boundary conditions for water boiler
I'm evaluating Caedium for use in industrial heat exchangers environment.
My application is a steady state regime with water heating as it flows into a custom forced circulation boiler (no phase change). We need to optimize the geometry.
The boiler is part of a closed system (of course only the boiler has been modelled), so the mass flow is constant and the water is pressurized at 1.5 bar.
Which boundary conditions would you suggest at inlet/outlet? I'm thinking about:
1) Inlet: "Default" (with reference velocity derived from the mass flow), or "Volume Flow Rate";
2) Outlet: "Default" or "Extrapolated" but from the tutorials I cannot understand the difference.
(As to heat transfer, we will apply fixed temperature/heat flux to the "active" walls of the fluid-volume).
Thanks a lot for your help.