通过实验研究了基于碳纳米管(CNTs)的含油纳米制冷剂(即由制冷剂R113、润滑油VG68和碳纳米管组成的纳米流体)的核态池沸腾换热特性,分析了碳纳米管对含油制冷剂核态池沸腾换热的影响.实验中采用了外径为15～80nm、长度为1.5～10μm的四种碳纳米管.实验的饱和压力为101.3 kPa;热流密度为10～80 kW/m2;纳米油(碳纳米管和润滑油的混合物)的质量分数为0～5％；在纳米油中碳纳米管的质量分数为0～30％.实验结果表明:碳纳米管增强了含油制冷剂的池沸腾换热,在测试工况下换热系数最大可增加61％.当纳米油中碳纳米管浓度为20％不变,纳米油浓度由1％提高到5％时,不同尺寸的碳纳米管对换热系数的增加幅度由27％～59％降低至23％～55％;当纳米油的浓度为1％不变,纳米油中碳纳米管浓度由20％提高到30％时,不同尺寸的碳纳米管对换热系数的增加幅度由27％～59％升高到33％～61％.通过实验获得了基于碳纳米管的含油纳米制冷剂池沸腾换热关联式,关联式的预测值与96％的实验数据偏差在±10％以内.%Influence of carbon nanotubes (CNTs) on nucleate pool boiling heat transfer characteristics of refrigerant-oil mixture was investigated experimentally. Four types of CNTs with the outside diameters from 15 nm to 80 nm and the lengths from 1.5 urn to 10 um were used in the experiments. Test conditions include CNTs mass fractions in the CNTs nanolubricant from 0 to 30 per cent and CNTs nanolubricant mass fractions from 0 to 5 per cent. The experimental results indicate that the presence of CNTs enhances the nucleate pool boiling heat transfer coefficient of R113-oil mixture by a maximum of 61% under the present test conditions. For fixed CNTs physical dimension, the enhancement range changes from 27%~59% to 23%~55% when CNTs nanolubricant mass fraction increases from 1% to 5%; the enhancement range changes from 27%~59% to 33%~61% when CNTs mass fraction in the CNTs nanolubricant increases from 20% to 30%. A correlation for predicting the nucleate pool boiling heat transfer coefficient of refrigerant-oil mixture with CNTs is proposed, and it agrees with 96% of the experimental data within a deviation of ±10%.
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