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!

*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

Variable speed for compressor??

Variable speed for compressor??

Variable speed for compressor??

Hi there, assuming that two compressors, operating at the same conditions (air compressed, 100 psi discharge, same power, etc) one of them centrifugal and the other one dry screw, which one would you select to operate with a variable speed driver???

Thanks a lot for your help

RE: Variable speed for compressor??

Centrifigul equipment loses both capacity and efficiency very quickly as you slow it down.  I would vary the speed on the screw (positive displacement) and keep the centrifigul spinning fast.

David Simpson, PE
MuleShoe Engineering

RE: Variable speed for compressor??

I agree with Zdas. Moreover, you will have surge problems if you go with variable speed centrifugal compressor. (as you reduce speed, the hydraulic head also gets reduced but you should require your compressor to run at same thermodynamic head as you have initially)

On the other hand a screw chiller can develop same pressure even if you reduce the speed (PD machines work on back pressure principle)


RE: Variable speed for compressor??

I fully agree with above replies. Just a question: why you do not use the capacity control capability of the screw compressor ?  

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! Already a Member? Login


Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now
The Great Project Profitability Debate
A/E firms have a great opportunity to lead the world into the future, but the industry’s greatest asset—real-time data—is sitting wasted in clunky, archaic ERP platforms. Learn how real-time, fully interactive dashboards in a modern ERP allow you to unlock data that will shape the future of the world. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close