ISSN Online: 2377-424X
ISBN CD: 1-56700-226-9
ISBN Online: 1-56700-225-0
PHASE-CHANGE HEAT TRANSFER IN MICROSYSTEMS
摘要
Recent work on phase-change heat transfer in microsystems, including flow boiling and condensation in microchannnels as well as bubble growth and collapse on microheaters, is reviewed. For flow boiling in microchannels, it was found that single-phase and two-phase alternating flows with large fluctuation of pressure and temperature existed in microchannels at low mass fluxes with a high degree of inlet subcooling. For flow condensation in microchannels, droplet flow, annular flow, injection flow, and slug-bubbly flow exist in the microchannels, depending on mass flux and quality. The breakup of the annular two-phase flow into slug-bubbly flow during condensation flow in microchannels is clearly shown in a visualization study. Effects of pulse heating widths, heater size and fluid viscosity on bubble growth and collapse on microheaters and its nucleation temperature are discussed.