三水合醋酸钠(SAT)应用范围广,但存在热导率低、过冷度大及相分离问题,对其在太阳能蓄热系统中的应用有较大负面影响。通过添加阴离子表面活性剂十二烷基硫酸钠(SDS)对膨胀石墨(EG)改性,制备了亲水性良好的改性膨胀石墨(MEG),当SDS与EG添加量为1∶2和1∶1时,过冷度仅为1.7℃和2.8℃,此前并未报道,同时提高了EG对SAT的包封率,最高可达92.52%。相应制得SAT与MEG复合相变材料(CPCM)的熔化焓高达236.5J/g和236.9J/g,相变温度56.7℃和56.5℃,热导率较SAT提高了51.56%和34.47%,在100次蓄放热循环后仍保持较好的热循环稳定性,具备实际应用价值。
Sodium acetate trihydrate (SAT) has a wide range of applications,but it suffers from low thermal conductivity,large subcooling and phase separation problems,which have a large negative impact on its application in solar thermal storage systems.Modified expanded graphite (MEG) with good hydrophilicity was prepared by modifying expanded graphite (EG) with anionic surfactant sodium dodecyl sulfate (SDS).When the additions of SDS and EG were 1∶2 and 1∶1,the supercooling degree was only 1.7℃ and 2.8℃,which had not been reported before,and the encapsulation efficiency of EG on SAT was also improved up to 92.52%.The melting enthalpies of SAT and MEG composite phase change materials (CPCM) were as high as 236.5J/g and 236.9J/g,the phase change temperatures were 56.7℃ and 56.5℃,and the thermal conductivities were 51.56% and 34.47% higher than those of SAT.After 100 cycles of storage and exothermic cycling,it still maintained good thermal cycling stability,which was of practical application value.
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基金资助
内蒙古自治区自然科学基金基金项目(2018MS05042)
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