Maximum Pressure Error on Multiphase Piecewise Linear Evaporation-Condesation

[ben.ludwig]

Hey Gang, I´d like to setup a VOF Multiphase Condensation Simualtion with a boiling point dependent on the absolute Pressure. To simplfy I assume Absolute Pressure = Static Pressure. Problem is, when I want to define the presure - Saturation Tempearature piecewise-linear table I get the following Error:

Pressure : [...] is greater than maximum.
Range is 0 to 30000

I already tried switching from Pa to atm, but then the problem only presits with a maximium pressure of 0.29... atm. I also tried it approximating the Antoine eqation with a polynomial but it seems I´m to dumb to enter the polynomial right. A preliminary solution would be a UDF but if possible I´d like to stick to a picewise linear definition.
Thanks in advance

[Mark O]

You cannot assume Absolute Pressure = Static Pressure. The saturation pressure temperature curve must use absolute pressure. A value of zero absolute pressure would be a vacuum. Absolute Pressure = Static Pressure + Operating Pressure. You can input the curve as polynomial function or a tabular text file . The Lee model will feed the absolute pressure in the cell to your saturation curve to compute the saturation temperature. Consequently it only works for boiling cases. That is, it only works for cases in which there are not multiple species in any phase. If you want it to work for the case of more than one species in a phase you would need to use a UDF that computes the partial pressure of the evporant species and then use that pressure to obtain the saturation temperature from the pure species saturation curve.