Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
(OP)
When there is a temperature cross in a Shell & Tube Heat Exchanger, we design Shells in series or use F-Shell.
May I know the limitations of Shell & Tube Heat Exchangers F Type shells with Longitudinal Baffles.
Are longitudinal baffles recommended for high shell side pressures.
May I know the limitations of Shell & Tube Heat Exchangers F Type shells with Longitudinal Baffles.
Are longitudinal baffles recommended for high shell side pressures.
RE: Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
RE: Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
1) F shells should not be used when the shell-side pressure drop exceeds around 7 psi due to the potential for shell-side bypass.
2) F shells should not be specified for tube bundles that are extracted frequently for cleaning due to the potential for damaging the sealing devices during bundle extraction/installation.
3) F shells should not be specified for applications with a large shell-side temperature range due to the potential for thermal leakage through the directly baffle (this one is probably debatable).
-Christine
RE: Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
4) F shells should not be used for exchangers that require very small surface areas (e.g. < 200 sq. ft.), as hairpin exchangers are preferred here.
5) F shells shouldn't be used for heat exchangers that have only 1 tube-side pass as this negates the 2-for-1 advantage of using F shells.
F shells also work best in exchangers where the shell-side heat transfer coefficient is controlling (they can markedly improve the shell-side heat transfer coefficient) and when there are only 2 tube-side passes (pure countercurrent).
-Christine.
RE: Shell & Tube Heat Exchangers. F Type Shells with Longitudinal baffle - Limitations
Weirdly enough, I recently sized a heat exchanger for a cryogenic application with a BFU designation. Total SA < 200 sq ft but this was chosen because;
V. low water temperature (dT of 4 degC)
I very briefly looked at a hairpin unit but struggled to raise skin temperatures above -120 degC at the cold end and the resultant steady-state ice thickness may have resulted in the flow path being fully blocked on the shellside.