ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Numerical Simulation of Condensing and Evaporating Annular Flows in Microchannels with Laminar and Turbulent Liquid Films
摘要
A new model for numerical simulations of condensing annular flows in microchannels was previously developed
by Nebuloni and Thome [14]. Presently, their condensation model has been extended by including
turbulent liquid films and evaporating annular flows. In particular, the treatment of dry patch formation in the
evaporating thin film of the annular flow is carried out. As such, the model is able to predict heat transfer and
fluid flow characteristics in a large portion of the flow pattern map for microchannels in both condensing and
evaporating conditions, for low and high mass velocities. The condensing turbulent liquid film and evaporating
two-phase flows were validated against a selection of experimental data. Particular emphasis was placed on the
analysis of the fluid flow and heat transfer differences between condensation and evaporation. Discrepancies
between the liquid film thickness distribution and liquid film velocities yielded different optimal geometries
for evaporation and condensation. The evaporation and turbulent flow data comparisons showed reasonable
agreement with the data.