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
OUTLINE
•
•
•
•
•
•
Introduction
Cold start technologies
Simultaneous heating of intake air and
injected ethanol
Cold start time
Cold start emissions
Conclusions
INTRODUCTION
•
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
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
COLD START TECHNOLOGIES FOR
FLEXIBLE FUEL VEHICLES
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•
•
•
•
•
•
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
CALIBRATED HOLE AND EXTRA FUEL
INJECTOR TECHNOLOGIES
CALIBRATED HOLE
Furo
FuroCalibrado
calibrado
EXTRA FUEL INJECTOR
COLD START TIME FOR
DIFFERENT CONFIGURATIONS
2000
VELOCIDADE (rev/min)
1750
1500
1250
1000
750
500
CONFIGURAÇÃO 1
CONFIGURAÇÃO 2
CONFIGURAÇÃO 3
CONFIGURAÇÃO 4
250
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
TEMPO (s)
3.5
4.0
4.5
5.0
EXTRA FUEL INJECTOR WITH
COMMON RAIL TECHNOLOGY
ETHANOL HEATING IN THE FUEL
INJECTORS
• 950 W electric resistance required to
heat ethanol in four injectors
• Cold start below 5C 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 JET FLOW
CHARACTERISTICS
NO HEATING
HEATED INJECTOR
TOTAL HYDROCARBON AND
CARBON MONOXIDE EMISSIONS
sem aquecimento
antes do catalisador
sem aquecimento
antes do catalisador
com aquecimento
antes do catalisador
sem aquecimento
depois do catalisador
com aquecimento
depois do catalisador
velocidade
no ciclo
Tempo (s)
CO acumulado (g)
THC acumulado (g)
com aquecimento
antes do catalisador
sem aquecimento
depois do catalisador
com aquecimento
depois do catalisador
velocidade
no ciclo
Tempo (s)
CHARACTERISTICS OF POLLUTANT
EMISSIONS DURING COLD START
• 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
SIMULTANEOUS HEATING OF ETHANOL
INJECTORS AND INTAKE AIR
EXPERIMENTAL METHODOLOGY
• Production vehicle powered by a 1.4-liter, 8valve, 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
COLD START TIME AT 0C
2250
2000
1750
70
60
1500
50
1250
40
1000
30
750
20
500
10
250
0
0
-10
0.0
0.5
1.0
1.5
2.0
TIME (s)
2.5
3.0
3.5
4.0
TEMPERATURE (oC)
ENGINE SPEED (rev/min)
80
MIXTURE TEMPERATURE AT INTAKE PORT
ETHANOL TEMPERATURE AT INJECTOR
AIR TEMPERATURE AFTER HEATER
ENGINE SPEED
TIME-RESOLVED RELATIVE
HYDROCARBON EMISSIONS
INSTANTANEOUS HC/TOTAL HC (%)
0.21
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
0.18
0.15
0.12
0.09
0.06
0.03
0.00
0
100
200
300
TIME (s)
400
500
INSTANTANEOUS CO/TOTAL CO (%)
TIME-RESOLVED RELATIVE
CARBON MONOXIDE EMISSIONS
0.90
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0
100
200
300
TIME (s)
400
500
INSTANTANEOUS NOX/TOTAL NOX (%)
TIME-RESOLVED RELATIVE OXIDES
OF NITROGEN EMISSIONS
0.100
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
0.080
0.060
0.040
0.020
0.000
0
100
200
300
TIME (s)
400
500
RAW EXHAUST HC, CO AND NOX
EMISSIONS AFTER COLD START
10.0
CONCENTRATION (g/km)
9.0
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
RAW EMISSIONS, COLD 505
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
THC
CO
NOX
POST-CATALYST EXHAUST HC, CO, NOX AND
CHO EMISSIONS AFTER COLD START
2.00
CONCENTRATION (g/km)
1.75
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
POST-CATALYTIC CONVERTER, COLD 505
1.50
1.25
1.00
0.75
0.50
0.25
0.00
HC
CO
NOX
CHO
POST-CATALYST EXHAUST HC, CO, NOX
AND CHO EMISSIONS FOR FULL CYCLE
0.45
CONCENTRATION (g/km)
0.40
HEATED INTAKE AIR AND ETHANOL
CONVENTIONAL COLD START SYSTEM
POST-CATALYTIC CONVERTER, FULL FTP-75 CYCLE
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
THC
CO
NOX
CHO
CONCLUSIONS
• 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
ACKNOWLEDGMENTS