1

TRUBA COLLEGE OF ENGINEERING & TECHNOLOGY

INDORE (M.P.)

“FABRICATION OF BASIC STIRLING ENGINE MODEL”

A MINOR PROJECT REPORT-2012

A minor project report submitted at

Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal

In partial fulfillment of the requirement as per the curriculum of

BE IIIrd

year in the Mechanical Engineering.

SUBMITTED BY

MANISH SOLANKI (0830ME091032)

MD. UMAR KHAN (0830ME091035)

ROHAN GORALKAR (0830ME091050)

SUBMITTED TO: GUIDED BY:

PROF. MRS. SUMAN SHARMA Asst.Prof. MR. VISHAL ACHWAL

(HEAD OF DEPARTMENT)

DEPARTMENT OF MECHANICAL ENGINEERING

2

TRUBA COLLEGE OF ENGINEERING & TECHNOLOGY

INDORE (M.P.)

“FABRICATION OF BASIC STIRLING ENGINE MODEL”

A MINOR PROJECT REPORT-2012

SUBMITTED BY

MANISH SOLANKI (0830ME091032)

MD. UMAR KHAN (0830ME091035)

ROHAN GORALKAR (0830ME091050)

SUBMITTED TO: GUIDED BY:

PROF. MRS. SUMAN SHARMA Asst.Prof .MR. VISHAL ACHWAL

(HEAD OF DEPARTMENT )

DEPARTMENT OF MECHANICAL ENGINEERING

3

TRUBA COLLEGE OF ENGINEERING & TECHNOLOGY

INDORE, (M.P.)

CERTIFICATE

This is to certify that the project work entitled

“ FABRICATION OF BASIC STIRLING ENGINE MODEL”

has been carried out by, MANISH SOLANKI, MD. UMAR KHAN ,

ROHAN GORALKAR students of third year B.E. Mechanical Engineering under our

supervision & guidance. They have submitted this Minor project report towards partial

fulfillment for the award of Bachelor of Engineering in Mechanical Engineering of

Rajiv Gandhi Prodyogiki Vishvavidyalaya, Bhopal

during the academic year 2011-2012.

Asst.Prof.Mr. Vishal Achwal Prof. Suman Sharma Madam

Project Guide Head of Department

Mechanical Engg Dept. TCET Mechanical Engg Dept. TCET

Director TCET, INDORE

DEPARTMENT OF MECHANICAL ENGINEERING

4

TRUBA COLLEGE OF ENGINEERING & TECHNOLOGY

INDORE, (M.P.)

RECOMMENDATION

This is to certify that

MANISH SOLANKI, MD. UAMR KHAN, ROHAN GORALKAR

Students of Final year B.E (Mechanical Engineering)

Of this institute have completed the project work entitled

“FABRICATION OF BASIC STIRLING ENGINE MODEL”

Based on the syllabus and have submitted a satisfactory report on it in the

Academic year 2011-2012.

INTERNAL EXAMINER EXTERNAL EXAMINER

Date- Date-

DEPARTMENT OF MECHANICAL ENGINEERING

1

ACKNOWLEDGEMENT

Working in this institute during this project had been a great learning

experience for us. We take this opportunity to express our sincere gratitude

to all those people who have been instrumental in making our project a

success.

“To make efforts is better than to achieve success and choose the capable

person for success is greater than to make and succeed.”

We feel deeply indebted to our project Guided by: Asst. Prof. Vishal

Achwal

( Lecturer Mechanical Engineering Department) who generously shared

his wisdom, experience and expertise with us and guided us through the

project. We thank him for all his valuable guidance and suggestions.

We also extend our sincere thanks to all the faculty members of

Mechanical Engineering Department for their constant guidance and

support.

We express our deep sense of gratitude to Dr.P.K.CHANDE

(Director, T.C.E.T.) for his liberal encouragement and moral support not

only during this project but also throughout the studies.

Manish Solanki

Md.Umar Khan

Rohan Goralkar

2

ABSTRACT

The performance of Stirling engines meets the demands of the efficient use

of energy and environmental security and therefore they are the subject of

much current interest. Hence, the development and investigation of Stirling

engine have come to the attention of many scientific institutes and

commercial companies. The Stirling engine is both practically and

theoretically a significant device, its practical virtue is simple, reliable and

safe which was recognized for a full century following its invention by

Robert Stirling in 1816. The engine operates on a closed thermodynamic

cycle, which is reversible.

The objective of this project paper is to provide fundamental information

and present a detailed review of the efforts taken by us for the development

of the Stirling cycle engine and techniques used for engine analysis. A

number of attempts have been made by us to build and improve the

performance of Stirling engines. It is seen that for successful operation of

engine system with good efficiency a careful design, proper selection of

drive mechanism and engine configuration is essential. This project paper

indicates that a Stirling cycle engine working with relatively low

temperature with air or helium as working fluid is potentially attractive

engines of the future, especially solar-powered low-temperature differential

Stirling engines.

