| Phase diagram is a powerful tool to guide the research field of material study for understanding the important information of temperature,composition and phase state.Heat storage technology of phase change material(PCM)can be used to solve three major energy utilization problems on large energy consumption,low utilization level and energy saving and reduce the emission.Its advantages of efficient storage and utilization of solar energy have been paid more attention by the energy industry at present years.However,due to the single component of PCM often cannot meet the actual requirements,two or more components of different PCMs are required to synthesize the phase change materials with suitable phase change temperature and latent heat.Although phase diagrams can provide important guidance in the synthesis of phase change materials as mentioned above,a large amount of experimental data are needed to established the phase diagrams.Database technology can effectively solve this problem by classifying,storing and searching data quickly.But so far,there are few studies on the solubility database of salt-water system.In this thesis,combining computer technology and database technology with solubility data of water-salt systems,a solubility inquiry system for salt-water system was established.In addition,the conventional inorganic salt phase change materials such as sodium,potassium,calcium and magnesium have serious super-cooling and low phase change temperature,which cannot meet the needs of heat storage of domestic water.So the synthesis of phase change materials based on octadecanoic acid and octadecanol was studied.The following results were obtained:(1)After configure the Apache-PHP-MySQL development environment under Windows system,a salt-water system database was established to serve for indexing of three conditions:composition,component and temperature.(2)After standardizing of the data format,the calculation formula of the Janecke index is input into the database,and the calculation of the Janecke index in the database is realized.(3)Relying on the Tencent cloud server and cloud database,the system was released to the Internet,and after a period of detection and bug repair,formal external services were provided to achieve commercial use.Users can login to the system home page(www.ourwaystd.com)to access the system for solubility queries.(4)Comparing several inorganic salt phase change materials found by colleagues through the database,we found that these materials are generally suitable for the low temperature field,but not suitable for the medium temperature field of domestic water.Therefore,in this paper the organic phase change materials with latent heat of 198.7 J/g,phase change temperature of 44.2? and thermal conductivity of 0.2352 W/(m·K)were synthesized by using octadecanoic acid(C18-acid)and octadecanol(C18-OH)as the basic materials.The chemical structure and thermal properties of the composite were characterized detailedly by differential scanning calorimetry,cooling curve,thermal conductivity,scanning electron microscopy and Fourier transform infrared spectroscopy.(5)Expanded graphite adsorption method was used to encapsulate PCMs.The thermal conductivity of PCMs increased 10 times to 2.434 W/(m K),and the phase transition temperature and latent heat decreased to 43.9 C and 179.2 J g,respectively.It was finally determined that the mass composition of the composite PCM was C18-acid-C18-acid-EG=55.05:36.69:8.26... |
PDF Full Text Request