1. The document discusses combustion processes in diesel engines, including premixed combustion, diffusion combustion, and post-injection combustion. Combustion models are presented that account for factors like fuel-air mixing time scales.
2. Emission sources from diesel engines are examined, including hydrocarbons from overmixing and undermixing of fuel and air as well as CO formation processes. Particulate matter formation and composition are also summarized.
3. NOx formation mechanisms like the Zeldovich mechanism are outlined, and the effect of equivalence ratio on NOx concentration is described. Control of engine emissions through combustion optimization and aftertreatment devices is briefly discussed.
Three basic methods used to control engine emissions:
1)Engineering of combustion process -advances in fuel injectors, oxygen sensors, and on-board computers.
2) Optimizing the choice of operating parameters -two Nox control measures that have been used in automobile engines are spark retard and EGR.
3) After treatment devices in the exhaust system -catalytic converter.
Three basic methods used to control engine emissions:
1)Engineering of combustion process -advances in fuel injectors, oxygen sensors, and on-board computers.
2) Optimizing the choice of operating parameters -two Nox control measures that have been used in automobile engines are spark retard and EGR.
3) After treatment devices in the exhaust system -catalytic converter.
An internal combustion engine is a heat engine (a device in which thermal energy is converted into mechanical
energy) in which the heat source is a combustible mixture that also serves as the working fluid. The working
fluid in turn is used either to (1) produce shaft work by pushing on a piston or turbine blade that in turn
drives a rotating shaft or (2) create a high-momentum fluid that is used directly for propulsive force.
Pollutant,their formation and control in Internal Combustion EnginesHassan Raza
This presentation was prepared by Mechanical Engineering students during their Internal Combustion Course. Students belong to a very prestigious Engineering institute of Pakistan "University of Engineering and Technology Lahore"
Diesel Engine Combustion Simulation using Computational Fluid DynamicsIDES Editor
Diesel engines are used in automotive and stationary
applications. The main problem with diesel engines is emissions
of nitrogen oxides (NOx) and particulates. In order to minimize
the emissions, it is necessary to design the diesel engine with
better in-cylinder flow (air-fuel mixing) and combustion
process. Computational Fluid Dynamics (CFD) simulation
helps to understand the Diesel engine temperature distribution
and NOx species concentrations with respect to time. A small
direct injection (DI) engine was chosen for the study. CFD
simulation results were compared with that of engine emission
tests. Results were found to be in agreement with NOx
emissions. This paper also presents the simulation results of
direct injection diesel engine in-cylinder flow (air-fuel mixing)
and combustion.
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.
An internal combustion engine is a heat engine (a device in which thermal energy is converted into mechanical
energy) in which the heat source is a combustible mixture that also serves as the working fluid. The working
fluid in turn is used either to (1) produce shaft work by pushing on a piston or turbine blade that in turn
drives a rotating shaft or (2) create a high-momentum fluid that is used directly for propulsive force.
Pollutant,their formation and control in Internal Combustion EnginesHassan Raza
This presentation was prepared by Mechanical Engineering students during their Internal Combustion Course. Students belong to a very prestigious Engineering institute of Pakistan "University of Engineering and Technology Lahore"
Diesel Engine Combustion Simulation using Computational Fluid DynamicsIDES Editor
Diesel engines are used in automotive and stationary
applications. The main problem with diesel engines is emissions
of nitrogen oxides (NOx) and particulates. In order to minimize
the emissions, it is necessary to design the diesel engine with
better in-cylinder flow (air-fuel mixing) and combustion
process. Computational Fluid Dynamics (CFD) simulation
helps to understand the Diesel engine temperature distribution
and NOx species concentrations with respect to time. A small
direct injection (DI) engine was chosen for the study. CFD
simulation results were compared with that of engine emission
tests. Results were found to be in agreement with NOx
emissions. This paper also presents the simulation results of
direct injection diesel engine in-cylinder flow (air-fuel mixing)
and combustion.
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.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
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.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
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
4. -10 TC
-20 10 20 30
Start of
injection
End of
injecction
Homogeneous Combustion in CI Engine
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.
5. Premixed combustion
• It is assumed that the rate of premixed combustion is
proportional to the mass of the fuel-air mixture prepared
during the ignition delay period and given as
c
j
mix
p
p
j
b m
C
dt
dm
,
,
l
c
S
where is the Taylor microscale and Sl is the laminar flame speed.
mmix,j is the mass of the fuel-air mixture in the given element.
Cp is an arbitrary tuning constant determined to (0.002 to 0.005)
to match the test bed data.
6. The Taylor microscale
• The Taylor microscale is given as
2
1
'
15
L
u
A
L
where u' is the rms value of turbulent fluctuation velocity,
L is the integral length scale, and is the kinematic
viscosity.
The constant, A, is set to be close to unity.
The integral length scale is given as
4
3
4
/
3 k
v
C
L
where the constant, Cv, is in the range of 0.06 – 0.12.
7. • 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 burning rate is controlled primarily by the fuel-air
mixing process.
-10 TC
-20 10 20 30
Start of
injection
End of
injecction
8. Diffusion combustion
• Fuel-air mixing is the dominant mechanism to determine the rate of
combustion during the diffusion combustion period.
9. Diffusion combustion
• Fuel-air mixing is the dominant mechanism to determine the
rate of combustion during the diffusion combustion period.
• The turbulent mixing time scale is introduced to represent the
rate of fuel-air mixing as,
c
ca
c
ca
j
e
d
j
b
dt
dm
dt
dm
for
,
,
c
ca
j
e
d
j
b
dt
dm
dt
dm
for
,
,
3
/
1
2
e
e
,
where
m
L
C
dt
dm
e
e
j
e
10. • where mb; and me are the masses of burned fuel and
entrained air in the element.
