Preliminary Consideration to Avoid Eruptive Flow Boiling in Microchannels

With boiling flows in very smooth heated channels, in general, the bulk liquid is superheated before the bubble formation takes place at the wall surface. Thus the eruptive boiling occurs once the superheat requirement for nucleation is satisfied, and this can be a source of flow instability. In the present work, a preliminary consideration has been given to predict the limiting heat flux for stable boiling in microchannels. The minimum heat-flux value to avoid this eruptive boiling is inversely proportional to the square of the channel diameter, and becomes enormously large as the channel diameter decreases. The stable heat-flux limit also depends on the cavity size in the channel wall. A map showing stable nucleation criteria was given and discussions were made on the simplifying assumptions made for the analysis.