Mô phỏng phối trộn xăng và ethanol tạo ra gasoline qua van bướm

VIETNAM NATIONAL UNIVERSITY, HO CHI MINH CITY
BACH KHOA UNIVERSITY
FACULTY OF CHEMICAL ENGINEERING
DIVISION OF OIL AND GAS PROCESSING

GRADUATION THESIS

SIMULATION OF FLUID FLOW THROUGH
VALVES FOR MIXING GASOHOL

INSTRUCTOR: TRAN HAI UNG
STUDENT: LE DUY THANH PHAT
STUDENT ID: 1412823

HO CHI MINH CITY, 2018


VIETNAM NATIONAL UNIVERSITY, HO CHI MINH CITY
BACH KHOA UNIVERSITY
FACULTY OF CHEMICAL ENGINEERING
DIVISION OF OIL AND GAS PROCESSING

GRADUATION THESIS

SIMULATION OF FLUID FLOW THROUGH
VALVES FOR MIXING GASOHOL

INSTRUCTOR: TRAN HAI UNG
STUDENT: LE DUY THANH PHAT
STUDENT ID: 1412823

HO CHI MINH CITY, 2018


ACKNOWLEDGEMENTS
First of all, I am greatly indebted to my thesis supervisor and instructor Tran Hai
Ung for providing me with a definite direction, professional guidance, constant
encouragement from the beginning of the work and moral support in many ways during
the study period. Thanks to all the study materials and adjustments during the study, my
thesis has done properly and on time.
Besides, I really appreciate the help of Mr. Nguyen Kim Trung, who is also a
responsible head teacher, for continuously updating more information about the thesis.
He has supported me all the way from the start of this project and always give his
students opportunities to accurately complete the project.
I want to say thanks to Dr. Dao Thi Kim Thoa, who is the head of the gas and oil
processing division, for encouraging me with this thesis. Also, I am grateful for the help
when I was having trouble with the thesis and for giving me another chance to do it
appropriately.
I would like to express my sincere thanks to all the professors in my chemical
engineering faculty, in general, and the division of gas and oil processing, particularly
for all the classes and knowledge during the past four years. These are the key for me to
finishing the thesis.
I am grateful to Bach Khoa University staffs for providing a great environment,
which are all the modern facilities in classes and laboratories, for students to study and
research.
Finally, my most beholden to my parents, who always encourage me on my
decisions, for the mentally and physically backing throughout my student life. Moreover,
I acknowledge the help, advice and guidance of all my friends, they always aid me when
I need the most, especially to my classmates and my roommate.

i

ABSTRACT
Gasohol is a mixture of ethanol and gasoline. By using the butterfly valves to create
a turbulent flow, which helps mixing gasohol through the valves and pipes. The quality
of the mixture is put into concerns such as deviation in volume fraction, head pressure
and the size of the system, thus, experiments with different variables are conducted to
make sure the valves’ combination works in the best conditions.
Firstly, study of Computational Fluid Dynamics is considered to support the
project. Methodologies and mathematical models regarding to CFD are essential, for
instance, I studied Navier-Stokes equations, the mass and energy conservation equations,
and the turbulence equations. By studying these CFD models, I could have sufficient
knowledge and ideas about boundary conditions, computational domains and flow
initial set up to conduct the researches in FS.
In this project, FS for blending gasohol is conducted by Solidworks, which provides
many tools to support the design and simulation. In order to model the system, the valve
is carefully studied and analyzed, then, divided into different parts. The parts are
designed in Solidworks with sketch tools, then, featured to become a 3-D model. Many
parts of the valve are assembled to complete the BV. Next, pipe sizing is decided to fit
the valve and start the FS package. Various experiments are conducted to ensure the
mixing process is working well with the variable of miscibility and pressure drop.
The final results are optimized in terms of energy consumption, which relating to
the pressure drop through valves and economic aspects, which belong to the initial cost
and operation cost. The results are potential, however, there are limitations in the
simulation, leaving the project a need for further experiments. Although having limits,
the results are acceptable regarding the head pressure and efficiency. All the variables
such as valve actuator’s angle, distance from ethanol intake pipe, the gap between valves
and valves’ position are optimized to meet the goals. In the final and optimized study,
the system only occupies a small space of roughly 2 m but could blend to a deviation of
1E-5 in volume fraction. The inlet required pressure approximately 150 kPa, results in

various choices for pump at about 25.9m of total head.

