automotive systems course (module 02) - internal combustion engine: energy efficiency, input/output...

7 de outubro de 2016 | 1

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ICE: energy efficiency, input/output flow and emissions

control

Mário Alves ([email protected])

mailto:[email protected]


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Outline

• Energy efficiency in ICE vehicles

• Energy contained in common fuel types

• Input/output flow

• Exhaust gases and pollutant emissions

• European emission standards

• Pollutant emissions mitigation methods

• Air/fuel ratio

• Catalytic converter operation

• Guidelines for optimal engine control


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ICE: energy efficiency

• Energy losses distribution for a typical ICE road vehicle

http://energy.gov/eere/vehicles/fact-880-july-6-2015-conventional-vehicle-energy-use-where-

does-energy-go

http://energy.gov/eere/vehicles/fact-880-july-6-2015-conventional-vehicle-energy-use-where-does-energy-go



























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• Energy losses distribution for typical ICE road vehicle [1]

[1] http://energy.gov/eere/vehicles/fact-880-july-6-2015-conventional-vehicle-energy-use-where-

does-energy-go





























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• Energy losses distribution for typical ICE road vehicle [1]

Types of Losses

Types of Driving

Combined City Highway

Engine Losses 68-72% 71-75% 64-69%

Thermal - radiator, exhaust heat, etc. 58-62% 60-64% 56-60%

Combustion 3% 3% 3%

Pumping 4% 5% 3%

Friction 3% 3% 3%

Parasitic Losses (water & oil pumps, alternator, A/C, synchroning belt, turbocharger)

4-6% 5-7% 3-4%

Power to Wheels dissipated as:

18-25% 14-20% 22-30%

Wind Resistance 9-12% 3-5% 13-19%

Rolling Resistance 5-7% 3-5% 6-9%

Braking 5-7% 7-10% 2-3%

Drivetrain Losses 5-6% 4-5% 4-7%

Idle Losses 3% 6% 0%

[1] http://energy.gov/eere/vehicles/fact-880-july-6-2015-conventional-vehicle-energy-use-where-

does-energy-go





























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[2] http://www.nature.com/nature/journal/v488/n7411/fig_tab/nature11475_F2.html

• Energy losses distribution for a conventional vehicle [2]

http://www.nature.com/nature/journal/v488/n7411/fig_tab/nature11475_F2.html


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Energy contained in common fuel types

http://greenecon.net/hostage-to-oil/energy_economics.html

kJ/g

kWh/gallon

1 gallon 3,78 litres









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ICE: input/output flow

• Basic input/output flow of an ICE

• Input: air + fuel

• Output: mechanical power + heat + exhaust gases

http://www.ngkntk.co.uk/index.php/technical-centre/lambda-sensors/what-does-the-lambda-

sensor-do/

http://www.ngkntk.co.uk/index.php/technical-centre/lambda-sensors/what-does-the-lambda-sensor-do/

















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ICE: exhaust gases and pollutant emissions

• Fossil fuel is a mixture of hydrocarbons

• ideal combustion process = producing only carbon dioxide (CO2) and

water vapor (H2O).

• exhaust gases are primarily composed of CO2+ H2O + unused engine

charge air

• volume ratios (changes with engine load/conditions):

• CO2 – 2-12%

• H2O – 2-12%

• O2 – 3-17%

• N2 – 60-90%

• Pollutants – 0-1%

https://www.dieselnet.com/tech/emi_intro.php#unreg




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• Gasoline (left) vs. Diesel (right)

https://www.ngk.de/en/technology-in-detail/lambda-sensors/basic-exhaust-

principles/exhaust-and-harmful-emissions/

https://www.ngk.de/en/technology-in-detail/lambda-sensors/basic-exhaust-principles/exhaust-and-harmful-emissions/



















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• Main exhaust gases are innocuous to health/environment

• except for CO2 due to its greenhouse gas properties

• Pollutant emissions:

• unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides

(NOx) and particulate matter (PM)

• affect human health and/or environment

• originate from various non-ideal processes during combustion:

• incomplete combustion of fuel

• reactions between mixture components under high temperature and

pressure

• combustion of engine lubricating oil and oil additives

• combustion of non-hydrocarbon components of diesel fuel, such as

sulfur compounds and fuel additives





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ICE: European emission standards

https://www.ngk.de/en/technology-in-detail/lambda-sensors/basic-exhaust-principles/euro-standards/
















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ICE: European emission standards

http://www.vdik.de/department/environment/european-exhaust-gas-emission-standards.html












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ICE: emissions mitigation

• Ways to mitigate pollutant emissions:

• optimizing fuel’s chemical properties

• optimizing ICE design for energy efficiency & emissions

mitigation (e.g. fuel consumption, adaptive cylinder mngmt)

