PCHE (Printed Circuit Heat Exchanger) - Performance Monitoring

[YoungPetrEng]

I'm a relatively young engineer in a new position and have been asked to develop a performance monitoring program for our PCHEs.

We have two of these PCHEs in parallel and have been noticing a gradual increase in DP across both. Upstream strainers were recently pulled and solids were found (presently being sent away for analysis).

We will not have another opportunity to clean these exchangers for quite some time so a monitoring program is important.

The installation of the exchanger is downstream of a centr. gas compressor.

The things I've started trending are
Delta Pres / Flow vs time
Delta Temp / Flow vs time


Any suggestions on what I should be monitoring??? Any suggestions would be appreciated!!!

Thanks

 

[cjnengr]

As you already know, the PCHE has very small channels. By the time you notice a change in pressure drop, you will probably be beyond the point of recovery.

I believe a better monitor is to monitor the "U". It requires more data but will allow you a closer look at the fouling that is actually going on in the unit. It also is more accurate than simply monitoring the temperature or heat load.

 

[TDSL]

The problems with PCHE's are exactly as you describe. The channels are so small ie 1mm deep x 2mm wide MAXIMUM that they are very susceptable to fouling and subsequently extremely difficult to clean succesfully.
As described in the earlier response if you have already noticed increase in DeltaP then the performance has probably dropped off considerably, but by measuring inlet/outlet temperatures and flows on both sides of the exchanger you will be able to calculate the overall heat transfer coefficient, and compare with the original design point.
You may end up having to replace the units which may be difficult due to the compact nature of PCHE's.
One option is to consider Plate & Shell Heat Exchangers, which are almost as compact but have much greater passage sizes.
Please let me know if you need further assistance

 

[IRstuff]

Which deltaT? In vs Out is one. The other is the T on the other side of the exchanger. The heat transfer equation is based on Q = htc*Area*(Thot-LMT), so knowing the hot side temperature will hypothetically allow you to explicitly compare whether the exchanger is really pulling the correct amount of heat out.

TTFN

FAQ731-376