issues associated with solid particle...

U R College of Engineering- Center for Environmental Research & Technology

Issues associated with solid particle measurement

Heejung Jung, Zhongqing Zheng, Thomas D. Durbin and Kent C. Johnson University of California, Riverside

David B. Kittelson University of Minnesota

Shaohua Hu and Tao Huai California Air Resources Board

ARB Chairman’s air pollution seminar series Jan 24th, 2012


Outline

• Challenges quantifying diesel emissions • Issues with particle number measurement • Background • Test results • Conclusion

2

Challenges quantifying ultra low diesel emissions

• PM (particle mass) of <50% of 2007 standard drives the total uncertainty >30% in the gravimetric method: – Swanson et al. SAE 2009-01-1516. – Burtscher et al. JAS, 2005, 36, 896. – And several papers by other researchers.

• Nuclei mode particles are difficult to have a repeatable conditions. – Solid particle number (PN) method (a.k.a. PMP=Particle

Measurement Programme) – Integrated particle size distribution (IPSD) – Chemically reconstructed mass method – Measurement of precursors of nuclei mode particles (organic acids,

sulfuric acid)


Outline

• Challenges quantifying diesel emissions • Issues with particle number (PN)

measurement • Background • Test results • Conclusion

4


Issues with number measurement

• Current PMP method regulates “solid” particles larger than 23 nm – For engines equipped with particle filters regulating to

23 nm effectively regulates all sizes. – For engines without filters (advanced fuels,

combustion modes, gasoline) there may be large concentrations of solid particles below 23 nm that are not counted by current method.

– The next generation of high efficiency direct injection gasoline engines are challenged by the current standard even with the 23 nm limit.

5


Issues with number measurement

• Extending solid PN (particle number) measurements to 10 nm. – Significant semi-volatile particles downstream of PMP VPR

(Volatile Particle Remover) often observed. – No significant semi-volatile formation downstream of catalytic

stripper (CS) in this size range.

• Extending solid PN (particle number) measurements to below 10 nm – problematic – Particles as small as sub 3 nm formed in large concentrations

downstream of PMP VPR (Volatile Particle Remover). – Some evidence of solid particle formation by VPR. – Sub 10 nm particle formation observed downstream of catalytic

stripper (CS) under some conditions. – Removal of sulfate or other low vapor pressure species is

critical.


Recent papers raised issues about solid particle measurements, especially when applied to particles smaller than 23nm.

• Work done at University of California, Riverside, CE-CERT – Johnson et al. (2009). Evaluation of the European PMP Methodologies

during On-Road and Chassis Dynamometer Testing for DPF Equipped Heavy Duty Diesel Vehicles, Aerosol Science and Technology, 43, 962– 969, 2009.

– Zheng et al. (2011). Investigation of solid particle number measurement: existence and nature of sub 23 nm particles under PMP methodology, Journal of Aerosol Science, 2011, 42, 883-897

– Zheng et al. (2011). Nature of sub 23 nm particles in the solid particle number measurement: a real time data perspective, Aerosol Science and Technology, 2012, in review

• Work done at the University of Minnesota, CDR – Swanson and Kittelson (2010). Evaluation of thermal denuder and

catalytic stripper methods for solid particle measurements, Journal of Aerosol Science, 41, 12, 1113-1122.

• Work done at California Air Resources Board – Herner et al. (2007). Investigation of ultrafine particle number

measurements from a clean diesel truck using the European PMP protocol, SAE 2007-01-1114

7


Outline

• Challenges • Issues with particle number measurement • Background of Particle Measurement

Programme (PMP) • Test results • Conclusion

8

CVS

T

u n n

,---------------~A~-------------------

Primary Dilution 150°C

Volatile Particle Remover

• •

• • •

• Evaporation Tube (ET) Secondary

3500c Dilution Particle Number Counter (Dso=23 nm)

Courtesy of William Robertson at CARB


Particle measurement programme

PMP system

Red: Semivolatile particles Black: Solid (mostly soot) particles 9

Why solid, why only larger than 23nm?

Courtesy of Dr. Kittelson


Engine out, light-load, low soot conditions: Most of the number emissions are solid with Dp<23nm

Courtesy of Dr. Kittelson

. E - -------------------------

-.

