The thermodynamic aspects of phase transformation of liquids in microc
hannels were analyzed to further understand the boiling characteristic
s, and a nondimensional parameter and related criteria that determine
the phase transition in microchannels were derived theoretically using
classical phase stability theory. It was found that the size of the m
icrochannels results in dramatically high heat fluxes for liquid nucle
ation when the microchannel is sufficiently small. This work provides
theoretical substance for further investigating, especially quantitati
vely describing the heat and mass transfer process.