Download - Report Stirling Engine Complete
STIRLING ENGINE 1
HEAT AND MASS TRANSFER
BMCT3143
STERLING ENGINE
Fakhrurazi Bin Aziz B040910051
Halimaton Basmatu AliB040910081
Mohd Azarul Syazari Bin Che Aziz B040910167
Muhammad Hafiz Bin Abd Rahim B040910092
Nurul Nadia Binti AbdullahB040910227
DUE DATE
25 MEI 2012
LECTURE
Pn. Mahanum Mohd Zamberi
Bachelor of Mechanical Engineering (Thermal-Fluid), Faculty of Mechanical Engineering,
Universiti Teknikal Malaysia Melaka, Durian Tunggal, Melaka.
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Table of Contents
Abstract……………………………………………………………………………………......3
Acknowledgement…………………………………………………………………………….4
Introduction………………………………………………………………………………....5-6
Chapter 1 : Theory…………………………………………………………………………6-8
Chapter 2 : Discussion……………………………………………………………………9-21
2.1. Design Details……………………………………………………………………..9-13
2.1.1. Flow chart…………………………………………………………………….14
2.1.2. Block diagram………………………………………………………………..15
2.2. Design Verification and Testing…………………………………………………...16
2.3. Discussion of Problem Encountered…………………………………………..16-17
2.3.1. Calculation………………………………………………………………..17-22
2.3.2. Application…………………………………………………………………...22
Chapter 3 : Conclusion……………………………………………………………………...22
References……………………………………………………………………………………23
Appendix A : Simple Performance Prediction Method……………………………….24-25
Appendix B : GANTT CHART…………………………………………………………….26
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Abstract
Despite vast research on energy generating engines for a long time, human particularly
the human society had not found the winning formula to create an engine that has 100%
efficiency. One of the closest engine that has a very high efficiency is the Stirling engine,
however it has several downfalls that deters any further application in our life. This report
subsequently is intended to find out the manufacturing process of a Stirling Engine using
recycled materials. The fabrication and assembly of all the parts requires knowledge about
theoretical application on how this engine works. Based on several dimensions and data from
the design, a Pressure-Volume(P-V) diagram had been obtained in order to know about the
theoretical performance of this engine. The engine had also been adds up with an application
in order to better understand its working principle. The application must not be overdone
because our engine design complies with only a small amount of torque so it cannot run on
heavy loads. The Stirling engine was used to remove the electrical load from the internal
combustion engine and to increase the fuel efficiency of the engine. The efficiency of heat
engine was limited by the law of thermodynamics. The powered of stirling engine was
causing by the differences of temperature at the radiator ends. The engine with high efficiency
helps to conserve fossil fuels and other natural resources, reducing global-warming emissions
and pollutants.
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Acknowledgement
The special thank goes to our lecturer, Puan Mahanum bt Zamberi. The supervision
and support was mostly helpful in progression and smoothness of this project. The co-
operation is much indeed appreciated.
Great deals appreciated to all team members that had give the support and struggle to
ensure this project was success. A big contribution and hard worked from all of team member
during eight week is very great indeed. This project would be nothing without the enthusiasm
and imagination from all team members.
Our grateful thank also go to all classmate members that give us support and briefly
idea that helpful in ensure this project was successful. Besides, due to this project there are
many new experiences in working environment which challenges us every minutes. We also
realized the value of working together as a team.
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Introduction
Stirling Engine is one of the reversible thermodynamic cycle application, it is
consisting of four phases that include heat addition (isovolumetric heating), expansion
(isothermal expansion), heat rejection (isovolumetric cooling), and compression (isothermal
compression) which is perform in one complete cycle. They are widely can found in industry
application because of the high thermal efficiency, form a quiet and safe operation, ease of
operation and able to working with form of thermal energy.
