Title: Course Specifications
1Course Specifications
-
- A Basic Information
-
- Course Title Heat Engine and Combustion (B)
CodeMPE321 - Lecture 2 Tutorial 2 Practical 0 Total 4
- Program on which the course is given B.Sc.
Mechanical Engineering (Power) - Major or minor element of program Major
- Department offering the program Mechanical
Engineering Department - Department offering the course Mechanical
Engineering Department - Academic year / level Third Year / Second
Semester - Date of specifications approval 10/5/2006
2- B- Professional Information
- 1- Overall aims of course
-
- By the end of the course the students will be
able to - Identify the different types of fuels and their
properties. - - Understand the concepts and principles of the
chemical reactions. - - Understand the basic principles of the chemical
and the phase equilibrium. - - Apply the first and second law of
thermodynamics on chemical reactions.- Know the
different types of flames and their theories. - - Know the construction and operation of the
industrial furnaces and their applications. - - Know the factors affecting the furnaces
performance.
32-Intended Learning Outcomes (ILOs)
- a) Knowledge and Understanding
- a.5) Methodologies of solving engineering
problems, data collection interpretation. - a.8) Current engineering technologies as related
to disciplines. - a.13) Fundamentals of thermal and fluid
processes. - a.18) Mechanical power and energy engineering
contemporary issues. - a.19) Basic theories and principles of some other
engineering and mechanical engineering
disciplines providing support to mechanical power
and energy disciplines
42-Intended Learning Outcomes (ILOs)
- b) Intellectual Skills
- b.1) Select appropriate mathematical and
computer-based methods for modeling and analyzing
problems. - b.5) Assess and evaluate the characteristics and
performance of components, systems and processes - b.7) Solve engineering problems, often on the
basis of limited and possibly contradicting
information. - b.11) Analyze results of numerical models and
appreciate their limitations. - b.13) Evaluate mechanical power and energy
engineering design, processes, and performance
and propose improvements.
52-Intended Learning Outcomes (ILOs)
- Professional and Practical Skills
- c.1) Apply knowledge of mathematics, science,
information technology, design, business context
and engineering practice to solve engineering
problems. - c.12) Prepare and present technical reports.
- c.16) Describe the basic thermal and fluid
processes mathematically and use the computer
software for their simulation and analysis.
61-Intended Learning Outcomes (ILOs)
- General and Transferable Skills
- d.3) Communicate effectively.
- d.4) Demonstrate efficient IT capabilities.
- d.7) Search for information and engage in
life-long self learning discipline. -
73- Contents
No Topic No. of hours ILOs Teaching / learning methods and strategies Assessment method
1 Fuel types and properties 2 a.8, c.12,d.4,d.7 Lecture Report
2 Chemical reactions Theoretical and actual combustion processes 2 a.5, a.13, b.5, b.7, b.13, c.1 Lecture tutorial Assignment
3 Enthaply of formation, enthalpy of reaction 2 a.5, a.13, b.5, b.7, b.13, c.1 Lecture tutorial Assignment
4 1st and 2nd law analysis of combustion processes 2 a.5, a.13, b.5, b.7, b.13, c.1 Lecture tutorial Quiz
5 Chemical equilibrium 2 a.13,b.7, c.1 Lecture tutorial Assignment
6 Chemical equilibrium (continued) 2 a.13,b.7, c.1 Lecture tutorial Quiz
7 Phase equilibrium 2 a.13,b.7, c.1 Lecture tutorial Assignment
8 Mid-term exam Mid-term exam Mid-term exam Mid-term exam Mid-term exam
9 Laminar premixed flames 2 a.8,a.13,a.19,b.7, c.1, c.12,c.16, d.3,d.7 Lecture tutorial Assignment
10 Laminar diffusion flames 2 a.8,a.13,a.19,b.7, c.1, c.12,c.16, d.3,d.7 Lecture tutorial Quiz - Report
11 Turbulent premixed and non-premixed flames 2 a.8,a.13,a.19,b.7, c.1, c.12,c.16, d.3,d.7 Lecture tutorial Assignment