3

CONTENT

Page No.

1. Introduction 5

1.1 Thermodynamic cycle 6

1.2 Heat and Work 7

1.3 Well known thermodynamic cycle’s 12

1.4 History of Stirling Engine 14

2. Literature Review 15

2.1 Presentation of Stirling Engines 18

2.1.1 Stirling thermodynamic cycle 18

2.2 Analysis of the Stirling-Cycle Engine 20

2.2.1 Work done by an ideal Stirling-cycle 20

2.2.2 Heat flow in an ideal Stirling-cycle 22

2.2.3 Efficiency of an ideal Stirling-cycle 23

2.2.4 Actual Stirling Engine 24

2.3 Engine configurations 25

2.3.1 Alpha Stirling 26

2.3.2 Beta Stirling 28

2.3.3 Gamma Stirling 30

2.4 Technical complexity of topic 31

3. Model Description 32

3.1 Design & Drawing 33

3.1.1 Stand & Cylinder 34

3.1.2 Piston 35

3.1.3 Fan Acting as Crank 35

3.1.4 Connecting Rod & Link 36

3.1.5 Assembly in Pro-Engineer software 36

3.2 Methodology 37

3.2.1 Assembly & Procedure 37

3.2.2 Our Stirling Engine Mode 39

3.3 Expenses 40

4. Advantages 41

4

Page No.

5. Disadvantages 43

5.1 Problems And Iteration 44

5.2 Causes Of Failure 44

6. Analyze From Economic Point 45

7. Applications of The Stirling Power 48

7.1. Cars 48

7.2. Submarine. 48

7.3. Nuclear power 48

7.4. Solar Energy 49

7.5. Aircraft engines 49.

8. Conclusion 50

9. References 52

10. List of Figures 54

11. List of Tables 55

5

INTRODUCTION

6

INTRODUCTION

1.1 Thermodynamic cycle

Thermodynamics

HEAT FLOW: FIGURE: 1

State:

Equation of state

Ideal gas · Real gas

Phase of matter · Equilibrium

Control volume · Instruments

Processes:

Isobaric · Isochoric · Isothermal

Adiabatic · Isentropic · Isenthalpic

Quasistatic · Polytropic

Free expansion

Reversibility · Irreversibility

Endoreversibility

Cycles:

Heat engines · Heat pumps

Thermal efficiency

7

Material properties:

Specific heat capacity

Compressibility

Thermal expansion

Potentials:

Internal energy

Enthalpy

Helmholtz free energy

Gibbs free energy

A thermodynamic cycle consists of a series of thermodynamic processes

transferring heat and work, while varying pressure, temperature, and other

state variables, eventually returning a system to its initial state. In the

process of going through this cycle, the system may perform work on its

surroundings, thereby acting as a heat engine.

State quantities depend only on the thermodynamic state, and cumulative

variation of such properties adds up to zero during a cycle. Process

quantities (or path quantities), such as heat and work are process dependent,

and cumulative heat and work are non-zero. The first law of

thermodynamics dictates that the net heat input is equal to the net work

output over any cycle. The repeating nature of the process path allows for

continuous operation, making the cycle an important concept in

thermodynamics. Thermodynamic cycles often use quasistatic processes to

model the workings of actual devices.

1.2 Heat and work

Two primary classes of thermodynamic cycles are power cycles and heat

pump cycles. Power cycles are cycles which convert some heat input into a

mechanical work output, while heat pump cycles transfer heat from low to

high temperatures using mechanical work input. Cycles composed entirely

of quasistatic processes can operate as power or heat pump cycles by

controlling the process direction. On a pressure volume diagram or

temperature entropy diagram, the clockwise and counterclockwise

directions indicate power and heat pump cycles, respectively.

8

Relationship to work

Example of P-V diagram of a thermodynamic cycle

FIGURE : 2

Because the net variation in state properties during a thermodynamic cycle

is zero, it forms a closed loop on a PV diagram. A PV diagram's Y axis

shows pressure (P) and X axis shows volume (V). The area enclosed by the

loop is the work (W) done by the process:

This work is equal to the balance of heat (Q) transferred into the system:

Equation (2) makes a cyclic process similar to an isothermal process: even

though the internal energy changes during the course of the cyclic process,

when the cyclic process finishes the system's energy is the same as the

energy it had when the process began.

If the cyclic process moves clockwise around the loop, then W will be

positive, and it represents a heat engine. If it moves counterclockwise, then

W will be negative, and it represents a heat pump.

9

The clockwise thermodynamic cycle indicated by the arrows shows that the

cycle represents a heat engine. The cycle consists of four states (the point

shown by crosses) and four thermodynamic processes (lines).

