Preparation And Performance Research Of Aluminum-based Composite Phase Change Thermal Storage Material Based On Thermal Storage Chemical Looping Combustion Technolog

The chemical-looping combustion（CLC）is a new energy technology,which can increase the thermal efficiency and having inherent advantages for CO₂ separation with minimum energy losses.Chemical-looping combustion system consist of fuel reactor and air reactor.The chemical reaction in air reactor is high temperature exothermic reaction,which can result in nonuniform of temperature distribution and hot spot.To make sure the smooth running of the chemical-looping combustion is a precondition of the commercial application.Thermal energy storage technology is very important to improve energy efficiency and move the gap between energy supply and request.In this paper,the phase change thermal storage technology was used in chemical-looping combustion process through building a thermal storage functional oxygen carrier,which can make the temperature of the oxygen carriers in the fixed bed more stable,and promote the heat exchange between the two reacters.A core-shell structure heat storage material（Al/AlN）was prepared through direct nitridation method.The composite material was characterized by XRD,DSC,SEM and thermal conductivity instrument techniques.The results show that increasing the nitridation temperature and time can promote the.nitridation reaction.The Al/AlN-Al₂O₃ material using 10%NH₄Cl as an additive and nitride at 900℃ for 2h showed excellent thermal storage performance and thermal stability.The phase-transition temperature,latent heat of fusion and thermal conductivity are 662℃ and 214J/g and 16.7 Wm^-1k^-1 respectively,the thermal storage density is as high as 729.8 J/g.The heat of fusion of the composite thermal storage material maintained 214 J/g after 20 thermal cycles.A new aluminium base heat storage material（Al/NiO-Al₂O₃）was prepared through replacement and high-temperature sintering techniques.Reaction temperature,reaction time and the content of NH₄Cl was investigated in detail,and reasonable parameters was determined that is the Ni²⁺ concentration and calcination temperature and treatment numbers are 0.084mol/L,800℃ forlh and two times.The composite material was characterized by XRD,TG-DSC,SEM and thermal conductivity instrument techniques.The results show materials possess high thermal storage density and excellent thermal stability.The phase-transition temperature,latent heat of fusion and thermal conductivity are 661℃ and 247 J/g and 3.26Wm^-1k^-1respectively,the thermal storage density is as high as 893 J/g.The heat of fusion of the composite thermal storage material maintained 244 J/g after 30 thermal cycles,which shows excellent thermal stability.The thermal storage functional oxygen carrier（Fe₂O₃/Al₂O₃-Al/NiO-Al₂O₃）was prepared through introduce Al/NiO-Al₂O₃ heat storage material into Fe₂O₃/Al₂O₃ oxygen carriers.H₂-TPR and CLC of CH₄ show the thermal storage functional oxygen carrier own heat storage and reactivity double effect.