氧化铝有机纳米流体的流动传热基础特性

以氧化铝为纳米粒子、丙二醇和水为基础液体制备了氧化铝有机纳米流体，分别测量了它的沸点、热导率、比热容和黏度。以1％～5％（体积分数）的氧化铝纳米流体作为冷介质，测试了在车用机油冷却器中的传热系数和流动阻力。试验结果表明，纳米粒子能够显著强化基础液体在机油冷却器中的换热能力，粒子体积分数和流体温度是影响纳米流体热物性的重要因素。氧化铝纳米流体的沸点高于120℃，比热容随体积分数增加而降低，热导率、黏度和在机油冷却器中的传热系数均随粒子体积分数的增加而提高。在试验Ⅱ中，5％（体积分数）纳米流体的平均传热系数比基础液体提高了124.56％，而流动阻力增幅较小。

Fluid flow and heat transfer characteristics of alumina organic nanofluid

To enhance heat exchange under high temperature condition，a nanofluid with alumina nano-particles suspended in propylene glycol and water（base liquid）was prepared.The boiling point，thermal conductivity，specific heat and viscosity were measured respectively by ebulliometer，transient hot-wire method，comparison method and rotation viscometer.The heat exchange coefficient and flow resistance of 1%—5%（vol）nanofluids were measured in the plate-pin oil cooler test.The experimental results showed that nanoparticles could significantly enhance the heat transfer capability of base liquid.Particle volume fraction and fluid temperature had important effect on thermal properties of nanofluids.The boiling point of nanofluids was over 120℃，a little lower than that of base liquid.Adding particle volume fraction would decrease specific heat but increase thermal conductivity，viscosity and heat exchange coefficient.In Test 2，the mean heat exchange coefficient of 5%（vol） nanofluid in the plate-pin oil cooler was 124.56％ higher than that of base liquid，while the flow resistance rose moderately.