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DESIGN AND FABRICATION OF AQUA SILENCER
A PROJECT REPORT
Submitted by
KARTHIK K. 412815114067
MAHA VISHNU M. S. 412815114077
RAJASEKAR D. 412815114099
SATHYA NARAYANA V. 412815114336
in partial fulfillment for the award of degree
of
BACHELOR OF ENGINEERING
in
MECHANICAL ENGINEERING
VALLIAMMAI ENGINEERING COLLEGE
KATTANKULATHUR, CHENNAI - 603 204
ANNA UNIVERSITY: CHENNAI 600 025
APRIL – 2019

BONAFIDE CERTIFICATE
This is to certify that the project entitled “design and fabrication of aqua
silencer” is a bonafide work carried out by the following students whose names
are given below
KARTHIK K. 412815114067
MAHA VISHNU M. S. 412815114077
RAJASEKAR D. 412815114099
SATHYA NARAYANA V. 412815114336
who successfully completed the project work under my direct supervision.
SIGNATURE
Dr. K. SIVAKUMAR, M.E, Ph.D,
HEAD OF THE DEPARTMENT
Mechanical Engineering
Valliammai Engineering College
Kattankulathur, Chennai - 603 204
SIGNATURE
Dr . K. SIVAKUMAR, M.E, Ph.D,
SUPERVISOR
HEAD OF THE DEPARTMENT
Mechanical Engineering
Valliammai Engineering College
Kattankulathur, Chennai - 603 204
Submitted for the Viva voce examination held on………………
Internal Examiner
Examiner
External
ii

ACKNOWLEDGEMENT
I sincerely express my deep sense of gratitude to Dr. T.R. Pachamuthu,
chairman and Dr. T.P. Ganesan, Director of Valliammai Engineering
College for providing all necessary facilities to earn knowledge from the
institution.
I convey my sincere thanks to respected principal Dr. B.
Chidambararajan, M.E., Ph.D., Valliammai Engineering College for his
encouragement and support extended throughout the course of our study.
We wish to express our profound thanks with gratitude to our head of
the department and project guide Dr. K. SIVAKUMAR, M.E., Ph.D., for his
excellent guidance, continuous motivation, and constant encouragements given to
us to do this project successfully..
We bestow our sincere thanks to our Project Coordinator Mr. P. RAMU, M.E,
without whose invaluable guidance, patient and constant encouragement, anything
would not have been materialized.
Lastly we would like to thank all our friends family members for
their moral and financial support during our project.
Iii

ABSTRACT
To conserve the earth’s environment from degradation and
also the public health from Air pollution it is very imperative than serious steps
are to be taken for conserving them and Aqua silencer is an attempt to do so.
Aqua silencer is mainly used for dealing with the emission and noise. An aqua
silencer is generally attached to the exhaust of 2-4stroke engine. In this Aqua
silencer both the Lime water wash method and Absorption method are used. The
gases like HC, CO from the engine exhaust are absorbed. The final emission is
analyzed using an automobile gas analyzer and the reduction of gases HC, CO is
measured.

CHAPTER 1
1.INTRODUCTION
1.1 AQUA SILENCER
Air pollution is a major problem. The main pollutants contributed by
automobiles are (CO), Un-burnt Hydro Carbon (UBHC), (NOx) and Lead etc.
Other sources which cause pollution are electric power generating stations and
Industries. So it is imperative that serious attempts should be made to conserve
earth’s environment from degradation. An aqua silencer is an attempt in this
direction. It mainly deals with control of emission and noise. An aqua silencer is
fitted to the exhaust pipe of an engine. Air pollution is the introduction of
chemicals, particulate matter, or biological materials that cause harm or
discomfort to humans or other living organisms or damages the natural
environment. These substances called pollutants can occur naturally or they can
be produced by human activities. Natural pollutants include dust, pollen, salt
particles, smoke from forest fires, and gases from organic waste. Most pollution
caused by human activities is directly or indirectly the result of burning of fuels in
furnaces or engines
An aqua silencer consists of a perforated tube which is installed at the end at the
end of exhaust pipe. The perforated tube have hole of different diameters. The
other end of the perforated tube is closed by plug. Around the circumference of
the perforated tube a layer of activated charcoal provided and further a metallic
mesh cover it. The whole until is then placed in water container . a small opening

