape-stabilized composite PCMs were reviewed. We studied the thermal conductivity enhancement techniques, which included impregnation of PCMs into porous materials with high thermal conductivity, introducing of high conductivity nano-materials and porous support materials into PCMs, construction of hybrid composite for shape stabilized phase change materials. The evaluation of each thermal conductivity enhancement technique was discussed. Finally, we had provided a brief outlook and future challenges in enhancing thermal conductivity of porous shape-stabilized composite PCMs.

     

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