No soution was found in solve block

Check your equations.

Here's what's happening with your first constraint:

Note that the Y-axis runs from 1 to 1, which means that the expression involving those V's only produces values close to 1 over the entire range of heb values. I checked all 8 values of hph from 1 to 8 mm: All about the same.

So how will you ever get the result between 7 and 9?

Success!

Luc