ETHANOL INTERNATIONAL WORKSHOP 2012

COLD START EMISSIONS OF

ETHANOL FUELLED VEHICLES

Prof. Luís Carlos Monteiro Sales, D.Sc

Prof. José Ricardo Sodré, Ph.D.

04/10/2012

• Introduction

• Cold start technologies

• Simultaneous heating of intake air and

injected ethanol

• Cold start time

• Cold start emissions

• Conclusions

OUTLINE

• Ethanol properties cause difficult cold start and

warm-up operation, with impacts on engine emissions

• Ethanol vaporization requires twice the energy

required by gasoline (0.744 MJ/l 0.325 MJ/l)

• Ethanol-fuelled engines do not start at temperatures

below 13°C, while gasoline-fuelled engines can start

at temperatures as low as - 40°C

• Ethanol vaporization temperature is 78°C, while the

light gasoline components can vaporize from 40°C

INTRODUCTION

PHYSICAL-CHEMICAL PROPERTIES

OF ETHANOL AND GASOLINE

PARAMETERS E22 HYDROUS ETHANOL

Density (kg/m3) 740 810

Low heating value (kcal/kg) 9400 5970

Stoichiometric air/fuel ratio 13.07 : 1 8.70 : 1

Chemical structure C6.39H13.60O0.61 C2H6.16O1.08

Carbon content (wt %) 76.7 50.59

Hydrogen content (wt %) 13.6 12.98

Oxygen content (wt %) 9.7 36.42

Evaporation temperature (ºC) 40 to 220 78

Latent heat of vaporization (kcal/kg) 105 237

Motor octane number 80 87

• Use of E85 blends

• Gasoline introduction through a calibrated hole

• Gasoline introduction through an extra fuel injector

• Gasoline introduction through an extra fuel injector

and common rail

• Ethanol heating in the fuel injectors

• Ethanol heating in the fuel injectors plus intake air

heating

• Aim at reduced cold start time and cold start

emissions

COLD START TECHNOLOGIES FOR

FLEXIBLE FUEL VEHICLES

CALIBRATED HOLE AND EXTRA FUEL

INJECTOR TECHNOLOGIES

Furo calibrado Furo Calibrado

CALIBRATED HOLE EXTRA FUEL INJECTOR

COLD START TIME FOR

DIFFERENT CONFIGURATIONS

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

TEMPO (s)

0

250

500

750

1000

1250

1500

1750

2000V

EL

OC

IDA

DE

(re

v/m

in)

CONFIGURAÇÃO 1CONFIGURAÇÃO 2CONFIGURAÇÃO 3CONFIGURAÇÃO 4

EXTRA FUEL INJECTOR WITH

COMMON RAIL TECHNOLOGY

• 950 W electric resistance required to

heat ethanol in four injectors

• Cold start below 5C between 2.0 s

and 4.0 s

• Cold start time for intake air heating

only using 600 W electric resistance

between 10 s and 27 s

ETHANOL HEATING IN THE FUEL

INJECTORS

ETHANOL JET FLOW

CHARACTERISTICS

NO HEATING HEATED INJECTOR

TOTAL HYDROCARBON AND

CARBON MONOXIDE EMISSIONS

Tempo (s)

TH

C a

cu

mu

lad

o(g

)

sem aquecimento

antes do catalisador

velocidade

no ciclo

com aquecimento

antes do catalisador

sem aquecimento

depois do catalisador

com aquecimento

depois do catalisador

Tempo (s)

TH

C a

cu

mu

lad

o(g

)

sem aquecimento

antes do catalisador

velocidade

no ciclo

com aquecimento

antes do catalisador

sem aquecimento

depois do catalisador

com aquecimento

depois do catalisador

Tempo (s)

CO

ac

um

ula

do

(g)

sem aquecimento

antes do catalisador

velocidade

no ciclo

com aquecimento

antes do catalisador

sem aquecimento

depois do catalisador

com aquecimento

depois do catalisador

Tempo (s)

