Plate Heat Exchanger Discharge Temp Stratification

[stoerw]

These are pictures from the N03 CCW heat exchanger outlets on the CCW side. There is a 5F – 6F degree temperature difference between the top and bottom of the pipe where the CCW exits the heat exchanger. We’re seeing this on both heat exchangers. Not sure why we would be seeing this kind of stratification out of the heat exchangers. At first, I thought it was some sort of phenomenon with the IR camera but when I put my hand on the top and bottom of the pipe, I can feel the difference. The inlet piping on the CCW side is in the range of ~96F so it almost looks like there is some sort of leak by or internal bypass from the inlet of the heat exchanger to the outlet but not sure what would cause that or if it is even possible. Any idea what may cause this? Any help you can provide is greatly appreciated.

 

[Heaviside1925]

OP,
What's your CCW velocity? I'm guessing laminar flow and very little mixing at the boundary layer. So, it's not so much stratification as it is the warmer fluid not mixing with the cooler fluid.

 

[LittleInch]

What am I looking at here?

Got a non IR photo, drawing, size, flowrate?

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

 

[stoerw]

B. Process Parameters / Operating Conditions

Fluid River water / Sea Water
Pressure 100 psig
Mass Flow Rate 2067951 lbm/hr H2O

 

[LittleInch]

So is this FRP Pipe?

Could the wall thickness be more on the inside of the bend than the outer?

Can you do thickness measurements?

Or you have some fouling or marine growth on the inside of the bend?

How often is it backwashed?


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

 

[Heaviside1925]

OP,
My other thought would be, a reflectivity vs. emissivity issue, using an IR to look at the FRP piping. Does this temperature gradation show up in other sections of the FRP piping?

 

[Compositepro]

There is an eddy in the flow downstream of the elbow.

https://ars.els-cdn.com/content/image/1-s2.0-S2215098615301610-jestch200-fig-0008.jpg

 

[georgeverghese]

You've got cheap NBR gaskets here on these plate frame gasketed units.
My guess is that if RW pressure is higher than CCW pressure, that you've got leakage of the cooler RW stream into the warmer lower pressure CCW stream some where close to the CCW exit through some leaking inter plate NBR gasket.

 

[pierreick]

Hi,
Internal Plate leakage due to corrosion, under gaskets? Did you open the unit(s)to check ?
Pierre

 

[stoerw]

The unit has not been opened up yet, however I believe that unit was Professionally Acid Cleaned. Also, out thoughts were possible inter plate leaks as well. So, thank you everyone for your input.