Strategies regarding technologies applied to improve the energetic and ecologic

parameters of automotive internal combustion engines

ENGINE

FUELEMISSIONS

1) POLLUTANTS

- HC

- CO

- NOx

- PM

2) GREENHOUSE GASES-CO2 ,N2O, CH4

- SI Engine- CI engines

1) CONVENTIONAL FUELS

- Gasoline

- Diesel fuel

2) ALTERNATIVE FUELS

1. Strategies regarding technologies applied to improve the energetic and ecologic parameters of automotive internal combustion engines

• HC pollution results when unburned or partially burned fuel is emitted from the engine as exhaust and when fuel evaporates directly into the atmosphere.

A component of most fuels, HCs also react with NOx in the presence of sunlight to form ozone.

EMISSIONS

• CO forms when the carbon in fuel isn’t burned completely due to a lack of oxygen.

That’s why high levels of CO generally occur at high altitude where less oxygen is present to help with combustion.

• NOx gases are formed when oxygen and nitrogen in the air react with each other during combustion. The most abundant pollutant, nitric oxide (NO) oxidizes in the atmosphere to form nitrogen dioxide (NO2), which can oxidize to form ozone or air particles known as PM2.5.

The formation of NOx is most common when there are high temperatures and excess oxygen. Because NOx is most abundant when combustion temperatures are high, and HC and CO are most abundant when temperatures are low, there is a trade-off among these emissions. Engines are calibrated to make the best of this trade-off.

• Particulate matter (PM) is a pollutant emitted primarily by diesel-fueled vehicles and poorly-maintained gasoline-powered vehicles. PM is made up of small particles that contain a variety of chemical components. Larger particles are visible as smoke or dust and settle out relatively rapidly. Smaller particles, such as PM2.5 can be suspended in the air for long periods of time and inhaled into the lungs.

Another significant tailpipe emission is carbon dioxide (CO2). CO2 is considered a greenhouse gas because it absorbs and re-emits infrared radiation that heats the earth’s surface—a process known as the “greenhouse effect.”

REGULATORY PROGRAM TIMING

Evolution of pollution standard

Euro 6 is the first step towards the implementation of world harmonized emission standards, encompassing Europe, North America and Japan, and this will facilitate coordination and development for future standards.

The Euro 6 levels are close to those applying in North America (EPA10) and Japan (Post NLT) starting in 2010. Euro 6 is the first time the new WHDC (world harmonized duty cycle) is stipulated for certification.

Euro 6 standard

EU Emission Standards for Passenger Cars (M1, M2)*

Stage DateCO HC

HC+NOx

NOx PM PN  

g/km #/km  

Compression Ignition (Diesel)  

Euro 1† 1992.072.72

(3.16)-

0.97 (1.13)

-0.14

(0.18)-  

Euro 2, IDI

1996.01 1.0 - 0.7 - 0.08 -  

Euro 2, DI

1996.01a 1.0 - 0.9 - 0.10 -  

Euro 3 2000.01 0.64 - 0.56 0.50 0.05 -  

Euro 4 2005.01 0.50 - 0.30 0.25 0.025 -  

Euro 5a2009.09b 0.50 - 0.23 0.18 0.005f -  

Euro 5b 2011.09c 0.50 - 0.23 0.18 0.005f 6.0×1011  

Euro 6 2014.09 0.50 - 0.17 0.08 0.005f 6.0×1011  

Positive Ignition (Gasoline)

Euro 1† 1992.072.72

(3.16)

-0.97

(1.13)

- - -

Euro 2 1996.01 2.2 - 0.5 - - -

Euro 3 2000.01 2.30 0.20 - 0.15 - -

Euro 4 2005.01 1.0 0.10 - 0.08 - -

Euro 5 2009.09b 1.0 0.10d - 0.06 0.005e,f -

Euro 6 2014.09 1.0 0.10d - 0.06 0.005e,f 6.0×1011 e,g

Notes:* At the Euro 1..4 stages, passenger vehicles > 2,500 kg were type approved as Category N1 vehicles

† Values in brackets are conformity of production (COP) limitsa. until 1999.09.30 (after that date DI engines must meet the IDI limits)b. 2011.01 for all modelsc. 2013.01 for all modelsd. and NMHC = 0.068 g/kme. applicable only to vehicles using DI enginesf. 0.0045 g/km using the PMP measurement procedureg. 6.0×1012 1/km within first three years from Euro 6 effective dates

The Euro 5/6 implementing legislation introduces a new PM mass emission measurement method (similar to the US 2007 procedure) developed by the Particulate Measurement Programme (PMP) and adjusts the PM mass emission limits to account for differences in results using the old and the new method.

