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REFERENCES
The first textbook was always on my desk when I was preparing these lecture notes. I
also list wikipedia, which was the source for many of the images and animations
plus many useful tidbits of information.
Energy and Environment
Professor Halim Gürgenci
(visitor from the University of Queensland)
Rm 4245; Phone : (212) 359 6436
[email protected]
©2006 Halim Gürgenci, The University of Queensland (Australia) and Bogazici University (Istanbul, Turkey)
Specific references are supplied on every slide except when the slide content is part of
common mechanical engineering lore and can be found in any relevant textbook.
• Fay, James A, and Golomb, Dan S, Energy and the Environment, Oxford
University Press (2002).
• Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Main_Page)
Vehicle Registrations in Turkey
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10
Transportation
Includes cars, trucks, buses, motorcycles, and tractors
millions of vehicles
Module 8
http://www.tuik.gov.tr
8
6
4
2
0
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004
1
Types of Vehicles
Internal Combustion Engines
6
• Spark-Ignition (otto cycle)
http://www.tuik.gov.tr
millions of vehicles
5
– Two-stroke
– Four-stroke
4
3
• Compression-Ignition (diesel cycle)
2
1
Tractor
Spec
Purpose
Motorcycle
Truck
Small truck
Bus
Minibus
Land
vehicle
Automobile
0
Four-Stroke Engine
1 – Intake
2 – Compression
3 – Combustion (Power Stroke)
4 - Exhaust
Some Facts
• Combustion takes place in about 50o, which is
2.31 ms at a crankshaft speed of 3600 RPM
• The air and fuel are premixed
• Combustion is initiated by a spark
– Knocking is an issue because of the advancing
flame front started by the spark
3
2
4
1
• To reduce power, the inlet is throttled
(reducing the amount of air+fuel mixture)
2
Two-Stroke Engine
Compression-Ignition (Diesel)
• The charge is introduced at the end of the compression stroke
and self-ignites as it enters the combustion chamber
– No knocking
-Exhaust and Intake are combined and fresh charge displaces the combustion products
-Lower fuel efficiency and noise make these less and less desirable
-Their use is limited to lawnmovers and small vehicles like motorcycles
-Honda has recently announced that they are phasing out their 2-stroke engine designs and
all new Honda motorcycles will be based on 4-stroke cycles
• The A/F ratio must be well above the stoichiometric ratio to
allow all fuel molecules meet oxygen molecules for
combustion
• The power is adjusted by metering the fuel
• Higher compression ratios are possible because knocking is
not an issue Æ higher thermal efficiencies
• Old diesel engines had high soot (unburned particles) in their
exhaust. They are getting better.
Homogeneous Charge Compression Ignition (HCCI)
Homogeneous charge compression ignition (HCCI) engines have the potential to provide high,
diesel-like efficiencies and very low emissions. In an HCCI engine, a dilute, premixed fuel/air
charge autoignites and burns volumetrically as a result of being compressed by the piston. The
charge is made dilute either by being very lean, or by mixing with recycled exhaust gases
(http://www.ca.sandia.gov/crf/research/combustionEngines/EGR.php )
This technology is still at developmental stage.
Engine Power
Pb =
BMEP × Ve
×N
n
BMEP
Avg pressure through the cycle (called Brake Mean Effective Pressure)
Ve
Engine displacement (Cylinder volume x No of cylinders)
n
Number of crank revs per cycle (2 for 4-stroke; 1 for 2-stroke engines)
N
Crankshaft speed
Pb
Brake Power (available on the engine output shaft before the transmission)
For cars running Spark-Ignition (SI) cycles, BMEP = 1 – 1.5 MPa. The BMEP stays
more or less constant across the speed range.
Note that the two-stroke engine delivers twice the power at the same BMEP and
volume. That is why it is suitable for small engines (albeit at the cost of reduced
efficiency and increased pollution).
New Scientist
3
BMEP and Brake Power
Thermal and Fuel Efficiency
•
•
•
•
SI cycle efficiency < 31%
LHVgasoline = 43.55 MJ/kg
SGgasoline=0.72
Best BSFC = 0.27 kg/kWh
BSFC[kg/MJ] =
•
•
•
•
CI cycle efficiency < 44%
LHVdiesel = 41.18 MJ/kg
SGdiesel=0.85
Best BSFC = 0.20 kg/kWh
1
ηth × LHV [MJ/kg]
Fay&Golomb,
Figure 8.4
Vehicle Performance
ρV
Wair = CD A
2
3
Air Drag
CD
Drag coefficient determined by CFD or wind tunnel(1) testing, ~ 0.25–0.50
A
Frontal area, m2
r
Density of air, kg/m3
V
Vehicle velocity, m/s
(1) http://wright.nasa.gov/airplane/tunnlint.html has an excellent computer simulation of the wind tunnel Wright
brothers built to test their airplane in 1901. Not exactly related here but I thought I should include it.
