Abstract: Heat transfer performance of nanofluids in nucleate pool boiling was experimentally investigated on a horizontal flat surface of cooper under atmospheric pressure.The surface roughness was controlled by sandpaper of grade 2000^#.The nanofluid was prepared by dispersing the δ-Al₂O₃ nanoparticle in the base fluid refrigerant 141b(R141b) in 0.001%,0.01% and 0.1% volume fractions.The results show that the heat transfer coefficient increases with the concentration of nanoparticle.Compared with the pure fluid R141b,the heat transfer coefficient is increased 50.2% for 0.1% volume fraction averagely under 30—130 kW·m^-2 heat flux.The surface deposition of particles is observed as one of the major factors for the enhancement.For pure R141b and low concentration nanofluid,the experimental results agreed well with the predictive results based on Rohsenow’s correlation.The maximum relative error is less than 13%.At higher concentrations,the correlation is no longer applicable.

Key words: nanofluid, nucleate pool boiling, heat transfer coefficient, deposition, contact angle

摘要： 对δ-Al₂O₃-R141b纳米流体在0.1 MPa系统压力下进行了池内沸腾传热性能测试。沸腾表面为2000^#砂纸打磨的光滑紫铜表面，沸腾热通量为30～130 kW·m^-2，纳米流体的体积浓度为0.1%、0.01%、0.001%。实验表明纳米流体强化了沸腾传热特性，且强化倍数随着纳米流体浓度的增加而增大。体积浓度为0.1%时，沸腾传热系数比基液增大了50.2%。分析认为表面颗粒沉积是强化换热的主要因素，而接触角的变化在此可以忽略。与Rohsenow关联式相比较，纯液体和较低浓度的纳米流体的实验数据与关联式吻合较好，相对误差最大不超过13%，高浓度时吻合较差关联式不再适用。

关键词: 纳米流体, 池内核态沸腾, 传热系数, 表面沉积, 接触角