ABSTRACT
This work analysed the performance of an automatic control system for the online
blending of petrol with corrosion inhibitor in the direct, continuous electronic fuel
injection automobile engine. The automatic control system was designed by
superimposing a feedforward control system on a feedback control system. The
design of the automatic control system was analysed by the method of direct
substitution. The governing equations used in analysing the blending process, as well
as the applicable equations which modelled the process disturbance were derived
from first principles – using transfer functions and block diagram representations. The
performance of the automatic control system was simulated with the aid of computer
software; and the results obtained from the simulation showed that the response of the
automatic control system is oscillatory and stable.
TABLE OF CONTENTS
Title Page i
Approval ii
Certification iii
Dedication iv
Acknowledgements v
Abstract vi
Table of Contents vii
List of Tables ix
List of Figures x
Nomenclature xii
CHAPTER ONE: INTRODUCTION 1
1.1 Background 1
1.2 Statement of the Problem 2
1.3 Objective of the Work 2
1.4 Scope of the Work 3
1.5 Justification of the Work 3
CHAPTER TWO: LITERATURE REVIEW 4
2.1 Petroleum Refining 4
2.2 Petrol Adulteration 4
2.3 Petrol Additives 5
2.4 Automobile Engines 5
2.4.1 Fuel Injection Systems 5
2.5 Control Systems 6
2.5.1 Control System Architecture 7
2.5.1.1 The Controlled Process 8
2.5.1.2 The Sensor/Transmitter Device 9
2.5.1.3 The Control Valve 11
2.5.1.4 The Controller 13
2.5.2 Control System Analysis 16
2.5.2.1 Steady-State Gain of the Control System 17
2.5.2.2 Stability of the Control System 17
2.6 Some Scholarly Works on the EFI Engine 17
CHAPTER THREE: METHODOLOGY 20
5.1 Description of Direct Continuous EFI Process 20
5.2 Designing the Automatic Control System 21
5.3 Modelling the Blending Process 23
5.3.1 Assumptions 23
5.3.2 Control Volume Diagram 24
5.3.3 Governing Equations 24
5.4 Modelling the Process Disturbance 43
viii
5.4.1 Assumptions 43
5.4.2 Governing Equations 44
5.5 Selecting the Control System Components 45
5.6 Analysing the Automatic Control System 47
5.6.1 Block Diagram Representation of the Control System 47
5.6.2 Characteristic Equation of the Overall Control Loop 52
5.6.3 Steady-State Gain of the Control System 56
5.6.4 Stability of the Control System 56
5.6.5 Dynamic Simulation of the Control System 56
3.6.5.1 Matlab with Simulink 57
CHAPTER FOUR: RESULTS AND DISCUSSION 60
4.1 Presentation of the Results 60
4.2 Discussion of the Results 65
4.2.1 Justifications for the Response of the Blending Process 66
4.2.2 Justifications for the Response of the Automatic Control System 67
4.3 Limitations of the Work 67
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION 68
5.1 Conclusion 68
5.2 Recommendations 68
References 69
CHAPTER ONE
INTRODUCTION
The recent technological revolution in the design of the automobile has begun to draw
the attention of engineers to the limitless opportunities that autonomous systems avail
the auto-industry, with regard to the growing demand for improved vehicle
performance and reliability. Presently, most parts in the automobile are being redesigned
with the aim of automating the operations of as many components as
possible. Already, some of the breakthroughs which have been recorded by the
adaptation of automatic control systems to the propulsion, transmission, braking and
safety systems include the Engine Management System (EMS), the Continuously
Variable Transmission (CVT) system, the Antilock Braking System (ABS) and the
Supplement Restraint System (SRS), respectively.Therefore, in order to explore other
opportunities for adapting control principles to the design of the different systems in
the automobile, this work seeks to analyse the prospects for designing an effective
automatic control system for the online blending of petrol with corrosion inhibitor in
the direct, continuous electronic fuel injection automobile engine.
1.1 BACKGROUND
Over the years, it has been observed that the quality of petroleum products in Nigeria
is usually compromised before the products get to the final consumer. This situation is
the result of a number of anomalies in the processing (owing to incomplete fractional
distillation in the refining process, emergence of local refineries in the Niger-Delta
creeks, adulteration of petroleum products by independent marketers, illegal
importation of petrol from overseas refineries, etc), pricing and marketing of
petroleum products.
Compromising the quality of petrol has far-reaching consequences on our national
economy and security. The adulteration of petroleum products is indeed one of the
notorious practices which have caused a lot of damage to engines and machines in
Nigeria. Osueke and Ofondu (2011), asserted that the adulteration of petrol increases
the tail-pipe emission of harmful pollutants from vehicles, and could lead to engine
damage.
In trying to mitigate the effect of petrol adulteration in automobile engines, vehicle
manufacturers introduced the use of petrol additives as a safeguard against engine
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damage due to adulterated petrol. However, it hasbeen observed that though the use of
petrol additives couldsafeguard the engine; there is yet to be a way to monitor
theoptimal quantity of the additive that will guarantee the safeguard. The reason is
because of the vagueness of the manufacturers’ prescription, which is often cast with
the rhetoric: “ADD ENTIRE CONTENTS TO A FULL FUEL TANK”; regardless of
the volume of the petrol tank, and the fact that motorists often refill their petrol
tanksbefore the tanks become empty. Fig. 1.1 shows the two sides of a typical can of a
petrol additive.
Hence, in order to monitor the optimal quantity of additive that blends with the petrol
in an automobile engine, at any transient time; one mustdesign a control system for
the blending process.
1.2 STATEMENT OF THE PROBLEM
There is an increasing rate of panic purchase (and application) of petrol additives in
Nigeria; owing to the worrisome rate of petrol adulteration in the marketplace, and the
vagueness of the prescription on most petrol additive packaging labels.
1.3 OBJECTIVE OF THE WORK
Following the earlier discussion, the objective of this work is to design an automatic
feedback control system which enables the blending of petrol with a specific quantity
Fig. 1.1: Re-sized Picture of a Petrol Additive (showing two sides of the can)
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of corrosion inhibitor, in the direct, continuous electronic fuel injection automobile
engine. In order to realise this objective, the control system shall ensure that the
composition of the mixture of petrol and corrosion inhibitor remains constant,
regardless of any variation in the flow velocity of the petrol which is supplied to the
automobile engine.
1.4 SCOPE OF THE WORK
The scope of this workcomprises the design of an automatic control system for
theblending process; and the derivation of generic expressions for the
functionwhichmodels the process disturbance, the response of the control system to
the process disturbance, the steady state gain of the system control loop, and the
stability of the system control loop.
1.5 JUSTIFICATION OF THE WORK
The analysis of an automatic control system for online blending of petrol with
corrosion inhibitor in the direct continuous electronic fuel injection automobile engine
is significant for the following reasons:
· The analysis will help to improve the life span of automobile petrol engines in
Nigeria, and elsewhere.
· It will contribute to the development of indigenous technology in Nigeria.
· It will help to increase cost savings in the maintenance of automobile engines
by eliminating the panic purchase and application of petrol additives.
· Above all, the result of the analysis (if utilised in the design and construction
of the actual automatic control system) will help to reduce consumer
complaints about the application of petrol additives, by increasingend-user
satisfaction.
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