Additional Information

Examine the detailed results for specific models.

If you are interested, you can inspect the more detailed results for various submodels.

Perhaps the most important of these results is the bubble size prediction next to the wall shown in plot Near-Wall Bubble size. Bubbles depart with a size of about 50 micron under these conditions. Where the water is still heavily subcooled, the S-Gamma model predicts that bubble size next to the wall is immediately smaller due to condensation. Once the liquid subcooling is small enough (liquid temperature is approaching saturation) the local condensation rate can no longer balance wall evaporation rate. At this point on the wall, net vapor production begins, and also bubble size starts to rise due to coalescence.

The Near-Wall Bubble Size plot is shown below:



Some other points of interest to boiling modeling are:

  • Near wall volume fraction reaches levels of 0.8 near the wall in this calculation. This result might not be physical, and could be modified with model adjustments. However, due to the difficulties of making measurements across narrow tubes operating at very high pressure, the Bartolemei (1967) ([971]) and Bartolemei (1982) ([972]) data provides no information to support such adjustments to radial distribution.

  • Bubble departure frequency is a simple model that essentially depends on departure size, so is also constant in this constant property calculation.

  • Bubble Influence Wall Area Fraction shows how the heat flux between the wall and the liquid phase is partitioned between fully developed convective heat transfer and bubble-induced quenching heat flux. Initially this fraction is small as bubble nucleation sites are far apart, but rises as the number of active sites increases with wall superheat.

  • The nucleation site number density plot shows a rapid change in number of active sites with very small change in wall superheat. It is this behavior at the heart of the wall boiling model that both enhances heat transfer rapidly and keeps the wall superheat relatively uniform along a boiling wall.