What‘s the usual solution of this kind of problem?

[seuer21322]

ValueError: unable to solve 1phase PY flash with Tmin=299.558, Tmax=3000 due to error: HSU_P_flash_singlephase_Brent could not find a solution because Hmolar [13860.9 J/mol] is below the minimum value of 15578.0225581 J/mol

This is how I set the Source.
nw.units.set_defaults(temperature="degC", pressure="MPa",mass_flow='kg / h') c1.set_attr(fluid={'water':1},T=311,p=0.46,m=10000)

[fwitte]

Hi @seuer21322,

can you post a minimal reproducible example code here? Otherwise I cannot reconstruct this. Typically, such errors can occur in the Newton iterations when solving the problem. Specifically, when the solver changes the variable values in a way, that the inputs cannot be handled by the fluid property library. This in turn is often (but not exclusively) caused by

• the selection of starting values in your problem
• unreasonable boundary constraints/parameters specifications

TESPy already deals with many of such issues in the backend but cannot catch all of them. A solution to that often can be

• to set up a model incrementally, to really understand what the pain points are
• to set up a model with simple boundary conditions applied first (direct specification of pressure, temperatures, enthalpies etc.) and solve it once, and then switch the specifications to the desired ones (which could be minimal pinch, terminal temperature difference, isentropic efficiency, ...) and solve the model a second time. Conceptually this is already in the tutorials on the documentation, but this comment also explains solution approaches: Help with connected heat exchangers modeling #593 (comment).

Best

Francesco