木基生物质碳化骨架负载聚乙二醇相变材料及表面修饰对蓄传热性能的强化

Enhanced heat storage and heat transfer performance of wood-based biomass carbonized skeleton loaded with polyethylene glycol phase change material by surface modification

以相变芯材为核心的复合相变材料的潜热储存技术,对解决可再生能源间歇性问题有着关键作用.本研究以天然竹木为原材料,使用高温碳化方法得到碳化竹木,并使其分别吸附氧化石墨烯和还原氧化石墨烯,最终与聚乙二醇(PEG2000)复合形成稳定的复合相变材料.实验结果表明,还原氧化石墨烯可以达到很好的包封率、热导率和光热转换效率提升效果.碳化竹木/还原氧化石墨烯/聚乙二醇三元复合相变材料包封率高达81.11%,熔化潜热为115.62 J/g,凝固潜热为104.39 J/g,热导率大幅提升至1.09 W/(m·K)(纯PEG2000的3.7倍),光热转换效率大幅提高至88.35%(纯PEG2000的3.1倍).

Thermal energy storage technology can shift the peak and fill the valley of heat,which lays the foundation for realizing the goal of“emission peak and carbon neutrality”.Among various thermal energy storage techniques,the latent heat storage technology based on composite phase change materials can provide large storage capacity with a small temperature variation,and shows great potential in solving the intermittency issue of renewable energy.As a sustainable and renewable material,natural wood has the advantages of a unique anisotropic three-dimensional structure,perfect natural channel,low price,and rich resources.Therefore,the carbonized wood obtained from high-temperature carbonization of natural wood is an excellent choice as a supporting skeleton of composite phase change materials.On the other hand,polyethylene glycol is widely used in energy storage because of its suitable phase transition temperature(46–65℃),high latent heat(145–175 J/g),and stable performance.In this study,carbonized bamboo is prepared at high temperatures.To improve heat storage,thermal conductivity,and photo-thermal conversion properties,the carbonized bamboo is functionalized by graphene oxide and reduced graphene oxide,respectively.Finally,polyethylene glycol is implanted into modified carbonized bamboo to form shape-stabilized phase change materials.Their microstructures,morphologies,and thermophysical properties are characterized.The experimental results show that graphene oxide and reduced graphene oxide can change the surface polarity of carbonized bamboo,thus reducing the interfacial thermal resistance between the carbonized bamboo skeleton and polyethylene glycol,and improving the encapsulation ratio,thermal conductivity,and photo-thermal conversion efficiency without affecting the crystallization behavior of polyethylene glycol.The encapsulation ratio of carbonized bamboo/reduced graphene oxide/polyethylene glycol ternary phase change material is as high as 81.11%(only 4.67%lower than the theoretical value),its latent heat of melting and solidification are 115.62 J/g and 104.39 J/g,its thermal conductivity is greatly increased to 1.09 W/(m·K)(3.7 times that of pure polyethylene glycol),accompanied by substantial growth in its photo-thermal conversion efficiency,reaching 88.35%(3.1 times that of pure polyethylene glycol).This research develops a biomass-derived porous composite phase change material with high heat storage density,high heat transfer rate,and high photo-thermal conversion ability.