×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

By pass valve

By pass valve

By pass valve

(OP)
Hi,

We have designed a fresh water cooled condenser for a refrigeration plant at 37 degC inlet water temperature. But later it is found that the inlet fresh water temperature is not stable. In winter it may go below to 5 degC. My question is "will the compressor/condensor unit will function properly without providing any bypass valve for recirculation"?

Thanks

RE: By pass valve

I must answer with question: what kind of load control you actually use for your condenser? You must have some system for load balancing because you need to have condenser outlet temperature contolled.

RE: By pass valve

More than likely, you will need to add a condenser water regulating valve (WRV) in order to keep the head pressure up to a specificied minimum.  In order for the refrigerant to feed properly from the high pressure side to the low pressure side, you will have a minmum discharge pressure or head pressure.  Contact the chiller manufacturer for the minimum discharge pressure on your unit.

If you want to tacle this on your own, look at Johnson Controls or Metrix fro water regulating valves.  These are self contained pressure operated (condenser pressure) valves.

Ken

TXiceman
www.rae-corp.com

RE: By pass valve

It wont work mate.The compressor will trip on low suction pressure as the regrigerant head pressure in the condenser would drop substantially with low water temperatures.
You do need a tower bypass control which would raise the water temperature to an acceptable level.

RE: By pass valve

SAK9. the common way around the start up issue is to use a timed starting bypass on the low pressure switch to allow the unit some time to build up pressure.  Also use a pressure regulator and check to pressurize the receiver...

Ken

TXiceman
www.rae-corp.com

RE: By pass valve

"Plant" seemed to be the operative word.  Large systems have been known to draw water directly from a pond, lake, or river source.  In those cases, a bypass is the only way to reliably control the water temperature.  Some chillers are very sensitive to condenser water temps, and there is little chance that a 2-way throttling valve or pressure regulator can keep the chillers online.  There simply isn't enough mass flow rate of the water at the reduced temperatures to keep the safeties from tripping.

Heating the water is not possible, either - unless you "punt" and put in cooling towers - the water source is an infinite heat sink.  Any fresh water system would have ample filtration and bypass capability built-in, though.  I would think it a simple matter to modify some of that to make a bypass loop somewhere in the system.  That would provide some degree of tempering by mixing the water streams.

It's all conjecture unless Redif gives us more detail, though.  Strategies differ depending on the size of the system.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources