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 degrees 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 (Tsat = 59.8 degrees C at 1 atm) that can satisfy the requirement for engineered surfaces in the nucleate boiling region. However, higher superheating at Delta TONB 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 Delta TONB. For saturated HFE-7100, boiling curves and visual bubble observations were obtained using an infrared camera and a high-speed video at atmospheric pressure. Delta TONB on the HPP reduced by 20 K relative that on the plain surface (Delta TONB = 35.6 K) due to nucleation cavities. Later, excessive superheating at Delta TONB was observed to restart nucleate boiling after the HPP was immersed in the HFE7100 liquid for 24 h (Delta TONB = 32.5 K) and 96 h (Delta TONB = 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 Delta TONB at a desirable value (Delta TONB = 18.3-20.4 K) after immersion.