The document summarizes combustion in compression ignition (CI) engines. It describes how combustion occurs simultaneously in many spots in a non-homogeneous fuel-air mixture, controlled by fuel injection timing. The four stages of CI engine combustion are ignition delay, premixed combustion, mixing-controlled combustion, and late combustion. Factors like injection timing and fuel quality can affect the ignition delay period. Knock may occur if ignition delay is too long. The document provides diagrams to illustrate CI engine combustion processes and types.
Actual cycles for internal combustion engines differ from air-standard cycles in many respects.
Time loss factor.
Heat loss factor.
Exhaust blow down factor.
PPT describes the engine performance parameters of the I.C. engine.
Engine performance is an indication of the degree of success of the engine performs its assigned task, i.e. the conversion of the chemical energy contained in the fuel into the useful mechanical work. The engine performance is indicated by the term efficiency, η. Five important engine efficiencies and other related engine performance parameters are:
Power
Indicated Thermal Efficiency (ηith)
Brake Thermal Efficiency (ηbth)
Mechanical Efficiency (ηm)
Volumetric Efficiency (ηv)
Relative Efficiency or Efficiency Ratio (ηrel)
Mean Effective Pressure (Pm)
Specific Fuel Consumption (sfc)
Fuel-Air or Air-Fuel Ratio (F/A or A/F)
Calorific Value (CV)
Power:-
The main purpose of running an engine is to obtain mechanical power.
Brake Power (B.P.)
The power developed by an Engine at the output shaft is called the brake power.
Brake Power= Brake Workdone/Time
B.P.=BWD/sec.
Indicated power (I.P.)
The total power developed by Combustion of fuel in the combustion chamber is called indicated power.
Indicated Power= Indicated Workdone/Time
I.P.=IWD/sec.
Frictional Power (F.P.)
The difference between I.P. and B.P. is called frictional power (f.p.).
FP = IP – BP
Thermal Efficiency (ηth)
Thermal efficiency is the ratio of Power to energy supplied by the fuel.
ηth= Power/ Energy
In I.C. Engine, thermal efficiency can be classified into two categories i.e.
Indicated Thermal Efficiency (ηith)
Indicated thermal efficiency is the ratio of indicated power to the heat supplied or added.
ηith= IP/Qs
2. Brake Thermal Efficiency (ηith)
Brake Thermal Efficiency is the ratio of brake power to the heat supplied or added.
ηbth= BP/Qs
Volumetric Efficiency (ηv)
This is one of the most important parameters which decide the performance of four-stroke engines. Four stoke engines have distinct suction stoke, volumetric efficiency indicates the breathing ability of the engine.
Volumetric efficiency is defined as the ratio of actual flow rate of air into the intake system to rate at which the volume is displaced by the system.
ηv= (푚 ̇"a/a" )/(푉푑푖푠푝푎푐푒푑 푋 푁/2)
"a"= Inlet density is taken atmospheric air density
N= Number of the cylinder in use
Actual cycles for internal combustion engines differ from air-standard cycles in many respects.
Time loss factor.
Heat loss factor.
Exhaust blow down factor.
PPT describes the engine performance parameters of the I.C. engine.
Engine performance is an indication of the degree of success of the engine performs its assigned task, i.e. the conversion of the chemical energy contained in the fuel into the useful mechanical work. The engine performance is indicated by the term efficiency, η. Five important engine efficiencies and other related engine performance parameters are:
Power
Indicated Thermal Efficiency (ηith)
Brake Thermal Efficiency (ηbth)
Mechanical Efficiency (ηm)
Volumetric Efficiency (ηv)
Relative Efficiency or Efficiency Ratio (ηrel)
Mean Effective Pressure (Pm)
Specific Fuel Consumption (sfc)
Fuel-Air or Air-Fuel Ratio (F/A or A/F)
Calorific Value (CV)
Power:-
The main purpose of running an engine is to obtain mechanical power.
Brake Power (B.P.)
The power developed by an Engine at the output shaft is called the brake power.
Brake Power= Brake Workdone/Time
B.P.=BWD/sec.
Indicated power (I.P.)
The total power developed by Combustion of fuel in the combustion chamber is called indicated power.
