Characterizing effect of particle size on flow boiling in sintered porous-microchannels

•Particle size significantly affects HTC and CHF of flow boiling in porous microchannels. Medium particle size achieves the best performance.•Flow boiling process is dominated by the nucleate boiling in low heat flux and by thin film evaporation or explosive boiling in higher heat flux.•Two boiling crisis phenomena are identified: (a) For medium size particle, rewetting-dryout cycle could been well established up to capillary limit; (b) in other samples, high wall superheat usually leads to explosive boiling frequently.