Nanoencapsulated Phase Change Emulsion Of RT42/polymer

With the rapid development of global economy and industry, the energy shortage hasbecome increasingly prominent. The technology of phase change energy storage, taking useof the latent heat during phase change process to realize thermal energy storage andutilization, is helpful to improve the efficiency of energy utilization and save energy.However, there are some disadvantages for phase change materials themselves, such as thefluidity during phase change process, the corrosivity and the poor compatibility.Encapsulation technology which fixes phase change materials into micrometer or nanonmetercontainers is expected to solve the above shortcomings.In this paper, the nanoencapsulated phase change materials (NEPCMs) with paraffinwax of RT42as core and polystyrene as shell were synthesized by ultrasonic technique andminiemulsion in-situ polymerization. The influences of ultrasonic parameters and reactionconditions, initiator, dispersant, surfactants, co-monomers, and the mass ratio of RT42andstyrene on polymerization were systematically investigated. The morphology, compositonand the thermo-physical properties of synthesized nanoencapsulated phase change materialsand latex were characterized by particle size analyzer, transmission electron microscope(TEM), fourier transform infrared spectroscopy (FTIR), differential scanningcalorimeter(DSC), thermogravimetric analyzer (TG), rotational viscometer and high-lowtemperature cycle test.The experimental results showed that, the latent heat of NEPCMs with2,2-azobisisobutyronitrile (AIBN) as initiator was obviously higher than that with potassiumpersulfate (KPS). The stability of emulsion and the dispersion of RT42were enhanced usingpolyvinylpyrrolidone (PVP) as dispersant. The combination of polymerizable emulsifier andtraditional emulsifier (sodium dodecylsulfate (SDS) and poly-(ethyleneglycol) monooctyl-phenyl ether (OP-10)) help to improve the stability of emulsion and produce uniformly sizedNEPCMs. Adding hydrophilic co-monomer was usful to improve the shell performance andform core-shell structure. The mass ratio of RT42and St determined the thermo-physicalperformance and the stability of NEPCMs.The optimal polymeriztion conditions of NEPCMs were that:55%power adjusted value, 15min ultrasonic time,6h reaction time,60℃reaction temperature,0.4%polyvinylpyrrolido-ne (PVP, mass fraction of the oil phase liquid, the same as follows),9%composite emulsifierwhich constituted by polymerizable emulsifier DNS-86, sodium dodecyl sulfate (SDS) andpoly-(ethylene glycol) monooctylphenyl ether(OP-10) with2:1:1mass ratio,0.4%AIBN,3%EA and3:5mass ratio of RT42and St. The average particle size of prepared nanocapsuleswas80.8nm and the phase change enthalpy was60.14kJ/kg. During the melting process,the peak of the specific heat capacity of powder sample reahed10.99kJ/kg·℃,and theencapsulation rate of RT42was92.9%. The tesed results of the synthesized latex showed that,the viscosity was only8.35cP at20%mass fration and40℃, and the thermal conductivitycoefficient and the specific capacity was0.83W/m·K and5.29kJ/kg·℃at42℃, respectively.In addition, after many times for high-low termperature thermal cycling experiment, the heatstorage capacity of emulsion was not significantly decreased. It suggests that the synthesizedNEPCMs emulsion was a potential candidate as latent functionally thermal fluid.