- E '

d

d

ummins ,. -' I _ I e-n ·ne- BP · fu I _.\ "L mo s

R College of Engineering- Center for Environmental Research & Technology

Spark ignition engines can also produce tiny solidnanoparticles, especially with metal additives

Spark ignition engines with metal additives show solid particles below 23nm.

---a::

0

IA- - 2 l•

s 0

U R

00

'(n t

College of Engineering- Center for Environmental Research & Technology

A modern gasoline direct injection engine shows solid particles below 23nm

E . .

• 10

d .

• ·1

• Ri h plo h olid fr c ·

• o t of th p ·cl e ..

. load. t mp . 'C er

1 ~ e

·ol tile b

e - in-c ·lin to l

cale e o .do

U R

e lproc

11


Gasoline engine in pure HCCI mode shows no solid particles above 10nm.

No solid particles above 10nm

From: David Kittelson, 2011 Particles Emissions from a Soot Free Engine, 15th

ETH-Conference on Combustion Generated Nanoparticles


Outline

• Challenges • Issues with particle number measurement. • Background • Test results

– Using exhaust particles – Using lab-generated model particles

• Conclusion

15

- - -- - -------- - -- -! ------- -►

!-------• '-------•

----------r-------►

'-------•


Unexpectedly large “solid” particle concentrations during UCR’s previous PMP study

• A heavy-duty truck equipped with a CRT (continuously regenerating trap) was tested over different driving cycles on road. – It showed large concentration of “solid” particles below 23 nm at high

load conditions. – These conditions favor sulfate particle formation. – Filtration efficiency for particles below 23nm should be very high.

1e+7

Primary Secondary Sampling & Measurement dilution dilution 1e+6

MEL secondary diluter Filter sampling train (gravimetric) 1e+5 MEL CVS

PMP diluter TSI 3790 CPC (23 nm) 1e+4

(Clone system) TSI 3760 CPC (11 nm) TSI 3025 CPC (3 nm) 1e+3

PMP diluter TSI 3760 CPC (11 nm) 1e+2

(Alternative system) TSI 3025 CPC (3 nm) 1e+1

TSI 3022 CPC (7 nm) 1e+0

3790 3760 3025 3022*

ETC UrbanETC CruiseARB Creep UDDS Route 1 Route 2

Par

ticle

con

cent

ratio

n (#

/cc)

Johnson et al. 2009, ASnT, 43, 962

Objective


Objectives

• Investigation of the nature of sub 23nm particles downstream the PMP system.

• Evaluation and comparison of the PMP and CS systems.

17

Catalytic stripper Evaporation & volatile compound oxidation

U R

►


Catalytic stripper (CS)

• Oxidation catalyst: • Wall temperature: 300°C • Length: 11 cm

• Diameter: 3.2 cm • Sulfur-trap (S-Trap):

• 75 g/ft3 of Pt • Wall temperature: 300°C • Length: 11 cm

• Particle penetration • Diameter: 3.2 cm

• 5% at 3 nm • BaO + SO3 → BaSO4

• 75% at 100 nm

Kittelson D.B.; Stenitzer, M. A

New Catalytic Stripper for Removal of Volatile Particles.

7th ETH Conference on Combustion Generated Particles,

Zurich, 18–20th August, 2003


Test conditions

• Comparisons of fully compliant PMP system and catalytic stripper system – Use a variety of counting instruments with different lower size

cutoffs • TSI 3022 – 7 nm Notation CPC_cutoff diameter_location • TSI EEPS – 6 nm CPC_7 or CPC_7_PMP • TSI 3790 – 23 nm • TSI 3772 – 10 nm • TSI 3025A – 3 nm • TSI 3776 – 2.5 nm

– Tests with exhaust aerosols from heavy-duty vehicle operating on chassis dynamometer

• Freightliner class 8 truck with 14.6 liter, 2000 Caterpillar C-15 engine, equipped with Johnson Matthey Continuously Regenerating Trap (CRTTM)

• Two steady state cruise conditions, constant speed 56 mph at 26% and 74% of full load

– Tests with laboratory challenge aerosols

Experimental set up for chassis test

CVS

CPC_10 CPC_2.5 CPC_3 nano-SMPS

to vacuum

needle valve

vent

rotameter

heated line

ejector venturi

CPC_10_CS

compressed air

vent

ball valve

EEPS_6

CPC_7_CVS

cyclone particle cut point 2.5 µm

Alternate between the PMP and CS systems

DR=21

DR=100 or 500

PMP system

1st dilution 2nd dilution ET

CPC_23_PMP

<.---------

IOI 0-,,______

________________ _. ________ _


fast-SMPS

E C

a. 0

500

100

10

0 1E3

500 1000

dN/dlogDp (#/cc)

1E4

1500 Time (s)

1E5 1E6

2000

1E7

2500

1E8


Steady state 74% load strongly bimodal

Measurement by Engine Exhaust Particle Sizer (EEPS) at the CVS.