ii


TABLE OF CONTENTS
NOMENCLATURE AND ABBREVIATION LIST ............................................ vii
LIST OF TABLES ................................................................................................ viii
LIST OF CHARTS ................................................................................................. ix
1. INTRODUCTION ................................................................................................1
General ...........................................................................................................1
Objectives ......................................................................................................2
Field of study .................................................................................................3
Study limitation ..............................................................................................3
2. LITERATURE REVIEW .....................................................................................4
Gasoline .........................................................................................................4
2.1.1. Additives .................................................................................................4
2.1.2. Properties ................................................................................................5
2.1.3. Safety ......................................................................................................6
Ethanol ...........................................................................................................6
2.2.1. Ethanol properties ...................................................................................7
2.2.2. Bioethanol production.............................................................................7
Gasohol ..........................................................................................................8
2.3.1. Industry of biofuel ..................................................................................8
2.3.2. Production of biofuel ..............................................................................9
2.3.3. Restriction in using gasohol ..................................................................10
Butterfly valve .............................................................................................11
2.4.1. Introduction ...........................................................................................11
2.4.2. Construction ..........................................................................................12
2.4.3. Operation ..............................................................................................13

iii


2.4.4. Characteristics .......................................................................................13
3. THEORETICAL BACKGROUND ....................................................................14
Fluid dynamic laws ......................................................................................14
3.1.1. Conservation laws .................................................................................14
3.1.2. Compressible vs incompressible flow ..................................................16
3.1.3. Newtonian vs non-Newtonian fluids ....................................................16
3.1.4. Inviscid, viscous and Stokes flow .........................................................16
3.1.5. Steady vs unsteady flow .......................................................................17
3.1.6. Laminar vs turbulent flow.....................................................................17
3.1.7. Subsonic vs transonic, supersonic and hypersonic flows .....................17
3.1.8. Reactive vs non-reactive flows .............................................................18
3.1.9. Magneto hydrodynamics.......................................................................18
3.1.10. Relativistic fluid dynamics .................................................................18
Computational Fluid Dynamic.....................................................................18
3.2.1. Basic principles .....................................................................................19
3.2.2. CFD methodology.................................................................................20
Solidworks ...................................................................................................22
3.3.1. Introduction ...........................................................................................22
3.3.2. Design method ......................................................................................23
3.3.3. Model editing ........................................................................................24
3.3.4. Flow simulation ....................................................................................25
4. METHODOLOGY .............................................................................................28
Phase one: Designing and simulation ..........................................................28
4.1.1. Parts ......................................................................................................28
4.1.2. Assembly and Flow simulation ............................................................29

iv


Phase 2: Results analysis and optimization .................................................30
4.2.1. Goals .....................................................................................................30
4.2.2. Influence factors ...................................................................................30
4.2.3. Influence of inlet distance and open angle ...........................................31
4.2.4. Different ethanol volume fractions and gasoline inlet velocity ............31
4.2.5. Valves’ angle influence ........................................................................32
4.2.6. Trend line of different gaps ..................................................................32
4.2.7. Position angle of two valves .................................................................32
4.2.8. Optimal variables ..................................................................................33
5. RESULTS AND DISCUSSION .........................................................................34
One-valve system .........................................................................................34
5.1.1. Typical pattern ......................................................................................34
5.1.2. Actuator’s angle and inlet distance .......................................................37
5.1.3. Inlet gasoline velocity and Ethanol ratio ..............................................41
Two-valve system ........................................................................................42
5.2.1. Typical pattern ......................................................................................43
5.2.2. Angles of two valves.............................................................................44
5.2.3. Distance between valves .......................................................................47
5.2.4. Positions of valves ................................................................................49
5.2.5. Comparison with one-valve system ......................................................52
5.2.6. Optimal results ......................................................................................53
6. SYSTEM DESIGN .............................................................................................57
Process .........................................................................................................57
6.1.1. Process Flow Diagram ..........................................................................57
6.1.2. System layout ........................................................................................57

v

Simple calculation ........................................................................................58
6.2.1. Requirements ........................................................................................58
6.2.2. Tanks .....................................................................................................58
6.2.3. Pipe .......................................................................................................61
6.2.4. Pump .....................................................................................................62
7. CONCLUSIONS ................................................................................................63
Conclusions ..................................................................................................63
7.1.1. Simulation .............................................................................................63
7.1.2. Results and optimization .......................................................................63
Recommendations ........................................................................................65
Further study ................................................................................................66
REFERENCES .......................................................................................................68

vi


NOMENCLATURE AND ABBREVIATION LIST
3D

Three Dimensions

BV

Butterfly Valve

CAD

Computer Aided Design

CFD

Computational fluid dynamic

d

diameter

E

Ethanol Volume Fraction

EtOH

Ethanol

FEM

Finite Element Method

FS

Flow Simulation

FVM

Finite Volume Method

LES

Large eddy simulation

M

Mach numbers

M83

Mogas 83

M92

Mogas 92

M95

Mogas 95

ON

Octane number

PFD

Process Flow Diagram

QCVN

Quy Chuan Viet Nam (Vietnam standards)

RANS

Reynolds-averaged Navier–Stokes

Re

Reynold Number

RON

Research Octane Number

SW

Solidworks

US

United States

vii


LIST OF TABLES
Table 1. Relation of inlet distance and open angle........................................................31
Table 2. Effects of E-number and velocity....................................................................31
Table 3. Valves’ angle combination influence ..............................................................32
Table 4. Impact of gap between two valves ..................................................................32
Table 5. Valves’ position matter ...................................................................................33

