electrical equipment heat dissipation
electrical equipment heat dissipation
(OP)
Good day,
I would like to ask on how to calculate electrical equipment(motors, machine shop equipment,etc.) heat dissipation
If the only given is the Input power of the equipment. this will be my consideration for my cooling load calculation.
For this type of room space, what would be the room temp requirement? Is it enough to provide ventilation only?
thank you.
I would like to ask on how to calculate electrical equipment(motors, machine shop equipment,etc.) heat dissipation
If the only given is the Input power of the equipment. this will be my consideration for my cooling load calculation.
For this type of room space, what would be the room temp requirement? Is it enough to provide ventilation only?
thank you.





RE: electrical equipment heat dissipation
RE: electrical equipment heat dissipation
The heat dissipation is not the total input power of the equipment. For a motor, you have to use the motor efficiency, the use factor, the motor load ans the power rating.
If you don't have these data, I suggest you to add a frequency and efficiency factor. For example :
Biomotor tool (200V @ 30A) = 6000W
- Factor use : 0.2, equivalent of 12min of usage in 1 hour (0.2*60min)
- Efficiency : 0.2, so 20% of the total input power is dissipated in heat
- Total heat : 6000W*0.2*0.2 = 240W, 240W*3.412 = 819 BTU/H
Unless the equipment is a electric coil, remember that not all the input power is dissipated in heat. Without these factor, your cooling load will be over estimated. Here is a rule of thumb to estimate the total cooling load :
http://bim.wikispaces.com/file/view/ASHRAE+Mechani...
What is the function of the room ? Lab, warehouse, office, mechanical room ? The function will clarify the room temp/RH requirement.
Hope this help!
RE: electrical equipment heat dissipation
RE: electrical equipment heat dissipation
Hm = Pm / hm
Hm = heat transferred from the machine to the room (W)
Pm = electrical motor power consumption (W)
hm = motor efficiency
The type of the room is a Laboratory. I want to determine any large cooling load caused by the equipment. Or it requires special ventilationand/ or exhaust requirements. thank you
RE: electrical equipment heat dissipation
RE: electrical equipment heat dissipation
Basic desktop computers you can figure 100-150 each plus another 150-200 W for flat screen monitors or 300 W for older CRT monitors. Personally I use 350 W for each computer station.
As for special ventilation or exhaust, get with the owner or equipment manufacturer. Generally though, special exhaust is only needed for high heat generating equipment such as autoclaves and ovens; but not for hot plates. If there are hazardous chemicals and or processes, then you will probably be dealing with fume hoods which have their own unique design challenges.
I have to disagree with Compositepro's statement "All the input power does eventually end-up as heat." If this were true you would not get any work done, computers wouldn't compute, centrifuges wouldn't spin, etc.
RE: electrical equipment heat dissipation
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RE: electrical equipment heat dissipation
RE: electrical equipment heat dissipation
RE: electrical equipment heat dissipation
With labs, diversity should also be factored into the equipment load profile. What constitutes an appropriate diversity factor for a lab? I don't know
Getting back to Chiz's questions. You appear on the right track with figuring heat from each piece of equipment. If you haven't already done so, get with the end user/owner and talk about what is in the lab and how it will be used. If they have an existing lab they will be moving out of, try to visit it, it will give you an idea how they use their stuff.
As for space temperature requirement, again this will be an owner driven variable. Often they don't care, in which case the ASHRAE normal 75°F / 50% RH are good to design to.
Ventilation only? It depends on what type of lab and the activities in the lab - talk to the owner (see a pattern here?). Owner likely won't be able to tell if a once-through system is needed, but can tell you what is happening in the lab and from that you can review codes and standards to determine if this is what is needed.