12 Introduction to industrial furnaces 2 a.8,a.13,a.19,b.7, b.13, c.1,c.12, d.4, d.7 Lecture tutorial Assignment
13 Heat transfer in industrial furnaces 2 a.8,a.13,a.19,b.7, b.13, c.1,c.12, d.4, d.7 Lecture tutorial Quiz
14 Saving energy in industrial furnacs 2 a.8,a.13,a.19,b.7, b.13, c.1,c.12, d.4, d.7 Lecture tutorial Assignment - Report
15 Final exam Final exam Final exam Final exam Final exam
8- Teaching and Learning Methods
- __v__ Lectures
- _____ Practical training / laboratory
- _____ Seminar / workshop
- ____ Class activity
- __v__ Tutorial
- _____ Case study
- __v__ Assignments / homework
- Other Self study
9- Student Assessment Methods
- ________ Assignments to assess knowledge
and intellectual skills. . - ________ Quiz to assess knowledge, intellectual
and professional skills. - ________ Mid-term exam to assess knowledge,
intellectual, professional and general skills. - ________ Oral exam to assess knowledge,
intellectual, professional and general skills. - ________ Final exam to assess knowledge,
intellectual, professional and general skills. - Other Self study to assess knowledge,
intellectual, professional and general skills. -
10- Assessment schedule
- Assessment 1 on weeks 2, 5, 9, 11
- Assessment 2 Quizzes on weeks 4, 6, 10, 13
- Assessment 3 Mid-term exam on week 8
- Assessment 4 Oral Exam on week 14
- Assessment 5 Final exam on week 15
- Weighting of Assessments
- Mid- Term Examination 15
- Final- Term Examination 60
- Oral Examination 15
- Practical Examination 00
- Semester Work 05
- Other 05
- Total 100
118- List of References
- 8.1- G. Van Wylen, R. Sonntag and C. Borgnakke,
"Fundamentals of Classical Thermodynamics", Jhon
Wiley Sons. 1994. - 8.2-.Yunis, A. Cengle, and Michael A. Boles,
Thermodynamics- an Engineering Approach Fifth
edition, - 8.3-.J. Warnatz U. Maas R.W. Dibble,
Combustion, Springer-Verlag Berlin Heidelberg
1996, 1999, 2001
12- Facilities Required for Teaching and learning
- Lecture room
- Presentation board, computer and data show
-
- Course coordinator Prof. Dr. Ramadan Y.
Sakr - Course instructor Prof. Dr. Ramadan
Y. Sakr - Head of department Prof. Dr. Maher G. A.
Higazy Date 26/10/ 2011
13Fuels Fuels Properties
14Crude Oil
- Found in rock formations that were ocean floors.
- Organic matter from seas became trapped by
sediments at ocean floor. - Progressing cracking of the molecules and
elimination of oxygen turned organic matter into
petroleum.
15Crude Oil
- Petroleum is made of 86 carbon and 14 hydrogen.
- Hydrocarbon molecules are accompanied by dirt,
water, sulfur and other impurities. - Crude oil must be refined to produce suitable
engine fuels.
16Fig. 5.1 Molecular Structures of Some
Hydrocarbon Fuel Families
17Fig. 5.2 Flow Diagram for Typical Petroleum
Refinery
18Fig. 5.3 Distillation Curve for Crude Oil.
19Distillation Temperatures
- 30 to 230 C for Gasoline
- 230 to 370 C for Diesel
- Most refineries utilize cracking units where
catalysts at high temperatures and pressures
crack the larger hydrocarbon molecules into
smaller ones shifting production towards
gasoline. - Fractionating towers allow smaller molecules to
condense out at cooler temperatures in the upper
portion of the tower.
20Ideal Combustion
- All of the H in fuel is converted to H20.
- All of the C in fuel is converted to CO2.
- Air is 21 O and 79 N by volume.
21Combustion of Gasoline
22Stoichiometric Air/Fuel Mixture
23Table 5.2 Representative Fuel Molecules
24Fig.1-1 Aliphatic hydrocarbons
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26Fig.1-2 Alicyclic and aromatic hydrocarbo
27Fig. 1-3 Structural formulae for oxygenous
hydrocarbons
28Fig. (1-4) Boiling graph for gasoline and diesel
fuel, as well as kerosene and water
29Definition of the octane number (ON) for gasoline
fuels
For the determination of ignition performance, we
use a so-called comparison fuel, i.e. a two
component fuel consisting of
The octane number is defined as the isooctane
fraction of the comparison fuel.
