3 replies to this topic

[Bal]

In HYSYS, what's the difference between a shell and tube from type E and a shell and tube from type F?

 

Why would changing the shell and tube type from E to F eliminate the error "low Ft correction factor?"

 

Thanks  

[srfish]

The LMTD Correction Factor depends on the number of shell passes. An E type shell has 1 shell pass and a F shell has 2 shell passes. Two shell passes gives a higher Correction Factor

[Lucian Gomoescu]

The correction factor is the ratio between the actual MTD and LMTD.

MTD=LMTD only if the two fluids flow is 100% countercurrent.

For example, a STHE with E shell + 2 pass tubes means 50% countercurrent (if the baffles effect is neglected, which means also cross flow zones), while a STHE with F shell + 2 pass tubes means 100% countercurrent (again, if the baffles effect is neglected). If the shell is of F type, but the tubes pass no. > 2 then MTD < LMTD.

Also, the position of the shell inlet and outlet nozzles influence the value of MTD.

[Bal]

Thanks a lot srfish and Lucian for your help