is provided at the top of the container to remove the exhaust gases and a drain
plug is provided at the bottom of the container for periodically cleaning of the
container.
1.2 CONVENTIONAL SILENCER
INTRODUCTION Modern day automobiles are getting more and more
clean and safe, thanks to new inventions and sophisticated technologies. Vehicle
refinement is a new term introduced and evaluated as vehicle performance
parameter alongside emission effectiveness. The internal combustion engine is a
major source of noise pollution. Engine noise is classified as aerodynamic noisedue
to the flow of gases and surface radiated noise- due to vibration of engine
components. Sources of engine noise include intake system, combustion and
exhaust system out of which exhaust noise is attenuated by the use of mufflers.
Excess engine noise also deteriorates the ride quality and indicates lower finesse.
Furthermore, automobiles are a source of air pollution too. Emissions as a result
combustion process led directly into atmosphere are of major concern because of
their negative impact on air quality, human health, and global warming.
Government bodies implement, control and regulate emission standards for
primary pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO),
nitrogen oxides (NOx), and particulate matter (PM). It is the role of an automotive
design engineer to develop vehicles with greater environmental potential keeping
detrimental effects as such to a minimum. The following study involves testing of
a motorbike- ‘1995 Hero Honda CD 100 SS’ for its performance based on
certified vehicular noise tests as well as government regulated emission control
norms.

1.3 HELMHOLTZ SILENCER
Based upon the vehicle parameters, operating conditions and
performance requirements an exhaust system has been designed and fabricated. It
is called the ‘Helmholtz Silencer’ which is a combinational muffler working on
rules of reactive silencing and absorptive silencing all together with Helmholtz
principle. The bike is equipped with a factory fitted conventional dissipative
exhaust system which produces a high pressure pulsating flow of charge
generating noise up to 110dB at engine speed of 5800rpm. As per the Helmholtz
principle of reactive silencing, the silencing system has to be a compromise
between efficient attenuation and frequency band of effective attenuation.
However, in a vehicle running under normal road conditions i.e. at 45-60kmph,
the exhaust pulse ranges from 0.5 to 0.2 milliseconds which produce a natural
frequency of around 200-500Hz. For an effective Helmholtz resonator with
minimum insertion loss, we considered the super critical grade for efficient noise
cancellation. Critical dimensions of inlet pipe, chambers and tail pipe were
determined by applying acoustic engineering principles and a three chamber
layout was advised. The developed design is one with a radial inlet, single tube
muffler having three chambers- reaction chamber, expansion chamber and
diffusion chamber. The housing is built using chromium-nickel steel pipe with
2mm thickness and sealed on both ends. The tube is insulated using braided glass
wool for acoustic absorption. The reactive chamber has a concave brass
diaphragm to reflect sound waves back to the source in radial direction which
lowers the kinetic energy of gaseous charge. The charge passes

CHAPTER 2
2. LITRATURE REVIEW
1. M. A. Alen, M. Akshay, R. Prem Sankar and M. Mohammed Shafeeque,
Fabrication and Testing of Aqua Silencer, Int. Res. J. Engg. Technol. (IRJET) e-
ISSN: 2395-0056, August (2015).
2. Keval I. Patel, Mr. Swastik and R. Gajjar, Student Assistant Professor Svmit
Bharuch Department of Thermal System Design, Design and Development of
Aqua Silencer for Two Stroke Petrol Engine
3. B. Mankhiar Ajay, L. S. Sindhu and G. Sasikala, An Advancement to Reduce
Pollution Effectively by Using TI Nano Tubes in Aqua Silencer, Int. J. Engg. Sci.
Res. Technol. (2014). Int. J. Chem. Sci.: 14(S2), 2016 693
4. S. Rawale Sudrshan, S. Patil and S. Nehal, Use of Aqueous Ammonia in
Silencer for Removal of CO2, SO2 and NOx from Exhaust Gases of IC Engines,
Int. J. Engg. Sci. Innovative Technol., 2(5) (2013)
5. Swastik R, Gajjar, Design and Development of Aqua Silencer for Two Stroke
Petrol Engine, Int. J. Innovative Res. Sci. Technol., 1(1) (2014).
6. Developments of Emission and Noise Control Device, Int. J. Modern Trends
Engg. Res., 2(1).
7. M. Amruthraj, J. R. Nataraj and Sushmit Poojary, Emission Control in IC
Engines, Int. J. Engg. Res. Development, 4(4) (2012).