Beta Stirling engine is one of the type of sterling engine, it is and improvment from
the alpha type of stirling engine. The new design have eliminated the hot seal failure that can
found in Alpha and the hot power piston is replaced by a displacer for the improvement. Other
design is still the same with. The power piston and the displacer is sharing the same common
cylinder and flywheel/crankshaft. Unlike the piston power, the displacer size need to be small
from the the cylinder so that the friction between the cylinder and the displacer will be lower
and easily to move up and downward.
Figure 1 Beta Sterling Engine
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In Beta Sterling Engine, it has four basic stages to complete one cycle of operation.
First stage is heating process. The heat will be supplied from the bottom of cylinder. Then the
displacer will going upward due to the heat energy being transferred to the atom in a form of
kinetic energy. The collision between the atom with each other and with the wall will produce
pressure that push the displacer. The piston power will also going upward because of the
compression state at upper cylinder. Then the heat being remove, the expand part is contract
because of the kinetic energy is converted into potential energy, the piston will followed the
same motion with the displacer. And once the heat being supplied again, it will repeat the
same process.
Chapter 1 : Theory
Based on SCHMIDT theory and the theory of stirling engine, there are four type of
stirling engine where it is APLHA, BETA, GAMMA and Low Temperature Displacer (LTD).
The theory that used an isothermal calculation for the stirling engine is a Schmidt Theory.
Where it was the simplest method for the Stirling engine. This theory is based on the
isothermal expansion and compression of an ideal gas.
Due to assumption of Schmidt Theory, the performance of engine can be calculated by using
P-V diagram. Where the volume in the engine can be calculated by internal geometry and the
mass of working gass and the temperature are decided. The pressure can be calculate using an
ideal gas method where shown on equation (1).
PV = mRT (1)
Where:
P (Pa) = engine pressure
V (m3) = total momental volume
m (kg) = total mass of working gas
R (J/kgK) = gas constant
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T (J) = space gas temperature
For the BETA-TYPE stirling engine, there are calculation model.
The equation that involve are;
VE = VSE / 2 (1- cos x) + VDE (2)
Vc = VSE / 2 (1- cos x) + VSC / 2 [ 1-cos(x-dx)] + VDC – VB (3)
Where;
VE = expansion momental volume
Vc = compression momental volume
VSE = swept volume of displacer piston
VSC = swept volume of power piston
dx = phase angle between the diesplacer piston and power piston
In case of stirling engine, the displacer piston and the power piston was located in the same
cylinder. An effective working space was created when the both piston was overlaps then
there are a stroke. The overlap volume (VB) was calculated based on equation (4);
VB = (VSE + VSC) /2 - √V SE2+V SC24
−V SEV SC2
cos dx (4)
So, the total momental volume (V) is
V = VE + Vc + VR (5)
To define the engine pressure;
P = [ Pmean √1– c 2 ] /[ 1-c.cos(x –a)]
= [ Pmin (1+c)] / [ 1-c.cos(x –a)]
= [ Pmax (1-c)] / [ 1-c.cos(x –a)] (6)
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Where;
Pmean = mean pressure
Pmin = minimum pressure
Pmax = maximum pressure
There are several ratios and coefficients are defined as;
t = TC / TE (7)
v = VSC / VSE (8)
XB = VB / VSE (9)
XDE = VDE / VSE (10)
XDC = VDC / VSE (11)
XR = VR / VSE (12)
a = tan ⁻1[ v sin dx /( t + cos dx + 1)] (13)
S = t + 2txDE + 4t XR / (1 + t) + v + 2XDC + 1-2XB (14)
B = √ t 2+2(t−1)v cosdx+v2−2t+1 (15)
c = B /S (16)
where;
TC = compression space gas temperature
TE = expension space gas temperature
VR = regenerator volume
Then, the P – V diagram of Beta-type Stirling engine can be made based on the equation
above.