Definition of the cetane number (CN) for diesel
fuels
In determining ignition performance, we use a
comparison fuel, which is, in this case, a two
component fuel composed of
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31A fuel can be considered as a finite resource of
chemical potential energy, i.e., energy stored in
the molecular structure of particular compounds
that may be released via complex chemical
reactions.
Some of the basic ideal combustion engineering
characteristics of a fuel include High energy
density (content) High heat of combustion
(release) Good thermal stability (storage) Low
vapor pressure (volatility) Nontoxicity
(environmental impact)
32THE FUEL-ENGINE INTERFACE
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35Gasoline Engine Exhaust
- SI engines are often operated with rich
air/fuel mixtures to produce more power
inadequate oxygen supply results in production of
CO (not all carbon is converted to CO2). - Even with lean mixtures, CO is still produced.
DO NOT OPERATE GASOLINE ENGINES IN CONFINED
SPACES!!!
36Diesel Air/Fuel Ratios
- Stoichiometric air/fuel mixture for CI engines
14.91. - However, most CI engines are operated with a
leaner air/fuel ration and therefore free oxygen
is often found in the exhaust.
37Diesel Engine Exhaust
- Small quantities of unburned fuel escape in
gaseous form. - At high temperatures N reacts with O to form NO
and NO2 (together these are known as NOx). - Federal government has established limits on CO,
NOx and unburned hydrocarbon in engine exhaust
Tier I through IV Regulations.
38Emission Regulations (EPA)
39Example 5.1
- What is the air/fuel ratio and the exhaust
products when ethanol is used as an engine fuel?
40Solution
41General Combustion Equations
- Equations are cast in a form that includes a
measure of richness, - where f is the richness term.
-
42General Combustion Equations
- The General Combustion Equation is,
- where x, y and z are the relative number of atoms
of C, H and O, respectively and U, R, V and W
are defined in the following relationships. -
43General Combustion Equations
44General Combustion Equations
- The actual A/F ratio becomes,
45General Combustion Equations
- The theoretical dry exhaust gas concentrations
(volumetric basis) become,
46Blended Fuels
- Blended fuels are common for example blends of
10 ethanol and 90 gasoline are used to meet
EPA requirements for oxygenated fuels in regions
of the country with impaired air quality.
47Blended Fuels
- The composite fuel molecule can be estimated
using, - where the p subscript denotes the primary fuel,
and s the secondary and variable f is the
faction (decimal form) of either fuel.
48Blended Fuels
- The resulting composite fuel molecule becomes,
49Octane Ratings
- Octane is a measure of gasolines resistance to
knock. - Knock is the uncontrolled release of energy
when combustion initiates somewhere other than
the spark plug. - Symptoms of engine knock include an audible
knocking or pining sound under acceleration.
50Fig. 5.5 Knock in SI engines.
51Causes of Engine Knock
- Knock is caused when the temperature in the
cylinder reaches the self ignition temperature
(SIT) of the end gases. - The end gases do not readily ignite, rather there
is an ignition delay caused by pre-flame
reactions. - Engine knock is more prevalent under conditions
that include - Lean air/fuel ratios
- High compression ratios
52Methods to Reduce Engine Knock
- Use wedge shaped combustion chambers to cool end
gases more readily. - Use gasoline with higher octane ratings these
ratings are associated with gasoline that has few
straight chain carbons have longer ignition delay
times.
53Octane Rating Measurement
- Procedure developed by the Cooperative Fuels
Research Committee (CFR). - The committee proposed a single cylinder SI
engine to measure octane the CFR engine has an
adjustable compression ratio. - Engine is driven at a constant speed with an
electric motor.
54Octane Rating Measurement
- Octane ratings are obtained by comparing fuel in
question to iso-octane (Octane Rating of 100) and
heptane (Octane Rating of 100). - CR is adjusted until knocking is detected with
fuel being tested. - Blends of iso-octane and heptane are tested until
the same level of knock is obtained. - Octane rating is of iso-octane in test blend.
55Fig. 5.6 CFR Engine
56Octane Ratings
- CFR developed initial method (Motor Octane Number
MON). - ASTM developed a new method (Research Octane
Number RON). - RON octane ratings are 8 points low than MON for
most gasoline. - Most retailers report the Anti-Knock Index which
is an average of MON and RON. - Octane ratings of fuel are adjusted for elevation
lower atmospheric pressure reduces the tendency
for engine knock to occur.
