An Experimental Study of PM Emission Characteristics of Commercial Diesel Engine with Urea-SCR System

Chunhwan Lee, Deokjin Kim, Kwangchul Oh, Chunbeom LeeEnvironmental Parts R&D Center, Korea Automotive Technology Institute (KATECH)

Undesirable particles come from Urea-SCR :Ammonium Sulfate, Ammonium Nitrate, New polymer Complex(by HNCO base), etc

Weight and Number of PM deeply depend on the Urea injection strategy & Urea Injection System Design

ConclusionsConclusions

Environmental Parts R&D Centerhttp://eprc.katech.re.kr Korea Automotive Technology Institute

SCR & Variable DilutorThermodenuder

ELPI & FPS

injector

NH4

HSO4

(NH4

)2

SO4

NH4

NO3

+ NH4

NO2

2SO3

→

→

NH3 + SO3

+ H2

O

2NH3 + SO3

+ H2

O

Ammonium Sulfate Formation :

→2NH3 + 2NO2

+ 2H2

O

Ammonium Nitrate Formation :

→2SO2

+ O2

SO2

Oxidation :

Particle Size DistributionSystem Configuration: DOC+DPF+Vanadium SCR, ELPI@ 1200rpm, 640Nm, 380℃, T.D=275℃, Adblue: 20g/min

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0.01 0.1 1 10

Size (um)

Num

ber (

1/cm

^3)

Base No injU4.7A1U4.7A2U4.7A2.5U4.7A3U4.7A3.5U4.7A4

water

Fresh

W/O Urea

W/ Urea

TGA/DSC TEMFTIR spectrum

600oC

W/ Adblue

injection

Urea from Adblue

Soot particle

0 100 200 300 400 500 600

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

-7

-6

-5

-4

-3

-2

-1

0

1

~415oC

~370oC

~345oC

~240oC

TGA

, m/m

o

Urea from Adblue Texh=380oC, Adblue injection

~145oC

DS

C

Temperature, oC

W/ Adblue

injection

Urea from Adblue

Urea (4.5bar)+Air(3bar)Urea (4.5bar)+Air(3bar)

Particle Size DistributionSystem Configuration: DOC+DPF+Vanadium SCR, ELPI

@ 1200rpm, 640Nm, 380℃, T.D=275℃, U : 4.5bar A : 3bar, Adblue

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0.01 0.1 1 10

Size (um)

Num

ber (

1/cm

^3)

0g

7.5g/min

15g/min

20g/min

27.5g/min

37.5g/min

CPC Concentration NumberSystem Configuration: DOC+DPF+ Vanadium SCR, ELPI

@ 1200rpm, 640Nm, 380℃, T.D: 275℃, U : 4.5bar, A : 3bar, Adblue

0

5000

10000

15000

20000

25000

1 51 101 151 201 251 301 351Time (s)

Num

ber (

1/cm

^3)

1200rpm, 640Nm, 380℃, T.D: 275℃, U : 2bar, A : 1bar, Adblue

Particle Size DistributionSystem Configuration: DOC+DPF+ Vanadium SCR, ELPI

@ 1200rpm, 640Nm, 380℃, T.D: 275℃, U : 2bar, A : 1bar, Adblue

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0.01 0.1 1 10

Size (um)

Num

ber (

1/cm

^3)

0g/min7.5g/min15g/min20g/min27.5g/min37.5g/min

CPC Concentration NumberSystem Configuration: DOC+DPF+ Vanadium SCR, ELPI

@ 1200rpm, 640Nm, 380℃, T.D: 275℃, U : 2bar, A : 1bar, Adblue

0

2000

4000

6000

8000

10000

12000

1 51 101 151 201 251 301 351 401 451Time (sec)

Num

ber (

1/cm

^3)

1200rpm, 640Nm, 380℃, T.D: 275℃, U : 2bar, A : 1bar, Adblue

Urea (2bar)+Air(1bar)Urea (2bar)+Air(1bar)Injection

Pressure

0g

7.5g

15g20g

27.5g37.5g

0g

7.5g

15g20g

27.5g

37.5g

Background-

Diesel engine: excellent fuel economy benefit, “Fun-to-Drive”

High Torque-

But, the regulation of emission: PM, NOx various Aftertreatment system -

NOx

: Utilization of SCR system using urea solution

as a reductant

Experiment1.

the experiment of a diesel engine equipped with Urea SCR system, and its emission characteristic including particle is analyzed and evaluated against its regulation.

2.

Measurement of PM: Diluter + Thermodenuder

+ ELPIunder various conditions of engine RPM and load (Particle number distribution of size range from 7nm to 10μm

Results:1. The particle number was increased in the proportion of amount of urea injection2. The increase of Fine particle range(< 2.5μm) was remarkable 3. The effect of thermodenuder

and engine exhaust temperature(250oC~450oC) is almost negligible for the change of particle number distribution

tendency4. But Increase of injection pressure (1bar~4bar) of Urea solution :

Fine particle (~1μm): Decrease of number of particle While, Ultra Fine particle(< 100nm) and Nano

particle(< 50nm) range: Increasing tendency 5. This particles: include new complex matter from urea decomposition process on SCR

catalysts and most dry-Urea FTIR , TGA/DSC, TEM.

Abstract

Experimental Setup

TEM Photograph

Chemistry

① [(NH2)2CO, 7H2O]n→ [(NH2)2CO]n + 7H2O ( >135℃ )

② Thermolysis[(NH2)2CO]n → NH3 + CO2[(NH2)2CO]n → HNCO + NH3

③ Hydrolysis(NH2)2CO + H2O 2NH3 + CO2

HNCO + H2O → NH3 + CO2

※ 3HNCO → [(HNCO)3]s ( <350℃ )

④ Fast Reaction : 4NO + 4NH3 + O2 → 4N2 + 6H2OSlow Reaction : 2NO2 + 4NH3 + O2 → 3N2 + 6H2OVery Fast Reaction : NO + NO2 + 2NH3 → 2N2 + 3H2O

⑤ 4NH3 + 3O2 2N2 + 6H2O

※ 2NO + O2 → 2NO2

Nano

PMNumber Distribution

Nano

PMNumber Distribution

Nano

PM Increase ▲

Urea Solution Injection

Nano

PM Increase ▲

Urea Solution Injection

Characteristicsof Particle

Characteristicsof Particle

Emission Regulations (EURO-IV)1.

Advanced FIE & Combustion2.

Urea-SCR System

Emission Regulations (EURO-IV)1.

Advanced FIE & Combustion2.

Urea-SCR System

White PM & PM Weight IncreaseWhite PM & PM Weight Increase

Particle distribution

Fine particle

Nanoparticle Fine particle

Effect of Injection Pressure

TGA/DSC FTIR spectrum

4000 3000 2000 10000.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

abso

rpvi

ty

wave number, cm-1

KBr T=600oC PM1 PM2 Urea

CO2

1120

1400

1630

PM weight-

ESC

base no urea w/ urea0.000

0.005

0.010

0.015

0.020

0.025

PM

, g/k

wh

case

Diesel BD20 BD5 BD05

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0

8 x 1 0 2

2 x 1 0 3

2 x 1 0 3

3 x 1 0 3

4 x 1 0 3

5 x 1 0 3

6 x 1 0 3

6 x 1 0 3

7 x 1 0 3

8 x 1 0 3

Num

ber d

ensi

ty(n

/cm

3 )

T im e (s e c )

w /o S C R w S C R u re a 9 0 % u re a 1 2 0 %