关键词: 潜热储热, 相变, 金属有机骨架, 复合材料, 热传导, 表面修饰

Abstract:

Solid-liquid phase-change materials (PCMs) are abundant in variety and have relatively high latent heat, thus making them important working media for latent heat storage systems. Combining solid-liquid PCMs with porous supporting materials is an effective way to improve their application performance and service life. Metal-organic frameworks (MOFs) is a new kind of porous material, which has advantages of large specific surface area, high porosity, adjustable pore size and surface properties, thereby making them promising supporting materials for solid-liquid PCMs. This paper thoroughly reviewed the MOF-based composite PCMs. Specifically, the composite PCMs directly employing the MOFs as the supporting materials, the composite PCMs employing the MOFs derived porous carbon materials as the matrices, and the composite PCMs employing the hybrid materials prepared by in-situ growing MOFs on thermally conductive matrices as the carriers, are introduced respectively. The strong capillary force generated by the microporous structure of MOFs had a strong fixation effect on the solid-liquid PCMs. Synthesizing the MOFs with large pore sizes or modifying the MOFs to adjust its interactions with the PCMs are useful to increase the loadings of the PCMs and thus the latent heat of the obtained composite PCMs. Carbonizing the MOFs at high temperatures to obtain MOFs derived porous carbon materials could enlarge the pores of the MOFs, and the accompanying nitrogen and phosphorus doping could enhance the hydrogen bonding between the supporting materials and PCMs, all of which helped to acquire the composite PCMs with high loadings and latent heat. The in-situ growing MOFs on thermally conductive matrices to build a continuous heat transfer network could effectively enhance the thermal conductivity of the obtained composite PCMs. The thermal conductivity of the composite PCMs could be further increased by employing the hybrid materials prepared by carbonizing the in-situ growing MOFs thermally conductive matrices as the carriers. In the end, it is pointed out that the types of MOFs and phase-change materials used in MOF-based composite phase-change materials, the influence of the interaction between MOFs and phase-change materials on the heat storage performance, and the stability of MOFs after compounded with phase-change materials needed further exploration in the future. Besides, developing multifunctional materials by combining the catalytic and detection functions of MOFs with the heat storage and temperature control functions of phase-change materials was also one of the future development directions.

Key words: latent heat storage, phase change, metal organic frameworks (MOFs), composites, heat conduction, surface modification