57Cetane Ratings and CI Engines
- Octane rating is not a good way to predict
knock in CI engines. - Combustion in diesel engines consists of a two
part delay physical and chemical. - Physical - the fuel is injected and atomized.
- Chemical - process proceeds with a pre-flame
chemical reaction, similar to that of SI engines.
58Fig. 5.7 Critical Compression Ratios and
Temperatures
59Combustion Process
- Pre-Mix Combustion prepared mixture burns
rapidly after compression ignition. - Diffusion Combustion fuel vapor diffuses into
burn-out zones from one side while oxygen
diffuses from the other sustaining the combustion
process. - Diffusion process is much slower than the
pre-mix. Pre-mix generate characteristic diesel
rattle.
60Fig. 5.8 Energy release from CI fuels.
61Altering Knock in CI Engines
- Ignition delay controls the relative release of
energy between the two phases of combustion a
longer delay results in more energy produces in
the pre-mix phase. - Since knock occurs when more energy is released
at the start of combustion, it follows that
knock is reduced with short delay periods.
62Cetane Ratings
- Cetane rating are an indication of the fuels
anti-knock resistance for CI engines. - Fuels with high cetane ratings are created by
increasing the proportion of long chain
molecules, thereby reducing the ignition delay. - Fuels with high Octane Rating have low cetane
ratings!
63Cetane Ratings
- CFR cetane rating process is similar to the
Octane process with a couple of differences - Cetane and hyptamethylnonane are the reference
fuels. - Hyptamethylnonane has a cetane rating of 15.
64Effect of Cetane Rating
- If cetane rating is too low, the ignition delay
results in hard starting (combustion after piston
is moving downward) and characteristic white
smoke. - High cetane ratings start the combustion process
to soon, and some the fuel is not volatized and
does not burn. - Black smoke in heavily loaded engines is a
symptom of high cetane ratings. - Minimum cetane rating for CI engines is 40
according to SAE. - Commercial fuels seldom exceed 50.
- Cetane rating should never exceed 60.
65Table 5 limiting values for diesel fuels.
66Fuel Properties
- Standards Organizations
- SAE Society of Automotive Engineers
- ASTM American Society for the Testing of
Materials - API American Petroleum Institute
67Specific Gravity
- A measure of the density of liquid fuels at 15.6
C as compared with water at the same temperature. - API devised the following scale,
- where SG is the specific gravity.
- A hydrometer, calibrated in APIo, is used to
measure the specific gravity.
68Fig. 5.9 Fuel hydrometer.
69Heating Value of Fuel
- Determined using bomb calorimeter.
- Bomb calorimeter measures low heating value
void of energy required to evaporate water. - High heating value is found by adding the
latent heat of vaporization of water to low
heating value.
70Table 5.4 Properties of selected fuels.
71Heating Value Estimates for Petroleum Fuels
- Heating values are estimated from the API
gravity, - where Hg is the gross (high) heating value and Hn
is the net (low) heating value.
72Fuel Volatility
- Volatility refers to the ability of the fuel to
vaporize at lower temperatures. - Reid vapor pressure and distillation curves are
indicators of fuel volatility. - Reid vapor pressure (RVP) is a standardized test
using bomb calorimeter at 37.1 C pressure is
measured using a suitable gage.
73Fuel Volatility
- Prior to 1990 winter gasoline volatility ranged
from 60 to 80 kPa. - Summer gasoline was 10 to 15 kPa lower to reduce
the potential for vaporization. - Clean Air Act (1990) limits maximum vapor
pressures to 56 kPa in the large Northern U.S.
cities and 49 kPa in large Southern U.S. cities.
74Distillation Tests
- 100 ml sample is distilled.
- Fuel temperature is recorded for first condensed
drop (boiling point), and then at 10 ml intervals
during the distillation process. - T10, T50 and T90 temperatures are important to
engine characteristics which include easy of
starting, warm-up, and crankcase dilution and
fuel economy, respectively.
75Fig. 5.10 Fuel distillation aparataus.