Table 6. Double-check results .......................................................................................33
Table 7. Courses' thickness calculation .........................................................................60

viii


LIST OF CHARTS
Chart 1. One-valve system typical volume fraction trend line ......................................35
Chart 2. Typical pressure drop through length of one specific case .............................36
Chart 3. Pattern of pressure drop by various angles and inlet distances .......................37
Chart 4. Deviation of volume fraction of gasoline for an inlet distance of 3d ..............38
Chart 5. Volume fraction with actuator of 50° and different inlet distances ................39
Chart 6. Effects of valve’s angle and inlet distance to pressure ....................................40
Chart 7. Deviation of volume fraction with various velocity and E number ................41
Chart 8. Effect of gasoline inlet velocity and E-ratio to inlet pressure .........................42
Chart 9. Typical trend line of a volume fraction in two-valve system ..........................43
Chart 10. Typical inlet pressure change by length through two valves ........................44
Chart 11. Volume fraction deviation by changes of actuator in the second valve ........45
Chart 12. Volume fraction deviation with the changes of actuator in the first valve....46
Chart 13. Pressure affected by different actuators' angles of two valves ......................47
Chart 14. Volume fraction affected by gaps and actuators' angles ...............................48
Chart 15. Different gaps and valves' angle effect on pressure ......................................49
Chart 16. Influence of valves positions to volume fraction deviation ..........................50
Chart 17.Valve positioning affects head pressure's value .............................................51
Chart 18. Volume fraction's comparisons of two valve 50°x60° and one valve 40° ....52
Chart 19. Pressure comparison between two valve 50°x60° and one valve 40° ...........52
Chart 20. Volume fraction deviation by different valves' angles ..................................53
Chart 21. Pressure influenced by various actuators of the two valves ..........................54
Chart 22. Comparison of volume fraction deviation between optimized and normal
valves' position ..............................................................................................................55

Chart 23. Comparison of inlet pressure between one optimized and normal positions
system ............................................................................................................................56
Chart 24. Vacuum pressure through valve by different actuators and inlet distances ..66
Chart 25. Pressure drop through valve by different actuators and inlet distances ........67

ix


INTRODUCTION
1. INTRODUCTION
General
Nowadays, a majority of energy is from fossil fuel, which has experienced an
increasing price due to the growing demand of these fuels. Therefore, there is a need to
find an alternative energy which is easily re-create and clean, for instance, biogas,
natural gas, forms of ester and hydro gas. Moreover, the mixture of gasoline and ethanol
is a cure for this problem. The recent development of biofuels has been driven by three
key global challenges.
Increasing energy demand will pose challenges to security of supply as resources
are scattered around the globe. Biofuels help enhance and safeguard energy security by
reducing the world's reliance on fossil energy sources. Biomass is a resource that is more
evenly distributed globally. Energy security is the constant availability and supply of
affordable energy for consumers and industry. Risks to energy security include, for
example, disruptions to the supply of imported fossil fuels, limited availability of fuel,
and energy price spikes. Responding to higher energy consumption, the expected
increase in world population, combined with significant economic growth in emerging
economies will result in substantially increasing energy consumption. To be able to
respond to this growing demand, we need to use natural resources more efficiently and
increase the use of renewable energy, such as biofuels.
Investment in biofuels could lead to a significant boost in economic development,
including the creation of new jobs and new sources of income for farmers. This would

be of particular benefit to developing countries in which a large proportion of the
population is employed in agriculture. Global economic growth has contributed to a
dramatic rise in world energy demand.
Combating climate change forces the world to seek alternative, low-carbon sources
of energy and fuel. Since traffic is one of the largest sources of greenhouse gas, i.e.
carbon emissions, substituting fossil fuels with renewable alternatives such as biofuels
are an efficient way to reduce these emissions. Biofuels offer a solution to reduce carbon
emissions of traffic when other solutions, such as switching to electric vehicles, is not
an option due to high vehicle costs or lack of vehicle charging network, for example.
Using waste and residue as raw materials for biofuels is an excellent example of
1


INTRODUCTION
answering to the needs of a circular economy. Reducing the amount of waste and making
the most of our valuable natural resources is crucial for our future survival.
Several common ethanol fuel mixtures are in use around the world. The use of pure
hydrous or anhydrous ethanol in internal combustion engines is only possible if the
engines are designed or modified for that purpose, and used only in automobiles, lightduty trucks and motorcycles. Anhydrous ethanol can be blended with gasoline (petrol)
for use in gasoline engines, but with high ethanol content only after minor engine
modifications.
Objectives
The objectives of this project are to simulate the flow in butterfly valves which are
used for mixing gasohol. In order to be more economically beneficial and proper,
efficient, optimization must be researched to meet the specifications, which are lower
the construction cost and installment expenses, lower the operation cost, free for space
and mixing efficiency.
Firstly, construction and installment expenses depend on the number of valves,
length of pipes and type of pump, in other words, the first cost of equipment. My goal
is to reduce the cost by using as fewer valves as possible; moreover, shorten pipes are