Picture on the web – designed in a wind tunnel?
Computers can be used to predict
forces on planes as well as cars
The engine should provide enough power to overcome the resistance to motion (air drag, rolling
fraction, gravity) and to accelerate the vehicle.
Weng = Wair + Wroll + W grav + Wacc
http://fantasygoat.livejournal.com/8178.html
http://www.engineers.auckland.ac.nz/~snor007/cfd.html
4
Rolling Friction
As seen on the left, the tyres deform in
motion. Due to this deformation, the net
resultant force on the tyre coming from the
road acts slightly to the front of the centre,
generating a torque resisting motion. The
engine has to generate the power to
compensate for this force :
Hill climbing
While climbing, the engine has to provide the torque required to overcome the force of
gravity:
W grav = mgV sin θ
Wroll = CR mgV
http://webphysics.davidson.edu/faculty/dmb/PY430/F
riction/rolling.html
where m and V are the vehicle mass and
speed, respectively.
CR depends on the elasticity of the tyre and the road. The following table can be used.
Tyre Type
Ordinary car tyre on concrete
Car on stone plates
Car bus on asphalt
Train wheels – steel on steel
Tram wheels on standard rails
from wikipedia
CR
0.010 – 0.015
0.020
0.030
0.001 – 0.0025
0.005
Acceleration
The difference between the engine power and the resistance to motion goes to accelerate
the vehicle:
Wacc = mVV + I ωω = Weng − (Wair + Wroll + W grav )
where m and V are the vehicle mass and the velocity, respectively.
I and ω represent the acceleration of rotating components such as the crankshaft, tyres,
etc. They are usually represented by a small correction ε on the vehicle mass and
Wacc = m(1 + ε )VV = Weng − (Wair + Wroll + W grav )
The Fuel Economy
The Turkish Law requires the car vendors to provide data on the fuel economy and the CO2
emissions for the cars they are selling (Yeni Binek Otomobillerin Yakit Ekonomisi Ve CO2
Emisyonu Konusunda Tüketicilerin Bilgilendirilmesine İlişkin Yönetmelik, Resmi Gazete
Tarihi: 28/12/2003). The Turkish codes comply with the European Union testing standards for
definition of fuel economy and CO2 emissions.
Summary from a larger table on the
American Fuel Economy Web Site.
The fuel economy is given as
MPG(miles per gallon).
City represents urban driving – the
car started in the morning (after
being parked all night) and driven in
stop-and-go rush hour traffic.
Highway represents a mixture of
rural and interstate highway driving
in a warmed-up vehicle, typical of
longer trips in freeflowing traffic.
5
Improving Fuel Economy
• Improve Vehicle Performance
– Reduce vehicle mass by smaller cars and/or lighter materials
– Reduce aerodynamic resistance
Electric Vehicles
The electrically-powered trolley-buses, trams, and trains have been with us for a long time.
These are powered by overhead cables and therefore constrained to specific routes.
• Limited by the laws of physics but there is usually no mass penalty for reduced drag
– Rolling resistance
• New tyres can be made with smaller CR but degrades with time
• Improve engine performance
– Intake stroke losses
– Turbocharging fits more air/fuel – smaller engine means smaller vehicle mass
– Use CI instead of SI
• the trade-off between increased efficiency and increased engine mass
• the diesel has higher emissions (being addressed with new cars)
A Dutch trolley bus (wikipedia)
A street tram in Hannover (wikipedia)
– Continuously-Variable Transmission – Use the best “gear ratio” at all speeds
• Hybrid cars
– The fuel replacement must justify the extra mass required by the hybrid system
Hybrid Electric Vehicles
ICE
The challenge for free-range elecric vehicles is the on-board storage of electricity. At
the current level of storage technology (90-180 kJ/kg), the electric vehicle is not a
feasible option unless it is favoured for other reasons, for example to avoid air
pollution in crowded cities.
