T-Q Curve

[Homayun]

How can one rate an existing Heat Exchanger using only the T-Q data?? Usually that kind of ratings is done using HTRI.

 

[sshep]

All you appear to have is some process data. You are asking how to rate an exchanger for which you appear to have no mechanical or design data what-so-ever.

The answer is you can't- you don't even have the surface area so where would you start?

best wishes,
sshep

 

[Homayun]

sshep,

When I say "Existing" exchanger that means that we know the geometry, number of tubes, Shell diamtere, etc.

 

[sshep]

That's better, I apologize for misunderstanding.

If you have a spec sheet then a simple method is proposed in the GPSA manual to estimate dP, film coefficients, and other new service results based on the new massflow and fluid properties. This works great for services where there is no phase change, but the given affinity rules are too simple for condensing/boiling.

If you must generate rating results just from geometry (rather than specsheet results from previous service) then it is more work. BJac, HTRI, HTFS are your easiest tools, although it is possible to do the calculations by hand. Since I have access to good tools, I haven't done such calculations by hand in many years. My old HTFS manual has good references for pressure drops accross tube banks and in baffle windows, but I don't know the best reference source that might be commonly available- sorry.

best wishes,
sshep

 

[dcasto]

The GPSA data book has some simplified U ranges to get your first look. The WinSim simulation program has a heat exchanger rating package and it will do any vaporizing / condensing curves that may exist.