better for financial efficiency; pump depending on the amount of required inlet hydraulic
pressure; however, still guarantee the quality of the final product.
Secondly, operation expenses, including the work of pump and maintenance. As the
lower the installment cost, the higher the operation cost because proper pumping section
leads to better efficiency with higher required inlet pressure. Therefore, balancing the
two costs is one of the goals of this project.
Thirdly, the size of the equipment including pump, valves and pipes, are also
essential for limited-space blending stations. As a result, the size is considered to be a
criteria of design.
Lastly, mixing efficiency is the most crucial criteria. The gasoline volume fraction
or an ethanol volume fraction must meet the specification after optimize these previous
costs to ensure the quality of biofuel.

2


INTRODUCTION
In addition, advantages and disadvantages of this design will be stated after the
simulation. Therefore, improvements of the method comparing to other method will be
discussed afterward.
Field of study
The main theoretical fields to apply are fluid dynamic laws and computational fluid
dynamics. There are 2 phases of this study:
First, designing BV in Solidworks. The valve design is broken into many parts,
including flange, body, upper lever, lower lever, upper stem, lower stem, disc, rubber,
opener-closer, lids, pipes, to sizing and calculating, then, the parts are drawn separately
with precision. Then, the parts are assembled to be a complete BV by mates for joining
the parts. Fluid FS of the assemble: The assemble is added the FS package with desired
conditions. The boundary conditions containing inlets volume of gasoline and ethanol,
and outlet pressure which is atmospheric pressure.

Then, analyzing results and calculating for storage: results are tracking for pressure
and concentration of gasoline through pipe’s length, then the information is operated to
create figures for research. Therefore, the process is optimized by different variables and
storage is calculated by regulations.
Study limitation
By simulating the valve, there are limits in designing and optimizing. Considering
designing valve, in reality, the valve is made of various materials with different frictional
properties; however, in Solidworks, valves are made of one material (the only
manipulation in SW is materials’ colors). Moreover, thermal properties also be taken in
accounts as the environment in the simulation is a constant temperature which is defined
by the user. Gravity is another concern as different high would result in different gravity;
fluids in the package are pre-defined, thus, it could be distinctive in another country such
as Vietnam. As the result, there is a certain deviation in materials and the design.
Regarding optimization, the flow is not totally simulated accurately due to physical and
thermal properties of materials. In the analysis, over 20 curves are created to stand for
the flow of fluid could be inaccuracy. Ultimately, the figures which are the results of the
simulation can be minor inability. Besides, the system design using basic calculation, so
the results may encounter errors.
3


LITERATURE REVIEW
2. LITERATURE REVIEW
Gasoline
Gasoline, or petrol, is a transparent, petroleum-derived liquid that is used primarily
as a fuel in spark-ignited internal combustion engines. It consists mostly of organic
compounds obtained by the fractional distillation of petroleum, enhanced with a variety
of additives. Gasoline is a mixture of C4 to C12 hydrocarbon compounds containing
single or double bonds. This petroleum fraction distills in the temperature range 30 to
220°C[1]. It is very dangerous because it can easily evaporate at room temperature and

atmospheric pressure, is highly inflammable, and becomes explosive when the volatile
gas is mixed with the air. The gasoline mixture also includes a small amount of
oxygenates, sulfur compounds, and nitrogen compounds[2]. The hydrocarbon
compounds in gasoline may be classified as n-paraffins, iso-paraffins, olefins, aromatic
compounds, and naphthenics.
Some types of petrol in Vietnam: The Mogas 95 (M95) is odorous, yellow in color
and is used for motors and engines, with a compression ratio over 9.5:1; applied for new
generations of car and racing motorbikes; the octane number is 95. The Mogas 92 (M92)
is distinctive odorous, green in color and qualified for an engine with compression ratio
less than 9.5:1; the ON is 92. The Mogas 83 (M83) is also odorous, yellow and applied
to engine with a compression ratio of 8:1; the ON is 83; but this type of gasoline is not
adopted in Vietnam petrol market. In 1/1/2015, E5 biofuel has been allowed to widely
trade and used.
2.1.1. Additives
The characteristic of a particular gasoline blend to resist igniting too early is
measured by its octane rating. Gasoline is produced in several grades of octane
rating. Tetraethyl lead and other lead compounds are no longer used in most areas to
regulate and increase octane-rating[3], but many other additives are put into gasoline to
improve its chemical stability, control corrosion, provide fuel system cleaning, and
determine performance characteristics under intended use.
2.1.1.1. Explosion-proof
Two possible fire phenomena are normal fire and explosion. The octane value of
gasoline demonstrates the anti-knock properties of gasoline. The higher the octane value,
4


