Maharg
Oct31-09, 12:57 AM
1. The problem statement, all variables and given/known data
1. A fly ash (ρ =1.8 g/mL) aerosol consists of particles averaging 13 μm in diameter and with a concentration of 800μg/m3. Use the average diameter to calculate the settling velocity (cm/s) and settling rate (μg/m/s) of the particles in air.
The Stokes-Cunningham slip correction factor is 1.015.
2. Relevant equations
vt = (pp - pa)C*g*dp^2/ 18n
vt = settling velocity in m/s
pp = particle density g/m3
pa = air density g/m3
C = stokes-cunningham slip correction factor (given in question)
g = acceleration due to gravity
dp = particle diameter in m
n = viscosity of air
3. The attempt at a solution
So first I had to figure out what each part of equation is since I was not given all of it.
pp was given in question as 1.8 g/mL converted to 1.8E6 g/m3 (is that correct conversion?)
pa I found online air density to be 1.184E3 g/m3 at 25 Celsius (note no textbook for this class)
g = 9/8 m/s2
n = 1.86E-2 g/m*s I also found this online
After this I plugged it all into equation.
vt = [(1.8E6 g/m3 - 1.184E3 g/m3)(1.015)(9.8 m/s2)(13E-5 m)]/[18(1.86E-2 g/m*s)]
= 2403.654 g/m / 0.3348 g/m*s
= 7179 = 7.2E3 s
my units don't make sense. everything cancels out but seconds. How go I get this in m(cm) a second. I don't know how to make it so m doesn't cancel?
Also I do not know how to do settling rate. We have never talked about rate in class. Any suggestions?
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
1. A fly ash (ρ =1.8 g/mL) aerosol consists of particles averaging 13 μm in diameter and with a concentration of 800μg/m3. Use the average diameter to calculate the settling velocity (cm/s) and settling rate (μg/m/s) of the particles in air.
The Stokes-Cunningham slip correction factor is 1.015.
2. Relevant equations
vt = (pp - pa)C*g*dp^2/ 18n
vt = settling velocity in m/s
pp = particle density g/m3
pa = air density g/m3
C = stokes-cunningham slip correction factor (given in question)
g = acceleration due to gravity
dp = particle diameter in m
n = viscosity of air
3. The attempt at a solution
So first I had to figure out what each part of equation is since I was not given all of it.
pp was given in question as 1.8 g/mL converted to 1.8E6 g/m3 (is that correct conversion?)
pa I found online air density to be 1.184E3 g/m3 at 25 Celsius (note no textbook for this class)
g = 9/8 m/s2
n = 1.86E-2 g/m*s I also found this online
After this I plugged it all into equation.
vt = [(1.8E6 g/m3 - 1.184E3 g/m3)(1.015)(9.8 m/s2)(13E-5 m)]/[18(1.86E-2 g/m*s)]
= 2403.654 g/m / 0.3348 g/m*s
= 7179 = 7.2E3 s
my units don't make sense. everything cancels out but seconds. How go I get this in m(cm) a second. I don't know how to make it so m doesn't cancel?
Also I do not know how to do settling rate. We have never talked about rate in class. Any suggestions?
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution