High temperatures limit?

[Gregor2019]

Dear Delphin-Team,
another question has arisen by analysing some of my models: whenever the cable´s temperature (material: copper) seems to rise above 100 degree Celsius (due to heat loss of e.g. 70 W/m), its temperature stagnates at 100 degree C. When I turned off the water balance, this phenomenon does not appear. Does that have to do with the boiling point of water or why is that? And is there any approach how to avoid this stagnation?

As always, I appreciate any help.

Kind regards,
Markus.

[fechner]

Dear Gregor,

We have a limit for temperatures in case of coupled heat and moisture calculations. Nearly all material properties and functions related to moisture are measured in a temperature range around 20°C. This also means that these material properties become more and more faulty with increasing temperature. It makes no sense to perform calculations in this high temperature range. Also some additional effects like liquid transport due to gas pressure will more and more important.

For pure thermal calculations its a bit easier. The main problem here is the temperature dependence of some of the properties. Mainly the temperature dependence of the thermal conductivity should not be neglected. Normally we don't have values for this dependence in our material database but you can add such a function easily.

[Gregor2019]

Dear Mr. Fechner,
thank you very much for this quick response.

Then I also have a general question concerning the liquid transport in the gas phase: as long as a material is not assigned "vapour_tight", this transport path is considered in the calculations, right?

[fechner]

Rigth.
This also means you need the transport properties necessary for vapor transport otherwise the solver will give you an error message. These are moisture storage function and vapor transport function (at least my value).
Setting a tight flag means, this transport is not calculated and the properties for this are not checked.