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simple air flow problem

simple air flow problem

simple air flow problem

(OP)
Administration kills engineering. Design calculation ability is a muscle, if not trained it atrophies...

I am curently designing a mobile generator unit in a closed area.I need to determine the amount of air flow requiered to maintain an ambiant temp of no more than 40ºc.

Known:
desired ambiant temp:  40ºc
outside temp (cooling air) :up to 30ºC
kw regected by components inside habitacle :205Kw

unknown:

air flow volume needed in order to maintain ambiant temp at no more than 40ºc in order to select exhaust fan and inlet damper/loovers?

air speed could reach up to 1000ft/min

I need reminding of practical equations/formulas and basic notions?

RE: simple air flow problem

Try the following basic formula:
Airflow (cu. ft. per minute)=Total Heat (Btu per hr)/(1.08*Temp. diff. in deg. F)

RE: simple air flow problem

(OP)
I have seen this formula before but i wish i could understand a little more where the 1.08 constant comes from ?

RE: simple air flow problem

I think it's might be so:
 Required flow can be calculated according to
  Q = H/c*p*(Ti - To)
assume that
 H = 205kWt or 11658 Btu/min,
 c = 0.24,
 p = 0.075,
 Ti = 30C or 86F,
 To = 40C or 104F,

    and Q = only 35981 CFM.

RE: simple air flow problem

The 1.08 in toolanimal's equation is
air density (0.075 lbm/ft3)
x
specific heat of air (0.24 Btu/lbm F)
x
60 min/hr

so that the answer comes up ft3/min

RE: simple air flow problem

17000 L/s with a louvre area of approximatly 3m x 3m (50% free area)

Good Luck!

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