the liquid film friction on the wall), the second term represents the gravitational pressure change (for the downward condensing flow in vertical tube the inclination angle is [theta] = -[pi]/2), and the third term represents the acceleration pressure change (the pressure change due to the acceleration or deceleration of the flow in the tube).
2]s) the gravitational pressure change is dominant, and as a result of that the pressure increases from the tube inlet to outlet (the gravitational pressure change term, for a down-ward condensing flow in vertical tube, will be [DELTA][p.
For the wet surface conditions, the driving potential is positive, and the condensing flow rate will be determined based on the driving potential and hence the latent heat transfer rate.
Finally, the condensing flow rate can be solved by applying the heat and mass transfer analogy.
Topics include: two-phase oscillatory thermal-hydraulic instability, oscillatory flow stability boundary, static instability, thermal-acoustic oscillations in heated channels, instability of condensing flows
, and cases of flow instability in pipelines.
The refrigerant mass flow rate, in general, is continuously changing, causing changes in refrigerant distribution in the system and because of two-phase condensing flows inside the tube; the local heat transfer coefficient varies in a great range at different locations.
Chen's correlation is adopted to estimate the local heat transfer coefficient of two-phase condensing flows.