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Chapter 2 : Discussion
2.1. Design Details
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Figure 2 : Connecting Rod
Figure 3 : Crankshaft Holder
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Figure 4 : Flywheel
Figure 5 : Displacer
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Figure 6 : Displacer Block
Figure 7 : Rendering of Stirling Engine in Solidworks
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Figure 8 : Isometric View
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2.1.1. Flow chart
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NO
START END
Brainstorming
Fabrication of engine block by
using aluminum tin
Selecting material
Engine testing
Assemble all part
Fabrication of crank shaft, connecting
rod, and flywheel by using compact disc.
Fabrication of power piston by using
balloon
Fabrication of displacer
Is the engine running
Is there any air leakage
Can it fit with the
tin
Is it a recycle material
YES
NO
NO
YES
YES
NO
YES
STERLING ENGINELIST OF COMPONENT
AND FUNCTION
ENGINE FRAMETo hold crankshaft and
flywheel together.
FLYWHEELSThe flywheel smoothes
out the pulse of the power stroke and its
inertia allows the crank shaft to continue
rotating.
CONNECTING RODSIt changes the
reciprocating motion of piston into at
crankshaft. This way connecting rod
transmits the power produced at piston to
crankshaft.
CRANKSHAFTReceives oscillating
motion from connecting rod and
gives a rotary motion to the flywheel
POWER PISTONto amplify the displacer stroke (power stroke)
DISPLACERto move the working gas back and forth
between the hot and cold heat exchangers.
BLOCK LEGTo create room for
heater( candle) compartment
ENGINE BLOCKthe bore of the cylinder
will create pressure difference between
upper and lower compartment
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2.1.1. Block diagram
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2.1. Design Verification and Testing
The verification is intended to check that a product, service, or system meets a set of
initial design requirements, specification and regulations. For the stirling engine project, the
functionality of the design and also the application needs to be evaluated in order to ensure
the project complies with regulations, specifications, or conditions imposed at the start of a
development phase. On this project, there are several benchmarks to be met by the product in
order to ensure it achieves a high standard.
The design of this engine speed is about 100 revolutions per minutes. The speed of this
engine does not necessarily be so high because the application for this system is light. For
ensure the application of this stirling engine project was run smoothly, the light application
was chosen that are shoes polisher. By using the minimal amount of heat, the engine was run
at least with two candles. Due to this application and design, it was safe for domestic usage
that are not be harmful towards costumer, however it was not suitable for children that was
below age of 7 years.
2.2. Discussion of Problem Encountered
This project development was divided into several phase that are multiple types of
problem that should be encounter in order to ensure the stirling engine was working.
The first type of stirling engine that was chosen was Low Temperature Displacer
( LTD)There was several factor that make the design of LTD was failure and it is down,
which is the heat required to run the engine was so high. Due to this requirement, the
displacer bore is quite spacious that in this stirling engine, it cannot been able to create the
sufficient amount of pressure to lift the displacer up. The factor that was affected this type of
stirling engine was diameter of the bore. The big displacer must been fabricate due to this type
of stirling engine where it was quite heavy. The crankshaft design had met a design
complication that caused the piston and displacer movement to be not smooth.
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Got a failure from the first design of stirling engine, the type of Beta stirling engine.
There are also several complication that was faced in terms of design and also application
before it was successful. The dimensions of bore and piston diameter was been ensure suitable
for the compression ratio of the engine. It was important because it has possibility to face with
malfunction of stirling engine. The balloon was inserting in the system that act as power
piston. The balloon has its nature elasticity that was used as advantage for air tight purpose. It
was installing carefully to ensure that it was tight properly. The complexity of the crankshaft
was design properly because it was important for the piston and displacer stroke smoothness.
The fabrication of cooling compartment is quite complicated as to cut the compartment to suit
the block diameter.