8. K. Kannan and M. Udayakumar, NOx and HC Emission Control Using Water
Emulsified Diesel in Single Cylinder Diesel Engine, ARPN J. Engg. Appl. Sci.,
4(8) (2009)
9 Alen. M. A, Akshay. M, Prem sankar. R, Mohammed shafeeque. M (Aug-
2015), “Fabrication and Testing of Aqua silencer”, International Research Journal
of Engineering and Technology, Vol. 2, Issue 5.
10 Akhil Anil Kumar, Anoop N, Aquib Jawed p.p, Bijoy E, Midhun T.V,
Mohammed shiyas. N.P, Ranjith Krishna P.T (May-2016), “International Journal
of Engineering and Innovative Technology, Vol. 5, Issue 11.
11 P. Balashanmugam, G. Balasubramanian (Jan-2015), “Design of Emission and
Noise control device (Aqua silencer)”, International Journal of Modern Trends in
Engineering and Research, Vol. 2, Issue 1.
12 SARATH RAJ, AJBIN K ANIYAN, AKSHAY AJI, ANANDHU RAJ,
ANANDU MOHAN, SHARON T.R (Oct-2015), “Fabrication and Testing of
Portable Twin filter Aqua silencer”, International Journal of Mechanical and
Industrial Technology, Vol. 3, Issue 2.

CHAPTER 3
3 WORKING PRINCIPLE
3.1 CONVENTIONAL SILENCER
The pulsating flow from each cylinder's exhaust process of an automobile petrol
or diesel engine sets up pressure waves in the exhaust system-the exhaust port and
the manifold having average pressure levels higher than the atmospheric. This
varies with the engine speed and load.
At higher speeds and loads the exhaust manifold is at pressures substantially
above atmospheric pressure. These pressure waves propagate at speed of the
sound relative to the moving exhaust gas, which escapes with a high velocity
producing an objectionable exhaust boom or noise.
A suitably designed exhaust silencer or muffler accomplishes the muffling of this
exhaust noise. The basics of silencing can be understood by recalling a few
principles of physics. The velocity of sound in the gas at a given temperature is
directly proportional to the square root of the product of the pressure and the ratio
of the specific heats (at constant pressure to that at constant volume), and
inversely to the square root of the density of the gas.
As the temperature varies, the velocity also varies directly as the temperature by
another square root law involving the product of the coefficient of thermal
expansion of the gas and the temperature. The exhaust noise can be reduced
appreciably by providing resonance chambers to offset the noise wave effects.
This is accomplished by the principle of the Helmholtz resonator. In principle, it
comprises the exhaust pipe, which goes through the large volume of a chamber.

The axial holes in the exhaust pipe enclosed by the chamber allow the gases to
vibrate with the large mass of the gases in the chamber (forming a spring-mass
vibrating system) and generate the sound of the same frequency but in opposite
phase to that which has to be nullified (called anti-sound).
To achieve this the muffler volume should be proportioned to the engine piston
displacement, and inversely proportioned to the engine speed and the square root
of the number of engine cylinders. The usual length to diameter (l/d) ratio of the
resonator is about 4:1 to 8:1.
A small l/d ratio muffler attenuates the sound well for a narrow frequency band,
where as the large l/d muffler attenuates the sound to a lesser degree but over a
wider frequency band. The effectiveness of the exhaust system in silencing the
exhaust depends also on the relative lengths of the exhaust pipe (from the exhaust
manifold to the muffler) and the tail pipe. A ratio of 1:2 is better than 4:1, and 1:1
is the poorest ratio.
Since the narrow frequency range limits the resonant chamber application, other
features are incorporated in the resonant chamber to produce friction effects and
filter off noise effects of other offending frequencies. Provision of baffles,
resonator mufflers with end baffles, resonator with centre baffle chamber and
four-chamber muffler are illustrative examples. In early stationary engines,
muffling of the sound was accomplished by allowing the gases to expand by
changing the direction of flow or by cooling them with injected water.
3.2 AQUA SILENCER
As the exhaust gases are entering into the perforated tube of the Aqua silencer, the
high mass bubbles are converted into low mass bubbles. The lime water is present

