Thank you very much, Harvey,
I have started to implement the model, without parametrization - until it will work. The code for HRSG economiser (cross-counterflow) looks as follows:
When I trace error, it says "Initial guess must consist of numbers and matrices". h_pT and Tsat_p are steam tables function names.
Probably there is some problem with nested vectors elements.
Is this good way? And do you know how to fix / force it to work?
Piotr