To explore the flow boiling heat transfer mechanism in the micro-rib array channel with different cross-sections

the deionized water is used as the working medium

the mass flow rate is 96-224 kg·m-2·s-1

and the effective heat flux density is 10-240 W·cm-2. The instability of flow boiling in microchannel was also analyzed in the experiment. The experimental results showed that the dominant heat transfer mechanism is nucleate boiling in the low heat flux region

while it is convective heat transfer of a thin liquid film evaporation in the medium and high heat flux regions. With the increase of heat flux and outlet quality

the boiling heat transfer coefficient decreases

but the two-phase pressure drop increases. The secondary channel width between the micro pin fins has a great influence on the heat transfer and the two-phase pressure drop. The wider the secondary channel is

the easier the bubble is to break out

the better the heat transfer effect

and the greater the pressure drop. The existence of micro fin inhibits the reverse flow of bubbles

which reduces the flow boiling instability and delays the occurrence of critical heat flux. The flow boiling stability of the elliptical micro pin fins is the best

while the flow boiling stability of the circular micro pin fins is the worst.