Air Quality 2 of 2

8/14/2019 Air Quality 2 of 2

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2 of 2

Air Quality

Virendra Sethi

[email protected]



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• An Inconvenient Truth – Film by Al Gore



Absorption: Individual GasesCH4

N2O

O3, O2

CO2

H2O

solar terrestrial

ixoto and Oort: Physics of Climate



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Simple Global Temperature Model

• Solar Energy Striking Earth = S(1-α ) .π R2

– S = solar constant (1370 W/m2)

– α = 0.31 (Albedo)

• Energy radiated back to Space by earth

= σ 4 π R2 Te4

σ =5.67E-8W/m2K4

• Equating

Te = [ S(1-α )/(4σ

4

)]

1/4

= 255 K (-18°C)



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Greenhouse effect

• If there was No Atmosphere

Radiation from earth = radiation to space (240 W/m2 )

• Implies Earth temperature = 255 K (-18°C)

• With AtmosphereRadiation from earth – Radiation to space = 155 W/m2

• Implies a 155 W bulb per m2 on the entire planet

• Average temperature = 288 K (15°C)



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Comparison with Mars and Venus

PLANET S

(W/m2)

α T

(Black Body)

(K)

Ts

(K)

GreenhouseWarming

( °C)

Venus 2620 0.76 229 710 521

Earth 1370 0.31 255 288 33

Mars 589 0.25 210 218 8

Adapted from Masters (1997)



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Greenhouse Gases - GWP

Gas Lifetime GWP(20 Years)

GWP(100 Years)

CO2 1 1

CH4 12.2 56 21

CFC-11 50 5000 4000

N2O 120 290 320



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Review

Dispersion and Mixing Influenced by :

• Wind – Speed

– Direction

– Wind Rose

• Temperature Lapse Rates

– Dry adiabatic – Wet Adiabatic

– Stability



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Results of the Class Exercise

• How many grams of Sulphur, if burnt in

PC Saxena Auditorium, would pose a

health risk to you ?

• Given : Regulatory Limit for SO2 in

Ambient Air is – 80 µ g/m3(0.03 ppm) for annual average

– 1300 µ g/m3(0.5 ppm) for 3 hour average



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Solution

• X gms of Sulphur would give 2X grms of

SO2

• 2X gm of SO2 / Vol of PCSA

= 1.3E-3g/m3

Estimate of Vol :



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Class Estimated Volume of PCSA

• Number of Students 178

• Average 1478.3 m3

• SD 1261.6 m3

• Range 216 to 8000 m3(Outliers 1.365, 35.56, 14,00,000m3 )

• Range of Sulphur 0.14 to 5.2 gm



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Air Pollution

• Concentration

• Duration – hours to days to years

• Criteria Pollutants – Primary (FIVE)

• SOx

• NOx

• CO

• PM-10

• Particulate Lead – Secondary (ONE)

• Ozone



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Stopped

in Nose

Respirable



15Source: Flagan and Seinfeld, 1988

Particle formation in coal combustion



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Physical Nature of Particulate Emissions from Engines

Typical Engine Exhaust Size Distribution both Mass and Number

Weightings (Source: Kittelson et al . 1999)



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Diluted Diesel Exhaust: Particle Number vs. Mass

0

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

18.000

1 10 100 1000 10000

Particle Size [nm]

Particle Number

[P/cm3]

0,0

0,5

1,0

1,5

2,0

2,5

Particle Mass

[mg/m3]

Courtesy : TSI Inc.



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Class Exercise

How would you

size and count aerosol particles in the

nanometer size range ?



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Air Pollution Control - PM

• MECHANICAL

– Gravity – Settling Chambers 20 -100 µ m

– Inertia - Cyclones > 25 µ m

– Diffusion – Filters > 0.1 µ m

• ELECTRICAL

– Electrostatic Precipitators > 0.1 µ m



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Instrumentation

• Inertial Impactors

– Mass based (> 56 nm)

• Optical Particle Counters

– Number based (> 100 nm)

• Electrical Mobility

–Sizing (> 6 nm) – Counting (Condensation Nuclei Counters)



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NOZZLE

Impaction Stage

Filter

TO Vac Pump



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MOUDIMicro-Orifice Uniform Deposit Impactor



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1



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Morphology of Particles Collected from

MOUDI Stages in Raw Producer Gas from

Wood and Rice Husk Gasifiers

0.2 µ m

2 µ m

TEM Image of Particles from 7th

Stage of MOUDI, Corresponding

Cut-Size 0.56 µ m

SEM Image of Particles from 1st

Stage of MOUDI, Corresponding

Cut-Size 10µ m



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Single Stage Impactor Developed at CESE



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Calibration of SSI

0.10

1.00

10.00

100.00

0.10 1.00 10.00 100.00

MOUDI Particulate Concentration (mg / Nm3)

S

S I P a r t i c u l a t e C o n c e n t r

a t i o n ( m g / N m

3 )

PM<2.5 NaCl

PM>2.5 NaCl



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Instrumentation






– Sizing (> 6 nm)

– Counting (Condensation Nuclei Counters)



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OPC’s

• Light Scattering

• Light Extinction

Limited to 0.09 µ m

0.4 > λ opt > 0.7 µ m

• Single Particle /Cloud of Particles



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Particle Size

I scatter Iscatter

Laser Source, λ



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• Simulation of OPC – http://aerosol.ees.ufl.edu/opc

• Performance – http://www.dustmonitor.com/articles/GRIMMvAPS.pdf

http://aerosol.ees.ufl.edu/opc

http://aerosol.ees.ufl.edu/opc



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Instrumentation






– Sizing (> 6 nm)

– Counting (Condensation Nuclei Counters)



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Scanning Mobility Particle Sizer



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Electrical Mobility Analysers

• Charge particles

• Electrical Field

SIZE

CPCOPC in Principle – Alcohol

used to grow size



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Source : TSI Inc.

Differential Mobility

Analyser (For size

separation using

electrical mobility)



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Source : TSI Inc.

Condensation Particle Counter (For growing the size separated

particles and detecting them using light scattering)



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Ambient Sampling

• High Volume

• PM10

• Parallel NOx & SOx

measurements

• http://www.envirotechindia.com/products.html



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Air Pollution Control - Gases

• Absorption

• Adsorption

• Chemical Reactions

– Catalysts – Flue gas Desulphurisation



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Structure for Regulations

• Ambient – Criteria Pollutants

• Industrial (Stationary, Mobile) – Emission Factors – Compliance requirements – BACT – Economic incentives – Trading of Permits

• Industrial Hygiene – Masks (Cartridges)



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ENERGY

• Human “Machine” 0.1 kW

• US per capita Power Consumption 10 kW ⇒

100 servants perpetually

100 W Bulb = 1 Servant

Car = 1000 servants

• “POPULATION” : India : USA :: ???

O i f E C ti



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Solar Units

Remarks

1 Earth Temperature 80°C

0.1 Earth Temperature 28°C

0.01 Upper Limit – Increase of 1°C

0.001 US Level of Power Generation

0.0001 World Level of Power Generation

Overview of Energy Consumption

in Solar Units and Impact on Earth

Temperature



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Thank you

Air Quality 2 of 2

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