LITERATURE REVIEW
the higher the detonation rate[4]. High octane gasoline is used for high compression
ratio engines. If using low octane gasoline for vehicles with high compression ratio will
cause fire explosion. While using high octane gasoline for vehicles with low

compression ratio, gasoline will be harder to burn and not burn, create coal deposits and
dust the machine and engine.
2.1.1.2. Proper evaporation
Gasoline in engines needs to evaporate, mixed with sufficient oxygen to achieve the
highest combustion efficiency, for internal combustion engines, they are mixed together
through the mixture the air. If the gasoline is not suitable, the engine will not be able to
handle all the fuel consumption, fuel consumption and technical problems such as gas
or gas choking phenomenon and petrol phenomenon.
2.1.1.3. High chemical stability
The ability to maintain a chemical nature against the effects of the surrounding
environment is called chemical stability of the gasoline. Chemical stability of the
gasoline is influenced by temperature, exposure to the air, the cleanliness and dryness
of the container, the level of storage and the duration of storage.
2.1.1.4. Prevent corrosion and mechanical impurities
Gasoline is corrosive to metals due to the presence of sulfur compounds, acids and
resin, which are not fully purified during processing. The mechanical impurities in the
gasoline include substances from the outside that fall into the process of pumping,
transporting such as sand, dust, substances added in the process of production and
processing such as fuel, water from the outside falls into the gasoline during the export,
import, store.
2.1.2. Properties
Gasoline has an overall density of approximately 750 kg/m3 (from 720 kg/m3 to 760
kg/m3 at 20ºC). The thermal expansion coefficient is 900⋅10-6 K-1. Boiling and
solidification points are not well defined because they are mixtures. Kinetic viscosity of
0.5⋅10-6 m2/s at 20 ºC. Vapor pressure varies from 50 to 90 kPa at 20 ºC, typically 70
kPa at 20 ºC.

5

LITERATURE REVIEW
RON varies from 92 to 98. This is a measure of auto-ignition resistance in a spark
ignition engine, being the volume percentage of iso-octane in a iso-octane/n-heptane
mixture having the same anti-knocking characteristic when tested in a variablecompression-ratio engine. Cetane number varies from 5 to 20, meaning that gasoline has
a relative large time-lag between injection in hot air and auto-ignition, although this is
irrelevant in typical gasoline applications.
2.1.3. Safety
In terms of environmental considerations, the main concern with gasoline for the
environment, aside from the complications of its extraction and refining, is the
potential effect on the climate through the production of carbon dioxide. Unburnt
gasoline and evaporation from the tank, when in the atmosphere, reacts in sunlight to
produce photochemical smog. The chief risks of such leaks come not from vehicles, but
from gasoline delivery truck accidents and leaks from storage tanks. Because of this risk,
most storage tanks now have extensive measures in place to detect and prevent any such
leaks, such as monitoring systems. Considering toxicity, people can be exposed to
gasoline in the workplace by swallowing it, breathing in vapors, skin contact, and eye
contact. Regarding flammability, like other hydrocarbons, gasoline burns in a limited
range of its vapor phase and, coupled with its volatility, this makes leaks highly
dangerous when sources of ignition are present. However, gasoline vapor rapidly mixes
and spreads with air, making unconstrained gasoline quickly flammable.
Ethanol
Ethanol, also called alcohol, ethyl alcohol, grain alcohol, or drinking alcohol, is a
chemical compound, a simple alcohol with the chemical formula C2H5OH and is often
abbreviated as EtOH. Ethanol is a volatile, flammable, colorless liquid with a slight
characteristic odor. It is a psychoactive substance and is the principal type of alcohol
found in alcoholic drinks. Ethanol is naturally produced by the fermentation of sugars
by yeasts or via petrochemical processes, and is most commonly consumed as a
popular recreational drug[5]. It also has medical applications as an antiseptic and
disinfectant. The compound is widely used as a chemical solvent, either for scientific
chemical testing or in the synthesis of other organic compounds, and is a vital substance

6


LITERATURE REVIEW
utilized across many different kinds of manufacturing industries. Ethanol is also used as
a clean-burning fuel source.
2.2.1. Ethanol properties
Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a smokeless
blue flame that is not always visible in normal light. The physical properties of EtOH
stem primarily from the presence of its hydroxyl group and the shortness of its carbon
chain. Ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it
more viscous and less volatile than less polar organic compounds of similar molecular
weight, such as propane.
EtOH is pure substance, which can be dissolved in water in all proportion. Of the
combustion characteristics, the auto-ignition temperature and the flash point are higher
than those of gasoline, which makes it safer for transportation and storage. The latent
heat of evaporation of ethanol is 3 to 5 times higher than that of gasoline[6], this makes
the temperature of the mixture in the intake manifold lower, which helps increase the
volumetric efficiency. However, the heating value of ethanol is much lower than that of
gasoline, so if the proportion of ethanol is high the engine power may decrease.
2.2.2. Bioethanol production
Bioethanol is preferentially made from cellulosic biomass materials instead of from
more expensive traditional feedstock such that starch crops. Steps processes in EtOH
production are: Milling, where the feedstock passes through hammer mills, which grind
it into a fine meal. Next, saccharification, the meal is mixed with water and an enzyme
and kept to 95 ºC[7] to reduce bacteria levels and get a pulpy state.
Coming up to fermentation, yeast is added to the mash to ferment the sugars to
ethanol and carbon dioxide. In a batch fermentation process, the mash stays in one
fermenter for about 48 hours[7] before the distillation process is started.

