Preparation And Application Of Phase Change Thermal Storage Building Aggregate

Phase change energy storage building material is a kind of material with phase change material(PCM)as core,which possesses high latent heat and high energy storage characteristics,in order to reduce indoor temperature fluctuation and realize energy saving performance.It is considered as one of the most effective approach and research focus in the field of building energy conservation.In order to solve the problem of poor compatibility with main building materials and low service life of existing products,the phase change energy storage aggregate with good sealing performance was prepared using capric acid(CA)and stearic acid(SA)eutectic mixture as phase change energy storage material,waste autoclaved aerated concrete as skeleton and slag-water glass-gypsum mixture as encapsulation material.Firstly,with the comfortable temperature(26 ?~27 ?)of the human body as the aim,the formulation of phase change energy storage material was designed by using DSC,FT-IR and SEM.The results show that the appropriate mass ratio of CA:SA is 9:1,with the melting temperature of 26.8 ? and phase change latent heat of 96.4 J/g.The composite phase change energy storage material complies with the design requirements.Secondly,the phase change material was absorbed into porous waste autoclaved aerated concrete particle under the vacuum condition.The optimal absorption conditions was obtained: temperature 70 ?,pressure 0.06 MPa and adsorption time 2 h.The adsorption amount of PCM accounts for 60 % of the total.In order to improve the leakage resistance of PCM,the waste autoclaved aerated concrete particles loaded with PCM need to be encapsulated.Considering of the compatibility of materials,the mixture of slag,water glass and gypsum was used as encapsulation material.The results show that the phase change energy storage aggregate have good leakage resistance of PCM.After 200 times of hot-cold cycle test,the variation of phase transition temperature and phase change latent heat are +0.01 ?and-0.13 J/g,respectively.The prepared phase change energy storage aggregate possesses good sealing performance and excellent stability.The phase change energy storage aggregate and cement were used to form simulating box.Good temperature adjustment performance was achieved for the box made from phase change energy storage aggregate: the highest temperature difference of the twocases reached 4 ?,time delay is about 360 s.With different mixing ratio and dosage of PCMs,the gypsum boards were prepared using capric acid(CA)and stearic acid(SA)eutectic mixture as phase change energy storage material.The thermal performance of the gypsum boards was tested and the mathematical model of the phase change heat transfer was built.With different proportions of PCMs,the energy saving performance of the phase change energy storage gypsum boards was simulated at spring season in Shijiazhuag area.The results showed that among the four different CA-SA dosages,the gypsum board with 30% PCM behaves the best in passive buildings and its energy saving is 8.77% more than that in blank.Increasing thermal conductivity and convective heat transfer coefficient of phase change thermal storage gypsum board can increase indoor temperature at night and thus reduce energy consumption,and the later is more significant.