核壳结构碳包铁纳米流体制备及导热特性.docVIP

 核壳结构碳包铁纳米流体制备及导热特性# 徐卓文，张海燕，徐睿杰，李春辉** （广东工业大学材料与能源学院，广州 510006） 5 10 15 20 25 30 35 40 摘要：采用直流电弧法制备具有核壳结构的纳米碳包裹铁粒子（碳包铁纳米粒子），经过不 同分散方式配制成碳包铁纳米流体，由 Hotdisk 瞬态热源法测量流体的导热系数，研究了表 面活性剂、超声分散时间、流体 pH 值和碳包铁纳米粒子含量对纳米流体分散稳定性及导热 特性的影响。实验表明, 添加表面活性剂能提高纳米粒子表面的亲水特性，超声分散能有效 地减少流体中纳米团聚粒子的粒径，这两种方法加强了纳米流体的分散稳定性。添加了聚乙 烯吡咯烷酮作表面活性剂的纳米流体其 pH 范围为 8~9 稳定效果最佳，对流体采取超声分散 的适宜时间为 300s，流体导热系数相对基液生理盐水的提高幅度随纳米粒子含量增加先升 高后下降，当纳米粒子增加量为 0.11%，流体导热系数达到最大值 0.9387W/mk，提高幅度达 到最大值 41%。 关键词：碳包铁；纳米流体；超声分散；导热系数 中图分类号：TK124 Preparation, dispersion and thermal conductivity of carbon-coated iron nanofluid XU Zhouwen, ZHANG Haiyan, XU Ruijie, LI Cunhui (School of Material and Energy,Guangdong University of Technology, GuangZhou 510006) Abstract: This paper presents a procedure for preparing carbon-coated iron nanoparticles by DC arc discharge method. By different means of dispersion, carbon-coated iron nanofluid was prepared and the thermal conductivity of nanofluid was measured with Hotdisk Transient Heat Source Method. The effect of carbon-coated iron nanoparticles in saline on the stability and evenness of nanofluid was analyzed and studied; the elements which affect thermal conductivity of nanofluid were taken into account, such as nanoparticles surfactant, sonication time, pH value and carbon-coated iron nanoparticles concentration. The results show that addition of surfactant improves the hydrophilic properties of the nanoparticles surface; Sonication reduces the particle size of aqqlomerated nanoparticles in the fluid, both addition of surfactant and sonication can enhance stability and evenness of nanofluid. The stability and evenness of nanofluid becomes better while the pH ranges of 8 to 9 and 300s sonication time dealed with the nanofluid. Compared with the saline, the thermal conductivity improvement of carbon-coated ion nanofluid increases first and then decreases with increasing content of nanoparticles, achieves maximum magnitude of 41%(0.9387W/mk) when nanoparticles mass fraction is 0.11%. Ke