Indicated Power= Indicated Workdone/Time
I.P.=IWD/sec.
Frictional Power (F.P.)
The difference between I.P. and B.P. is called frictional power (f.p.).
FP = IP – BP
Thermal Efficiency (ηth)
Thermal efficiency is the ratio of Power to energy supplied by the fuel.
ηth= Power/ Energy
In I.C. Engine, thermal efficiency can be classified into two categories i.e.
Indicated Thermal Efficiency (ηith)
Indicated thermal efficiency is the ratio of indicated power to the heat supplied or added.
ηith= IP/Qs
2. Brake Thermal Efficiency (ηith)
Brake Thermal Efficiency is the ratio of brake power to the heat supplied or added.
ηbth= BP/Qs
Volumetric Efficiency (ηv)
This is one of the most important parameters which decide the performance of four-stroke engines. Four stoke engines have distinct suction stoke, volumetric efficiency indicates the breathing ability of the engine.
Volumetric efficiency is defined as the ratio of actual flow rate of air into the intake system to rate at which the volume is displaced by the system.
ηv= (푚 ̇"a/a" )/(푉푑푖푠푝푎푐푒푑 푋 푁/2)
"a"= Inlet density is taken atmospheric air density
N= Number of the cylinder in use
Definition of Supercharging ,
Effect of Supercharging ,
Need of Supercharging ,
Types of Supercharging
1) Centrifugal Supercharger
2) Rootes Supercharger
3) Vane Supercharger ,
Advantages & Disadvantages of Supercharging
this is the ppt on 2 stroke and 4 stroke petrol engine. . i made this ppt with the help of dhrumil patel .who is in the L.D. college of engineering in chemical department. . i am very thankful to him for being my great partner. . .thanx dhrumil..
Theoretical cycle based on the actual properties of the cylinder contents is called the fuel air cycle.
The fuel air cycle takes into consideration the following.
The ACTUAL COMPOSITION of the cylinder contents.
The VARIATION OF SPECIFIC HEAT of the gases in the cylinder.
The DISSOCIATION EFFECT.
The VARIATION IN THE NUMBER OF MOLES present in the cylinder as the pressure and temperature change
Definition of Supercharging ,
Effect of Supercharging ,
Need of Supercharging ,
Types of Supercharging
1) Centrifugal Supercharger
2) Rootes Supercharger
3) Vane Supercharger ,
Advantages & Disadvantages of Supercharging
this is the ppt on 2 stroke and 4 stroke petrol engine. . i made this ppt with the help of dhrumil patel .who is in the L.D. college of engineering in chemical department. . i am very thankful to him for being my great partner. . .thanx dhrumil..
Theoretical cycle based on the actual properties of the cylinder contents is called the fuel air cycle.
The fuel air cycle takes into consideration the following.
The ACTUAL COMPOSITION of the cylinder contents.
The VARIATION OF SPECIFIC HEAT of the gases in the cylinder.
The DISSOCIATION EFFECT.
The VARIATION IN THE NUMBER OF MOLES present in the cylinder as the pressure and temperature change
A COMPREHENSIVE REVIEW ON COMBUSTION OF COMPRESSION IGNITION ENGINES USING BI...IAEME Publication
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alternative fuels for IC engines. Biodiesel is an alternative fuel for conventional diesel engines and can be used without major modification of the engines
It contains Working, Construction of 4 stroke petrol engine with PV Diagram and Advantages & Disadvantages.Very useful & all info compiled at same place.
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Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
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Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
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2. 2
Combustion in CI Engine
Combustion in a CI engine is quite different
from that of an SI engine. While combustion in
an SI engine is essentially a flame front moving
through a homogeneous mixture, combustion
in a CI engine is an unsteady process
occurring simultaneously in many spots in a
very non-homogeneous mixture controlled by
fuel injection.
Air intake into the engine is unthrottled, with
engine torque and power output controlled
by the amount of fuel injected per cycle.
3. 3
Only air is contained in the cylinder during
compression stroke, and a much higher
compression ratios (12 to 24) are used in CI
engines.
In addition to swirl and turbulence of the
air, a high injection velocity is needed to
spread the fuel throughout the cylinder and
cause it to mix with the air.