• The time scales, c and ca, denote the mixing time and the
time corresponding to one degree crank angle.
• The arbitrary tuning constant, Ce, is chosen here to be 3.0 -
- 5.0 X 10-5 to match the test bed data.
11. Post Injection Combustion
• The models during the fuel injection period may not be
applicable after the end of fuel injection for the spray detached
from the nozzle and moving downstream.
• The in-cylinder flow effects need to be considered to predict the
combustion after the end of fuel injection.
• This is described as a mixing process with the available air at a
rate controlled by turbulence in the fuel jet as,
m
e
a
e,
,
,
a
e
j
e
C
dt
dm
where mea is the total mass of unused air in the cylinder.
The constant, Ce,a, is determined from the continuity of the
combustion rate at the end of fuel injection.
12. Post (End of ) Injection Combustion
• The models during the fuel injection period may not be
applicable after the end of fuel injection for the spray detached
from the nozzle and moving downstream.
• The in-cylinder flow effects need to be considered to predict the
combustion after the end of fuel injection.
• This is described as a mixing process with the available air at a
rate controlled by turbulence in the fuel jet as,
m
e
a
e,
,
,
a
e
j
e
C
dt
dm
where mea is the total mass of unused air in the cylinder.
The constant, Ce,a, is determined from the continuity of the
combustion rate at the end of fuel injection.
13. • 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 TC
-20 10 20 30
Start of
injection
End of
injecction
15. Hydrocarbon Emission Sources for CI Engines
Overmixing of fuel and air - During the ignition delay period
evaporated fuel mixes with the air, regions of fuel-air mixture are
produced that are too lean to burn.
Some of this fuel makes its way out the exhaust.
Longer ignition delay more fuel becomes overmixed.
Undermixing of fuel and air - Fuel leaving the injector nozzle at low
velocity, at the end of the injection process cannot completely mix
with air and burn.
17. Formation of CO in CI Engines
• The mean air-fuel mixture present in the combustion chamber
per cycle is far leaner in the diesel engine than in the SI
engine.
• Due to a lack of homogeneity of the mixture built up by
stratification, however, extremely “rich” local zones are exist.
• This produces high CO concentrations that are reduced to a
greater or lesser extent by post-oxidation.
• When the excess-air ratio increases, dropping temperatures
cause the post-oxidation rate to be reduced.
• The reactions “freeze up”.
• However, the final CO concentrations of diesel engines
therefore are far lower than in SI engines.
• The basic principles of CO formation, however, are the same
as in SI engine.
18. Particulates
• A high concentration of particulate matter (PM) is manifested
as visible smoke in the exhaust gases.
• Particulates are any substance other than water that can be
collected by filtering the exhaust, classified as:
• Solid carbon material or soot.
• Condensed hydrocarbons and their partial oxidation products.
• Diesel particulates consist of solid carbon (soot) at exhaust gas
temperatures below 500oC, HC compounds become absorbed on
the surface.
• In a properly adjusted SI engines soot is not usually a problem .
• Particulate can arise if leaded fuel or overly rich fuel-air mixture
are used.
• Burning crankcase oil will also produce smoke especially during
engine warm up where the HC condense in the exhaust gas.
20. 20
The soot formation process is very fast.
10 – 22 C atoms are converted into 106 C atoms in less than 1 ms.
Based on equilibrium the composition of the fuel-oxidizer mixture soot ,
formation occurs when x ≥ 2a (or x/2a ≥ 1) in the following reaction:
Mechanism of Formation of Particulates (soot)
)
(
)
2
(
2
2 2
2 s
C
a
x
H
y
aCO
aO
H
C y
x
Experimentally it is found that the critica C/O ratio for onset of soot
formation is between 0.5 and 0.8.
The CO, H2, and C(s) are subsequently oxidized in the diffusion flame
to CO2 and H2O via the following second stage.
O
H
O
H
CO
O
s
C
CO
O
CO 2
2
2
2
2
2
2
2
1
)
(
2
1
Any carbon not oxidized in the cylinder ends up as soot in the exhaust!
21. NOx Formation in I.C. Engines
Three chemical reactions form the Zeldovich reaction are:
Forward rate constants:
T
k
T
k
T
k
f
f
f
/
450
exp
10
1
.
7
/
4680
exp
10
8
.
1
/
38370
exp
10
8
.
1
10
,
3
7
,
2
11
,
1
Zelodvich reaction is the most significant mechanism of NO
formation in IC engines.
22. 22
Global Reaction Rate
• Using the chemical reactions given, one can write the
following expression for the rate of change of nitric oxide
concentration.
• Where the brackets denote concentrations in units of molecules/m3.
• Approximations to solve above equation:
• The C-O-H system is in equilibrium and is not perturbed by N2
dissociation.
• This means that the pressure, temperature, equivalence ratio and
residual fraction of fluid element only are required to calculate NO
concentration.
• N atoms change concentration by a quasi-steady process.
• This means that one can solve for the N atom concentration by
setting the rate of change of atoms to zero.
H
NO
k
OH
N
k
O
NO
k
O
N
k
N
NO
k
N
O
k
dt
NO
d
b
f
b
f
b
f ,
3
,
3
,
2
2
,
2
,
1
2
,
1
25. Emissions Control
• Three basic methods used to control engine emissions:
• 1)Engineering of combustion process -advances in fuel
injectors, oxygen sensors, and on-board computers.
• 2) Optimizing the choice of operating parameters -two Nox
control measures that have been used in automobile engines
are spark retard and EGR.
• 3) After treatment devices in the exhaust system -catalytic
converter.
25