process chiller help

[talon771]

I need some advice and maybe help with the basics:
I have a Budzar (AC-08) 8 ton air cooled water chiller hooked up to my process. 35gpm/40 psi centrifugal pump. Feed/return lines are 2 inch, 32 foot climb up to my cooling line loop. 1" feeds from that to my process.
The chiller maintains a 7 to 10 degree F differential, but the water temp climbs up. The compressor runs, no cycle. Pressure on the exit of the pump jumps between 25 and 35 psi. Even when I shut down my process it take awhile for the water temp to come down. I have used similiar sized chillers in the past that have had no problems.

I have tried opening a cross over valve in my main cooling loop lines to make sure I have good flow through the chiller. Before I did this the compressor would shut off with a low pressure fault.(refrigerant).
The chiller charge has been checked, pump, strainer and other lines checked.

The chiller is not new to the company. Could the heat exchanger be scaled up?

Or is my pump just not big enough?
Past chiller I have used had the same flow but higher pressure capacity. Other plant had only 20 foot high lines.

I was told if there is not enough flow through the chiller it won't cool right.

Any help or pointing to some info to help would be appreciated.

[The Viking]

By the sound of things there is a capacity problem somewhere and for some reason.

Unfortunately so is there numerous reasons for this to happen and you really need to get a professional refrigeration engineer to have a hands on look at your system to determine where the fault/issue lies.

[Grizzly]

Sometimes as an engineer the real trick is knowing when to admit you are not sure and ask for assitance.
" I was told if there is not enough flow through the chiller it won't cool right."
Also with insufficent flow and incorrect safety setups you can crush the evaporator tubes rendering it useless.
As Viking says Get Help.
Cheers Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

[1torr]

'Pressure on the exit of the pump jumps between 25 and 35 psi'. if the pressure is going up and down and the pumps sound is changeing simultaneously, to me this sounds like the inlet to the pump is being starved of water. Not enough water flow through the evaperator can cause LP trips.

[Gary]

I assume the water loop has an automatic fill from city water supply through a pressure regulating valve (PRV) at the bottom of the loop. These valves come adjusted from the factory at 12psi. Your system needs the PRV adjusted to 16psi due to the height of the loop.

Increase the water fill pressure and let us know how it worked out.

[MilosBog]

Post a schematic with all valves and if you have something else specific...I've had once a problem only with unbalanced pipe network. The chiller worked excellent after but before it couldn't cool down more than DT of 2K. Lets take a look at schematic and than we can discuss...
BR

[Gary]

This thread is from 2007. I assume it has been fixed by now... although the OP did not let us know the outcome.

[1buck]

Does the chiller have capacity contol..ie hot-gas by pass?

[TXiceman]

Don't you just love it when they never come back and tell you the out come. I would like to know what the problem was or did he get fired before it was fixed.

Ken