In the present work, pool boiling on copper porous coating and polished surface are studied experimentally at atmospheric pressure to explore the characteristics and the regime of boiling. A high-speed camera (maximum frame rate 10000 fps) with attached magnifying lens allowed precise observation of the incipient nucleation of boiling on the two surfaces. The observed boiling phenomena suggest different characteristics in the wall superheat, the heat transfer coefficient, the departure diameter of the bubble and the frequency of the bubble generation on two substrates for two working medium at different input power. The results indicate that the heat transfer performance is greatly enhanced by using porous coating and nano-fluids. The heat transfer coefficient on the porous coating is three to four times of that on the polished surface. Meanwhile, the temperature at incipience of boiling on the porous coating is lower than that on the polished surface qualitatively for the same working medium. The new contribution of this work is that we combined nano-fluids and porous surface together to explore the heat transfer performance and conducted visual experiments to observe the behavior of the bubbles of this assembly in the pool boiling.

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