Operating Temperature of Heat Exchanger

[Abdulla Alishaq]

Hi all,

I am wondering if the operating temperature of the shell side inlet is higher than the tube design temperature, could that damage the tube since the fluid is touching the outer tubes?

Let's say the inlet shell is 90 degC and the outlet shell is 50 degC. The design of the shell is 120 degC and the design of the tube side is 80 degC. Would this damage the tubes?

Thanks!

 

[SuperSalad]

What is the temperature range of the tube side material?

If I had to guess, based on the 90C to 50C range you're getting on the shell side, the tube side might not actually be exceeding the 80C design limit in these conditions, in which case it should be fine.

However, the potential to exceed that limit does exist if the tube side material did vary upwards in temperature somehow.

Andrew H.

http://www.MotoTribology.com

 

[Abdulla Alishaq]

The range of tube side is 40C to 50C only

 

[LittleInch]

Abdullah,

Is this the same thread as your other two posts?

https://www.eng-tips.com/viewthread.cfm?qid=478580

&

https://www.eng-tips.com/viewthread.cfm?qid=466366

We now have three bits of information in three separate threads.

Please delete your current two and combine them into ONE thread and link to you previous one.

Please try and keep all the information in one place....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Abdulla Alishaq]

LittleInch,

Only the first link is relevant.

 

[SuperSalad]

If the tube side maximum is 50C, the tube itself should not be exceeding 80C except for maybe very locally on the exterior of the tube near the inlet of the shell side.

Any monitoring/inspections you can do would be worthwhile, but the design temperature of the shell side being 80C seems adequate for the fluid temperatures you are working with.

Andrew H.

http://www.MotoTribology.com

 

[georgeverghese]

This is not a good mechanical design for this HX, the design temp for both sides should be 120degC.
When tubeside flow is low, at the moment, the mean tube wall temp will exceed 80degC.
Temporary solution would be to limit shellside inlet temp to be <75degC or so.
See if you can ask the HX manufacturer to review and increase tubeside temp to 120degC (ideally)
If your new shellside feed temp is 90degC max, then you may get away with a revised tubeside design T of 95-100degC.

 

[don1980]

Those design T values (120 degC Shell / 80 degC Tube) are unusually low - are you sure those are the correct values? Even if they are correct, the risk of over-stressing the tubeside is very low. The shell side inlet T is only 10 degC above the stated tubeside design T (80 degC), and the remainder of the tube bundle is close to 50 C. That small section of tubes (at the shell inlet nozzle) will probably not exceed 80 degC since the fluid inside the tubes is no higher than 50 C. And even if that section of tubes reached 90 degC, the mechanical stress on the tubesheet will not be excessively high. The resulting stress would most likely be much lower than the design value because the remainder of the tube bundle is much cooler than 80 C. I wouldn't be concerned.