simple air flow problem 1

[ddace]

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?

 

[toolanimal]

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

 

[ddace]

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

 

[SilFox]

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.

 

[McCormick93]

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

 

[remp]

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

Good Luck!