[rydol]

Dear all,

I am trying to simulate the water evaporation driving the natural convection flow within a single vertical hellical coil using the Eulerian boiling model. I have used folliwing settings:

- boiling model : tried RPI and non equiblirum boiling with similar results
- water properties and saturation temperature given by rgp tables
- mass transfer by default settings
- heat transfer coefficient given by tomyiama
- forces using pretty all recommanded settings including virtual mass coefficient = 0.5
- accounting for buoyancy effect by setting operation density =0
- using const. Temperature profile > Tsat at the tube outer wall

The solution converges nicely, however the steam volume fraction at the outlet is way higher than the corresponding heat transfer rate

For example I would expect for transfered heat of 2kW at given mass-flow a volume fraction about 0.3, but the solution shows 0.8.

You can imagine how the diferrence in the outlet density impacts the whole naturally driven flow.

I tried to tweak these liquid/vaport interface transfer coefficiens within the boiling model options, to lower the outlet volume fraction and match it with the corresponding heat transfer rate, but without any major influence on the overall solution.

Does anyone have a similar experience or am I missing something?

Thank you.
R.