The Euro 5b legislation also introduces a particle number (PN) emission limit in addition to the mass-based limits. Because gasoline direct injection engines have gained relevance, a particle number emission limit for gasoline vehicles is to be defined by September 2014, when Euro 6 is implemented.

PM by sector

Greenhouse emissions

• Some examples of activities that contribute to greenhouse gas levels are as follows:

• Combustion fossil fuels – oil, gasoline, gas and coal;

• Industrial processes and mining; • Landfills, septic and sewer systems; • Agricultural practices, including fertilizer and

manure management; • Land use practices, including deforestation.

The greenhouse gas, the most commonly produced by human activities, is carbon dioxide (CO2). It is responsible for 63% of the global warming caused by human activities.

The primary greenhouse gases produced by the transportation sector are:• carbon dioxide (CO2),• methane (CH4), • nitrous oxide (N2O), and • hydrofluorocarbons (HFC).

Absolute change of GHG emissions by gas in the EU-27, 2010 - 2011 and total GHG emissions by gas in the EU-27, 2011

Greenhouse gas emissions by sector in EU 27 [2010]

Greenhause emissions in Romania, 2010

The atmospheric lifetimes are estimated to be:

• CO2 50-200 years, • CH4 9-15 years, • N2O 120 years.

The three GHGs should be combined with their global warming potentials:

• 1 for CO2, • 23 for CH4,• 296 for N2O,.

The CO2 emissions from transport, can be measured precisely by multiplying the quantity of fossil fuel used by the corresponding emission factor.

Emission factor:

2.9 for gasoline;

3.0 for kerosene; or

3.1 for diesel fuel.

One of the main priorities in EU climate change policy is the reduction of CO2 emissions on new road vehicles.

The target for CO2 emission and fuel consumption

Vehicle categories

Year 2015 Year 2020

CO2[g/km]

Fuel [l/100 km]

CO2[g/km]

Fuel [l/100 km]

SI CI SI CI

Car LDV 130 5,6 4,9 95 4,1 3,6

Year 2017 Year 2020

Van 175 7,5 5,6 147 6,3 5,5

The greenhouse gas emissions from transport is expected to rise to between 30 and 50%, by 2050 (today it is around 20-25%)

Effective road transport scenarios must meet multiple objectives referring to motor vehicle and road traffic, such as:

• Reduction of CO2 emissions in order to diminish the impact on climate changes;

• Drastic reduction of chemical pollutants and noise emissions;

• Preservation or increase of power train’s energetic parameter

• Providing security of fuel supply;• Developing an effective sustainable mobility policy.

Four strategies to reduce transportation GHG and pollutant emissions:

• Introducing low-carbon fuels;

• Improving vehicle fuel economy;

• Increasing transportation system efficiency and

• Diminishing carbon-intensive travel activity.

The greenhouse gas emissions from transport sector is directly influenced by fuel consumption. Road transport accounted for the largest share of their energy consumption and even exceeded 90 % of the total among new Member States.

Final energy consumption, by mode of transport, EU-27 (Mtoe) 1999-2009

Final energy consumption in transport, by fuel, EU-27 (Mtoe) 1999-2009.

Within the transport sector of the EU-27, road transport was the most energy consuming mode with an 82 % share of the total in 2009.

In absolute terms, motor spirit consumption decreased by 29 % between 1999 and 2009. On the other hand, the consumption of all other fuels increased. Gas/diesel oil consumption recorded a 30 % increase, kerosene’s consumption grew by 17 % and the consumption of biofuels grew 26 times. From 2008 to 2009, in EU-27 the consumption of all fuels but biofuels dropped.[25]

FUELS

• Introducing Low-Carbon Fuels

Specifically, a full lifecycle analysis includes: • The full fuel cycle, including upstream emissions (sometimes called “well-to-wheel” analysis) associated with drilling, exploration and production, crude oil transport, refining, fuel transport, storage, and product retail, as well as downstream disposal or recycling of oil products.A well-to-wheels (WTW) analysis estimate: the geenhouse gas emissions and the energy efficiency, the industrial costs of powertrain options and automotive fuels.

• A Well-to-Wheels analysis is main basis to assess the impact of future fuel and powertrain options. – fuel production pathway ;– powertrain efficiency are key to GHG emissions and energy use.

A WTW analysis is also called a fuel cycle analysis in the transportation fuel area and a lifecycle analysis in consumer reporting.

Well-to-Wheels analysis

Low-carbon fuelLow-carbon fuel strategies include the development and strategies include the development and

introduction of alternative fuels that have lower carbon introduction of alternative fuels that have lower carbon

content and generate fewer transportation GHG content and generate fewer transportation GHG

emissions. emissions.

The alternative fuels includeThe alternative fuels include: : ethanol, biodiesel, natural ethanol, biodiesel, natural

gas, liquefied petroleum gas, synthetic fuels, hydrogen, gas, liquefied petroleum gas, synthetic fuels, hydrogen,

and electricity.and electricity.