CO

ac

um

ula

do

(g)

sem aquecimento

antes do catalisador

velocidade

no ciclo

com aquecimento

antes do catalisador

sem aquecimento

depois do catalisador

com aquecimento

depois do catalisador

• Catalytic converter efficiency is low during the

first 55 s after cold start

• During this period HC and CO concentrations

account for about 40% and 30% of the total

amount during FTP-75 emission test schedule

• Aldehyde emissions are about 70% of the total

amount during emission test cycle

• NOX emissions during cold start is very low

CHARACTERISTICS OF POLLUTANT

EMISSIONS DURING COLD START

SIMULTANEOUS HEATING OF ETHANOL

INJECTORS AND INTAKE AIR

• Production vehicle powered by a 1.4-liter, 8-

valve, flex fuel engine operating with hydrous

ethanol

• Cold start tests at 0ºC

• Emission tests following FTP-75 cycle at 25ºC

• Simultaneous heating of ethanol injectors and

intake air activated 8.0 s before cold start

• Ethanol injection pressure 3.5 bar

EXPERIMENTAL METHODOLOGY

COLD START TIME AT 0C

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

TIME (s)

0

250

500

750

1000

1250

1500

1750

2000

2250E

NG

INE

SP

EE

D (

rev/m

in)

-10

0

10

20

30

40

50

60

70

80

TE

MP

ER

AT

UR

E (

oC)

MIXTURE TEMPERATURE AT INTAKE PORTETHANOL TEMPERATURE AT INJECTORAIR TEMPERATURE AFTER HEATERENGINE SPEED

TIME-RESOLVED RELATIVE

HYDROCARBON EMISSIONS

0 100 200 300 400 500

TIME (s)

0.00

0.03

0.06

0.09

0.12

0.15

0.18

0.21IN

ST

AN

TA

NE

OU

S H

C/T

OT

AL

HC

(%

) HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEM

TIME-RESOLVED RELATIVE

CARBON MONOXIDE EMISSIONS

0 100 200 300 400 500

TIME (s)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90IN

ST

AN

TA

NE

OU

S C

O/T

OT

AL

CO

(%

) HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEM

TIME-RESOLVED RELATIVE OXIDES

OF NITROGEN EMISSIONS

0 100 200 300 400 500

TIME (s)

0.000

0.020

0.040

0.060

0.080

0.100IN

ST

AN

TA

NE

OU

S N

OX/T

OT

AL

NO

X (

%)

HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEM

RAW EXHAUST HC, CO AND NOX

EMISSIONS AFTER COLD START

THC CO NOX

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0C

ON

CE

NT

RA

TIO

N (

g/k

m)

HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEMRAW EMISSIONS, COLD 505

POST-CATALYST EXHAUST HC, CO, NOX AND

CHO EMISSIONS AFTER COLD START

HC CO NOX CHO

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00C

ON

CE

NT

RA

TIO

N (

g/k

m)

HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEMPOST-CATALYTIC CONVERTER, COLD 505

POST-CATALYST EXHAUST HC, CO, NOX

AND CHO EMISSIONS FOR FULL CYCLE

THC CO NOX CHO

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

CO

NC

EN

TR

AT

ION

(g

/km

)

HEATED INTAKE AIR AND ETHANOLCONVENTIONAL COLD START SYSTEMPOST-CATALYTIC CONVERTER, FULL FTP-75 CYCLE

• The use of 300 W electric resistance to heat the intake air together

with 150 W electric resistances to heat ethanol injectors allowed for

satisfactory cold start time

• At 0°C the cold start time defined by the period from ignition key

switch until the engine reached 800 rev/min was 1.7 s, which is 15%

below acceptable standards

• Simultaneous ethanol and intake air heating produced significant

reductions on raw exhaust HC and CO emissions, especially in the

first 150 s of the U.S. FTP-75 test schedule

• Catalytic converter efficiency for HC and CO reduction was also

increased with heated intake air and ethanol

• NOX and aldehyde emissions were not significantly altered by the

new cold start system

CONCLUSIONS

ACKNOWLEDGMENTS