Fuel is injected into the cylinders late in
the compression stroke by one or more
injectors located in each cylinders.
Injection time is usually about 200 of
crankshaft rotation (150 bTDC and 50 aTDC).
4. 4
Cylinder pressure as a function
of crank angle for a CI engine.
A : point of fuel injection
B : point of ignition
C : end of fuel injection
AB : delay period
5. 5
Combustion in CI Engine
In a CI engine the fuel is sprayed directly into the
cylinder and the fuel-air mixture ignites spontaneously.
These photos are taken in a RCM under CI engine
conditions with swirl air flow
0.4 ms after ignition 3.2 ms after ignition
3.2 ms after ignition Late in combustion process
1cm
6. 6
In Cylinder Measurements
This graph shows the fuel injection flow rate, net heat release
rate and cylinder pressure for a direct injection CI engine.
Start of injection
Start of combustion
End of injection
7. 7
Four Stages of Combustion in CI Engines
Start of
injection
End of
injecction
-10 TC-20 10 20 30
8. 8
Combustion in CI Engine
The combustion process proceeds by the following stages:
Ignition delay (ab) - fuel is injected directly into
the cylinder towards the end of the compression
stroke. The liquid fuel atomizes into small drops
and penetrates into the combustion chamber.
The fuel vaporizes and mixes with the high-
temperature high-pressure air.
Premixed combustion phase (bc) –
combustion of the fuel which has mixed with
the air to within the flammability limits (air at
high-temperature and high-pressure) during
the ignition delay period occurs rapidly in a
few crank angles.
9. 9
Combustion in CI Engine – contd.
Mixing controlled combustion
phase (cd) – after premixed
gas consumed, the burning
rate is controlled by the rate
at which mixture becomes
available for burning. The
rate of burning is controlled in
this phase primarily by the
fuel-air mixing process.
Late combustion phase (de) – heat release may
proceed at a lower rate well into the expansion
stroke (no additional fuel injected during this phase).
Combustion of any unburned liquid fuel and soot is
responsible for this.
10. 10
CI Engine Types
Two basic categories of CI engines:
i) Direct-injection – have a single open
combustion chamber into which fuel is
injected directly
ii) Indirect-injection – chamber is divided into
two regions and the fuel is injected into the
“pre-chamber” which is connected to the
main chamber via a nozzle, or one or more
orifices.
11. 11
CI Engine Types – contd.
• For very-large engines (stationary power
generation) which operate at low engine speeds
the time available for mixing is long so a direct
injection quiescent chamber type is used (open or
shallow bowl in piston).
• As engine size decreases and engine speed
increases, increasing amounts of swirl are used to
achieve fuel-air mixing (deep bowl in piston).
• For small high-speed engines used in automobiles
chamber swirl is not sufficient, indirect injection is
used where high swirl or turbulence is generated in
the pre-chamber during compression and
products/fuel blowdown and mix with main
chamber air.
12. 12
Types of CI Engines
Direct injection:
quiescent chamber
Direct injection:
swirl in chamber Indirect injection: turbulent
and swirl pre-chamber
Orifice
-plate
Glow plug
13. 13
Direct Injection
quiescent chamber
Direct Injection
multi-hole nozzle
swirl in chamber
Direct Injection
single-hole nozzle
swirl in chamber
Indirect injection
swirl pre-chamber
14. 14
Combustion Characteristics
Combustion occurs
throughout the chamber
over a range of
equivalence ratios
dictated by the fuel-air
mixing before and
during the combustion
phase.
In general most of the
combustion occurs under
very rich conditions
within the head of the jet,
this produces a
considerable amount of
solid carbon (soot).
15. 15
Ignition Delay
Ignition delay is defined as the time (or crank angle
interval) from when the fuel injection starts to the onset
of combustion.
Both physical and chemical processes must take place
before a significant fraction of the chemical energy of
the injected liquid is released.
Physical processes are fuel spray atomization,
evaporation and mixing of fuel vapour with cylinder air.
Good atomization requires high fuel-injection pressure, small
injector hole diameter, optimum fuel viscosity, high cylinder
pressure (large divergence angle).
