To explore the effect of the open structure on the boiling heat transfer of a micro-ribbed rectangular channel

a visual experimental study was conducted on the flow boiling heat transfer performance of open drop-shaped micro-rib channels and compared with the flow boiling heat transfer performance of a water droplet microchannel. At the same time

the flow and growth processes of bubbles under different flow rates in the channel were recorded and analyzed using a high-speed camera. Using deionized water as the working fluid

the inlet temperature was set at 30 °C

with a flow rate of 0.2–7.2 kg/h

heating voltage of 60 V

and shooting frequency of 500 fps. The experimental results show that the opening structure of the micro-fin array affects the flow characteristics. The open structure increases the heat transfer area

which is beneficial for the formation of the vaporization core and heat transfer. At lower and higher Re

the convection heat transfer of the unclosed droplet-shaped micro-fin array is better than that of the water-droplet-shaped micro-fin array. The waiting time and growth time of bubbles in microchannels II and III increase with an increase in Re

and the bubble growth time is greater than the waiting time. In addition

the waiting and growth times of region II were shorter than those of region III.