Then distillation, the fermented mash contains about 10% EtOH, as well as all the
non-fermentable solids from the feedstock and the yeast cells. The mash is pumped to
the continuous flow, multicolumn distillation system where the alcohol is removed from
the solids and the water.
After that, dehydration takes place to get rid of the water in the azeotrope, most
ethanol plants use a molecular sieve to capture the remaining water and get anhydrous
7


LITERATURE REVIEW
ethanol. Finally, denaturing, fuel ethanol is denatured with a small amount of some
products such as gasoline, to make it unfit for human consumption.
In Vietnam, ethanol fuel has been piloted produced, and some ethanol plants using
corn and cassava as raw materials are now under construction such as Petrovietnam
Biofuels Joint Stock Company (100 million liters/year, at Phu Tho province), Green
Field Joint Stock Company (100.000 ton/year, at Quang Ngai province) and Sai Gon
Biofuels and Petroleum Company (40 million liters/year, at Cat Lai HCM city) [8].
However, due to specific characteristics of vehicles used, weather and climate, research
activities on the effects of using ethanol fuel on engine performance, exhaust emissions
and durability should be conducted upon the published international papers regarding
these issues. This was done within a cooperative research between Green Field JointStock Company and Laboratory of Internal Combustion Engine, Institute of
Transportation of Engineering, Hanoi University of Technology. There are many
different processes to mix gasohol, in this project, the process of mixing gasohol using
butterfly valves is simulated by Solidworks.
Gasohol
Several common ethanol fuel mixtures are in use around the world. The use of pure
hydrous or anhydrous ethanol in internal combustion engines is only possible if the
engines are designed or modified for that purpose, and used only in automobiles, lightduty trucks and motorcycles. Anhydrous ethanol can be blended with gasoline for use
in gasoline engines, but with high ethanol content only after minor engine modifications.
Ethanol fuel mixtures have "E" numbers which describe the percentage of ethanol

fuel in the mixture by volume, for example, E85 is 85% anhydrous ethanol and 15%
gasoline. Low-ethanol blends, from E5 to E25, although internationally the most
common use of the term refers to the E10 blend. In 1/1/2015, E5 biofuel has been
allowed to widely trade and used in Vietnam.
2.3.1. Industry of biofuel
Nowadays, ethanol has been widely used in many countries either as a gasoline
additive or as a substitution for gasoline. In 2007, the world market for ethanol fuel
totaled 49.6 billion liters, in which two major producers (Brazil and the US) outputted
19 and 24.6 billion liters respectively, and those took 88% of the worldwide ethanol fuel
8


LITERATURE REVIEW
[9]. Brazil is the most successful country, which has the biggest bio-fuel program all
over the world. In 2006, Brazilian ethanol fuel production met 18% fuel consumption
demand in transportation area and up to April 2008, ethanol fuel met more than 50% of
total required gasoline. The number of 20% on road vehicles using 100% ethanol fuel
(including vehicles using only ethanol and flexible fuel vehicles) shows clearly the
popularity of the alcohol program in this country.
The US is the biggest ethanol fuel production and consumption country in the
world. Almost vehicles can use 10% ethanol in blended gasoline, and the car makers
have been releasing models that are able to run in higher ethanol proportions. In 2007,
Portland and Oregon became the first cities where gasoline on-sale was required to
contain at least 10% ethanol. Then in January 2008, Missouri, Minnesota and Hawaii
states applied also this requirement. In Asia, China had taken the third place of ethanol
production in the world from 2004 to 2006, then fourth place in 2007. Another country
in South East Asia named the seventh place of ethanol fuel production is Thailand,
where gasohol E10 has been widely used. Since early 2008 gasohol E20 started to be
used and gasohol E85 is released in the third quarter of the same year [10].
Blends of E10 or less are used in more than 20 countries around the world, led by

the United States, where ethanol represented 10% of the U.S. gasoline fuel supply in
2011[11]. Blends from E20 to E25 have been used in Brazil since the late 1970s. E85 is
commonly used in the U.S. and Europe for fuel vehicles. Hydrous ethanol or E100 is
used in Brazilian neat ethanol vehicles and flex fuel light vehicles and hydrous E15
called hE15 for modern petrol cars in the Netherlands.
2.3.2. Production of biofuel
Blending methods, including: agitation method, circulation pump, static mixing and
noble gas stripping. Through researches, School of Transportation Engineering, Hanoi
University of Science and Technology proposed a gasohol blending technology for
massive production (500 liters/batch) and a circulation method for smaller batch [12].
The general process of mixing gasohol consists of 2 stages. Firstly, denaturants
which are gasoline from the more volatile section of fractional distillation of crude oil
are applied to mark the purpose of using materials, belong with four types of additives
– bonding admixture, friction modifier, anti-oxidation and rust-corrosion inhibitors to
9


