细圆管内纳米悬浮液对流换热的实验研究

EXPERIMENTAL INVESTIGATION ON CONVECTIVE HEAT TRANSFER OF COPPER OXIDE NONOPARTICLE SUSPENSIONS INSIDE MINI-DIAMETER TUBES

实验研究了细圆管内氧化铜纳米颗粒悬浮换热特性。试验段的管径为0.68mm、1.01mm和1.28mm,氧化钢纳米颗粒平均粒径为50um,悬浮液中氧化铜纳米颗粒质量分数分别为0.02,0.04和0.06,分散剂十二烷基苯磺酸钠(SDBS)质量的分数为0.02。为进行对比分析,还测试了水的换热特性。实验结果表明,在所研究的尺寸下,层流时去离子水的努谢尔特数Nu要高于已有液体对流换热关联式计算之值,纳米颗粒悬浮液的对流换热系数高于水的,且纳米颗粒的质量分数越高,悬浮液的对流换热系数越大。随着流动从层流向湍流的转换,强化效果也越明显。

Experiments were conducted to investigate the convective heat transfer of water with copper oxide nanoparticle suspensions flowing through circular stainless steel tubes. The internal diameters of the tube are 0.68 mm, 1.01 mm and 1.28 mm. The mean diameter of the nanoparticle is 50 nm. The mass fractions of copper oxide nanoparticles in the experiment, w, are 0.02, 0.04 and 0.06. The mass fractions of surfactant SDBS is 0.02. The convective heat transfer performance of water and SDBS solution is also tested to compare with nanoparticle suspension. The result of the heat transfer experiment shows that the Nu number of water is higher than theory especially in smaller tube, and the Nu number of the nanoparticle suspensions is higher than that of water. The Nu number increases with the mass fraction of the nanoparticle. The effect of the particle is stronger in transition zone than laminar zone.