supply air rate

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Hi All,
What is the range for supply air cfm/sqft for conditioned spaces
Thanks
Sambhav.

sambhav tiwari's picture
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Joined: 2011-09-30
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That depends on what you're trying to do with the air Shambav. If you
are meeting outdoor air requirements to maintain Indoor air quality then
refer to ASHRAE 62.1. If you are attempting to condition the space (heat
or cool) with the air then volume flow

V = Q / rho.Cp.deltaT

where Q = Heating / Cooling rate, Rho = density of air, Cp = specific
heat, DeltaT = difference in room air temperature and off coil.

A VAV system does both of these (supplies outdoor air and room
conditioning) and uses a mixing box.

If you want to understand VAV get hold of LearnHVAC
.

Cheers

Chris Yates

Chris Yates2's picture
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Sambhav,
http://bepan.info/class-notes/e1-bldg-shell-environ
Click on F15 - Air-Quantities
I have also attached the section
Varkie

Varkie Thomas's picture
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Funny how this has expanded from the original question: "what is the range
for supply air cfm/sqft for conditioned spaces". I took it to be him asking
for OA+RA quantities that get delivered to a space, since I was just talking
about that with a colleague recently. Perhaps Sambhav can let us know if we
met his needs.

Thank you once again, Varkie, for sending us another of you papers. I
appreciate all information I get from you and I actually read it!! Good
stuff.

Cheers,

Carol

cmg750's picture
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Carol,
You are right. The question was what is the range for supply air in CFM/sqft. SA standards for medical and industrial facilities are in ACH. The minimum value for OA & SA are set by standards but the maximum SA value cannot be anything that CFM = BTUH (cooling) / (1.08 * (Ti - Ts)) produces. The type of space determines the maximum and there is a limit to the SA and after which other cheaper methods (supplying air is expensive) are used for heating and cooling and judgement is also involved. It helps to understand the whole subject. Refer to OSHA for the answer to the question. http://www.osha.gov/
Varkie

Varkie Thomas's picture
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Sorry, this isn't a modeling question, but I think some people here could
answer this question.

I have a geothermal well field serving heat pumps. Is there any convention
on labeling the pipes?

Condenser water supply / return => CWS / CWR
Ground water supply / return => GWS / GWR

I know I can make up anything I want, but I didn't know if something is
starting to become the standard.

(Something like HWS / HWR)

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Jeurek's picture
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