LITERATURE REVIEW
create a mixture of multifunction denaturants. Then, 99.5% ethanol is blended with the
previous mixture to form the denaturants-ethanol mixture. Finally, gasohol is formed
by mixing ethanol mixture and gasoline with different ratios for various goals (E5, E10,
E15 or E20 gasohol). Notice that the ethanol in biofuel blending is denaturant ethanol
and gasoline is lead-free petrol. In Vietnam, there are 2 types of gasohol: E5 biofuel
with 4-5% volume of ethanol and E10 gasohol with 9-10% volume of ethanol.
Vietnam, December 28 2012, after the approval of the Ministry of Science and
Technology, the Ministry of Industry and Trade BCT (by state circulars 48/2012/TTBCT) has proposed the national standard of devices, apparatus and methods in blending,
storing and transporting ethanol and biofuel (E5, E10) at gas stations, which is QCVN
09: 2012/BCT.
To guarantee the quality of blending biofuel, in section 2.3 of QCVN 09: 2012/BCT,
blending method and facilities of the mixing station by an organization or individual

must apply one or combine these four methods: Closed-circulation pump (in-tank:
bottom suction and top discharge); blending by static mixer; and in-line mixing at the
gas station. The standard also qualifies devices and equipment, storage tank and
transportation of gasohol. In addition, there are standards for materials of blending
equipment, tank and pipes; also standards for floating floats, breathe out, primer tank,
pipeline technology used for ethanol, filters, sieves on pipes, regulation by means of
transportation of ethanol, regulations on equipment, auxiliaries, means used to prepare,
store and transport bio-fuel.
For example, section 2.2.2. Specification of tank specifications: Storage of biofuels
by tanks (fixed roof, floating-inner tube, cylindrical horizontally), biofuels should not
be stored with floating tanks, riveted tanks, other tanks used for bio-fuel storage must
have a closed cap and a vent valve installed.
2.3.3. Restriction in using gasohol
The use of ethanol blends in conventional gasoline vehicles is restricted to low
mixtures, as ethanol is corrosive and can degrade some of the materials in the engine
and fuel system. Also, the engine has to be adjusted for a higher compression ratio as
compared to a pure gasoline engine to take advantage of ethanol's higher oxygen content,
thus allowing an improvement in fuel efficiency and a reduction of tailpipe emissions.
10


LITERATURE REVIEW
Disadvantages to ethanol fuel blends when used in engines designed exclusively for
gasoline include lower fuel mileage, metal corrosion, deterioration of plastic and rubber
fuel system components, clogged fuel systems, fuel injectors, and carburetors of
composite fuel tanks, varnish buildup on engine parts, damaged or destroyed internal
engine components, water absorption, fuel phase separation, and shortened fuel storage
life. Many major auto, marine, motorcycle, lawn equipment, generator, and other
internal combustion engine manufacturers have issued warnings and precautions about
the use of ethanol-blended gasolines of any type in their engines.

Butterfly valve
A BV is a valve that isolates or regulates the flow of a fluid. The closing mechanism
is a disk that rotates. Many different types of valves are used in flow control. They are
used for a variety of reasons, such as phase (liquid or gases), pressure, piping restrictions
and solids content. Other valves are chosen for their capability to open and close in a
quarter turn. Of all the valve types, the BV is used as a control device for many reasons,
including some or all of the above.
2.4.1. Introduction
A BV is a flow control device that incorporates a rotational disk to control the
flowing media in a process. The disk is always in the passageway, but because it is
relatively thin, it offers little resistance to flow. Early use of butterfly valves focused on
water applications, but new designs and component materials have allowed them to be
utilized in growing industrial fluid applications. Presently, butterfly valves can be found
in almost every chemical plant handling a variety of diverse fluids.
The BV can be used for on-off service or modulating service. Actuation is typically
achieved either manually or through an external power source to cycle the valve
automatically. Automatic actuators include electric, pneumatic and hydraulic operators.
There are many advantages offered by butterfly valves compared to other types of
valves including an inherently simple, economic design that consists of fewer parts,
which makes butterfly valves easy to repair and maintain. The wafer-shaped body and
relatively light weight offer a savings in the initial cost of the valve and installation
costs-in person-hours, equipment and piping support.

11


LITERATURE REVIEW
2.4.2. Construction
The body of a butterfly valves consists of a circular casting with lugs and a neck.
The neck encloses the valve stem, a stem bushing, a stem seal and a stem retaining ring.

