Experimental study on critical heat flux of high-velocity circular jet impingement boiling on the nano-characteristic stagnation zone

This experimental study investigates the critical heat flux (CHF) of high-velocity circular jet impingement boiling on the nano-characteristic surface of the stagnation zone with different surface wettability. The wettability of the copper surface is varied to hydrophilic or hydrophobic nano-characteristic surfaces by modifying surface topography and chemistry. The effect of impact velocity, subcooling and solid–liquid contact angle (CA) on the CHF are studied thoroughly. The experimental relationship between CA and CHF of the heat transfer surface is summarized by further discussion. The semi-theoretical correlations proposed by the author previously for predicting the CHF of saturated and subcooled circular jet impingement boiling on the stagnation zone are improved and expanded to higher impact velocity and wider CA range. The comparison results indicate the predicted value of the improved correlations agrees well with the experimental data.