Construction And Heat Storage Mechanism Of Wood-based Phase Change Heat Storage Materials

Phase change heat storage wood is a new type of green environmental protection and energy saving material.It mainly uses the multi-scale structure of wood to shape and encapsulate the phase change heat storage material,so that the wood has the ability to save energy and adjust temperature.It has broad development prospects in the fields of building interiors and furniture.It is of great significance to improve the added value of fast-growing wood.However,phase change materials have problems such as easy leakage,low thermal conductivity,and poor bonding with wood.In this paper,the construction and thermal properties of phase change heat storage wood were studied,and phase change heat storage wood with high thermal conductivity,strong loss resistance and excellent thermal performance was prepared.The main conclusions are as follows::（1）PEG 800,methacrylate,glycerol ester（GMA）,and ethylene glycol dimethacrylic acid were blended,and the polymer-based fixed phase change heat storage material was prepared.The results show that there is an open-loop reaction between the non-saturated double bonds of GMA and PEG 800 to generate a long chain structure,and when the PEG 800 content is 90%,the melting enthalpy of PGMA is121.10 J/g and 99.56 J/g,respectively,the melting and crystallization temperature are 28.64°C and15.03°C.Ther is no leakage phenomenon and the PGMA has high thermostability.（2）Reactive wood skeleton was prepared by the grafting reaction between maleic anhydride and decomine poplar and decomine balsa wood,then the PGMA was impregnated into the wood cells by high temperature pressurization.The results show that the molten enthalpy and coagulation enthalpy of phase change in balsa wood as matrix is from 50.18 J/g and 65.28 J/g,which is excellenter than poplar.In order to further increase the latent heat value of the phase change,PGMA prepared by mixing PEG 800 and PEG 1000 is introduced into the reaction type wood skeleton by mass 3:7.The molten enthalpy and the coagulation enthalpy are 119.30 J/g and 118.50 J/g,respectively.（3）The surface of carbon black（CB）was grafted with dopamine（DA）and octadecyl isocyanate,and CB exhibited durable dispersion properties in organic solvents.The delignified balsa wood was impregnated with a CB as a thermal conductivity enhancing filler by high temperature and high pressure method,and then PGMA was impregnated into wood cells by high temperature pressure impregnation method to obtain thermal conductivity enhanced phase change heat storage wood.The thermal conductivity reaches 0.4456 W/（m·K）,which is 24%higher than the thermal conductivity of the phase change heat storage wood without nano thermal conductive particles,and it is better than the thermal insulation of the phase change heat storage wood without the addition of thermal conductive nanoparticles under low temperature conditions.The heat storage time was extended by 295s.（4）The KH550 grafted BN and graphene quantum dots co-doped BN were respectively impregnated into the reactive wood skeleton to form a thermal conduction path,and the PGMA was impregnated into the wood cells by the high temperature pressure impregnation method to obtain a thermal conductivity-enhanced phase change heat storage wood.The thermal conductivity is 0.4185 W/（m·K）and 0.3916W/（m·K）,respectively,which are 30%and 22%higher than that of the phase change heat storage wood without nano thermal conductive particles,respectively.Compared with the non-addition of thermal conductive nanoparticles,the heat preservation time of phase change heat storage wood was prolonged by 465s and 246s,respectively.（5）Fe₃O₄ was formed in situ in the wood skeleton,and PGMA was immersed into wood cells using high temperature pressurized impregnation.The results show that the molten enthalpy and coagulation enthalpy of phase change heat storage wood have reached 140.00 J/g and 132.00 J/g,respectively.The secondary impregnation treatment of phase change heat storage wood by alkylaized carbon black,KH550grafted BN,the graphene quantum dots co-doping BN,which solves the leakage problem of phase change heat storage wood.The Phase change latent heat value of KBN/Fe-PCES@Balsa is the largest,the molten enthalpy and the coagulation enthalpy have reached 128.50 J/g and 121.90 J/g,the overhelation and heat loss rate is relatively small,and the thermal conductivity is 0.4134 W/（m·K）.