RobsVette
Mechanical
- Apr 15, 2009
- 94
Hi Guys,
I'm working on a project where we have purchased a brand new double effect, direct fire, absorption chiller from York. Its the largest one they make at 700 tons.
The problem we are having is that our evaporator tubes seem to be coated with some kind of grease or oil that is preventing heat transfer. While operating the machine we were getting a 7 degree F approach (or small temp difference in the evap.) We tried flushing the tubes with an alkaline detergent and that seemed to help, but only marginally.
This was a replacement of an existing machine. We took out an old hitachi (the blue old style absorbers) chiller and replaced with the new machine, so I dont believe it has anything to due with the existing system.
Would anyone have some thoughts as to where the oil could have come from? Here are my thoughts, feel free to comment on these or any other ideas.
1) Possibly left over from the process of extruding the tubes in the head plate. I believe they do oil the expander as it goes through the tube and it has to hit both end tube sheets and the intermediate support sheets. I feel this is the most likely candidate.
2) The old machine had not been operated in cooling mode for some time, so the chilled water piping was probably stagnant for a period of many years. I'm sure lots of dirt collected there before we returned the machine to cooling service and circulated chilled water, but I don't think stagnant water would explain the oily residue.
3) Could this possibly be left over from the manufacturing process of the tubes? I believe they are extruded, but don't think this would be a likely reason, since it would have to be a more widespread problem.I imagine they make these tubes by the thousand so it should be a problem that is not specific to my machine if so.
The machine was purchased to be field assembled so it was never ran at the factory, which I am sure explains why I have never encountered this before.
Any thoughts or insights would be hugely appreciated. At this point we are flushing with a degreaser so hopefully this works and gets rid of the residue. Next its on to the condenser tubes. Hopefully I don't have the same problem again.
Thanks in advance for any help.
Rob
I'm working on a project where we have purchased a brand new double effect, direct fire, absorption chiller from York. Its the largest one they make at 700 tons.
The problem we are having is that our evaporator tubes seem to be coated with some kind of grease or oil that is preventing heat transfer. While operating the machine we were getting a 7 degree F approach (or small temp difference in the evap.) We tried flushing the tubes with an alkaline detergent and that seemed to help, but only marginally.
This was a replacement of an existing machine. We took out an old hitachi (the blue old style absorbers) chiller and replaced with the new machine, so I dont believe it has anything to due with the existing system.
Would anyone have some thoughts as to where the oil could have come from? Here are my thoughts, feel free to comment on these or any other ideas.
1) Possibly left over from the process of extruding the tubes in the head plate. I believe they do oil the expander as it goes through the tube and it has to hit both end tube sheets and the intermediate support sheets. I feel this is the most likely candidate.
2) The old machine had not been operated in cooling mode for some time, so the chilled water piping was probably stagnant for a period of many years. I'm sure lots of dirt collected there before we returned the machine to cooling service and circulated chilled water, but I don't think stagnant water would explain the oily residue.
3) Could this possibly be left over from the manufacturing process of the tubes? I believe they are extruded, but don't think this would be a likely reason, since it would have to be a more widespread problem.I imagine they make these tubes by the thousand so it should be a problem that is not specific to my machine if so.
The machine was purchased to be field assembled so it was never ran at the factory, which I am sure explains why I have never encountered this before.
Any thoughts or insights would be hugely appreciated. At this point we are flushing with a degreaser so hopefully this works and gets rid of the residue. Next its on to the condenser tubes. Hopefully I don't have the same problem again.
Thanks in advance for any help.
Rob