Heat load of motors 2

[quark]

I, once again, want to bring up the issue of heat load of motors to your kind notice. I have been observing the designers using the following equations for heat load of motors, that confused me since I started learning about HVAC.

Motor and driven machine inside control space - HPx2545/eff.
Motor out driven machine in - HPx2545
Motor in driven machine out - HPx2545x(1-eff)/eff

Now coming to my question, if I have a chiller placed inside a controlled space (may not be within the same space which is conditioned by this particular chiller), what will be the heat load due to this chiller to the controlled space?

I am sincerely awaiting some discussion on this topic.

 

[walkes]

This is a tricky situation, it depends also on chiller type, come compressors are refrigerant cooled so the heat gain to the control space is lower, some are air cooled and require a fan coil in the space to cool the compressors.
Refrigerant cooled, heat rejected to the condenser water loop and rejected outside, heat gain to space is minimum.

So this should be a call to the manufacturer in this case.

 

[imok2]

Have you tried comparing your calculations with these to see howclose they are?

http://www.engineeringtoolbox.com/electrical-motors-heat-gain-dHPx2545/eff._707.html

 

[quark]

Good leads by both of you and that confirm my own logic.

imok2,

I have been to the engineeringtoolbox site plenty of times but somehow overlooked this particular topic. Though the formulae are same more or less, the footnotes are quite useful and reiterate my ideas.

walkes,

You commented as if you read my mind. My next question would have been about the cooling tower capacity in this situation, if I didn't get replies in the same note.

The calculation for heat load due to equipment, thus, should be calculated, not by standard set of formulae but, on case to case basis, in terms of energy contained in a particular situation. I feel this thread will be a reference for similar threads that were asked in the past and/or that will be asked in future.

Thanks for your replies.

 

[Yorkman]

On the York VFD centrifugals we use a cooling coil, that circulates a coolant solution to pick up heat in the drive cabinet to keep internal cabinet ambient temps below 140 degrees. We also use this solution to cool the IGBT heatsinks (max. temp. 160)
What we don't address and I've seen this become a problem is the heat put out by the 500 H.P. motor connected to this drive. I've seen several chiller mechanical rooms where there in no cooling in the room, and even with all the heat rejection the drive has we still expeirence overheating issues.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

http://home.comcast.net/~offsetaj/

 

[KiwiMace]

In non-brand-specific tender situations, where we can't predict whether we'll be offered a hermatic or non-hermatic motor, we design the plantroom cooling to cater to the non-hermatic type where the heat is rejected to the plantroom, and the cooling towers sized for hermatic motors. When the tender is being awarded we adjust for the actual situation and cut out the provision and cost. This saves variation costs.