Temperature of air ventilated from pump room???

[kmtswims]

I am trying to figure out the temperature of the air that I am ventilating from a pump room to decide whether it needs to be exhausted to the outdoors. I have (2)20hp pumps, I have done a rule of thumb to figure out the Btuh that these will be giving off and came up with 15026 Btuh. (110 Watts per hp> (110*40=4400 Watts > converted to Btuh = 15026). I am moving 1000 cfm out of the room and intaking the same. The room is approximately 100 sq. ft.

 

[MintJulep]

13 degrees F warmer than the intake air.

 

[kmtswims]

Thanks for the reply. I am sorry, I really should have clarified that I don't have a good concept of what the intake air temperature is going to be. This room is in a ventilated garage that is partially buried underground. I am obviously trying to figure out worst case scenario. This building is in South Florida.

 

[trashcanman]

air temp rise = 15026/(1000*1.08)= 13.91 Deg.F

Assuming 95 Deg. Entering air, leaving air = 95 + 13.91 = 108.9 Deg.F

Hope this helps.

 

[jphaymond]

First, I think your heat gain from the motors is low. ASHRAE has a guideline for this, and a 20hp pump with both motor and pump in the same space releases 58,500 btu/hr. If both pumps are running, that's 117,000 btu/hr.

The air temperature rise = btu/hr divided by 1.08 x cfm.

If both pumps run continuously, this will be an extremely hot room.

 

[kmtswims]

Thanks for the post. I agree that the 13 degree dT seems very low for (2) 20hp pumps. Can you tell me where ASHRAE states the guideline for the pump heat gain?

 

[HVACctrl]

108 deg temp rise? (117,000 / (1000cfm x 1.08))

Sounds pretty hot. Is that reasonable?

Ed

 

[walkes]

Not all of the motor energy will be converted to heat. Depending on what the pumps are doing some energy will be transfered to the fluid.

See this thread:

http://www.eng-tips.com/viewthread.cfm?qid=59911