pH值对TiO2-H2O纳米流体稳定性及热物性影响的实验研究与评价方法

Experimental study and evaluation method of effect of pH value on stability and thermophysical properties of TiO2-H2O nanofluids

通过两步法制备质量分数为0.1%的TiO2-H2O纳米流体,测量纳米流体在pH值为2,4,6,8,10,12基液下的Zeta电位、导热系数、黏度,进行静置实验以及透射电镜(TEM)扫描,研究pH值对TiO2纳米流体稳定性和热物性的影响,比对PER模型和优值Mo数分析的评价方法。研究表明,TiO2纳米流体在pH值为2和12时Zeta值分别为24.10和-40.60,pH值为12的样品在20℃时导热系数相比于基液提高了1.04倍,60℃时提高了1.17倍;pH值为2样品在20℃时导热系数相比于基液提高了1.06倍,60℃时提高了1.14倍,两种评价模型表明,pH=2,pH=12,在特定温度下,均满足PER值<5,优值Mo模型Cμ/Cλ<4,表现最为稳定且热物性表现最优。pH值为6,8的纳米流体处于Zeta电位不稳定的缓冲区,稳定性差,热物性表现差。

Nanofluids containing 0.1%titanium dioxide were prepared by two-step method.Zeta potential,thermal conductivity and viscosity of nanofluids at pH2,4,6,8,10 and 12 were measured.Static experiments and transmission electron microscopy(TEM)scanning were carried out to study the effect of pH value on the stability and thermophysical properties of nanofluids.The final ratio was PER.The evaluation method of model and optimal Mo number analysis.The results show that the Zeta values of nanofluids are24.10 and-40.60 at pH2 and 12,respectively.The thermal conductivity of samples with pH 12 is 1.04 times higher than that of base fluids at20℃and 1.17 times higher at 60℃.The thermal conductivity of samples with pH2 is 1.06 times higher than that of base fluids at20℃and 1.14 times higher than that of base fluids at 60℃.The model shows that:pH=2,pH=12,at a specific temperature,all meet PER<5,the best value of Mo model Cμ/Cλ<4,the performance is the most stable and the thermal physical performance is the best.The nanofluids with pH values of 6 and 8 are in the buffer zone of unstable Zeta potential,which results in poor stability and poor thermophysical performance.