The studis made on alternative road fuels and their potential to replace conventional gasoline and diesel fuels need to consider their potential to save energy and GHG. At the 2010-2020 horizon, alternative fuels can only be reasonably expected to supply 10% to 20% of the road fuel demand.

The EU has adopted the European Strategic Energy Technology Plan (SET-Plan) as a road-vehicle to accelerate the development and the large scale use of low carbon technologies

Primary production of biofuels, EU-27 (Thousand tones).

• In the last decade, significant changes were observed in the fuel mix consumed by the EU-27 transport sector.

In 2009, gas/diesel oil accounted for 52 % of the total, an increase of 9 percentage points compared to 1999.

Over the same period, the share of motor spirits dropped from 41 % in 1999 to 27 % in 2009.

Biofuels accounted for 3 % of total transport consumption in 2009.

In absolute terms, motor spirit consumption decreased In absolute terms, motor spirit consumption decreased

by 29 % between 1999 and 2009. by 29 % between 1999 and 2009.

On the other hand, the consumption of all other fuels On the other hand, the consumption of all other fuels

increased. increased.

Gas/diesel oil consumption recorded a 30 % increase, Gas/diesel oil consumption recorded a 30 % increase,

kerosene’s consumption grew by 17 % and the kerosene’s consumption grew by 17 % and the

consumption of biofuels grew 26 times. consumption of biofuels grew 26 times.

From 2008 to 2009, in EU-27 the consumption of all fuels From 2008 to 2009, in EU-27 the consumption of all fuels

but biofuels droppedbut biofuels dropped

Greenhouse Gas Emissions. ( WTTanalysis)

Production of petroleum-based fuels and natural gas-based methanol, results in a smaller amount of GHG emissions than production of H2 (gaseous and liquid) and electricity generation

GHG emission values of the three ethanol production pathways are negative because of carbon sequestration during growth of corn plants, trees, and grass.

Total Energy Use. ( WTTanalysis)

For the same amount of energy delivered to the vehicle tank for each of the fuels, petroleum-based fuels and CNG are subject to the lowest energy losses. Methanol, hydrogen from natural gas, and corn-based ethanol are subject to moderate energy losses. Liquid hydrogen from natural gas, electrolysis hydrogen(gaseous and liquid), electricity generation, and cellulosic ethanol are subject to large energy losses.

The studies made on alternative road fuels and their potential to replace conventional gasoline and diesel fuels need to consider their potential to save energy and GHG. At the 2010-2020 horizon, alternative fuels can only be reasonably expected to supply 10% to 20% of the road fuel demand.

Alternative Fuels

Primary energy resources and automotive fuels

The European Commission has identified the following main objectives of biofuels’ policy:

Greenhouse Gas Saving;

Security of Supply;

Employment.

Biomass energy resources and automotive fuels

NOx - Emissions

91

847

141

690

0

100

200

300

400500

600

700

800

900

SuperGasoline -7000 rpm

E100 - 7000rpm

SuperGasoline -7500 rpm

E100 - 7500rpm

NO

x (

pp

m)

NOx

CO2 - Emissions

9,89 9,92

10,17

9,66

9,4

9,5

9,6

9,7

9,8

9,9

10

10,1

10,2

10,3

Super Gasoline -7000 rpm

E100 - 7000 rpm Super Gasoline -7500 rpm

E100 - 7500 rpm

CO

2 (%

)

CO2

Comparison of NOx and CO2 emissions for an engine fuelled with gasoline and alcohol

Alcohol used as fuel in SI Engine

Using biofuels should take into account the following facts:

• the greenhouse gas emissions must be at least 35% lower compared to the use of the fossil fuel. From 2017, the increase need be up to 50% and from 2018 the saving must be at least 60%;

• the raw materials for the biofuels cannot be sourced from land with high biodiversity or high carbon stock.[20]

Improving vehicle fuel economy;

Vehicle and fuel efficiency strategies comprise: • developing advanced engine and transmission designs, • lighter-weight materials, • improved vehicle aerodynamics, and • reduced rolling resistance

Many of these technological improvements (such as hybrid-electric powertrains, truck aerodynamic improvements, and more efficient gasoline engines) are well developed and could be further incorporated into new vehicles.

Influence of vehicle technology on vehicle’s fuel saving improvment and GHG emission reduction

GHG emission reduction in HDV appling new technologies

Technologies applied to HDV

ENGINE

Advanced engines (ICEs)

There are two ways to achieve the tasks regarding diminishining of: fuel consumption, pollutant and CO2 emissions:

Improving the internal combustion engine processes using the latest technologies;

Using new fueling systems and alternative fuels in ICE.

Conventional road fuels are widely expected to provide the bulk of road transportation needs for many years to come.