Exhaust Emissions
Internal Combustion Engine
MG1
Motor / Generator 1 (typically "closer" to the
engine and "smaller")
MG2
Motor / Generator 2
R, C, S
Ring, Carrier (Planet) and Sun Gear
Fay&Golomb,
Figure 8.9
6
Emission Legislation - USA
In most countries, the exhaust emissions are tightly controlled by legislation that is getting
increasingly stringent.
US and European codes are important. US has traditionally been more concerned with particulate
matter and NOx emissions than the fuel economy. California has the most stringent emission
standards of the world. The two codes are converting at the heavy-duty end but there are still
significant differences at the light vehicle end.
US codes specify the emissions by g/mile. The baseline is given by the “Tier 1” standard. Further
limitations are specified under the following categories:
TLEV – Transitional Low Emission Vehicle
LEV – Low Emission Vehicle
Emission Legislation - Europe
The following has been introduced over the past decade:
Euro 1 (1993) for passenger cars - 91/441/EEC [2] (also 93/59/EEC)
Euro 2 (1996) for passenger cars - 94/12/EC (& 96/69/EC)
Euro 3 (2000) for any vehicle - 98/69/EC
Euro 4 (2005) for any vehicle - 98/69/EC (& 2002/80/EC)
Euro 5 (2008/9) for any vehicle - (COM(2005) 683
Compliance is determined by running the engine at a standardised test cycle. Noncompliant vehicles
cannot be sold in the EU, but new standards do not apply to vehicles already on the roads.
ULEV – Ultra-Low Emission Vehicle
SULEV – Super-Ultra Low Emission Vehicle
ZEV – Zero Emission Vehicle
Since 2005, US has been phasing in “Tier II”, which introduces more string versions of the above,
e.g. TLEV-II, LEV-II, etc, and some new ones.
Diesel Emission Limits - EU
wikipedia
EU Emission Limits for Petrol Cars
wikipedia
7
“Türkiye’de Temiz Araçlar Kapsamında Fırsatlar ve Engeller” by Hulya Ercan, 04 Mayıs 2006
Turkish Automotive Industry
Turkish Emissions Codes
UYGULAMA TARİHLERİ
SGMSGM-2000/77 – 03.12.2000 , SGMSGM-2001/7 – 17.06.2001 ve SGMSGM-2001/12 –
22.10.2001 Tebliğ
Tebliğlerine Gö
Göre Emisyon Mevzuatı
Mevzuatı:
PROTOTİP ONAY YILI
MOTOR
SİLİNDİR
HACMİ (cc)
1993
1994
1995
1996
1997
1998
1999
ÜRETİM BAŞLANGICI
01.01.199
4
01.01.1995
01.01.1996
01.01.199
7
01.01.1998
01.01.1999
01.01.2000
EURO 93
EURO 93
EURO 93
EURO 93
EURO 93
1800 ve üstü
15.04*
EURO
93*
1600 - 1799
15.04
15.04
EURO 93*
EURO 93
EURO 93
EURO 93
EURO 93
1400 - 1599
15.04
15.04
15.04
EURO
93 *
%30
EURO 93*
%60
EURO 93*
%100
EURO 93
15.04
EURO
93*
1399'dan
küçük
15.04
15.04
15.04
15.04
15.04
Benzinli Araç
Araçlar
Faz III (98/69/ATve 1999/102/AT ile değ
değişik 70/220/AT OBD hariç
hariç)
Yeni Araç
01.01.2001
Araçlar
Mevcut Araç
30.09.2001 (01.07.2001) (SGM/2001/7)
Araçlar
Hafif Dizel Araç
Araçlar
(91/441/AT ile değ
değişik 70/220/AT veya R 83.01)
Yeni Araç
01.01.2001
Araçlar
Mevcut Araç
31.12.2002 (01.01.2002) (SGM/2001/12)
Araçlar
Ağır
ğır Dizel Araç
Araçlar
Faz I (91/542/AT ile değ
değişik 88/77/AT veya R 49.02)
Yeni Araç
01.01.2001
Araçlar
Mevcut Araç
31.12.2002 (01.10.2001) (SGM/2001/12)
Araçlar
Turkish Fuel Standards
More Turkish Codes on Exhaust Emissions
Tebliğ
Tebliğlerden sonra Yö
Yönetmelikler yayı
yayınlanmış
nlanmışttır. Bunlar;
70/220/AT Yö
Yönetmeliğ
netmeliği (24.09.2003 – 25239 sayı
sayılı R.G)
Akaryakı
Akaryakıt kalitesi ile ilgili 98/70/AT Yö
Yönetmeliğ