Accumulation mode

Nucleation mode

21


At 74% load PMP compliant system closely tracks the accumulation mode

Mass C

oncen

tration (µ

g/m 3) E

xhaust Tem

perature (

°C)

60 50

40

30

20

10

0

After CRT

Before CRT

Nucleation mode

Accumulation mode

CPC 10_CS

CPC 23_PMP

Nucleation mode

Accumulation mode

0 500 1000 1500 2000 2500 Time (s)

a

b

c

1.0E+07

1.0E+06

1.0E+05

1.0E+04

500 1.0E+03

Num

ber C

oncentration (#/cc) 480

460

440

420

The CPC_23_PMP is always connected thru the PMP system and the CPC_10_CS is always connected thru the CS. The lower reading with the CS is due to thermophoretic losses ~40%.

a --CPC_2.5 ··· · · CPC_3 - CPC_10 · · · · · CPC 10 CS--CPC 23 PMP

6x105 ....::;::::==============::==========::'...,__~

---(.) (.) -::i:t: -- 105 C 0 ~ ro I.... +-' C Q) (.) C 0 (.)

I.... Q)

..0 E :J 104 z

3x103

0

PMPS00 PMP100 CS PMPS00 PMP100 CS PMPS00 PMP100 CS

'

I . . . ~

;

)

f :

500

CPC 23 PMP

1000 1500 Time (s)

2000 2500


74% load, CPC_23_PMP and CPC_10_CS Changing PMP dilution ratio does not change

results - it should not.

PMP500-PMP system, 500 dilution ratio


CS-Catalytic Stripper

CVS-sampling directly from main dilution tunnel, no removal of The CPC_23_PMP is always connected volatile particles thru the PMP system and the CPC_10_CS

is always connected thru the CS. The lower reading with the CS is due to thermophoretic losses ~40%.

I --CPC 2.5 · ··· · CPC 3 - CPC 10 a - -

C: 0

+:i co ~ +-' C: (1) (.) C: 0 (.)

~

(1) .c E ::l z

· · · · · CPC 10 CS--CPC 23 PMP 6x 105 ...:;=======================================---------.

PMP500 PMP100 CS PMP500 PMP100 CS PMP500 PMP100 CS

. I . .

I I

CPC 23 PMP

CPC 10 CS

CPC 10

3x103 --~---.-.............. ,........,....---...--..-.----............. ---.-.............. ,........,....---...--..-.----............. ---.-.............................

0 500 1000 1500 Time (s)

2000 2500


74% load CPC_10 switched between PMP and CS system

No particles between 10 and 23nm under APC

Switching from 100 to 500 overall dilution ratio has no impact on the PMP results-the desired result

I

--CPC_2.5 · ···· CPC_3 - CPC_10 a -- --- CPC 10 CS - CPC 23 PMP

6x 1 05 ..:;:=====::::=::::::=:::::::::::::===:::=:::::=======::::::...------.

C 0 -ro I... -C Q) u C 0 u I... Q)

..Q

E ::::J z


.. . 4' l \

•

CPC_23_PMP

3x103 - .!.l.t.------------------~,.............. 0 500 1000 1500

Time (s)

2000 2500


74% load CPC_2.5 switched between PMP and CS system

• Under the PMP • CPC_2.5>>CPC_23_PMP due to particle formation below 10nm.

• Under the CS • CPC_2.5 reads progressively higher than the CPC_10_CS again indicating sub 10nm particles.