2.2.1. Calculation
Given that( from stirling engine):
T = 650c
R= 287.06
VSE = 0.000184 m3 ( volume of piston)
VSC = 1m3
VR = 0.00010053 m3
dx = 900c
Tc = 65 0c
Te = 600c
X = 0 ( ideal stirling engine)
t = 0.8 sec (complete one cycle)
VE = Πr2 h = π (3x 10-2)2 (6.5x10-2) = 0.1838x10-3 m3
VC = Πr2 h = π (3x 10-2)2 (4.5x10-2) = 0.127x10-3 m3
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V = VE + VC + VR = 0.000184 + 0.000127 +0.00010053 = 0.000412m3
To find the pressure on the stirling engine,
PV= m RT,
ρ = m / V,
To find mass expansions of gas,
ρ = mE / V
From table 2;
T1 =350c, ρ = 1.1455 kg/m3
So, ρ = mE / VE
1.1455 kg/m3 = mE / (0.1838x10-3 m3)
mE = 0.0002105KG
To find mass compression of gas,
ρ = mc / Vc
From table 2;
T1 =350c, ρ = 1.1455 kg/m3
So, ρ = mc / Vc
1.1455 kg/m3 = mc / (0.127x10-3 m3)
mc = 0.0001457KG
so, the pressure are;
Pmax (Pexpansion) : PVE = mE RT
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(Pmax)(0.1838 X10-3) = (2.105 X 10-4)(287.06)(65+ 273)
Pmax = 111.13kPa
Pmin (Pcompression) : PVC = mC RT
(Pmin)(0.127x10-3) = (1.4574 X 10-4)(287.06)(65+ 273)
Pmin = 111.35kPa
Pmean = 111.13 kPa+111.35 kPa
2 =111.24kPa
After that, to find the overlap volume;
VB = (VSE + VSC) /2 – √V SE2+V SC2
4−V SEV SC
2 cos dx
VB = (0.000184+ 1) /2 – √ ( 0.000184 )2+(1)2
4−
(0.000184 )(1)2
cos (90)
VB = 9.2 x 10-5m3
Engine pressure;
P = [ Pmax (1-c)] / [ 1-c.cos(x –a)]
C = B / S
B = √ t 2+2(t−1)v cosdx+v2−2t+1
B = √ (0.8 )2+2 (0.8−1 ) (0.000412 ) cos (90 )+(0.000412)2−2(0.8)+1
B = 0.2
S = t + 2txDE + 4t XR / (1 + t) + v + 2XDC + 1-2XB
S = 0.8 + 2(0.8)(0) + 4(0.8)(0) / (1 + 0.8) + 0.000412 + 2(0) + 1-2(0)
S = 1.800412
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C = B / S
C = 0.2 / 1.800412 = 0.11109
t = TC / TE = (65/ 60) = 1.08
a = tan ⁻1[ v sin dx /( t + cos dx + 1)]
a = tan ⁻1[ (0.000412) sin (900) /( 1.08 + cos (900) + 1)] = 0.01135
P = [111.13x103 (1-0.11109)] / [ 1-0.11109cos(0 –0.01135)] = 111.12 kPa
After that, by using the simple performance prediction method for stirling engine (ver. 1.8J,
koichi Hirata (31 March, 1998)).
Step to used;
1) The mean pressure, a swept volume, gas temperature, and a type of working gas was
added on the calculated condition.
2) Due to this stirling engine, it was operate by using the design and permitted value.
3) After complete the fill in the blank of the table, the button start was click.
4) The maximum output power and the engine speed was calculate when the engine was
at maximum output power due to the experimental equations.
The result that was get from these experimental equations is;
Viscosity coefficient, vlim = 1.74E-5 m2/s
Gas constant, R = 287.3 J/kgK
Engine speed, N = 11552.7 rpm
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Graph 1 : P – V DIAGRAM
Based on the Graph 1 for the stirling engine that had been plotted due to the
calculation that had done, the amount volume of compression are 0.127x 10-3m3. While
volume of expansion on this stirling engine are 0.1838x10-3m3. This is due to the volume
displacement that involve during the stirling engine cycle. The total volume of the can that
was assumed as cylinder is 3.6757 x 10-4 m3. The heights of the cylinder are 13 cm and the
diameters of the can are 6cm. The volumes of the displacer that are on the cylinder are half of
the height of the cylinder where it was 6.5 cm. Amount of pressure that involve on this stirling
engine is due to the volume of expansions and compression. Pressure at expansion are 111.13
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STIRLING ENGINE 22
kPa while at compression, the pressure was at 111.35 kPa. The heating process was happen at
pressure 1 until pressure 2. Where between 111.13kPa until 111.35kPa. The expansion
process was happen during 111.35 kPa until 111.24 kPa. At this situation, the work done of
expansion was out while the flow rate was in the system. On the cooling process, the pressure
from 111.24 kPa was drop until 111.12 kPa. The compressions on the system were happen
from pressure 4 to pressure 1.
