aerosol sampling issues and system design...apex workshop cleveland, ohio bruce anderson, nasa larc...

November 8-10, 2004 - 1 APEX Workshop Cleveland, Ohio Bruce Anderson, NASA LaRC

Aerosol Sampling Issues and System Design

Bruce Anderson NASA Langley Research Center, Hampton, VA


• Characterize particle size, number, mass and composition as a function of engine power

• Examine spatial variation of across exhaust plane

• Monitor changes in particle concentrations and properties as plume dilutes and cools

• Evaluate new instruments and sampling techniques

APEX Particle Measurement Objectives


Processes Influencing Particle Size and Concentration

INSTRUMENTS

ENGINE

Inertial Effects

Loss in Bends

Thermophoretic Effects

Turbulent Deposition

Gravitational Settling

Coagulation


10 1001E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

10

Nf/No=0.28

15 m pipe @ 10 LPM

Coagulation for EI=5e15/kg

2 Seconds Later

Initial

dN/d

Log(

Dp)

Diameter (nm)

Sampling System Design Challenges


10 100 1000

1

10Velocity Ratios (m/s) Exhaust/Inlet

Effects of Non-isokinetic Sampling

50/150

300/150

300/100

300/30300/10

Frac

tiona

l Pen

etra

tion

Diameter (nm)



Relative Humidity of Sample100 % Power Setting

4:1

290 295 300 305 3100

80

160

240

Rel

ativ

e H

umid

ity (%

)

285

No Dilution

8:1

2:1

Sample Temperature (K)



• Perform dilutions close to inlet tip

• Draw samples isokinetically if possible

• Include multiple inlet tips at 1 m to allow exhaust profiling

• Include secondary inlets at 10 and 30 m to facilitate aging study

• Include automated valving system to speed up sample selection

• Provide 50 LPM total flow with low pressure drop across system

• Minimize bends, connections, line lengths, and sample residence times

Sampling System Design Criteria


DC-8

APEX Experimental Setup

10 m RAKE

1 m RAKE

30m PROBE

UMR 1

EPA

ARI

3

2 lines,one dedicated to EPA unheated, no dilution

1 m Rake, 6 ports 10 m Rake, 6 ports 30m Probe, 1 port

EPA Trailer will housed LaRC equip. and valving system

3/4”

3/8”

AEDC


EPA Trailer

0.29”x 1.8 m

1.9” x 29.3 m

Valve Box

10 m Rake 0.19”x 1.5 m

0.29”x 1.8 m

1 m Rake 0.19”x 1.5 m

Valve Box

0.62”x 23.8 m

0.62”x 20.7 m

30 m probe

APEX Aerosol Sampling System


APEX Aerosol Sampling System


APEX 1 m Sampling Rake


AEDC Aerosol Sample Inlet


Converging Manifold

HEPA

6 – Port Sample Rake

Dilution Gas (Dry N2)

3/8 “ S.S. Tubing

3/8 “ Solenoid Valves

Zero Gas Line

Aerosol Sample To EPA Trailer

3/4” S.S. Tubing

1/4” S.S. Tubing 3/8” S.S. Tubing 1/4” to 3/8

Dilution Lines

3/8” I.D. Ball Valves Pneumatically Actuated

1 and 10 m Aerosol Rake Systems


Aerosol Sample Valve Boxes


Aerosol Sample Distribution System


Sampling Flow Parameters 1m Probe 10 m Probe 30 m ProbeSystem vol rate velocity Reynolds res time res time res timeElement (lpm) (m/s) Number (s) (s) (s)

0.25" tube 50 42 35,000 0.04 0.040.375" tube 50 19 24,000 0.09 0.09 0.16

0.5" tube 50 9.8 17,000 0.22 0.22 0.050.75" tube 50 4.1 11,000 5.80 5.051.8" tube 1152 11.7 34,000 2.50

Totals 6.2 5.4 2.7

Sample System Flow Characteristics


10 100 1000

0.0

0.2

0.4

0.6

0.8

1.0

30 Probe

1 and 10 m Rakes

Diffusional and Inertial Particle Losses

Frac

tiona

l Pen

etra

tion

Particle Diameter (nm)

Sample System Flow Characteristics


-5 0 5 10 15 20 25 30 350.00E+000

1.00E+014

2.00E+014

3.00E+014

4.00E+014

5.00E+014

65%

85%

100%

Baseline Fuel

Nonv

olat

ile C

N EI

(#/k

g)

Sampling Distance (m)

Relative Sampling Efficiency of Inlets


0 5 10 15 20 25 30

1.00E+014

2.00E+014

3.00E+014

4.00E+014

5.00E+014

65%

85%

100%

Hi Sulfur Fuel

Nonv

olat

ile C

N EI

(#/k

g)

Sampling Distance (m)

Relative Sampling Efficiency of Inlets


Impact of Dilution on EI

Engine Power

Sample CO23200 ppm1600 ppm800 ppm

50 60 70 80 90 1000

5

10

15

20

25(X 1.E15)

Impact of Dilution upon Aerosol Samples


0 20 40 60 80 100

0

5

10

15

20

25

30

35

40

45

50

DC-8 Plume Dilution

10 meters

30 meters

Di

lutio

n Ra

tio

Engine Power (%)



0 20 40 60 80 100

10

100Aerosol Sample Dilution at 1 m

Di

lutio

n Ra

tio

Engine Power (%)



0 10 20 30 40 50 60 70 80

1E14

1E1540% Power, 1 m Rake

Total

Nonvolatile

CN

Em

issio

n In

dex

(#/k

g)

Dilution Ratio



0 10 20 30 40 50

1E14

1E15

40% Power, 1 m Rake

Total

Nonvolatile

CN

Em

issio

n In

dex

(#/k

g)

Dilution Ratio



0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.56.00E+013

8.00E+013

1.00E+014

1.20E+014

1.40E+014

1.60E+01440% Power, 10 m Rake

Total

Nonvolatile

CN

Em

issio

n In

dex

(#/k

g)

Dilution Ratio



0 20 40 60 80 100

1E14

1E15

1 m Aerosol Probe

Hi Aromatic Fuel

CFM-56 Emissions

1 m Gas Probe

Parti

cle E

I (#/

kg)

Engine Power (%)

Impact of Inlet Probe upon Sample Integrity


0 20 40 60 80 100

1

10

100

1 m Gas Rake

1 m Aerosol Rake

Hi Aromatic Fuel

CFM-56 Emissions

1 m

Blac

k Ca

rbon

EI (

mg/

kg)

Engine Power (%)

Impact of Inlet Probe upon Sample Integrity


Summary

• Multi-port aerosol sampling system was designed, built, and successfully deployed during APEX

• Experiments suggests that sample dilutions were adequate to prevent both coagulation losses and formation of new particles within sample lines

• Comparison of data from 1 and 10 m probes indicate that thermophoretic and inertial losses are not a significant problem

• Comparison of data from “aerosol” and “gas” sample inlets suggest that standard gas sampling tips/lines perturb aerosol samples, reducing both numbers and mass

aerosol sampling issues and system design...apex workshop cleveland, ohio bruce anderson, nasa larc...

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