netmeliğinde belirtilen tedbirlerin
yürürlü
rlüğe giriş
girişiyle
Yeni araç
01.01.2007
araçlar
Mevcut araç
01.01.2008
araçlar
88/77/AT Yö
Yönetmeliğ
netmeliği ( 24.06.2003 – 25148 sayı
sayılı R.G)
Yeni araç
01.01.2007
araçlar;
Mevcut araç
01.01.2008
araçlar;
Ayrı
Ayrıca Çevre ve Orman Bakanlığı
Bakanlığı Tarafı
Tarafından
Yayı
Yayınlanan Yö
Yönetmelikler:
•
98/70/AT Benzin ve Motorin Kalitesi Yö
Yönetmeliğ
netmeliği
(11.06.2004 – 25489 sayı
sayılı R.G)
•
Trafikte Seyreden Motorlu Kara Taşı
tlarıından
Taşıtlar
kaynaklanan Egzoz Gazı
Gazı Emisyonları
Emisyonlarının Kontrolü
Kontrolüne
Dair Yö
Yönetmelik (08.07.2005 – 25869 sayı
sayılı R.G)
72/306/AT Dizel Motorlardan Çıkan Kirletici Emisyonlar
80/1268/AT CO2 Emisyonları ve Yakıt Tüketimi
80/1269/AT Motor Gücü
8
Gasoline Prices in Turkey
Alternative Fuels
Ethanol-Gasoline Comparison
Engine Wear with Ethanol
Pure ethanol and gasoline
behave similarly. Extra
wear is caused by water.
Unfortunately, ethanol is
more likely to contain
water as part of the
production process and
also because it absorbs
water.
Yahagi, Y & Mizutani, Y
1984, 'Corrosive Wear of
Steel in GasolineEthanol-Water
Mixtures',Wear, vol. 97,
pp. 17-25. (quoted by
Andrew Prout)
Sinor, J & Bailey, B 1993, 'Current and Potential Future Performance of Ethanol
Fuels', SAE Paper, vol. 930376. (quoted by Andrew Prout’s Thesis at UQ)
9
Corrosion with Ethanol
Australian studies (see Andrew
Prout’s Thesis) observed no
appreciable wear and corrosion
at 10% ethanol. Wear on some
engine components were
observed at 20% ethanol. This
is most likely due to the water
content in ethanol.
Energy budget for Ethanol?
ScienceDailyCom reports : Pimentel and Tad W. Patzek, professor of civil and environmental
engineering at Berkeley, conducted a detailed analysis of the energy input-yield ratios of
producing ethanol from corn, switch grass and wood biomass as well as for producing biodiesel
from soybean and sunflower plants. Their report is published in Natural Resources Research
(Vol. 14:1, 65-76):
• corn requires 29 percent more fossil energy than the fuel produced;
• switch grass requires 45 percent more fossil energy than the fuel produced; and
• wood biomass requires 57 percent more fossil energy than the fuel produced.
They had similar results for biodiesel:
• soybean plants requires 27 percent more fossil energy than the fuel produced, and
Ethanol Production
Ethanol in US is produced from corn; in Brazil from sugar cane.
In USA, 103 ethanol plants has the capacity to produce 5000 million gallons of ethanol per
year, mostly from corn.
According to a 1995 study by the US Dept of Agriculture(1), , The US corn yield is about
110-120 bu/acre, which is 0.70-0.75 kg/m2 or 1.7-1.9 t/dönüm (2). Average ethanol
conversion is about 2.5 gallons/bushel or 0.37 liters of ethanol from one kg of corn.
(1)
Estimating the Net Energy Balance of Corn Ethanol. By Hosein Shapouri, James A. Duffield, and Michael S.
Graboski. U.S. Department of Agriculture, Economic Research Service, Office of Energy and New Uses. Agricultural
Economic Report No. 721.
(2)
1 bushel of corn is exactly 56 pounds or about 25.4 kg. 1 US gallon = 3.78 litres.
Ethanol Conflict
Environmental Management News, 19 September 2006
SEVERAL experts are arguing that use of food crops and livestock feed to produce ethanol and
biodiesel could push up food prices.