Rate of vaporization of the fuel droplets depends on droplet
diameter, velocity, fuel volatility, pressure and temperature of
the air.
16. 16
Physical processes are fuel spray atomization,
evaporation and mixing of fuel vapour with
cylinder air.
Chemical processes similar to that described
for auto-ignition phenomenon in premixed fuel-
air, only more complex since heterogeneous
reactions (reactions occurring on the liquid fuel
drop surface) also occur.
Ignition Delay
17. 17
Fuel Ignition Quality
The ignition characteristics of the fuel
affect the ignition delay.
The ignition quality of a fuel is defined
by its cetane number CN.
For low cetane fuels the ignition delay is
long and most of the fuel is injected
before autoignition and rapidly burns,
under extreme cases this produces an
audible knocking sound referred to as
“diesel knock”.
18. 18
Fuel Ignition Quality
For high cetane fuels the ignition delay
is short and very little fuel is injected
before auto-ignition, the heat release
rate is controlled by the rate of fuel
injection and fuel-air mixing – smoother
engine operation.
19. 19
Cetane Number
The method used to determine the ignition
quality in terms of CN is analogous to that
used for determining the antiknock quality
using the ON.
The cetane number scale is defined by
blends of two pure hydrocarbon reference
fuels.
By definition, isocetane (heptamethylnonane,
HMN) has a cetane number of 15 and cetane
(n-hexadecane, C16H34) has a value of 100.
20. 20
Cetane Number
In the original procedures a-
methylnaphtalene (C11H10) with a
cetane number of zero represented the
bottom of the scale. This has since been
replaced by HMN which is a more stable
compound.
The higher the CN the better the
ignition quality, i.e., shorter ignition
delay.
21. 21
The method developed to measure CN uses a
standardized single-cylinder engine with
variable compression ratio
The operating condition is:
Inlet temperature (oC) 65.6
Speed (rpm) 900
Spark advance (oBTC) 13
Coolant temperature (oC) 100
Injection pressure (MPa) 10.3
Cetane Number Measurement
22. 22
With the engine running at these
conditions on the test fuel, the
compression ratio is varied until
combustion starts at TC, ignition delay
period of 13o.
The above procedure is repeated using
blends of cetane and HMN. The blend that
gives a 13o ignition delay with the same
compression ratio is used to calculate the
test fuel cetane number.
Cetane Number Measurement – contd.
23. 23
Cetane vs Octane Number
The octane number and cetane number
of a fuel are inversely correlated.
Gasoline is a poor diesel fuel and vice versa.
24. 24
Factors Affecting Ignition Delay
Injection timing – At normal engine conditions the
minimum delay occurs with the start of injection
at about 10-15 BTC.
The increase in the delay time with earlier or later
injection timing occurs because of the air
temperature and pressure during the delay
period.
Injection quantity – For a CI engine the air is not
throttled so the load is varied by changing the
amount of fuel injected.
25. 25
Increasing the load (bmep) increases the
residual gas and wall temperature which results
in a higher charge temperature at injection
which translates to a decrease in the ignition
delay.
Intake air temperature and pressure – an
increase in ether will result in a decrease in the
ignition delay, an increase in the compression
ratio has the same effect.
Factors Affecting Ignition Delay – contd.
27. 27
Factors Affecting Delay Period (DP)
1. Compression Ratio: DP decreases with
increase of CR.
2. Engine Speed: DP decreases with increase
of engine speed.
3. Power Output: DP decreases with increase
of power output.
4. Fuel Atomization: DP decreases with fineness
of atomization.
5. Fuel Quality: DP decreases with higher
cetane number.
6. Intake Temp. & Pressure: DP decreases with
increase of Temperature and pressure.
29. 29
Knock in CI Engines
Knock in SI and CI engines are fundamentally
similar. In SI engines, it occurs near the end of
combustion; whereas in CI engines, it occurs
near the beginning of combustion.
Knock in CI engines is related to delay
period. When DP is longer, there will be more
and more accumulation of fuel droplets in
combustion chamber. This leads to a too rapid
a pressure rise due to ignition, resulting in
jamming of forces against the piston and rough
engine operation. When the DP is too long, the
rate of pressure rise is almost instantaneous
with more accumulation of fuel.