| With the rapid development of society,energy demand is increasing,and the problems of energy shortage and environmental pollution are becoming more serious,and energy problems affect national security and social stability.Therefore,the focus of research is on how to use and store energy effectively.Renewable energies such as solar,wind and tidal energies are affected by multiple factors such as climate and region,causing intermittent problems.Phase-changing materials can absorb or release large amounts of heat during the phase-changing process,effectively solving intermittent problems with renewable energies such as solar and wind energy.However,while most inorganic phase change materials are corrosive,organic phase change materials have drawbacks such as low thermal conductivity and low flammability.These defects can be effectively resolved by encapsulating the phase change material in microcapsules and preparing the phase change microcapsules.Phase-changing microcapsules have the advantages of high heat storage density,excellent heat transfer performance,and stable performance,and have a wide range of applications in the textile,construction,solar energy utilization,and military fields.Therefore,studying the heat storage and heat transfer properties of phase-changing microcapsules has excellent potential application prospects.In this article,paraffin wax is used as the core material,PSF is used as the wall material,and phase change microcapsules are prepared by volatilization of the solvent.Compared with other methods for preparing microcapsules,solvent volatilization method has the advantages of simple operation,low requirement of experimental environment,simple preparation equipment and short preparation period.Nanoscale graphite,SiO2 and TiO2 are used as modifiers.The added amount of nanoscale graphite is 0%,0.5%,1%,1.5%and 2%of the mass of the base material,and the added amount of SiO2 at the nanoscale is the wall material.0%,1%,3%,5%,7%by mass and the added amount of TiO2 at the nanoscale is 0%,1%,2%,3%,5%of the mass of the wall.The effects of its addition amount on the surface morphology,chemical structure,thermal stability and phase change characteristics of phase change microcapsules were studied.The search results are as follows:1.The effect of phase change microcapsules prepared by a magnetic stirrer at 800r/min and 1000r/min on its performance was studied.The results show that when the rotational speed is 1000r/min,the particle size of the phase change microcapsule is 118.96 ?m,the enthalpy of fusion is 102.20 J/g,the enthalpy of crystallization is 101.50 J/g,the wrapping rate is 66.96%and the particle size is less than the rotational speed of 800r/min.The phase change microcapsules with a speed of 800r/min,phase change enthalpy,winding speed and thermal stability are better than phase change microcapsules with speed of 800r/min.2.Investigate the effect of the added amount of nanoscale graphite modifier on the performance of phase change microcapsules.The results show that the addition of nanoscale graphite modifier has no effect on the chemical structure of phase change microcapsules.When the addition amount is 1.5%,the average particle size of the microcapsules is 326.6 ?m,the melting temperature and the enthalpy of fusion are 29.87? and 94.00 J/g,the crystallization temperature and the enthalpy of crystallization are 23.61? and 92.95 J/g,the packaging of microcapsules The rate is 61.46%When the temperature rises to 220?,the loss of The heat of the microcapsules is 23.87%,which has good thermal stability and the overall performance of the microcapsules is the best.3.The effect of the added amount of nanoscale SiO2 modifier on the performance of phase change microcapsules was investigated.The results show that the addition of nanoscale modified phase change microcapsules SiO2 has no effect on the chemical structure of the microcapsules.The addition of a certain amount of nano-SiO2 reduces the particle size of the microcapsules,but with the addition of nano-SiO2,voids appear on the surface of the microcapsules,hence the phase change enthalpy and the rate Encapsulation of microcapsules are SiO2 at the nanoscale improves the thermal stability of microcapsules.Because small voids appear on the surface of phase change microcapsules with the addition of nanoscale SiO2,which can cause leakage of phase change materials,phase change enthalpy and rate Encapsulation of the addition of nanoscale SiO2 microcapsules are not as good as those without nanoscale addition SiO2:phase change microcapsules.4.The effect of the added amount of nanoscale TiO2 modifier on the performance of phase change microcapsules was investigated.The results showed that the use of nanoscale TiO2 modified phase change microcapsules had no effect on the chemical structure.It can increase the continuity and thermal stability of the wall material of the phase change microcapsule,and has little effect on the phase change enthalpy and the encapsulation rate of the microcapsule.When the amount of TiO2 nanometer additive is 3%,the overall performance of microcapsules is the best.The average particle size of the microcapsules is 103.83 ?m,the melting temperature and the enthalpy of fusion are 30.52? and 104.50 J/g,and the crystallization temperature and enthalpy of crystallization are at 22.60? and 104.00J/g,the encapsulation rate of the microcapsules is 68.54%.When the temperature rises to 220 ?,the heat loss of the microcapsules is 25.02%,which has good thermal stability.In summary,the rate of agitation in preparing microcapsules has some effect on particle size,phase change enthalpy,and rate of encapsulation of microcapsules.Adding a small nanometer amount of graphite,SiO2 and TiO2 as modifiers has no effect on the chemical structure of the microcapsules.Adding an appropriate amount of nanometer graphite and TiO2 modified phase change microcapsules can increase the continuity and warmth of the phase change microcapsule wall material.Stability and can increase phase change enthalpy and winding speed. |
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