Study Of Polystyrene-silica@tetradecane Composite Nanoencapsulated Phase Change Materials For Cold Energy Storage

Latent functionally thermal fluid (LFTF) is a sort of heat transfer fluid with encapsulatedphase change material dispersed in, which can effectively increase the heat capacity of theheat transfer fluid. The traditional organic phase change microcapsule is weak in large size,low thermal conductivity and thermal stability. Therefore, research on new LFTF which canreinforce coefficient of thermal conductivity and specific heat capacity, that is syntheses asingle particle fluid with high thermal conductivity as well as high specific heat capacity, hasimportant theoretical guiding significance and practical application value.In this paper, a novel PS-SiO2@Tet composite nanoencapsulated phase change material(PCM) as LFTF for cold thermal energy storage was synthesized by miniemusion in-situpolymerization. The experimental factors of modified silica sol, the amount of emulsifier,monomer and initiator and other factors were systematically investigated. The morphology,chemical structure and thermal performances of composite nanoencapsulated PCMs and latexwere measured by particle size analyzer, scanning electron microscope (SEM), transmissionelectron microscope (TEM), Fourier transform infrared (FTIR), X-ray photoelectronspectroscopy (XPS), differential scanning calorimetry (DSC), thermogravimetric analysis (TG)and Hot Disk, respectively.Studies have shown that: the dosage of ammonia, water and silane coupling agent greatlyinfluence the particle size and dispersing performance of modified silica sol. Emulsionformed by single emulsifier has poor stability and larger particle size, while compositeemulsifier can easily form stable capsule, and composite nanoencapsulated PCMs obtainedhave large latent heat. By adding MMA monomer, the phase change latent heat of compositenanoencapsulated PCMs increases obviously. Oil-soluble initiator AIBN can form capsule,but the conversion rate and phase change latent heat of composite nanoencapsulated PCMsdepend on the amount. The mass fraction and addition time of modified silica sol affect theparticle size and phase change latent heat of the nanoparticles.The optimized experimental conditions were as following: m(TEOS)=5g,V(C2H5OH)=30ml, n(NH3·H2O)=0.016mol, n(H2O)=0.28mol, m(KH-570)=2%,4%monomer (MMA),3%composite emulsifier (SDS:OP-10=1:1),0.4%initiator (AIBN) and7%modified silica sol. Under the optimized condition, a uniform spherical compositenanoencapsulated PCMs with average diameter of64.90nm was prepared. XPS resultsshowed the content of Si of composite nanoencapsulated PCMs is3.27%. Phase change latentheat by DSC is83.38kJ·kg-1, suggesting composite nanoencapsulated PCMs has good energy storage capacity. The test results of the emulsion showed the coefficient of thermalconductivity and specific heat capacity of emulsion were better than those of the unmodifiedemulsion. Due to its good thermal properties and mechanical stability, the PS-SiO2@Tetnanoparticle displays a good potential for cool energy storage.