Environmental Engineering
posted by Jimmy .
Consider the air over a city to be a box 100km on a side that reaches up to an altitude of 1.0 km. THe air is blowing into the box along one of its sides with a speed of 4 m/s. Suppose an air pollutant with a reaction rate of K = 0.20/hr is emitted into the box at a total mass loading rate of 10 kg/s. Find the steady state concentration if the air in the box is assumed to be perfectly mixed.

what would be the CO consentration in the box?

V= 100*100*1 = 10000 km^3
Q = 4/1000*1*100 = 0.4 km^3/s
m (loading) = 10kg/s, k = 0.20/hr
1 km^3 = 10^12 L (if u want kg/L as concentration)
Cin = 10kg/s / 0.4 km^3/s = 25 kg/km^3
for CSTR: Cout = Cin/(1+k*t), t = V/Q = 25000 s or 6.94 hr
Cout = 25/(1+0.20*6.94) = 10.47 kg/km^3