Screw or Reciprocating chiller.
Screw or Reciprocating chiller.
(OP)
Hi Every Engineer,
We are working in a replacements of 7 reciprocating air-cooled chiller with new chillers with the same cooling capacity,but we are concerning about screw chiller technology as some big company's represintative told us that this technology needs high experience, is that right?
Is there any web site talks about this kind of chillers in details?
any resonse will be appreciated,
We are working in a replacements of 7 reciprocating air-cooled chiller with new chillers with the same cooling capacity,but we are concerning about screw chiller technology as some big company's represintative told us that this technology needs high experience, is that right?
Is there any web site talks about this kind of chillers in details?
any resonse will be appreciated,





RE: Screw or Reciprocating chiller.
RE: Screw or Reciprocating chiller.
go to http://www.trane.com/worldwide/commercial/rlcprc003e4pdf.asp
RE: Screw or Reciprocating chiller.
Benefits of screw chillers over recips.
1. Fully modulating capacity controls via slide valve. i.e. load match exactly with your building load and avoid overcooling you get with stepped control. But check maufacturer first.
2. Compressor servicing virtually nil with screw. With recips you need to do top end overhaul every 15000 hrs operation (costly). Again check screw manufacturer as some need bearing inspections regularly.
3. Reliabilty - screw compressors typically have three moving parts, recips have 40 plus. My experience is that on a four compressor recip chiller you get a failure every year. Its unusual to get a screw fail.
Which manufacturers for screws:
Trane, Carrier and Mcquay. I've seen bad reports about Macquay reliabilty and remember reading a post in this forum some time ago on them. On balance nothing between Trane and Carrier, although Trane have been in screw market longer. The Carrier compressor is high speed (upto 14000rpm) gear driven and generally the chiller is smaller footprint. Trane is conventional two rotor (2800rpm)and focus on reliabilty.
I'd get the Trane and Carrier reps in and get them to give presentation.
RE: Screw or Reciprocating chiller.
RE: Screw or Reciprocating chiller.
RE: Screw or Reciprocating chiller.
Advantage of screw over recip
1. Lesser moving parts.
2. Better part load power consumption (in most cases).
3. More reliable.
4. Generally, resistance to liquid slugging is better in screw compressors.
4. Not much to choose between Trane and Carrier, though Trane ventured into screw technology earlier. High speed of Carrier machines makes the machine smaller. I don't think that's an issue. York also has good units, not sure of McQuay though. Footprint of Carrier is generally smaller as compared to others.
RE: Screw or Reciprocating chiller.
Other than that, dunno jack about screws.
Between the F18's landing at MCAS Miramar overhead and those two chillers a cell phone is useless!
Clyde
RE: Screw or Reciprocating chiller.
The best thing to do,no matter what,is scrap the the recip.air cooled program.Rotary Screw cillers are so much more economical in operation and maintenance!I'm with a large chiller manufacturer as a mechanic,and I will simply state that recips are fragile compared to these rotaries.However,like anything else,the technology is getting fierce.But to meet the wide application criteria that so many buildings require now,you are not going to do it with a recip,so they changed the rules on us both.Rotary screw chillers have magnificent capacity control with a computer on board to protect them.Hang in there when the recips are changed out,like I did,you'll get used to them as
well.The best thing always is,pay a flat rate on a service contract,and let that be their problem.TRUST ME ON THIS!
Be aware of one thing,you can really damage these machines if you goof up on procedures.Let me know if I can help in any way...
RE: Screw or Reciprocating chiller.
Agree, that rotary's are loud but, the dba is just a tad over a recip. Also failure rates are about 1%.