Preparation And Study On Fatty Acid-fatty Alcohol/expanded Perlite Phase Change Building Heat Storage Materials

Once thermal energy storage technology based on phase change materials is widely used in life,it will become an effective way to realize building energy efficiency.Based on the selection and improvement of phase change materials and the composite method of phase change materials and expanded perlite,this paper explored composite materials applicable to the field of building energy conservation and the optimum preparation process of lauric acid-palmitic acid-tetradecyl alcohol/expanded perlite composite phase change building heat storage material.Firstly,capric acid(CA),lauric acid(LA),myristic acid(MA),palmitic acid(PA),tetradecyl alcohol(TD)and hexadecyl alcohol(HD)were selected as phase change materials.Secondly,the composition ratio and phase change temperature of fatty acidfatty alcohol binary and ternary complex system and fatty acid-fatty acid binary and ternary complex system were obtained by using the theoretical estimation formula.Finally,five kinds of composite phase change materials with phase change temperature ranging from 25 ℃ to 30 ℃ were preliminarily obtained,and lauric acid-palmitic acidtetradecyl alcohol suitable for building energy saving was obtained through comparison and analysis.Among the 30 kinds of binary and ternary composite phase change materials,the phase change temperature ranged from 9.1 ℃ to 46 ℃,which was basically concentrated in the region of medium-low temperature.And the theoretical phase change temperature and latent heat of lauric acid-palmitic acid-tetradecyl alcohol were 25.12 ℃ and 102 J/g,respectively.Secondly,the optimum preparation technology of lauric acid-palmitic acidtetradecyl alcohol/expanded perlite was studied by adsorption experiment and leakage experiment,and the evaluation criteria of the retention rate and stability were used as evaluation indexes.The results showed that the feasibility of theoretical estimation formula to guide the experiment was verified because the actual phase change temperature of lauric acid-palmitic acid-tetradecyl alcohol determined by step cooling curve method was 24.8 ℃,which was only 1.3% different from theoretical phase change temperature.The reasonable adsorption temperature of lauric acid-palmitic acidtetradecyl alcohol adsorbed by expanded perlite was 65 ℃ and the reasonable adsorption time was 60 min.And when the design content of lauric acid-palmitic acid-tetradecyl alcohol was 60%,the phase change temperature of the composite phase change building heat storage material was 24.7 ℃.At the same time,the expanded perlite had the best adsorption effect on lauric acid-palmitic acid-tetradecyl alcohol at this ratio,and the leakage stability of the composite phase change building heat storage material was also within a reasonable range.Finally,the microstructure,structural compatibility,cyclic stability,heat resistance and temperature control properties,and thermal performance of the composite phase change building heat storage materials with the designed content of 60% lauric acidpalmitic acid-tetradecyl alcohol were characterized and analyzed by SEM,FT-IR,stability analysis,heat storage/exothermic performance analysis and DSC.The results showed that lauric acid-palmitic acid-tetradecyl alcohol can be evenly and compactly distributed in the pores inside the expanded perlite.There was no chemical reaction between expanded perlite and lauric acid-palmitic acid-tetradecyl alcohol,and its compatibility was good.The mass loss rate of the composite phase change building heat storage material after 30 cycles of cold and heat from 20 ℃ to 70 ℃ was 0.67%,which had good cycling stability and heat resistance.Compared with expanded perlite,lauric acid-palmitic acid-tetradecyl alcohol/expanded perlite composite phase change building heat storage material can carry out heat storage and heat release and play an obvious role in regulating and controlling the ambient temperature.It takes 270 s and 790 s respectively for expanded perlite and lauric acid-palmitic acid-tetradecyl alcohol/expanded perlite to rise from 20 ℃ to 50 ℃,and 640 s and 1180 s respectively to decrease from 50 ℃ to 20 ℃.In summary,the composite phase change building heat storage material was prepared by adsorption of screened lauric acid-palmitic acid-tetradecyl alcohol with completely dried expanded perlite under prevailing pressure.It had high application value in large-scale continuous production,and had important reference significance for the application of composite phase change building heat storage material in the field of building energy conservation and heat storage.