A Reuters report last week said one-fifth of this year's corn crop in the US would be used to
produce ethanol for use in vehicles.
"In our rush to secure our energy security, we could easily neglect the fundamental need for food
security," Reuters quoted Dan Glickman, who was agriculture secretary during the Clinton
administration, as telling a House of Representatives sub-committee on agriculture.
Glickman said US ethanol output could double to 10 billion gallons (around 13.8 billion litres)
annually by 2010, pushing corn prices to record levels.
•sunflower plants requires 118 percent more fossil energy than the fuel produced
Other people differ with Pimental and Patzek but their numbers seem to add up.
10
Cost of corn
Turkish corn to cost more in 2006
• Corn prices go up and down. Lately, they have been going up
due to demand from ethanol in USA
• The price reached $3/bu in June 2006; some predict prices of
$5/bu in the future
• The average ethanol conversion is 2.5 ga/bu
• Corn cost in ethanol is then around $1/ga or ¢26/L.
• The corn prices in the past lagged behind the petroleum prices
(see next slide). This might change if ethanol from corn stays.
• The corn price in Turkey is around 30 yeni kurus/kg, which
translates to $5/bu. Ethanol in Turkey will cost more than US
ethanol because Turkish corn costs more.
KONYA - Türkiye Ziraat Odaları Birliği (TZOB) Yönetim Kurulu Üyesi ve Konya'nın merkez
Meram ilçesi Ziraat Odası Başkanı Mustafa Hepokur, genelde tavuk yemi olarak kullanılan mısır
fiyatının, kuş gribi nedeniyle geçen yıl yetiştirenleri zarara uğrattığını, bu yıl ise 36 YKr
seviyelerine yükselerek yüzünü güldürdüğünü belirtti. Hepokur şunları söyledi: "Geçtiğimiz yıl
28-30 YKr civarında satılan mısırın fiyatı, şimdi 36 YKr seviyelerine çıktı. Bunda, yeniden
toparlanan tavukçuluk sektörünün mısır talebini artırmasının payı büyük. Mısır üreticilerimizin
durumu geçtiğimiz yıla göre daha iyi. Mısır fiyatı bu seviye ya da biraz daha yukarıda seyrederse
durumdan memnun oluruz. Ancak fiyatın düşmesi durumunda mısır üreticisi yine zarar eder.“
Corn Prices in Canada
Mısır fiyatı 36 YKr'ye çıktı
www.dunyagazetesi.com.tr 29/09/2006 08:35:12
Biofuels in Turkey
Tarım ve Köyişleri Bakanlığı tarafından hazırlanan ‘Ulusal Biyoyakıt Raporu’ndan:
Ülkemizde Biyoetanol ağırlıklı olarak şeker fabrikalarında melastan üretilmektedir.
Ülkemizin yıllık benzin tüketimi 4.5 milyon m3 ‘tür. TSE standartlarında kabul edildiği
gibi % 5 karışım esas alınarak hesaplandığında yıllık 225 000 m3 biyoetanole ihtiyaç
vardır. Mevcut teknoloji ile 1 lt biyoetanol için 2.5 kg buğday kullanılması gerekir.
Biyoetanol üretiminin artırılabilmesi için hammadde üretim miktarlarının artırılması
gerekir. Biyoetanol üretimi için en uygun hammaddeler mısır ve buğdaydır. Her iki
ürünün üretimlerinin de ülkemizde artırılma imkanı vardır. Mısır üretiminin 5 yıl
içerisinde 8 milyon tona, buğday üretiminin de 23 milyon tona çıkartılması mümkündür.
Yıllık motorin tüketiminin yaklaşık 10 milyon ton olduğu ülkemizde % 2 lik karıştırma
oranı için biyodizel ihtiyacı 200 000 m3, ’dür.
http://www.ontariocorn.org/facts/spec0796.html , a special report posted on the web site of
Ontario Corn Producers’ Association.
11
Gas-To-Liquid
South African Sasol is building
the world’s largest facility in
Qatar to convert reservoir gas to
diesel fuel.
Qatar plant will open at the end
of 2006 and will generate the
equivalent of 34000 barrels a
day at a capital investment of
about US$1b (EMN,24/11/06).
The Qatar process is sketched in
the diagram on the left. Note that
the bottom part (the actual GTL
process) can be implemented
with any methane-rich gas
including the syngas that can be
obtained by coal gasification.
12

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