CONVENTIONAL FUELS Carlos Sousa AGENEAL, Local Energy Management Agency of Almada

ALTERNATIVE FUELS AND VEHICLES

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CONVENTIONAL FUELS

Carlos Sousa

AGENEAL, Local Energy Management Agency of

Almada



DIESEL AND PETROL ENGINES

• 4 Stroke Cycle

• Main components

• Auxiliary Systems



DIESEL 4 Stroke Cycle

INTAKE

Air enters the combustion chamber



COMPRESSION

With all the valves closed, the piston goes up, compressing the air inside the cylinder

Increase in air temperature and pressure




INJECTION

The fuel is injected into the cylinder at high pressure, after the compression of the air




EXPANSION

The fuel inflames when it contacts with the hot air

The mechanical delivered the engine is now generated




EXHAUST

After the combustion, the hot gases leave the cylinder through the exhaust valve(s)




INTAKE COMPRESSION EXPANSION EXHAUSTINJECTION

COMBUSTÃO




• Compression Ratio = resV

Vmax



MAIN COMPONENTS OF THE ENGINE



• Piston – Transmits the movement to the

rod

• Connecting Rod – Transmits the

movement to the cranshaft

• Crankshaft – Transforms the alternative

movement in circular movement

MAIN COMPONENTS OF THE ENGINE



• Distribution (opening / closing of the valves)

• Cooling system (prevents components from overheating)

• Lubrication (reduces sheer, washes components, etc.)

• Fuel (fuel intake)

MAIN AUXILIARY SYSTEMS



Double OverHead Cam, DOHC

Lateral Cam

DISTRIBUTION



DISTRIBUTION



Objectives

COOLING SYSTEMS

1. Cool engine components:

keep the engine at a suitable operating temperature (i.e.

prevent the melting of components)

keep the physical and chemical proprieties of the lubricating oil

(can deteriorate with exessive temperature)

2. Provide heat to acclimatize the interior of the vehicle

3. Improve cold start



• Water pump

• Thermostat

• Radiator

• Fan

• Heating system

COOLING SYSTEMS



The function of the engine oil is much more than lubricating.

The oil must also have:

•High detergent and dispersant power

•High anti-oxidation power

•Good cooling capacity (contributes to engine cooling)

•Good capacity to neutralize acids

•Maintain its with temperature change (cold and hot)

LUBRICATING SYSTEM



LUBRICATING SYSTEM



FUEL SYSTEM

Objective:

• Introduce fuel in the engine, that will mix with the hot air inside the cylinder, evaporate, auto-inflame and burn



1. Indirect injection

2. DIRECT INJECTION

• Direct injection in the cylinders

• Higher injection pressures

• More expensive and demanding

technology

• Multiple jet injectors

FUEL SYSTEM



Direct Indirect

Losses Lower thermal lossesHigh thermal losses between

chambers

Performance Higher Lower

Speed Slow engine speed Higher engine speed

Fuel Demands higher quality fuelsWorks with lower quality fuels

(viscosity, cetane number)

InjectionMulti-jet

(higher injection pressure)Single-jet

(lower injection pressures)

DIRECT INJECTION vs. INDIRECT INJECTION



Advantages Inconvenients

Lower fuel consumption Price

Power Noise

Cold start Vibration

DIRECT INJECTION vs. INDIRECT INJECTION



DIRECT INJECTION



Squish and Swirl

DIRECT INJECTION



TYPES OF INJECTION SYSTEMS

• Radial and in-line pump

• Injector-pump

• Common Rail




In-line pump

600...700 bar 1 000 bar at the tip of the injector




Radial pump

1 000 to 1 500 bar at the tip of the injector



INJECTION SYSTEMS

Advantages

• No high-pressure fuel lines

• Higher injection pressures

• Lower fuel consumption

• Better torque and power at low engine speeds

Injector Pump

2000 bar



Pressão máx. 1350 – 1500 barINJECTION SYSTEMS

Common-Rail

1 800 2 000 bar

Advantages

• Better injection control

• Reduction of noise and vibration

• Good fuel consumption

• Good torque and power

• Reduction of pollutant emissions



INTAKE IN PETROL ENGINES

A petrol engine can admit:

• A mixture of air and fuel

• Air, with the fuel being injected directly into the cylinder – Direct Injection Engines

Source: Total



TURBOCHARGING

Objective: Increase the power/weight ratio

A compressor increases the density of the air before being admitted to the cylinders

Disadvantages (relative to atmospheric engines - “non-turbo”):

• Higher complexity and cost

• Higher physical and thermal strains on the engine

Advantages:

• More torque and power

• Better fuel consumption



TURBOCHARGING



Variable geometry

• More torque over all engine speed

range

• Better fuel consumption

• More power

TURBOCHARGING



TURBOCHARGING INTERCOOLER

Objective: Increase the power/weight ratio

Cools the air after the compression, before admitting it to the cylinders:

• Higher mass of air inside the cylinders

• More fuel

• More torque

•More power



POLLUTANTS FORMATION AND CONTROLCombustion in Diesel engines is characterised by a high concentration of fuel droplets (poor atomization/vaporization of the fuel).

