Ultrafine particles in a changing landscape of engines and

emissions control

Matti MaricqResearch and Advanced Engineering,

Ford Motor Company

May 5, 2020 HEI Ultrafine Particles and Health Webinar

Outline Where we’ve come from: Overview of technology and

PM emissions changes over the past 15 years Size, composition, number, etc. Implications for interpretation of older studies?

Where we are now: Implications of current and near term technology developments for UFPs in US/Europe. LEV III, Tier 3, and solid PN Gasoline direct injection technology

Where are we headed in the future? UK rules to abandon the internal combustion engine… How do they compare, e.g. to brake and tire wear emissions? Hybrids, smart vehicles and other fuel/technology developments?

2

Where we’ve come from Diesel

2007 – US EPA regs require <10 mg/bhphr PM emissions

2011 – EU5b introduces solidparticle # standard 6x1011/km

3

Gasoline Engines utilize port fuel injection Air / fuel control to make catalyst

work also ensures low PMMay et al., Atmos. Environ 88, 2014

25 xlower

soot oxidation

rich combustionfuel jet

sootsolid – forms in engine

nucleation modeliquid – forms as exhaust cools

Diesel engine PM

PM2.5

ultrafine?

Typical PM break down: ~75% soot ~25% semivolatile

Heavy hydrocarbons, e.g., lube oil Sulfate from fuel (300 ppm S)

PM emissions pre 2007Engine PM on filter

Where we are now GDI engines introduced to improve

fuel economy & CO2

Lev III and Tier 3 promulgated to avoid backsliding

EU extends solid PN regs to GDI

6

PM mass versus number

PM mass (mg/km)0.1 1 10 100

Parti

cle

num

ber (

#/km

)

1e+10

1e+11

1e+12

1e+13

1e+14

CNGgasolineGDIdieselDPF diesel

Filters remain nearly white Filter weight – 150 mg PM collected ~ 0.04 mg Gaseous artifact ~0.01 mg Composition ~75% soot &

25% semivolatile ?

Nanoparticles in medicine & environ., Springer, 2010

EU

USCA

GDI combustionDirect fuel injection: Increases fuel economy Decreases CO2 Higher air fuel inhomogeneity

increases PM

7

GDI fuel injection

Soot formationFuel jets

GDI engines PM characteristics

nuclei mode soot mode

cold start

urban

hot start

GDI PM mostly similar to diesel Varies with driving condition;

e.g., cold start, acceleration

ultrafine ?

slope = 0.3±0.1

slope = 0.79±0.03

0

10

20

30

0 10 20 30 40

Soot

mas

s (m

g/m

i)

gravimetric PM mass (mg/mi)

US06FTP

PM composition depends on driving condition

Soot fraction during FTP

Soot fraction during US06

0100

200300

400500

600

10

100

time (s)

dm (nm)

GDI vehicleUS06

Particle size depends on driving condition

Nucleation mode is very vehicle and condition dependent

Starts part way into US06

ultrafine

Where are we headed?

Real world emissions Gasoline particulate filters Hybrid & plug in hybrids Brake and tire PM

11

Traffic information Connectivity Autonomous driving

Hybrid vehiclesElectric motor allows engine to be run at higher efficiency and lower PM than conventional vehicle

Smart vehicles

Gasoline particulate filters can significantly reduce PM

12

0.0

5.0e+7

1.0e+8

1.5e+8

2.0e+8 0

500

1000

1500

2000

2500

3000

10 100

dN/d

logd

m (c

m-3

)

time

(s)

dm (nm)

post GPF

0.0

5.0e+7

1.0e+8

1.5e+8

2.0e+8 0

500

1000

1500

2000

2500

3000

10 100

dN/d

logd

m (c

m-3

)

time

(s)

dm (nm)

pre GPF

Challenge remains to design GPFs that don’t reduce fuel economy

Non-tailpipe PM

10 µm

Brake particles: Grinding – PM10 & PM2.5

“combustion” - ultrafine

Past, present, future of ultrafine PM PM mass and number emissions have decreased substantially to

keep pace with regulations Particle types remain the same: accumulation mode, solid soot

~100 nm; nucleation mode, mostly semivolatile, ~20 nm Relative composition: soot & sulfate down, organic up

How does “ultrafine” fit into the health effects picture? Use in literature is ambiguous No clear demarcation to define UFP – perhaps “sub half micron”? Size is important (penetration into lung) - but Other properties determine impact e.g., liquid particles dissolve,

solid translocate (see talks in “Particle Components & Associated Health Effects webinar)

Summary