in the silencer the bubbles get react with the lime water, then it neutralizes the
acid present in water, this is a primary filtering process. After that, the bubbles are
passing through the activated charcoal layer which again purifies the gas bubbles
by absorbing the pollutants; this is a secondary filter process. This charcoal layer
is covered with outer shell that shell is surrounded by water. Due to that the sound
level gets reduced because of small sprockets present in the water molecules
which lower the Amplitude of sound wave. Hence Aqua silencer reduces the
pollution as well as noise.
3.3 ACTIVATED CHARCOAL
Carbon filtering is a method of filtering that uses a bed of activated carbon to
remove contaminants and impurities, using chemical absorption. Each
particle/granule of carbon provides a large surface area/pore structure, allowing
contaminants the maximum possible exposure to the active sites within the filter
media. One pound (450 g) of activated carbon contains a surface area of
approximately 100 acres (40 Hectares). Activated carbon works via a process
called adsorption, whereby pollutant molecules in the fluid to be treated are
trapped inside the pore structure of the carbon substrate. Carbon filtering is
commonly used for water purification, in air purifiers and industrial gas
processing, for example the removal of siloxanes and hydrogen sulfide from
biogas. It is also used in a number of other applications, including respirator
masks, the purification of sugarcane and in the recovery of precious metals,
especially gold. It is also used in cigarette filters. Active charcoal carbon filters
are most effective at removing chlorine, sediment, volatile organic compounds
(VOCs), taste and odor from water. They are not effective at removing minerals,
salts, and dissolved inorganic compounds. Typical particle sizes that can be
removed by carbon filters range from 0.5 to 50 micrometres. The particle size will

e used as part of the filter description. The efficacy of a carbon filter is also
based upon the flow rate regulation. When the water is allowed to flow through
the filter at a slower rate, the contaminants are exposed to the filter media for a
longer amount of time
Charcoal filters are used in a variety of fashions. The most common purpose for
using a charcoal based filter would be to eliminate impurities. Gas mask are a
good example of how charcoal filters provide protection to individuals by
eliminating the impurities (chemical warfare, police riot squads, etc..). Charcoal
filters are used in the purification process of many liquids (water processing
facilities, coffee machines, aquariums, etc..). Image from
http://furnacefiltercare.com/residential/carbon-filter/ Image from
http://www.airgle.com/blog/airpurifiers/charcoal-air-purifier-charcoal-filterchemical-
Charcoal filters are used in air conditioning units and exhaust fans to
rid air of unwanted odors (smoke, fumes, and animal odor). Some forms of
alcohol, such as whiskies, are put through various forms of charcoal filters, either
before or after aging. The process is known as leaching (Removal of materials by
dissolving them away from solids). Charcoal filters come in different forms such
as solid carbon, impregnated foam materials, powder and cloth (The Flatulence
Deodorizer). Charcoal is carbon & Activated charcoal is charcoal that has been
treated with oxygen to open up millions of tiny pores between the carbon atoms.
The use of special manufacturing techniques results in highly porous charcoals
that have surface areas of 300-2,000 square meters per gram. These so-called
active, or activated, charcoals are widely used to adsorb odorous or colored
substances from gases or liquids.

CHAPTER 4
4 COMPONENTS & EXPLAINATION
The aqua silencer in this project mainly consists of:
4.1 Perforated tube:
A tube of 20 mm diameter, 230 mm long is drilled with 500 holes with different
diameters. The purpose of these holes on the tube is to break down the large mass
of gas entering, into smaller ones as shown in Fig. 1. This perforated tube is
attached to the exhaust of the engine. The other end of the perforated tube is
closed by plug.