I --CPC_2 .5 ····· CPC_3 - CPC_10

a · · · · - CPC 10 CS CPC 23 PMP 5x105


,-... () ()

~ .._.. C 0

:.;::;

~ +-' C Q) () C 0 () ,_ Q) .0 E ::s z

CPC_23_PMP

CPC_10_CS

CPC_10

3x103 ---..--.----.--.-............ ---r---.----.-.,........,.---.-......--.....-,........,..---.--.-,.........,..--.----.---.-............ ---.----.--'

0 500 1000 1500 Time (s)

2000 2500


Summary of the results at 74% load cruise

•Downstream of PMP system − CPC_23_PMP and CPC_ 10 agree-no particles between 10 and 23nm − CPC_3 and CPC_2.5 agree and read progressively higher than CPC_10 and CPC_23_PMP as time goes on -particles forming between 3 and 10nm − Same trend at 100 and 500 dilution ratio

•Downstream of CS −In first time window all instruments agree-no particle below 23nm −In second and third time windows CPC_2.5 and CPC_3 read higher than CPC_10_CS-particle formation between 3 and 10nm

C and CPC_10_CSb

---u u -=it ...__,

C 0 +-' ro ~

+-' C Q) u C 0 u ~

Q) .0 E ::J z

--CPC_2.5 · · · · · CPC_3 - CPC_10 · · · · · CPC_ 10_CS--CPC_23_PMP

PMP500 PMP100 CS PMP500 PMP100 CS CVS

105

104

CPC 23 PMP

\

103

. •' .:..~...;.:.;,.,,,.,!,,, , ' ·9: .,,;,~,"'ti

• fl · "~. ·' ._: •

CPC 10 CS 6x102 -1--------~--~------------------1

0 500 1000 1500 2000 2500

Time (s) U R College of Engineering- Center for Environmental Research & Technology

26% load, CPC_23_PMP Changing PMP dilution ratio changes results -

it should not.



CS-Catalytic Stripper

CVS-sampling directly from main dilution tunnel, no removal of volatile particles

C 0 +-' ro ~

+-' C

~ C 0 (.) ~

Q) .0 E ::J z

b --CPC_2.5 · · · · · CPC_3 - CPC_10 · · · · · CPC_ 10_CS--CPC_23_PMP


CPC 23 PMP

\

CPC 10 CS 6x102 ....... ------~--~-------..----.--...------1

0 500 1000 1500 2000 2500


26% load CPC_10 switched between PMP and CS

When connected thru the PMP system the CPC_23_PMP and CPC_10 agree – no particles between 10 and 23 nm but some additional particles above 23 nm at the lower PMP dilution ratio

C 0 +-' ro ~

+-' C

~ C 0 (.) ~

Q) .0 E ::J z

b --CPC_2.5 · · · · · CPC_3 - CPC_10 · · · · · CPC_ 10_CS--CPC_23_PMP


CPC 2.5

/

CPC 23 PMP

\

CPC 10 CS 6x102 -+----.---..----.---.----r----.---,---.-----,-------1

0 500 1000 1500 2000 2500


26% load CPC_2.5 switched between PMP and CS

When connected thru the PMP system the CPC_2.5 shows higher concentration than the CPC_23_PMP indicating particles below 10nm, especially at higher dilution ratio, little evidence of this with CS.

105

---u u -=it ...__,

C 0 +-' ro ~

+-' C 104 Q) u C 0 u ~

Q) .0 E ::J z

103

6x102

0

--CPC_2.5 · · · · · CPC_3 - CPC_10 · · · · · CPC_ 10_CS--CPC_23_PMP

PMP500 PMP100 CS PMP500 PMP100 CS

CPC 3

500 1000 1500 2000

Time (s)

CVS

2500 U R College of Engineering- Center for Environmental Research & Technology

26% load CPC_2.5 and CPC_3

The CPC_2.5 and CPC_3 disagree at the higher dilution ratio downstream of the PMP system but agree for 50 nm calibration aerosols suggesting that the particles are near the lower detection sizes of the instruments, < 3 nm.

When connected directly to CVS, no removal of volatiles, CPCs agree and show lower concentration than when volatiles are removed at 500 DR

b --CPC 2.5 ····· CPC 3 - CPC 10 - - -- · · - · CPC_10_CS--CPC_23_PMP


105

t·• 1 --- .-l .::.. () .' ~· () '· ,' -::i:t:: •,, -- . ,, C 0

:.=; ro .... -C 104 (I) () C 0 () .... (I) ..c E :::J z

.•1,.".i. "~ . 'l/~,.,.,u.¾-1.,· .· 103

. _. ... , ,~.,,,,,,~ft-..' .. -..""

