Abstract:

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.