Preparation And Application Of Large Hysteresis Reversible Phase Change Energy Storage Microcapsules

Energy is always a hot topic in the world.It is an important task to find new energy and energy storage materials to solve the energy problem.In northwest China,the temperature difference between day and night is large,the sunshine time is long during the day,and the temperature is low at night.If the heat generated during the day is stored to supply the cold at night,the economic problems caused by energy consumption can be alleviated.In this paper,the preparation of phase change energy storage microcapsules and their applications in coatings are reviewed,and the hysteresis phase change materials are prepared by means of melt blending,the hysteresis mechanism of phase change materials is discussed,and the hysteresis phase change materials with great hysteresis are screened out.On the basis of previous studies,the effects of preparation process parameters on the morphology and performance of microcapsules were comprehensively discussed,and the effects of experimental parameters on the thermal performance of phase change coating were studied by applying the reversible phase change energy storage microcapsules with large hysteresis to phase change coating for the first time.The main experimental results are as follows:(1)4-phenyl ethyl decanoate benzyl oxygen radicals(DAE)substrate will work,respectively and bisphenol A(BPA),4,4'-(1-phenethyl)bisphenol A(AP)and crystal violet lactone(CVL)by melt blending quality percentage,composite phase change materials,was determined by X-ray diffraction spectrum is basic the cause mechanism of phase transition behavior of composite materials,using differential scanning calorimetry(DSC)characterization of the phase change characteristic of the composite phase change materials and lagging performance.The results showed that The large hysteresis effect of phase change energy storage materials was derived from the influence of the molecular structure of DAE and the temperature regulator BPA,AP and CVL on the crystallization of the methylene chain segment of the DAE molecular chain.DAE will work when the ambient temperature above 60? melting of molecules formed random liquid,when the temperature dropped to 31.7?,the DAE will work molecular motion ability is abate,the molecular chain of the methylene chain segments to crystallization nucleation,to join the large volume of BPA,AP and CVL,interfere with DAE will work further molecular chain methyl central Asia chain segment of crystallization nucleation,lead to molecular crystal DAE will work lag is more obvious;The temperature regulator changed the crystal structure of DAE molecule,produced new crystal types,and caused the crystallization of DAE molecule in the molten state to produce obvious hysteresis effect.The larger the volume of the molecule regulator,the more obvious the hysteresis effect.The melting enthalpy and crystallization enthalpy of the ternary blend system were lower than that of the binary blend system,and the crystallization temperature of CVL/BPA/DAE was lower than that of CVL/AP/DAE,and the lag temperature difference was as high as 46?.(2)Hysteresis phase change materials were added to styrene maleic anhydride polymer(SMA)for dispersion.Under acidic action,melamine-urea-formaldehyde(MUF)prepolymer was added for condensation to form microencapsulated phase change materials,and large lag reversible phase change energy storage microcapsules were obtained.Using infrared spectroscopy to determine the chemical structure of the microcapsule,through deeply reflecting microscope and scanning electron microscope(SEM)to observe the morphology of microcapsule,nano-meter particle size instrument with particle size and distribution of the microcapsule,using DSC technology instrument with the phase change behavior of microcapsule,phase change characteristics and thermal hysteresis performance,and testing the stability of the microcapsules dispersion.The results showed that: Ratio of core and shell of 1.25,4.0g emulsifier,reaction speed 800 rpm,MUF prepolymer melamine 7.2g and 0.8g of urea,reaction temperature 80?,obtained form is complete,the big lag reversible phase change microcapsule particle size uniformity,covering rate is as high as 78.5%,compared with the phase change materials are not coated,the melting enthalpy of phase change materials of microcapsules and crystallization enthalpy decreased,the lowest crystallization temperature can drop to 39.8?,the lag of up to 83.7?,the temperature difference but melt temperature have no obvious impacts.(3)the delay reversible phase change microcapsule is first to add curing agent,additives,preparation phase change paint,spraying on tinplate tank,preparation phase change coatings,discusses the emulsifying agent,stirring speed,reaction temperature,different phase change energy storage phase change energy storage coating made of microcapsule emulsion and the influence of the thickness of the coating on tank temperature control behavior,and the phase change heat transfer performance of tank,thermal hysteresis performance and thermal regulation performance test.The results show that Phase change coatings have a lower heat transfer rate than conventional coatings.At the same rate of temperature rise and fall,the phase change coating has a certain regulating effect on temperature rise and fall,and has obvious temperature delay.And the thicker the coating,the more obvious the thermal hysteresis effect,the more significant the heat preservation and storage effect.