For SI engines, the main contribution to fuel efficiency improvement comes from downsizing (minus 30%) associated with supercharging

Several new energy-efficient propulsion systems are currently being investigated :

• GDI and diesel engines;• Turbo/super charging;• Highly active intake systems;• Electronically controlled valve actuation/timing;• Drive by wire systems;• Cylinder deactivation;• EGR;• Engine start/stop systems.

SPARK IGNITION ENGINES

Conventional λ1 Spark Ignition (SI): Naturally Aspirated Spark Ignition Variable and optimized cooling rates at different operating conditions, Variable valve timing (Miller/Atkinson cycles), Reduced mechanical friction losses May be either pre-mixed or DISI IVT: λ1 Spark Ignition with Infinitely Flexible Valve Timing and Boosting (Turbocharged)

SPARK IGNITION ENGINES

DISI: Direct Injection Turbocharged Gasoline Engine Combustion system development for stratified operation across entire part load range Lean with NOx treatment (20%) or Stoichiometric (5%)

DNSZ SI: Downsized, highly boosted DISI 30% reduction in displacement Turbocharged Lean with NOx treatment (30%) or Stoichiometric (10%)

Fuel Economy Benefits from Engine Boosting Downsizing and Downspeeding

• Reduced Engine Displacement and Decreased Engine Speed Increase Engine Load for Reduce Fuel Consumption

-Good low end torque is essential

• Gasoline Direct Injection is a Key to Improve Low End Torque in Boosted Engines

-Improved Volumetric Efficiency -Direct injection with cam phasing allows scavenging with fresh air to reduce residual gas fraction -Reduced knock propensity -In-cylinder fuel vaporization reduces charge temperature-Improved combustion phasing -Charge motion increases burn rate • Benefits -Fuel economy improvement -9-15% for homogeneous systems -15-21% for stratified systems -Improved fuel control and rapid catalyst light-off with split-injection during cold start -Increased power and responsiveness

3 and 4 Cylinder Engine Analysis Comparison

• 3 Cylinder Engine Offers Improved Engine Breathing at Full Load - Reduced firing frequency increases scavenging for improved full load torque

• 3 Cylinder Engine Provides Reduced Fuel Consumption and Emissions -Reduced heat transfer surface area -Reduced quench layer and crevices -Lower friction

• 3 Cylinder Engine Increases NVH -Unbalanced 1st and 2nd order torque pulses require counterbalancing -Results in slight friction increase • Overall Conclusion: 3 Cylinder Engine is the Preferred Configuration for Displacements < 1.5L

DIESEL ENGINES

• HSDI: (High Speed) Direct Injection Diesel (lean)

Turbocharged – perhaps multi stage Lean NOx exhaust gas treatment Diesel particulate filter

DIESEL ENGINES

LTE: Low Temperature Engine (lean) Also known as HCCI, PCCI or CAI Power boosting – perhaps electrically assisted turbocharger Advanced controls including start of combustion sensing Low-temperature oxidation catalyst

NOx aftertreatment technology, such as:

Selective catalytic reduction (SCR)technology using ammonia from external source as a reductant,

Lean NOx catalysis (LNC) using hydrocarbons from the engine or by exhaust fuel injection as a reductant,

or Storage catalysts with periodic regeneration (lean NOx traps (LNT)).

Euro 6, proposed emissions limit values may be achieved by adding new technology package.

For diesel cars, included two components over those needed for the Euro 5. The components are:

Internal engine measures, such as : Reduced engine compression ratio, Increased exhaust gas recirculation (EGR), Advanced fuel injection systems, Advanced turbocharging and Advanced combustion control; and

hV  = volumetric efficiency            Vair = volume of air taken into cylinder [cc, L, or m3]            Vc = cylinder swept volume [cc, L, or m3]

* Increase the engine volumetric efficiency increase engine power- Engine of normal aspiration has a volumetric efficiency of 80% to 90%- Engine volumetric efficiency can be increased by using:(turbo and supper charger can increase the volumetric efficiency by 50%)

            r = compression ratio            Vs = cylinder swept volume (combustion chamber volume) [cc, L, or m3]            Vc = cylinder volume     [cc, L, or m3]* Increase the compression ratio increase engine power- r (gasoline engine) = 7:12, the upper limit is engine pre ignition- r (diesel engine) = 10:18, the upper limit is the stresses on engine parts

  imep = is the indicated mean effective pressure [N/m2]            Ac = cylinder area [m2]            L = stroke length [m]            n = number of cylinders            N = engine speed [rpm]            z = 1 (for 2 stroke engines), 2 (for 4 stroke engines)            Vc = cylinder swept volume [m3]            Ve = engine swept volume [m3]            Ti = engine indicated torque [Nm]            ω = engine angular speed [1/s]