原位合成纳米ZnO对太阳盐比热容的影响

Effect of the in situ synthesis of nano-ZnO on the specific heat capacity of solar salt

太阳盐具有良好的热物性,在太阳能热发电储热系统中有良好的应用前景。提高太阳盐比热容可以显著提高其储热能力。本文采用水热法在太阳盐中原位合成片状纳米Zn O,采用燃烧法在太阳盐中原位合成颗粒状纳米Zn O。借助X射线衍射(XRD)、能谱分析技术(EDS)、场发射电子扫描显微镜(FE-SEM)、透射电子显微镜(TEM)和差式扫描量热仪(DSC)研究纳米Zn O对太阳盐的结构与性能影响。结果表明,水热法制备的改性太阳盐中Zn O纳米片的尺寸为50~200 nm,当Zn O纳米片含量为1%(质量分数)时,Zn O纳米片能够较好分布在基盐中,改性太阳盐固态和液态比热分别达到2.09 J/(g·℃)和1.78 J/(g·℃),分别提高71.3%和38.0%。燃烧法制备的改性太阳盐,Zn O纳米颗粒的尺寸在30~200 nm,当Zn O纳米颗粒含量为0.75%时,在基盐中分散性好,改性太阳盐固态和液态比热分别达到2.20 J/(g·℃)和1.88 J/(g·℃),分别提高82.0%和45.7%,比热性能要更优于水热法制备的改性盐。本研究有助于推动纳米颗粒改性无机盐的应用,为高比热容的太阳盐技术的研发提供实验依据。

Solar salt as a heat storage material with optimum thermal properties has promising application prospects with respect to the thermal power and heat storage of solar energy. By enhancing the specific heat capacity of solar salt, it is possible to considerably improve the thermal storage capacity. In this study, nano-Zn O flakes were synthesized in situ in solar salt via the hydrothermal method, and granular Zn O was synthesized in situ in solar salt via the combustion method. XRD, EDS,FE-SEM, TEM, and DSC were used to study the effect of nano-Zn O on the structure and properties of solar salt. Results show that the size of Zn O nanosheets is between 50 and 200 nm, the size of Zn O nanoparticles is between 30 and 200 nm, and nano-Zn O has good dispersibility in salt. When the weight content of Zn O nanoflakes in solar salt was 1%, the specific heat of the solid and liquid of modified solar salt reached 2.09 and 1.78 J·(g·℃)-1, which denote an increase of 71.3% and 38.0%, respectively.When the Zn O nanoparticle weight content in solar salt was 0.75%, the solid and liquid specific heat of modified solar salt reached 2.22 and 1.88 J·(g·℃)-1, which denote an increase of 82.0% and 45.7%,respectively. The addition of granular Zn O has a better specific heat capacity enhancement effect on solar salt than that of Zn O nanoflakes.