The stem bushing insures proper stem alignment within the valve by absorbing actuator
side thrusts. There are some main parts of the valve which are:
2.4.2.1. Body
Butterfly valves generally have bodies that fit between two pipe flanges. The most
common body designs are lug and wafer. The lug body has protruding lugs that provide
bolt holes matching those in the pipe flange. A wafer body does not have protruding
lugs. The wafer valve is sandwiched between the pipe flanges, and the flange bolts
surround the body. Each type of body has advantages, some of which are listed: The
wafer style is less expensive than a lug style. Wafer designs do not transfer the weight
of the piping system directly through the valve body. A lug body allows dead-end
service or removal of downstream piping.
2.4.2.2. Disk
The flow closure member of a BV is the disk. Many variations of the disk design
have evolved relative to the orientation of the disk and stem in an attempt to improve
flow, sealing and/or operating torque. The disk is the equivalent of a plug in a plug valve,
gate in a gate valve or a ball in a ball valve. Rotating the disk one-quarter turn or 90
degrees opens and closes the BV.
2.4.2.3. Stem
The stem of the BV may be a one-piece shaft or a two-piece (split-stem) design. The
stem in most resilient seated designs is protected from the media, thus allowing an
efficient selection of material with respect to cost and mechanical properties. In highperformance designs, the stems are in contact with the media and, therefore, must be
compatible, as well as provide the required strength for seating and unseating the disk
from the seat.
2.4.2.4. Seat
The seat of a resilient-seat BV utilizes an interference fit between the disk edge and
the seat to provide shutoff. The material of the seat can be made from many different

12

LITERATURE REVIEW
elastomers or polymers. The seat may be bonded to the body or it may be pressed or
locked in.
2.4.3. Operation
Butterfly valves are generally favored because they cost less than other valve design,
and are lighter weight so they need less support. The disc is positioned in the center of
the pipe. A rod passes through the disc to an actuator on the outside of the valve.
Rotating the actuator turns the disc either parallel or perpendicular to the flow.The disc
is always present within the flow, so it induces a pressure drop, even when open. A BV
is from a family of valves called quarter-turn valves. In operation, the valve is fully open
or closed when the disc is rotated a quarter turn. When the valve is closed, the disc is
turned so that it completely blocks off the passageway. When the valve is fully open,
the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the
fluid. The valve may also be opened incrementally to throttle flow.
There are different kinds of butterfly valves, each adapted for different pressures
and different usage. The zero-offset BV, which uses the flexibility of rubber, has the
lowest pressure rating. The high-performance double offset BV, used in slightly higherpressure systems, is offset from the center line of the disc seat and body seal and the
center line of the bore. This creates a cam action during operation to lift the seat out of
the seal resulting in less friction than is created in the zero offset design and decreases
its tendency to wear[13]. The valve best suited for high-pressure systems is the triple
offset BV. In the case of triple offset valves the seat is made of metal so that it can be
machined such as to achieve a bubble tight shut-off when in contact with the disc.
2.4.4. Characteristics
The following are some general control valve terms and characteristics for butterfly
valves when used for modulating service. A valve having a stated inherent characteristic
may provide a different installed characteristic due to interaction with the
system. Regarding linear, the flowrate is directly proportional to the amount of disk
travel. For example, at 50% open, the flowrate is 50% of maximum flow.
Equal percentage. Equal percentage characteristic means that equal increments of
valve travel produce equal percentage changes in flowrate as related to the flowrate that

existed at the previous travel position.
13


THEORETICAL BACKGROUND
3. THEORETICAL BACKGROUND
Fluid dynamic laws
Fluid dynamics is a sub-discipline of fluid mechanics that describes the flow of
fluids-liquids and gases. It has several sub-disciplines, including aerodynamics and
hydrodynamics. Fluid dynamics has a wide range of applications, including calculating
forces and moments on aircraft, determining the mass flow rate of petroleum through
pipelines, predicting weather patterns, understanding nebulae in interstellar space and
modelling fission weapon detonation.
Fluid dynamics offers a systematic structure—which underlies these practical
disciplines—that embraces empirical and semi-empirical laws derived from flow
measurement and used to solve practical problems. The solution to a fluid dynamics
problem typically involves the calculation of various properties of the fluid, such as flow
velocity, pressure, density, and temperature, as functions of space and time.
3.1.1. Conservation laws
Three conservation laws are used to solve fluid dynamics problems, and may be
written in integral or differential form. The conservation laws may be applied to a
region of the flow called a control volume. A control volume is a discrete volume in
space through which fluid is assumed to flow. The integral formulations of the
conservation laws are used to describe the change of mass, momentum, or energy within
the control volume.
3.1.1.1. Conservation of mass
The rate of change of fluid mass inside a control volume must be equal to the net
rate of fluid flow into the volume. Physically, this statement requires that mass is neither
created nor destroyed in the control volume, and can be translated into the integral form
of the continuity equation[14]:


 dV     u  dS
S
t V
Above,  is the fluid density, u is the flow velocity vector, and t is time. The lefthand side of the above expression is the rate of increase of mass within the volume and
contains a triple integral over the control volume, whereas the right-hand side contains

14