76Adjusting Distillation Temperatures
- Gasoline sold during the winter must be more
volatile for easy starting in the winter. - Gasoline sold for use in high elevations must be
less volatile to avoid vapor lock in the
summer. - Volatility is adjusted by adding butane and
lighter hydrocarbons.
77Adjusting Distillation Temperatures
- For diesel engines
- Low T10 values aids cold weather starting.
- Low T50 values minimize smoke and odor.
- Low T90 values reduce crankcase dilution and
improve fuel economy.
78Fig. 5.11 Distillation curves.
79Fuel Viscosity
- Viscosity is a measure of the flow resistance of
liquid. - Fuel viscosity must be high enough to insure good
lubrication of injection pump mechanisms in CI
engines. - Fuel viscosity must be low enough to insure
proper atomization at the time of injection.
80Cloud and Pour Points
- Cloud point is the temperature at which crystals
begin to form in the fuel. - Pour point is the temperature at which the fuel
ceases to flow. - Cloud point are typically 5 to 8 C higher than
pour point, - Not an issue for gasoline.
- Values are important for diesel.
81Fuel Impurities - Sulfur
- Sulfur oxides can convert to acids which
corrode engine parts and cause increased wear. - Assessed by immersing copper strip in fuel for
three hours, then comparing corrosion to standard
strips.
82Fuel Impurities - Ash
- Ash small solid particles or water-soluble
metals found fuels. - Defined as un-burned fuel residue left behind.
- Can cause accelerated wear of close-fitting
injection system parts.
83Fuel Impurities Water and Sediment
- Moisture can condense in fuel storage tanks, or
seep in from underground leaks. - Fuel should be bright and clear, and visibly free
of water and sediment.
84Fuel Impurities - Gum
- Gum can form in gasoline, leaves behind deposits
on carburetors. Gum is dissolved by gasoline
more prevalent in gasoline that is made by
cracking. - Antioxidants are now added to both diesel and
gasoline to extend storage life without gum
formation.
85Fuel Additives
- Until 1970, gasoline contained TEL (tetraethyl
lead). TEL was used as an octane booster. - MTBE (methyl tertiary butyl ether) is often
substituted as an octane booster could be
phased out/banned by EPA soon.
86Table 5.5 Gasoline additives
87Fuel Storage
- Fuels classified according to flammability
gasoline is more dangerous with a flash point of
-40 C. - Major concern with regard to environmental
contamination
88Fig. 5.12 Lubricating Theory
89Fig. 5.13 Action of Journal Bearings
a) at rest, b) in mixed-film lubrication, and c)
in hydrodynamic lubrication
90Fig. 5.14 Newtonian Viscosity
91Fig. 5.15 Cannon-Fenske Viscometer
92Reporting of Viscosity
- Kinematic viscosity (n) is reported as,
- where m is absolute (or dynamic) viscosity, and r
is the fluid mass density.
93Typical Units
- Centipoise (cP) was the popular unit of dynamic
viscosity. - Centistoke (cSt) was the popular unit of
kinematic viscosity.
94Table 5.6 SAE Motor Oil Classification
95Motor Oil Service Ratings
- S- SERVICE CLASSIFICATIONS FOR GASOLINE ENGINES
- SH- For 1994 Gasoline Engine Service --
Classification SH was adopted in 1992 and
recommended for gasoline engines in passenger
cars and light trucks starting in 1993 model
year. This category supercedes the performance
requirements of API SG specification for
1989-1992 models, which is now obsolete.
Applications that call for an API service
classification SG can use the SH specification.
The specification addresses issues with deposit
control, oxidation, corrosion, rust and wear and
replaces. - SJ- For 1997 Gasoline Engine Service --
Classification SJ was adopted in 1996 and
recommended for gasoline engines in passenger
cars and light trucks starting in 1997 model
year. Applications specifying API SH can use the
newer API SJ service classification. Note that
where applicable certain letters in the sequence
will be skipped to prevent confusion with other
standards. In this case, SI was skipped since
industrial oils are currently rated according to
SI classifications. - SL- For 2001 and Newer Gasoline Engine Service-
Current Spec. -- Recommended for gasoline engines
in passenger cars and light trucks starting in
July 2001. SL oils are engineered to provide
improved high temperature deposit control and
lower oil consumption. Applications specifying
API SJ can use the new API SL service
classification. Note that some SL rated oils may
also meet the latest ILSAC specification and/or
qualify as energy conserving. SL is the latest
specification.
