M E 433
Professor John M. Cimbala
Lecture 09
Today, we will:
•
Continue to discuss flux chambers, and do an example problem
•
Discuss EFs for tank-filling applications, and if time, do an example problem
Flux Chamber = an enclosure around a source of air pollutant with which we measure the
source strength Sj of the pollutant.
Flux chamber
Mixing fan
Blower
cj,a
Qa
cj(t)
cj(t)
Sj
Qa
In
Out
To sampling
instrument
Source
Conservation of mass of species j:
dm j
= c j ,aQa + S j − c j ( t ) Qa
dt
(1)
Example: Methane from a Manure Tank
Given: Methane (CH4) is emitted
Flux chamber
from a 2 m × 1 m manure tank in
a barn. A flux chamber is built
on top of the tank to measure the
emission rate. The following
cj,a
quantities are measured:
cj(t)
Q
3
a
•
cj,a = 0.0020 mg/m (ambient
Sj
mass concentration of CH4 in
In
the barn)
•
Qa = 0.18 m3/s (bulk air flow
Tank
Manure
rate into the flux chamber)
•
cj,ss = 1.5 mg/m3 (steady-state
mass concentration of CH4 leaving the flux chamber)
To do:
Solution:
Mixing fan
Blower
cj(t)
Qa
Out
Generate an emission factor, EF, for methane from a manure pile.
To methane
sampling
instrument
Tank Filling
Qair, out
Qliquid, in
Air + VOC vapors, Vbulk air
Pj, cj
Evaporation
Liquid VOC, Vliquid