Comparative Study Of Size Effect Of Micro Bubble Dynamics By Sub-100 Microsecond And Millisecond Pulse Heating

Two groups of boiling patterns generated by a set of different sizes of micro bubble actuators were observed using new stroboscopic video microscopy. Above the critical heater size, bubble collapse as an oblate vapor film; while the other case, single spherical bubble was observed. The critical sizes are 1-3 tun and 5-10 mu m for the heating pulse widths of 40 mu s and 1.66 ms, respectively. A simple model based on thermal diffusion length was successfully employed to predict the critical size of bubble actuators.