Hello,
I would like to ask if a temperature cross (Hot outlet - Cold Outlet < 0 ) is possible to reach in a TEMA Type Heat Exchangers with 2 tube passes.
Let's imagine to have a BEU TEMA Type exchanger (2 tube passes, 1 shell pass) where in both shell and tubes we have hydrocarbons.
If for the design case (highest duty and highest flowrate) we have considered a temperature approach Hot Outlet - Cold Outlet = 0, at reduced duty and flowrate (both on tube and shell side) it's possible to have temperature cross (Hot outlet - Cold Outlet < 0 )?
I've simulated with PRO/II the two scenarios (design and reduced flowrate) and, keeping for both the UA calculated in the design case, I got a temperature cross for the reduced flowrate case. Is this possible? Lot of forums say that temperature cross is not possible in multipass heat exchangers.
Thank you.