Main pollutants:

• Particulate Matter (PM)

• Unburned Hydrocarbons, HC

• Carbon Monoxide, CO

• Nitrogen Oxides, NOx



POLLUTANTS FORMATION AND CONTROLEmissions control:

• Exhaust Gas Recirculation, EGR

• Particulate Filters

• Catalytic Converters



POLLUTANTS FORMATION AND CONTROLEmissions control

Diesel:

• Exhaust Gas Recirculation, EGR (prevents the formation of NOx)

• Particulate Filters, active and passive (PM)

• Oxidation Catalytic Converters (HC and CO)

• Selective Catalytic Reduction, SCR (NOx into N2 and H2O)

Petrol:

• 3-way Catalytic Converters

• Oxidation Catalysts (CO and HC into CO2 and H2O)

• Reduction Catalysts (NO into N2 and O2)



Fuel Quality, Diesel:

• Diesel is cetane derived (C10H22)

• Cetane Number: Indicates the higher or lower capacity of the fuel to auto-ignite ( lower delay to auto ignition)

• 15: Low capacity to auto-ignite: isocetane

• 100: High capacity to auto-ignite: cetane

• Minimum cetane number demanded: 51

• Sulphur content: Less than 50 ppm Low sulphur fuel

• Eliminate emissions of sulphur dioxide (SO2)

• Reduce PM emissions

• Less than 10 pmm: Sulphur free fuel (From 2009)



HC CO NOx PM

Diesel

Petrol

POLLUTANTS FORMATION AND CONTROL



EUROPEAN EMISSIONS STANDARDS

Standard Year CO HC HC + NOx NOx PM

Euro 1 1992 2.72 - 0.97 - 0.14

Euro 2 - IDI 1996 1.00 - 0.70 - 0.08

Euro 2 - DI 1999 1.00 - 0.90 - 0.10

Euro 3 2001 0.64 - 0.56 0.50 0.05

Euro 4 2005 0.50 - 0.30 0.25 0.025

Diesel Passenger vehicles 2.5t (values in g/km)



ENERGY EFFICIENCY

TORQUE

Energy generated in one revolution of the engine, resulting from the combustion of the fuel [kg.m or N.m].

1 kg.m=9.8 N.m

The higher the torque, the more efficient is the engine for a given engine speed.

POWER

Energy generated per unit of time [W or CV].

1kW = 1,36 CV

1 CV = 0,736 kW



ENERGY EFFICIENCY

Torque curve

• Shows the torque distribution along the entire engine speed range, at full engine charge (full throttle).

• Should be as flat as possible, which means good engine response at all engine speeds.

• RPM x N.m (or kg.m)



ENERGY EFFICIENCY

Power curve

• Shows the power distribution along the entire engine speed range, at full engine charge (full throttle).

• RPM x kW (or CV)



ENERGY EFFICIENCY

• CO2 emissions per litre: Petrol a little lower Diesel

• CO2 emissions per km: Diesel uses less fuel... …emits less CO2

• Energy efficiency is a function of the compression ratio

• Diesel engines use variable fuel to air ratios

• Petrol engines use a constant air to fuel ratio (stoichiometric: 14.7 to 1), no matter what the speed and load are

• Diesel engines have an unthrottled intake and the air to fuel ratio at idle speed can go as low as 100 to 1, thus giving a much greater partial load fuel efficiency than petrol engines



ENERGY EFFICIENCY

Compression ratio

The

oret

ical

eng

ine

effic

ienc

y

Diesel engines

Petrol engines

resV

Vmax



ENERGY EFFICIENCY

Useful work

Ideal process

Stoichiometric losses

Combustion losses

Speed variations

Loss

es

Friction losses

Losses

87%

Petrol engine, urban driving



DIESEL vs. PETROL

Diesel Petrol

Admission Air Air and fuel

CombustionAuto ignition, due to the high pressure and temperature inside the cylinder

Spark ignition

FuelMust vaporize easily and auto-ignite (high cetane number)

Must be resistant to auto-ignition(high octane number)

Compression ratio Highest possible (15 to 24)Limited by fuel characteristics (9 to 12)

Efficiency ~35% Less than 30%

Turbo chargingWhenever possible. Increases efficiency and improves combustion

Not common, but is becoming a popular solution



DIESEL vs. PETROL

Diesel Petrol

Fuel consumption Lower Higher

Fuel priceUsually lower, but depends on the taxes applied in each country

Higher

Weight Heavier Lighter and more compact

Start Almost immediate Immediate

Vibration and noise High Low

Engine speedLimited by the characteristics of the cycle and fuel

High



CAR INDUSTRY – ONE CURIOSITY

In 1976, Volkswagen came up with the designation “GTI”, but did not register it.

Almost all auto makers used it!!

But, in 1991, Volkswagen came up with the designation “TDI” and registered it. The result was…



CAR INDUSTRY – ONE CURIOSITYTDI – VAG Group TiD - Saab

JTD - Alfa, Fiat, Lancia D- 4D - Toyota

d - BMW D5- Volvo

CRD - Chrysler, Jeep HDI - Peugeot, Citroën

TDdi - Ford Di-D – Mitsubishi

TDCi - Ford dTi - Renault

CDTi - Honda dCi - Renault

CRDi - Hyundai CDT – Rover

DvTdi – Mazda DTI – Opel

DiTD – Mazda

CDI – Mercedes

DDTi – Nissan



Summary

Advantages Diesel engines:

• Better energy efficiency: Use less fuel/energy (work with higher compression ratios)

Advantages Petrol engines:

• Better cold start

• Less noise and vibrations

• More elasticity (higher engine speeds)

• Lighter

• More power for the same engine size



Summary

Investments in Diesel engines/technology intend to:

• improve atomization of the fuel (higher injection pressures)

• improve flow inside the cylinder

• optimize injection to reduce noise and vibration

• maximize power and torque without sacrificing fuel consumption (optimize turbo charging)

• optimize fuel injection to reduce fuel consumption (e.g.: injection technologies)



Oil companies are working to:

• Increase cetane number

• Lower sulphur content

Summary



Thanks to Prof. Tiago Farias

Technical University of Lisbon



Thank you for your attention!

CONVENTIONAL FUELS Carlos Sousa AGENEAL, Local Energy Management Agency of Almada

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