Experimental Investigation of Single-Phase Microjet Array Heat Transfer

The heat transfer performance of two microjet arrays was investigated using degassed deionized water and air. The inline jet arrays had diameters of 54 mu m and 112 mu m, a spacing of 250 mu m, a standoff of 200 mu m (S/d=2.2 and 4.6, H/d=1.8 and 3.7), and jet-to-heater area ratios from 0.036 to 0.16. Average heat transfer coefficients with deionized water were obtained for 150 < Re-d < 3300 and ranged from 80,000 W/m(2) K to 414,000 W/m(2) K. A heat flux of 1110 W/cm(2) was attained with 23 degrees C inlet water and an average surface temperature of 50 degrees C. The Reynolds number range for the same arrays with air was 300 < Re-d < 4900 with average heat transfer coefficients of 2500 W/m(2) K to 15,000 W/m(2) K. The effect of the Mach number on the area-averaged Nusselt number was found to be negligible. The data were compared with available correlations for submerged jet array heat transfer.