脉冲加热下微加热器在Al2O3纳米流体中的沸腾换热

Boiling heat transfer of microheater in Al_2O_3-H_2O nanofluids under pulse heating

以Al2O3-H2O纳米流体中的微加热器为研究对象,通过实验方法对脉冲加热条件下微加热器的温度响应曲线和气泡动力学行为进行了详细的研究。比较了在纯水及浓度为0.1%和0.2%的Al2O3-H2O纳米流体中微加热器的温度变化和气泡动力学行为。发现在脉冲加热条件下,微加热器在不同浓度的纳米流体中将出现不同的温度响应曲线,加热膜表面的气泡动力学行为也不相同。实验表明,在脉冲加热条件下,微加热器在Al2O3-H2O纳米流体中的换热效果要明显高于纯水,纳米粒子的浓度对于加热膜表面的气泡动力学行为有明显影响,对微加热器换热的影响也很大。最后根据实验结果以及纳米粒子对气液固三相线的影响,对实验中Al2O3纳米流体的换热情况进行了合理的解释。

The bubble dynamics and temperature response curve of a microheater in Al2O3-H2O nanofluids were experimentally investigated.The bubble dynamics and temperature variation in water and nanofluids with different concentrations of Al2O3-H2O [0.1% and 0.2%（mass）]are compared.Under pulse heating,the temperature response curves are different in nanofluids with different concentrations,and the bubble dynamics on the microheater are also different.Results show that the heat transfer coefficient of the microheater is significantly higher in Al2O3-H2O nanofluids than in pure water.The nanoparticle concentration has important effects on the bubble dynamics on the microheater and the heat transfer coefficient.According to the experimental results and the influence of nanoparticles on the gas-liquid-solid contact line,the phenomenon that bubbles detach from the microheater more easily in nanofluids than in pure water is analyzed and the heat transfer enhancement in the nanofluids in terms of a model considering the effect of nanoparticle on bubbles is explained.