Improvement in the onset of the nucleate pool boiling of HFE-7100 with the use of a honeycomb porous plate and heated fine wire

Boiling is an efficient heat dissipation method implemented in microelectronic devices. However, given that microelectronic components have operating temperature limits (below 85 °C), suitable coolants and enhanced technology for the onset of nucleate pool boiling (ONB) are crucial for their further application. The hydrofluoroether fluid HFE-7100 possesses superior environmental properties and a low boiling point (T_sat = 59.8 °C at 1 atm) that can satisfy the requirement for engineered surfaces in the nucleate boiling region. However, higher superheating at ΔT_ONB is observed before nucleate boiling is triggered due to the high wettability of HFE-7100. In this study, pool boiling experiments were performed with a honeycomb porous plate (HPP) attached to an indium–tin oxide (ITO) heater to examine ΔT_ONB. For saturated HFE-7100, boiling curves and visual bubble observations were obtained using an infrared camera and a high-speed video at atmospheric pressure. ΔT_ONB on the HPP reduced by 20 K relative that on the plain surface (ΔT_ONB = 35.6 K) due to nucleation cavities. Later, excessive superheating at ΔT_ONB was observed to restart nucleate boiling after the HPP was immersed in the HFE-7100 liquid for 24 h (ΔT_ONB = 32.5 K) and 96 h (ΔT_ONB = 32.6 K). This finding indicated that large amounts of cavities were flooded by the highly wetting liquid during the immersion period. Therefore, a coupled section combining the HPP and a metal fine wire with a continuous small input power was developed to reactivate nucleate cavities. This section successfully maintained ΔT_ONB at a desirable value (ΔT_ONB = 18.3–20.4 K) after immersion.