Study on Pool Boiling Performance of the Mixed Wettability Microstructure Surface With Wedge-shaped Channels
To study the effect of micro-structured surface with wedge-shaped channel on pool boil-ing heat transfer performance of FC-72,three kinds of mixed wettability surfaces with area ratio of the micro-pillar region to the smooth channel region of approximately 1∶1 were fabricated in this study(the surfaces were denoted as the Snowflake surface,Multi star surface,and Less tip surface).The experimental results indicated that for the three surfaces,bubbles are firstly generated and grown in the hydrophobic micro-pillar array region,and then slid laterally to the smooth hydrophilic channel region,where they continue to grow up until the final detachment.The opening of the smooth channel on Less tip surface is toward the surface center,and the closer to the center the wider the smooth channel.The cooling liquid can be quickly supplied to the micro-pillar area where bubbles are generated,meanwhile the abundant liquid inside the smooth channel can also promote the timely departure of large bubbles,which accordingly leads to the best boiling heat transfer per-formance on Less tip surface.The CHF value of all surfaces increase with liquid subcooling.The formation of vapor film at the bottom of vapor columns gravely impedes the fresh liquid supply to heat transfer surface,resulting in the local dryout and the trigger of CHF.
micro-pillar arraywedge-shaped channelmixed wettabilityheat transfer enhance-mentpool boiling
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