Experimental Study of Critical Heat Flux on a Graphite Film

Saturated pool boiling experiment with heater surfaces of smooth graphite films was conducted under atmospheric pressure, and the deionized water was used as working fluid. The test results showed that the graphite film began to expand and fracture in some parts of the surface as the heat flux reached 1.83 MW/m2. Then the expanded area enlarged and the resistance of the graphite film rapidly increased with the increase of the heat flux, until the whole film was expanded and the surface was ruptured uniformly under a heat flux of 2.40 MW/m2, while the resistance increased slowly during this process. Ultimately, the graphite film was burned out at a heat flux of 3.17 MW/m2. Consequently, the critical heat flux of the graphite film could be enhanced by an adaptively expanding processing with an enhancement ratio of 73%. The visualization results through a high-speed camera showed that compared with the smooth surface, the quantity of nucleation was greater, the bubble departure diameter was smaller, and the bubble departure frequency was higher on an expanded graphite surface under the same heat flux condition. © 2020, Science Press. All right reserved.