CPC 10 cs - -6x102

0 500 1000 1500 2000 2500

Time (s)

Summary of results at 26% load cruise • Much lower concentrations than at 74%

•Downstream of PMP system •In first time window, DR = 500

•CPC_23_PMP and CPC_10 agree – no particles between 10 and 23 nm •CPC_2.5 and CPC_3 read much higher and disagree – many particles below lower cutoff size of these instruments, 2.5 to 3 nm

•In second time window, DR = 100 •CPC_23_PMP and CPC_10 read higher but agree – no particles between 10 and 23 nm but formation above 23 nm •CPC_2.5 and CPC_3 agree but read only slightly higher than CPC_23_PMP and CPC_10 – nearly all particles have grown to above 23 nm

•Downstream of CS •Consistently lower reading and agreement between instruments

• In last time window instruments bypass volatile particle removal systems and are directly connect to CVS – measure total solid and volatile particles – fewer particles than DR = 500 PMP, clear evidence of particle formation by PMP system.


Outline



• Conclusion

32

Lab and engine tests both show concentration swings tracking evaporation tube (ET) temperature

Chassis test (74% load) Lab test

CVS 1st 2nd dilution ET dilution

1st dilution 2nd dilution ET

PMP

CPC_23

CPC_2.5

APC ET temperature oscillation

Hydrocarbon heat and evaporate

l

: Sulfuric acid heat and evaporate

I I

r Mixture heat to 250°C

-----------------------------1 I --- ~----, I

! o - ._________. Di I .__~ I

I I I '-----------------------------

a 5x103-------------------~ 358

0 4x103

(.)

~ C 0

+= 3x103 ~ c Q) (.)

C

8 2x103 ... Q) .0

E ::::,

z 1x103

Laboratory test: sulfuric acid and tetracontane

0 50

ET temperature

100 150 200 250 300 350 Time (s)

356

354

352 ~ ::::, cii

350 ~ E ~

348 Gj

346

-----------------------------1 I --- ____ 1

.______________· 101--Qt I i I I I

I : I '--------------------1--------1 I

b 2.5x105 -------------------~ 358 CPC_2.5

356 2.0x105

354

5 1.5x105

~ 352 ~ ::::,

c ~ Q) (.)

§ 1.0x105 350 ~

E Q) (.) ...

Q) .0 E

1-

348 tu ~ 5.0x104

346

Accumulation mode particles 0.0 -+-----r---..--,------r------r---r--,-----1 344

1850 1900 1950 2000 2050 2100 2150 2200 2250 Time (s)

(23nm)

(3nm)

CPC_23 Cyclone PMP

33

Lab test shows some residue particles exist downstream of the PMP system

Upstream of PMP Upstream of CS Downstream of CS

Hydrocarbon heat and evaporate

I I

r Mixture heat to 250°C

,--------------------------. I I

: ~~ .--. 1 Catalytic stripper · o T ________________________ JJ .__.... r 108 -.---------------------,

106 u 0

# -;: 105

0 C)

.2 "O z 104

"O

-a- Upstream PMP ----- Downstream PMP ____._ Downstream PMP-CS

\ I Aerosol in ~ lcs l---- Aerosol out

102 +--------.----.-----.-,--,----.-..-,-------.------,------.--,------,--.-,

1 10

Op (nm)

80

Penetration efficiency by total particle number

1st 2nd dilution dilution at PMP (150C) at PMP

Evaporation tube (300C)

PMP

H2SO4+HC

H2SO4

HC (C24 or C40)

0.1%

1%

0.6%

PMP

0%

0%

0.55%

CS

Solid residue


Outline



• Conclusion

35


Conclusion

• Current PMP method regulates “solid” particles larger than 23 nm – For engines equipped with particle filters regulating to 23 nm

effectively regulates all sizes – For engines without filters (advanced fuels, combustion modes,

gasoline) there may be large concentrations of solid particles below 23 nm that are not counted by current method

– The next generation of high efficiency direct injection gasoline engines are challenged by the current standard even with the 23 nm limit

Conclusion (continued)

• Extending solid PN (particle number) measurements to 10 nm – Significant semi-volatile particles downstream of PMP VPR often

observed – No significant semi-volatile formation downstream of catalytic

stripper in this size range

• Extending solid PN (particle number) measurements to below 10 nm – problematic – Particles as small as sub 3 nm formed in large concentrations

downstream of PMP VPR – Some evidence of solid particle formation by VPR – Sub 10 nm particle formation observed downstream of CS under

some conditions – Removal of sulfate or other low vapor pressure species critical


Acknowledgement

• CARB – For funding and instruments. – A. Ayala and J. Herner for encouraging this study.

