| With the rapid development of global industry and the short supply ofthe energy, it is quite necessary to study on the energy storage theoryand energy storage technology. Phase change energy storage is aneffective way of the energy storage by using phase change materials(PCMs). PCMs absorb heat and release latent heat through phasechange process, which eliminates mismatch between energy supply andenergy demand in space and time and increased energy efficiency, so asto attain the objective of saving energy. In recent years, PCMs havebeen widely used in various fields, such as solar heating system,electricity system, textiles and fabrics, air-conditioning system,preservation of food, waste heat recovery and building energyconservation.In this thesis, binary fatty acid eutectic mixtures was selected as phasechange energy storage material to prepare form-stable phase changecomposite by using sol-gel method and vacuum absorption method.Field-emission scanning electron microscope (FSEM), and Fouriertransform infrared (FT-IR), differential scanning calorimetry (DSC)and thermogravi metric analysis apparatus (TG) were applied t odetermine chemical structure and microstructure, therma l propertiesand thermal reliability of materials.Capric acid(CA) was mixed separately with lauric acid(LA), myristicacid(MA), pal mitic acid(PA) and stearic acid(SA) to prepare binaryfatty acid eutectic mixtures, which selected as phase change energystorage materials. Co mbined with actual conditions, the CA-MA eutectic mixture was selected as energy storage material. The meltingand freezing temperatures of the CA-MA eutectic mixture was measuredas23.64℃and15.25℃, the melting and freezing latent heat wasmeasured as147.7J/g and146.5J/g, respectively.CA-MA/silicon dioxide form-stable phase change energy storagecomposite material has been prepared by using sol-gel method in thisthesis. In the composite, ethyl silicate was selected as slica source andCA-MA was selected as phase change material. The optimal reactioncondition for the composite preparation is determined to be ethylsilicate: ethyl alcohol: water=1:4:8, pH=3and reaction temperature is60℃. FSEM, FT-IR, DSC and TG were applied to determine che micalstructure and microstructure, ther mal properties and ther mal reliabilityof CA-MA/silicon dioxide composite. The results show that theCA-MA/silicon dioxide composite ma terials containing45%CA-MAhas a me lting temperature of20.96℃and latent heat of70.17J/g.CA-MA uniformly imbedded into the net of silicon dioxide withoutleakaging from the composite. TG and ther mal cycling test resultsshowed that the CA-MA/silicon dioxide composite had no weight losebelow100℃and had good ther mal stability.CA-MA was selected as phase change material, and diatomite, whitecarbon black， zeolite respectively were selected as porous inorganicmaterials to prepare form-stable phase change materials by usingvacuum a bsorption method. SEM, FT-IR, DSC and TG were applied todetermine chemical structure and microstructure, therma l propertiesand ther mal reliability of form-stable phase change comp osite materials.The maximu m absorption of CA–MA in the three composite PCM wasdetermined as45%,66.6%and30%, respectively. The CA-MA was well adsorbed into the porous network of porous inorganic materials bycapillary and surfa ce tension forces and hence leakage of the meltedCA-MA from the composite is prevented. TG and therma l cycling testresults showed that the three composite PCM had no weight lose below100℃and had good ther mal stability.At last, a novel phase change energy storage mor tar was prepared withCA-MA/WCB form-stable PCMs, and the main mechanical propertiesand thermal property were studied. The compressive strength of thephase change energy storage mortar was slightly lower than the generalmortar. However, the therma l properties of the phase change energystorage mortar were superior to general mortar. |
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