Experimental Investigation on the Effect of Flow Pattern Transformation on CO2 Flow Boiling Heat Transfer
In this paper,the flow boiling heat transfer and flow pattern visualization experiments of CO2 in a horizontal smooth tube with an inner diameter of 5 mm are carried out,and the flow boiling heat transfer characteristics are investigated in combination with the diabatic flow pattern visualization data.The results show that the top of the tube intermittent dry-out at low vapor quality with gravity,resulting in its heat transfer coefficient far lower than the bottom heat transfer coefficient.The reduction of the saturation temperature promotes the transition of the flow pattern,effectively diminishes the difference in local heat transfer of the tube caused by intermittent dry-out,and improves the average heat transfer coefficient.The average heat transfer coefficient is increased by approximately 50％when the saturation temperature is dropped from 15℃ to 9℃.
CO2flow boilingflow pattern visualizationboiling heat transfer characteristics
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