Study On The Preparation And Properties Of Diatomite Based Phase Change Energy Storage Plasterboard

Phase change energy storage building materials,as novel functional building materials,have both the advantages of traditional building material and phase change energy storage material,which has good bearing capacity and excellent heat storage and temperature adjustment.It is an important research direction in the field of building energy conservation at present.Five common fatty acids were chosen as raw phase change materials.Their phase transition temperature,phase change enthalpy were analyzed by differential scanning calorimeter(DSC).A formula of the low eutectic theory was introduced to calculate the eutectic point mass ratio,phase-transition temperature and latent heat of four kinds of multi fatty acid eutectics.According to the calculated quality ratio,four kinds of low eutectic compounds were prepared by melt blending,which were tested by DSC.The results of DSC test were compared and verified with the theoretical values.which showed that calculated values agreed well with experimental data.Among those,Cupric acid(CA)-palmitic acid(PA)eutectic phase change temperature is 26.44?and the latent heat is 130.63 J/g,which suitable for use in the field of building energy conservation,so that CA(cupric acid)-PA(palmitic acid)was chosen as the main study object.The properties of the prepared CA-PA composite fatty acid phase-change materials were tested and characterized.Fourier transformation infrared(FT-IR)analysis results showed that there was no chemical reaction between CA and PA and the molecular structure remained unchanged.The solid-liquid expansion rate of CA-PA was 4.65%.After 200 times thermal cycling test,CA-PA phase transition temperature increased 2.77?,phase change latent heat of 5.20 J/g,fell by 3.98%,which both were not obvious.Furthermore,FT-IR spectra of CA-PA before and after circulation were basically consistent,which showed that CA-PA eutectic compound fatty acid has good thermal stability.The diatomite which had a porous structure was used as the shaping supporting material,maturing with CA-PA,The form-stable PCMs,namely,CA-PA/diatomite was prepared by melting and soaking.Diatomite was modified and CA-PA/modified diatomite stabilized phase change material was prepared.The properties of two types of phase change materials were characterized.DSC test showed that the two phase change materials had higher latent heat of phase change and the adsorption of modified diatomite was more stable.FT-IR analysis showed that the reaction between diatomite and CA-PA was physical adsorption without chemical reaction.TG experiments showed that when the temperature was below 100?,two kinds of form-stable PCMs has good thermal stability.After 200 thermal cycling tests,the phase transition temperature of two kinds of form-stable PCMs changed slightly,which indicated that its long-term thermal cycling stability was better.Phase change plasterboard was prepared by direct mixing method to study how the dosage of CA-PA/diatomite affect water resistance and mechanical properties of the gypsum board.The results showed that the water absorption rate and the compressive strength of gypsum specimen declined with the augment of dosage of phase change materials while the softening coefficient(KR)first rose and then lowered.When the dosage of CA-PA/diatomite were 25%,phase change plaster has the best ability,which all met the demand of basic mechanics performance of the retaining structure material and had good resistance to use many times.The thermal properties and thermal properties of the phase-change gypsum board with 25 percent of CA-PA/diatomite and the common gypsum board were studied.The results showed that compared with ordinary gypsum board,the change of the plasterboard over time was more moderate and far away from the heat source side temperature fluctuation is smaller.when the temperature rises to 23 degrees Celsius,the temperature phase change away from the heat source side of the gypsum board is gentle,which resulted from phase change materials absorbing some heat when the temperature achieved the phase change point,which showed that after adding CA-PA/diatomite,gypsum board has certain heat accumulation effect.DSC test analysis showed that phase transition temperature of phase change plasterboard was 23.28?,close to the human body comfortable temperature,phase change latent heat was 8.81 J/g.By the thermal constants were the coefficient of thermal conductivity of phase change plasterboard and heat storage coefficient measured by the thermal constants were 0.437 W/(m?K)and 7.29 W/(m~2?K).Compared with the ordinary plasterboard,phase change plasterboard thermal conductivity were lower,the heat storage coefficient were higher and its heat storage capacity is better.