• optimizing ICE operation (e.g. air/fuel ratio, fuel rail pressure,

fuel injection, EGR)

• using/optimizing catalyst converters & particle matter filters

• Air/fuel ratio (lambda factor) is paramount

• for proper ICE operation

• to maximize power

• to minimize fuel consumption

• to minimize pollutant emissions

http://www.pelicanparts.com/techarticles/mult_air_fuel_monitor/FIG2.JPG




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ICE: air/fuel ratio

• “Ideal” air/fuel ratio = stoichiometric ratio

• mass ratio = 14,7 kg (air) : 1 kg (fuel)

• optimizes catalyst operation (minimizes emissions)

• maximizes air/fuel combustion (and thus power)

• minimizes fuel consumption

• Usually expressed as

lambda () factor

• =𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑎𝑖𝑟 𝑚𝑎𝑠𝑠

𝑖𝑑𝑒𝑎𝑙 𝑎𝑖𝑟 𝑚𝑎𝑠𝑠

• = 1 ideal mixture (stoichiometric)

• > 1 lean mixture

• < 1 rich mixture





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ICE: air/fuel ratio

• Air-Fuel ratio changes with engine conditions 1

• cold engine (rich)

• acceleration (rich)

• high altitudes (lean)

• fuel cut-off (lean)

http://www.mummbrothers.com/SRF_Stuff/Secrets/Driveline/Air_Fuel.htm




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ICE: air/fuel ratio

• The air/fuel ratio has a great impact in pollutant emissions

• stoichiometric ratio of 14.7:1 leads to a good compromise

between power, economy and emissions (with catalyzer)

http://www.endtuning.com/afr.html




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ICE: catalytic converter efficiency

• Catalytic converter filtering efficiency

• close to 100% filtering for = 1 (stoichiometric)

http://www.crypton.co.za/Tto%20know/Emissions/catalitic_converters.html

http://www.crypton.co.za/Tto know/Emissions/catalitic_converters.html



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ICE: catalytic converter and lambda sensor operation

• 3-way (catalytic converter) = 3 tasks

1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2

2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2

3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:

[NOx] + [CO, HC] → N2 + CO2 + H2O

http://www.crypton.co.za/Tto%20know/Emissions/catalitic_converters.html

ECU basic algorithm (closed-loop, real-time)

1. oxygen (or lambda) sensor gives air/fuel ratio to ECU

2. ECU computes optimal control parameters (injection timing/duration,…)

3. secondary oxygen sensor enables to check catalytic converter failures




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ICE: guidelines for optimal engine control

• For optimized operation, it is mandatory for the engine ECU to: • monitor all relevant physical quantities, e.g.:

• intake air pressure (depression)

• crankshaft rotational speed (RPM) and position (angular)

• engine (coolant) and intake air temperature

• throttle position (angular)

• vibration (knock)

• …

• control (closed-loop real-time) all relevant systems, e.g.:

• air/fuel ratio: injection timing + fuel quantity + intake air flow

• ignition timing (SI engines)

• exhaust gas recirculation (EGR)

• adaptive intake/exhaust valve timing control

• adaptive cylinders activation/deactivation

• pre-heating systems (glow plugs in CI, oxygen sensors)

• …


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ICE: a snapshot of ICE control

• A typical ICE control diagram

• notice arrow directions at

the ECU

• ECU = sensors

• ECU = actuators

http://enginepartsdiagram.com/1994-toyota-pickup-electronic-

fuel-injection-system-efi-diagram/

http://enginepartsdiagram.com/1994-toyota-pickup-electronic-fuel-injection-system-efi-diagram/



















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Tips for saving fuel

• Do not warm up at idle – drive immediately after starting the engine

• Always drive in the highest possible gear

• Be light with the accelerator pedal

• Do not overspeed – fuel consumption increases disproportionately high over 100

km/h (due to drag force and more frequent braking/acceleration)

• Keep enough distance from the vehicle ahead; this improves safety and enables

smoother braking/acceleration

• Release the accelerator pedal when travelling downwards (do not use the neutral

position); this allows engine-assisted braking and cutting-off injection.

• Switch off the engine both at metro/railway crossings and whenever you predict

longer wait times at traffic lights; you begin saving fuel after just 30 seconds

• Avoid superfluous cargo, rooftop equipment or mechanical loads (such as air

conditioning, defoggers)

• Regularly check tire pressure; use recommended pressure for predicted load

• Use synthetic engine oil and low-rolling-resistance tires

• Regularly check glow/ignition plugs and fuel injection


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Glossary (English/Portuguese)


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Recommended bibliography

automotive systems course (module 02) - internal combustion engine: energy efficiency, input/output...

Engineering