2.1.1. Application
By manipulate the stirling engine system and translate it into shoes polisher as the
application. How the shoes polisher is working? By manipulate the heat being transfer to the
system, the air in the cylinder will expend due to the pressure increased. Once the pressure
increased, it will push away the displacer upward and make a half cycle. At upper cylinder
included power piston is placed and ice that will make a temperature difference. Because of
the low temperature being supplied, the pressure at the power piston will contract due to the
kinetic energy being transferred into potential energy. The power piston will push away the
displacer to the downward movement and make another half cycle. The complete cycle will
make a rotational movement and transfer to the crank shaft and then transfer to the span that
will act as shoes polish.
Chapter 3 : Conclusion
From the project that have been build, many type of properties need to be considered
to perform a good result in this project. From the fabrication process, each of the dimensions
need to be precise or otherwise the project will not running at all. This is due to the friction
factor between the displacer and the tin, temperature difference that not meet specification
that have been stated and maybe will form a leakage place that will lowered the performance
of the engine. Engine that had high efficiency is the one that can manipulated the lower
temperature an in this project it can run by using at least with two candle.
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References
[1] LARRY KEEGAN'S EXPERIMENTS WITH STIRLING ENGINES. Retrieved from
http://www.keegan.org/larry/stirling.html
[2] The Stirling engine. Retrieved from http://www.pha.jhu.edu/~broholm/l39/node5.html
[3] Simple Performance Prediction Method for Stirling Engine. Retrieved from
http://www.bekkoame.ne.jp/~khirata/academic/simple/simplee.htm
[4] SCHMIDT THEORY FOR STIRLING ENGINES. Retrieved from
http://www.bekkoame.ne.jp/~khirata/academic/schmidt/schmidt.htm
[5] STIRLING ENGINES. Retrieved from http://www.robertstirlingengine.com/theory.php
[6] Beta Type Stirling Engines. Retrieved from
http://www.ohio.edu/mechanical/stirling/engines/beta.html
[7] Stirling engine http://en.wikipedia.org/wiki/Stirling_engine
[8] Beta And Gamma Engine Phase Angle Calculation. Retrieved from
http://newenergydirection.com/blog/2008/11/beta-and-gamma-engine-phase-angle-
calculation/
[9] Innovative Rotary Displacer Stirling Engine: Sustainable Power Generation for Private
and Fleet Vehicle Applications. Retrieved from
http://scholar.lib.vt.edu/ejournals/JOTS/v37/v37n2/foster.html
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Appendix A : Simple Performance Prediction Method [3]
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Appendix B : GANTT CHART
( TIME DURATION OF PLANNING STIRLING ENGINE PROJECT)
ACTIVITIES
DURATION
22/3 – 29/3 29/3 – 5/4 5/4 – 12/4 12/4 – 19/4 19/4 – 26/4 3/5 – 10/5 17/5 – 24/5
24/5 – 25/5
IDENTIFYING THE PROBLEM
BRAINSTORMING AND PLANNING THE PRODUCT OF STIRLING ENGINEPROCESS DESIGN AND DEVELOPMENT
DETAILED TECHNICAL DESIGN
DESIGN FUNCTIONALITY AND EFFECTIVENESS
PRODUCT DESIGN ANALYSIS
PRESENTATION
REPORT
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