目的 探究多壁碳纳米管的浓度、管径以及超声声强对纳米流体的蓄冷特性和换热性能的影响规律。方法 将 5~12 nm、10~20 nm、20~30 nm 3种不同管径的多壁碳纳米管和质量分数为0.05%~0.2%的多壁碳纳米管分别制备成不同的纳米流体样品，并搭建试验台对样品进行蓄冷实验。结果 在质量分数从0.05%变为0.2%时，纳米流体的平均过冷度减小了0.7 ℃，管径由20~30 nm变至5~12 nm时，平均过冷度下降了64.3%;1级超声声强使传热能力提高了5.3%，而4级超声声强使传热能力提高了7.8%。结论 研究表明，多壁碳纳米管浓度的增加及管径的减小，可使纳米流体的换热能力增大，过冷度减小，超声声强对多壁碳纳米管/水纳米流体有强化传热作用。

The work aims to investigate the effects of the concentration, diameter and ultrasonic intensity of carbon nanotubes on the cold storage characteristics and heat transfer properties of nanofluids. In this paper, multi-walled carbon nanotubes with three different tube diameters of 5-12 nm, 10-20 nm and 20-30 nm and 0.05%-0.2% mass fraction were prepared as different nanofluid samples, and a test rig was set up to conduct cold storage experiments on the samples. When the mass fraction changed from 0.05% to 0.2%, the average supercooling degree of the nanofluid decreased by 0.7 ℃. And when the tube diameter changed from 20-30 nm to 5-12 nm, the average supercooling degree decreased by 64.3%; the first-order ultrasonic intensity increased the heat transfer capacity by 5.3%, and the fourth-order ultrasonic intensity increased the heat transfer capacity by 7.8%. The results show that with the increase of carbon nanotubes mass fraction and the decrease of tube diameter, the heat transfer capacity of the nanofluid increase and the supercooling degree decrease. The ultrasonic intensity can enhance the heat transfer capacity of multi-walled carbon nanotubes/water nanofluids.