Baffle Orientation

[mechmania]

Hello All,

We have vertical Condenser designed for concurrent flow.

Vapor Inlet at top tubeside and Brine inlet top at shell side. Shell side inlet and out let nozzles are at 90 deg to each other. And the baffle cut for the 1st baffle at the inlet is parallal to nozzle inlet.

How does it make difference themal performance wise if we use the same condenser with countercurrent flow with brine inlet at the bottom of the shell.We can not change the configration of the baffels as tubes are already fixed in to the tubesheet and fabrication is completed.

Can we use the sam unit with countercurrent flow?

Any input is appreciated.

Thanks.

 

[speco]

Mechmania,

If your condenser is isothermal on the tubeside, there should be no difference in performance by changing to countercurrent flow. However, if you have mixed vapors, the condensing will occur over a temperature range. Then there should be an improvement in performance by changing to counterflow.

Regards,

Speco (

http://www.stoneprocess.com)

 

[unclesyd]

I don't quite understand your baffle arrangement as the baffle cut should be perpendicular to the inlet on the opposite side of the bundle.

You want to make sure your baffle arrangement is configured to keep all the tubes wet at the top tubesheet. You don't need an air pocket near the top tubesheet.

 

[Montemayor]

Unclesyd is exactly right. Always, always make every attempt to avoid feeding cooling water at the top of a heat exchanger - or more importantly, a condenser. You are inherently creating a collection of ex-dissolved gases (a.k.a., non-condensables) at the top tube sheet in a vertical unit.

Any attempt to describe a shell & tube apparatus should always start with the TEMA type specification. That says it all, plus the orientation. What is being described is not a normal application. A normal condenser is oriented horizontally; vertical orientation is for very special needs and has its trade-offs. Condensation is normally assigned to the shell side - hardly ever to the tube side (again, except in special applications).

I suspect we are not being told a lot of data and facts about this application and, as a result, we're going around in circles guessing at what is going on and why. I've done horizontal, vertical, partial and total condensing so I'm very familiar with what can -and will - happen. However, I need to know more details and facts before I can comment further than the above.

Generally, I would use a horizontal, BEM unit with cold brine in the tubes. The film coefficient for the brine on the shell side must be horrible due to the very low Reynolds Number and little turbulence. I have no idea of how one could justify a downward, con-current brine flow on the shell side of a condenser and can only speculate that it is just a major screw-up on the part of the contractor who installed it. But then again, we don't have ALL the data and the facts, so it's just speculation.

 

[0707]

Try to find the aswer for you question through the TEMA

luis