13 replies to this topic

[SadiqChemy]

Hello

 

Can we do thermal design of non TEMA heat exchanger using HTRI software ?

[Bobby Strain]

Why not?

 

Bobby

[SadiqChemy]

Bobby:

 

For example , if I have vertical pressure vessel (top & bottom will ellipsoidal head) .... the shell inlet and outlet nozzles are ellipsoidal heads (top & bottom). Tubes are oriented horizontally inside the vessel ( 30 rows , each row 12 tubes , U-tube type )..

How can I manage to design it thermally in HTRI program??

What do I put in TEMA type section (specifying the three letters)

[Bobby Strain]

An exchanger such as this usually has a shroud to direct the vapor flow. So pick an arrangement that is similar to yours.

 

Bobby

[latexman]

A dimensioned drawing is worth a thousand words.

[Art Montemayor]

SadiqChemy:

 

You have furnished an excellent arrangement drawing, but failed to tell us the type of duty you expect from this setup and whether there are any phase changes.

 

Is it a type of reboiler?
What fluid is in the tubes?
What fluid is on the shell side?

Is this a pool boiling application with steam or a thermal fluid in the tubeside?

Is this a type of condenser?
Is this a preheater?
Is this a vaporizer?
What fluids are involved?

 

This information might be helpful in determining whether the design can be fitted into the HTRI format.

 

Also, you stated you have a horizontal "U" tube design in your previous post - but yet your drawing shows two other type of arrangements:

• a helical internal coil; and
• what appears to be internal panels manifolded together.

Neither of these are horizontal.  What is the story behind the discrepancies?

[SadiqChemy]

SadiqChemy:

 

You have furnished an excellent arrangement drawing, but failed to tell us the type of duty you expect from this setup and whether there are any phase changes.

 

Is it a type of reboiler? No , gas heater

What fluid is in the tubes? Dowtherm A oil

What fluid is on the shell side? Process gas

Is this a pool boiling application with steam or a thermal fluid in the tubeside? there is no change in phase

Is this a type of condenser? NO
Is this a preheater? Can be
Is this a vaporizer? No
What fluids are involved? Mentioned above

 

This information might be helpful in determining whether the design can be fitted into the HTRI format.

[SadiqChemy]

 

 

 

Also, you stated you have a horizontal "U" tube design in your previous post - but yet your drawing shows two other type of arrangements:

• a helical internal coil; and
• what appears to be internal panels manifolded together.

Neither of these are horizontal.  What is the story behind the discrepancies?

 

in datasheet is is mentioned that tube orientation is horizontal , No of tubes / row : 12

No of inlets:12

Number of rows:30

Pitch pattern: Tringular ( See "D1" )

 

For a helical internal coil I am not sure of it , but maybe you mean the circle fins?

[Bobby Strain]

I would talk to the people who designed the thing. They probably use some proprietary methods. But you can try two things. First, see if you can rate it as a crossflow shell with 30 passes of 12 tubes each. Second, make some alterations to the rating for an air cooler. But I think I would look to the supplier method.

 

It's not obvious from the drawing how the tube ends are sealed to keep the gas flow directed across the tubes. Maybe there is some more detail you didn't show us. If you want to check, you will likely have to do some calculations to evaluate heat transfer coefficients on both sides.

 

Bobby

[SadiqChemy]

Bobby:

 

Do you mean that I can rate it as a horizontal heat exchanger with 30 passes?

[Bobby Strain]

You will have to check it out. It's likely that you won't find what you need in the usual heat exchanger design programs. So, you will have to resort to the basics. Probably the best model is for an air cooler. But, of course, you can only take guidance from such software. Best to check with the designer and assure that the design method is correct. You would be wasting your time to rate it. Best to spend efforts on more useful things. You need to know when you don't know.

 

Bobby

[SadiqChemy]

You will have to check it out. It's likely that you won't find what you need in the usual heat exchanger design programs. So, you will have to resort to the basics. Probably the best model is for an air cooler. But, of course, you can only take guidance from such software. Best to check with the designer and assure that the design method is correct. You would be wasting your time to rate it. Best to spend efforts on more useful things. You need to know when you don't know.

 

Bobby

 

So , you mean using the design software would not be useful ?

[Bobby Strain]

It seems that you don't have any heat exchanger design software. So, maybe you can tell us what your objective is. We are just going in circles at the moment. Others might help if they know what you want to achieve and what tools you have.

 

Bobby

[Mahdi1980]

Hi SadiqChemy,

 

I believe that some special cases cannot be designed base of TEMA standard, consequently cannot be formulated by common software such as Aspen Bjac, HTFS and etc.

Most of the time, vendors have their own software to design these equipment.

Why you don't design it by hand based on the reputable methods of designing heat exchangers.

You can also make a computer program by Matlab/ Visual basic. You can get better results.

 

Mahdi