Preparation And Performance Of Form-stable Composite Phase Change Materials Based On Porous Carbon

Based on the urgent need for energy conservation in buildings in China and low thermal conductivity of existing phase-change energy storage materials,novel form-stable composite phase change materials?FS-PCMs?were prepared by the incorporation of PCMs into carbonization biomass waste porous carbon and phenolic resin foam carbon.Biomass porous carbon can maintain the original pore structure of biomass materials,with abundant pores and large specific surface area,which not only solves the problem of leakage during the phase transition of organic solid-liquid phase change materials,but also effectively improves thermal conductivity of composite phase change energy storage materials.In this thesis,lauric acid-palmitic acid eutectic mixture PCMs?LA-PA PCMs?and lauric acid-stearic acid eutectic mixture PCMs?LA-SA PCMs?having a suitable phase temperature and a high energy storage density was prepared,and the thermal performance was characterized.The LA-SA/CNCC FS-PCMs,LA-PA/CAR FS-PCMs,PF/BPC FS-PCMs and PEG/CF FS-PCMs were prepared,and the thermal performance,thermal conductivity and compressive strength were characterized.The phase transition temperature of LA-PA PCMs and LA-SA PCMs during the melting stage are 35.7°C and 37.5°C,respectively,and the latent heat is 171.8 J/g and199.6 J/g;the phase transition temperature in the solidification stage is 28.2°C and29.9°C,and the latent heat values are 160.5 J/g and 186.5 J/g,respectively.The temperature is just within the appropriate temperature range of human life.Both LA-PA PCMs and LA-SA PCMs have excellent chemical stability,thermal stability and thermal cycle stability.The biomass solid waste corncob,waste rice,and peel are used as carbon sources to prepare porous carbon-based composite phase change energy storage materials.The phase transition temperatures during melting are 31.5°C,34.3°C,and 44.3°C,respectively;The latent heat of phase change is 148.3 J/g,135.4 J/g and 149.1 J/g respectively;the phase change temperature during solidification is 29.7°C,28.6°C and54.0°C,and the latent heat of phase change is 144.2 J/g,124.8 J/g and 155.14 J/g.The loading rate of phase change energy storage materials reach 77.9%,78.2%and 83.7%respectively.Both LA-SA/CNCC FS-PCMs,LA-PA/CAR FS-PCMs,PF/BPC FS-PCMs have good chemical stability and thermal stability,and no leakage occurs in 200thermal cycles,and the thermal conductivity are 1.93 times,1.83 times and 2.43 times that of phase change energy storage materials.The phenolic resin is used as the carbon source to prepare the carbon foam materials.When the phenolic resin concentration is 35 wt.%,the compressive strength of the carbon foam is 0.625 MPa,and the phase change material loading rate is 70.2%.The phase change temperature of the carbon foam based composite phase change energy storage material during melting is 55.9°C,the latent heat of is 135.7 J/g;the compressive strength is up to 1.202 MPa.And PEG/CF FS-PCMs has good chemical stability,thermal stability and mechanical strength.The thermal conductivity is 0.531Wm^-1K^-1,which is 2.09 times of the PEG.When 2 wt.%Carbon nanotubes are added,the thermal conductivity reaches 0.597 Wm^-1K^-1,which is 2.25 times of the PEG.