4.2 Activated charcoal
Activated charcoal is used as an absorber to absorb the smoke. Activated charcoal
has more absorbing capacity because it has more surface area. A layer of activated
charcoal was wrapped around the perforated tube using a thin mesh.

4.3 Non return valve:
The use of non-return valve is to enable the flow of fluid in one direction only. 20
mm diameter non-return valves are fixed at both inlet and outlet. The non-return
valve is used to prevent the back flow of gases and water and to maintain
upstream pressure. The whole setup is surrounded by water. Two openings are
present at both the top and bottom. The opening at the top is used to remove the
exhaust gases and the one at bottom is to clean the container. The container also
contains a filler plug. The back flow of the gases and water is regulated by a
return valve at the exhaust. Main aim is to control sound and noise6 .

CHAPTER 5
5. TECHINACAL SPECIFICATION
5.1 SPECIFICATION OF ENGINE
Stroke- two or four stroke petrol engine.
Type - Air cooled
No. of cylinder – single cylinder or multi cylinder
Displacement – 100cc
Maximum power -3.5hp at 5500 rpm
Max. torque -4.5 Nm at 5000rpm
5.2 SPECIFICATION OF WATER
Thermal properties of water
Maximum density -1000 kg/m3
Specific weight – 9.807 KN/m3
Freezing point -273K
Boiling point – 373K
Latent heat of melting – 334KJ/Kg
Latent heat of evaporation -2270 KJ/Kg
Specific heat -4-187 KJ/KgK
Thermal expansion _277K-373K
5.3 SPECIFICATION OF AQUA SILENCER
Diameter of outer shell - 150mm
Diameter of inlet pipe-20mm
Diameter of outlet pipe -20mm
Diameter of water inlet and out let pipe-20mm

Charcoal chip size-20-40mm
Non return valve-24mm
Inner core diameter-24mm
Flange thickness -3mm
Flange diameter-150mm
Length of inner and outer pipe-300mm
Number flange used-2

CHAPTER 6
6. DESIGN CALCULATION
For the experiment, an existing petrol engine has been used. Calculation are done
on the basis of data collected from the engine: however , some data on applicable
to all engine. For designing, the following data required.
1) SOUND CHARACTERISTICS (WITHOUT SILENCER)
Obs no. Regulation Conventional
silencer
Aqua silencer
Percentile
reduction
1 85dB 53dB 31dB 41.5%
2 85dB 64dB 37dB 42.2%
3 85dB 60dB 33dB 45%
Table no
Bar chart No.
90
80
70
60
50
40
30
Series1
Series2
Series3
20
10
0
Regulation
Conventional
silencer
Aqua silencer

2) SOUND ANALYSIS WITH FREQUENCY ANALYZER (TO OBTAIN
THE DOMINATING FREQUENCY )
Two dominating frequencies, the low level and high level have been obtain.
These are
Frequency level
Frequency (Hz)
Low 270
High 4000
Table no
Bar chart no.
Frequency (Hz)
4000
3500
3000
2500
2000
Frequency (Hz)
1500
1000
500
0
Low
High

CHAPTER 7
7. RESULT
Emission test result
Emission test taken three time to check the exact result at first time the test
taken without aqua silencer and at second time the test taken with aqua
silencer and final test is taken with aqua silencer with activated charcoal
wash with lime water
1) Emission test taken without installing aqua silencer:
2) Emission test taken with aqua silencer

3) Emission test taken with aqua silencer with activated charcoal wash

CHAPTER-8
8. CONCLUSION
1. In this review paper complete focus was given on the
study about the use of aqua silencer enhances the
reduction of noise and toxic emission and all the
various applications.
2. Use of water as a medium lowers the noise levels and
activated charcoal in water control the exhaust
emission to a greater level and increases its efficiency.
3. Energy efficiency increases with increase in flow rate of
back pressure (engine exhaust in the experiment under
consideration).
4. It gives smokeless and pollution free emissions.