不同pH下水合Al2O3纳米流体的稳定性和导热性实验研究

Experimental study on stability and thermal conductivity of Al2O3-H20 nanofluids under different pH

本文利用两步法制备了Al2O3水合纳米流体，测试了不同pH值下，不同体积分数的Al2O3纳米流体的zeta电位、粒径和导热系数，实验结果表明：对不同体积分数的Al2O3纳米流体，pH存在一个优化值对应zeta电位的最大绝对值和颗粒最小粒径；同样随着pH的变化，也存在一个最优值对应于Al2O3纳米流体的导热系数增加到最大值；在相同的pH下导热系数随纳米粒子体积分数增加而增大。因此实验结果表明，对Al2O3纳米颗粒来说，要得到稳定分散和高导热系数的纳米流体pH值应在8．5左右为最佳；纳米流体的稳定性和导热性与pH值有密切的关系，此结论与文献[5]和[13]中的结论一致。

In this paper Al2O3-H20 nanofluids were prepared by two-steps method. The Zeta potential, particle size and thermal conductivity of Al2O3-H20 nanofluids were measurement under different volume fraction and pH values. The experimental results showed that： for different volume fraction of Al2O3 nanofluids there was an optimum pH corresponding to the highest magnitude Zeta potential and the smallest particle size, and the higher magnitude Zeta potential of nanofluids was, the more dispersion and stability of the nanofluids were. Similarity, there wais an optimum pH value corresponding to the highest enhancement of effective thermal conductivity than based fluid with the process of pH changing, and the effective thermal conductivity also increased with the Al2O3 nanoparticle volume fraction increasing. Therefore, the experimental results indicated that to get more stability suspension the pH value should be adjusted about to 8.5 for Al2O3 nanoparticle, and it also noted that the stability and thermal conductivity of nanofluids were very relative to the suspension pH condition that is agree with the results in references [5] and [13].