• AVL LIST GmbH Inc. – Providing a PMP system (AVL particle counter) and technical support. – B. Giechaskiel, M. Linke, R. Frazee, S. Roeck, & W. Silvis

• UCR/CE-CERT – D. Pacocha, J. Valdez, and E. O’ Neil – P. Ziemann and D. Cocker

• University of Minnesota – J. Swanson

• Johnson Matthey – M. Twigg (For catalysts to assemble the catalytic stripper)


Thank You

39

a 1.0x10 6

Sampling location

--- PMP, DR= 100 8.0x105 --- cs

,--... 5 8 6.0x10 Total number concentration ---=t::I:

PMP: 6.64 X 104 #/cc -0.. 0 CS: 4.74 x 104 #/cc Ol 5 0 4.0x10

"O

---z "O

2.0x105

2 10 70

Op (nm)

b 1x10 4

Sampling location

8x103 I

--- PMP, DR= 100 I --- cs

Total number concentration

8 6x103 PMP: 4 .55 x 102 #/cc --- 6.81 x 102 #/cc =t::I: CS: -0.. 0 0)

0 4x103 "O

---z "O

2x103

0 i--lll::::ll:::lt=J~~-=,tl=l!l:::ll~=11T--=-==-r:i-=-=-t==------.----,i--1"--1 2 10

Op (nm)


70

Backup slide: nano-SMPS measurement

74% load 26% load

~ 1.E+o5 ,.,E ~ ~ CJ J:,

E I 1.E+-04 0 Cl)

.9

~ 1.E+o3 'O

~

.. . .. .. ..

I-

••

1.E+o2 +-'----+----'+------.c;...._--1

10 100 1000 mobility diameter [lllu]

..... .. ....... . . .


Why only particles larger than 23nm? N

orm

aliz

ed C

on

cen

trat

ion

(1/

Cto

tal)d

C/d

log

Dp

0

0.05

0.1

0.15

0.2

0.25

1 10 100 1,000 10,000

Diameter (nm)

Number Surface Mass

Fine Particles Dp < 2.5 µm

Ultrafine Particles Dp < 100 nm

Nanoparticles Dp < 50 nm

Nuclei Mode - Usually forms from volatile precursors as exhaust dilutes and cools

Accumulation Mode - Usually consists of carbonaceous agglomerates and adsorbed material

Coarse Mode - Usually consists of reentrained particles, crankcase fumes

PM10 Dp < 10 µm

In some cases this mode may consist of very small particles below the range of conventional instruments, Dp < 10 nm

PM2.5

23 nm

•D50=23 ensures soot particles are measured but limits detection of any nucleation mode particles that escape the evaporation tube.

Giechaskiel et al. (2009) SAE 2009-01-1767

• Figures courtesy of D. Kittelson

• Figures courtesy of H. Burtscher (2005)

•Sulfate>HC> Ammonium Biswas et al. (2009)

u 104 (.)

!, C 0

:.:; ro I... -C Q) u C 0 103 u I... Q)

..0

I I E --CPC7 CVS ::I z

102 -+---.---..--------.-----.--~---r--~-.----,----,

0 500 1000 1500 2000 2500 Time (s)

107

u (.) --~ C 0

:.:; ro I... -C Q) 106 (.) C 0 (.) I... Q)

..0 E ::I z

105

0 500 1000

-- CPC 7_CVS - EEPS_5.6_CVS

1500 Time (s)

2000 2500


Steady state total particle number measurement

26% load 74% load

Table 1 Specifications of instruments us d in this study.

In trument Cut off size (nm)

CPC 3022A_CVS 7 EEPS 5.6 CPC 3790~APC 23 CPC 3772_CS 10 fa t SMPS 3 CPC 3025 A 3 CPC 3772 10 CPC 3776 2.5 nanoSMPS 3

Max. cone. ( # /cc)

9.99 X 106

1 X 104

1 X 104

9.99 X 104

1 X 104

3 X 105


Instrument specifications

43www.cert.ucr.edu

www.cert.ucr.edu

issues associated with solid particle...

Documents