Microjet array single-phase and flow boiling heat transfer with R134a

An experimental study of single-phase and flow boiling heat transfer of a submerged microjet array was conducted with R134a. The staggered array of seventeen 112-μm diameter orifices impinged onto a 1 × 1-mm heater. Single-phase data were gathered over the range 3050 ⩽ Red ⩽ 10,600 with 53.6⩽Nud¯⩽128. Boiling experiments were conducted with liquid subcoolings of 10, 20, and 30 °C at jet velocities of 4, 7, and 10 m/s. Boiling was generally found to enhance heat transfer with a maximum heat flux of 590 W/cm2. However, temperature excursions occurred at low superheats and were found to be related to non-condensable gas content.