×
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

Heat Rejection

Heat Rejection

Heat Rejection

(OP)
Hi,

I am trying to do heat rejection calculations for a few buildings on an ethanol plant that is being started up.  I am supposed to just take the light and motor starters into account to calculate the heat rejection.  Is there a standard for this and where can I find it?  I was told to look through IEEE 141 and could not find anything on this.

Doug

RE: Heat Rejection

You might search this forum - seems like there was a thread on this not too long ago.  

As far as indoor lighting - every watt will end up as heat.

For motor starters, I know I posted this information here within the last couple of years.  Or see MCC technical data from major vendors.  

For motors, start with basic motor efficiency to determine heat rejected directly by the motor.  Then add in pump/fan  losses, then piping heat/friction losses.  

What is the purpose of the calculation, exactly?

RE: Heat Rejection

(OP)
The purpose is to be able to determine how much air condition will be required.

I have been digging through these forums and from what I have found it seems like people just assume that 10% of the power the motor consumes turns into heat. Is this how it is usually  calculated?  

RE: Heat Rejection

thread238-29865: Heat Losses in Switchgear

Link above is to an old thread with some typical data.  

10% loss in a motor is a reasonable,conservative approximation for what you are doing, but my point was that there are many other sources of heat loss in addition to motors.  

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