96Motor Oil Service Ratings
- C- COMMERCIAL CLASSIFICATIONS FOR DIESEL
ENGINES - CF-For 1994 Off-Road Indirect Injected Diesel
Engine Service -- API Service Category CF denotes
service typical of off-road, indirect injected
diesel engines and other diesel engines that use
a broad range of fuel types, including those
using fuel with higher sulfur content (over 0.5
wt sulfur fuel). Effective control of piston
deposits, wear and corrosion of copper-containing
bearings is essential for these engines, which
may be naturally aspirated, turbocharged or
supercharged. Oils designated for this service
may also be used when API Service Category CD or
CE is recommended. CF is a current
specification. - CF-2- FOR 1994 Severe Duty 2-Stroke Cycle Diesel
Engine Service -- API Service Category CF-2
denotes service typical of two-stroke cycle
engines (such as Detroit Diesel) requiring highly
effective control over cylinder and ring-face
scuffing and deposits. Oils designated for this
service have been in existence since 1994 and may
also be used when API Service Category CD-II is
recommended. These oils do not necessarily meet
the requirements of CF or CF-4, unless they pass
the test and performance requirements for these
categories. CF-2 is a current specification. - CF-4- For 1990 Diesel Engine Service -- Service
typical of severe duty turbocharged, 4-stroke
cycle diesel engines, particularly late models
designed to give lower emissions. These engines
are usually found in on-highway, heavy-duty truck
applications. API CF-4 oils exceed the
requirement of CE category oils and can be used
in place of earlier CC, CD and CE oils. CF-4 oils
provide for improved control of piston deposits
and oil consumption. The CF-4 classification
meets Caterpillars 1k engine requirements, as
well as earlier Mack Trucks (T-6 T-7) and
Cummins (NTC-400) multi-cylinder engine test
criteria. When combined with the appropriate S
category, they can be used in gasoline and diesel
powered cars and light trucks as specified by the
vehicle and/or engine manufacturer.
97Motor Oil Service Ratings
- CG-4- For 1995 Severe Duty Diesel Engine Service
-- API Service Category CG-4 describes oils for
use in high speed, four-stroke cycle diesel
engines used in highway and off-road
applications, where the fuel sulfur content may
vary from less than 0.05 by weight to less than
0.5 by weight. CG-4 oils provide effective
control over high temperature piston deposits,
wear, corrosion, foaming, oxidation stability and
soot accumulation. These oils are especially
effective in engines designed to meet 1994
exhaust emissions standards and may also be used
in engines requiring API Service Categories CD,
CE and CF-4. Oils designated for this service
have been in existence since 1995. CG-4 is a
current specification - CH-4- For 1999 Severe Duty Diesel Engine Service
-- API Service Category CH-4 describes oils for
use in high speed, four-stroke cycle diesel
engines used in highway and off-road
applications. CH-4 oils provide effective
control over engine deposits, wear, corrosion,
oxidation stability and soot accumulation. These
oils are especially effective in engines designed
to meet 1999 emission standards and may also be
used in engines requiring API Service Category
CG-4. Oils designated for this service have been
in existence since 1999. CH-4 oils are engineered
for use with diesel fuels ranging in sulfur
content up to 0.5 weight. CH-4 is a current
specification. - CL-4- For 2002 Severe Duty Diesel Engine
Service -- API Service Category CL-4 describes
oils for use in those high speed, four-stroke
cycle diesel engines designed to meet 2004
exhaust emissions standards and was implemented
in October 2002. These oils are engineered for
all applications where diesel fuel sulfur content
is up to 0.05 by weight. These oils are very
effective at sustaining engine durability where
EGR ( Exhaust Gas Recirculation) and other
exhaust emissions systems are used and provide
for optimum protection in the areas of corrosive
wear, low and high temperature stability, soot
handling properties, piston deposit control,
valvetrain wear, oxidative thickening and foaming
and viscosity loss due to shear. API CL-4 oils
are superior in performance to those meeting
API-CH-4, CG-4 and CF-4 and can be used and will
effectively lubricate diesel engines specifying
those API service Classifications.
98Table 5.8 Lubricating Oil Additives
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100Fig. 5.16 Pressure-Feed and Splash Lubrication
System.