For example the pressure-volume mechanical work done in the heat engine

cycle, consisting of 4 thermodynamic processes, is:

If no volume change happens in process 4->1 and 2->3, equation (3)

simplifies to:

Thermodynamic cycles may be used to model real devices and systems,

typically by making a series of assumptions.simplifying assumptions are

often necessary to reduce the problem to a more manageable form.For

example, as shown in the figure, devices such a gas turbine or jet engine can

be modelled as a Brayton cycle. The actual device is made up of a series of

stages, each of which is itself modelled as an idealized thermodynamic

process. Although each stage which acts on the working fluid is a complex

real device, they may be modelled as idealized processes which

approximate their real behavior. A further assumption is that the exhaust

gases would be passed back through the inlet with a corresponding loss of

heat, thus completing the idealized cycle.

The difference between an idealized cycle and actual performance may be

significant. For example, the following images illustrate the differences in

work output predicted by an ideal Stirling cycle and the actual performance

of a Stirling engine:

10

Ideal Stirling cycle

FIGURE: 3

Actual and ideal overlaid, showing difference in work output

FIGURE: 4

11

Actual performance

FIGURE: 5

The adiabatic Stirling cycle is similar to the idealized Stirling cycle;

however, the four thermodynamic processes are slightly different (see graph

above):

180° to 270°, pseudo-Isothermal Expansion. The expansion-space is

heated externally, and the gas undergoes near-isothermal expansion.

270° to 0°, near-constant-Volume (or near-isometric or isochoric)

heat-removal. The gas is passed through the regenerator, thus cooling

the gas, and transferring heat to the regenerator for use in the next

cycle.

0° to 90°, pseudo-Isothermal Compression. The compression space is

intercooled, so the gas undergoes near-isothermal compression.

90° to 180°, near-constant-Volume (near-isometric or isochoric) heat-

addition. The compressed air flows back through the regenerator and

picks-up heat on the way to the heated expansion space.

12

With the exception of a Stirling thermoacoustic engine, none of the gas

particles actually flows through the complete cycle. So this approach is not

amenable to further analysis of the cycle. However, it provides an overview

and indicates the cycle work.

As work output is represented by the interior of the cycle, there is a

significant difference between the predicted work output of the ideal cycle

and the actual work output shown by a real engine. It may also be observed

that the real individual processes diverge from their idealized counterparts;

e.g., isochoric expansion (process 1-2) occurs with some actual volume

change.

1.3 Well-known thermodynamic cycles

In practice, simple idealized thermodynamic cycles are usually made out of

four thermodynamic processes. Any thermodynamic processes may be

used. However, when idealized cycles are modeled, often processes where

one state variable is kept constant are used, such as an isothermal process

(constant temperature), isobaric process (constant pressure), isochoric

process (constant volume), isentropic process (constant entropy), or an

isenthalpic process (constant enthalpy). Often adiabatic processes are also

used, where no heat is exchanged.

13

Some example thermodynamic cycles and their constituent processes are as follows:

Cycle Process 1-2

(Compression)

Process 2-3

(Heat

Addition)

Process 3-4

(Expansion)

Process 4-1

(Heat

Rejection)

Notes

Power cycles normally with external combustion - or heat pump cycles:

Bell

Coleman adiabatic isobaric adiabatic isobaric

A reversed

Brayton cycle

Carnot isentropic isothermal isentropic isothermal

Ericsson isothermal isobaric isothermal isobaric

the second

Ericsson cycle

from 1853

Rankine adiabatic isobaric adiabatic isobaric Steam engine

Scuderi adiabatic

variable

pressure

and volume

adiabatic isochoric

Stirling isothermal isochoric isothermal isochoric

Stoddard adiabatic isobaric adiabatic isobaric

Power cycles normally with internal combustion:

Brayton adiabatic isobaric adiabatic isobaric

Jet engines

the external

combustion

version of this

cycle is known as

first Ericsson

cycle from 1833

Diesel adiabatic isobaric adiabatic isochoric

Lenoir isobaric isochoric adiabatic

Pulse jets

(Note: Process 1-

2 accomplishes

both the heat

rejection and the

compression)

Otto adiabatic isochoric adiabatic isochoric Gasoline / petrol

engines

Known Thermodynamic Cycles: TABLE: 1

14

1.4 HISTORY:

The Stirling engine were invented in 1816 by Robert Stirling in Scotland,

some 80 years before the invention of diesel engine, and enjoyed substantial

commercial success up to the early 1900s. A Stirling cycle machine is a

device, which operates on a closed regenerative thermodynamic cycle, with

cyclic compression and expansion of the working fluid at different

temperature levels. The flow is controlled by volume changes so that there

is a net conversion of heat to work or vice versa. The Stirling engines are

frequently called by other names, including hot-air or hot-gas engines, or

one of a number of designations reserved for particular engine arrangement.

In the beginning of 19th century, due to the rapid development of internal

combustion engines and electrical machine, further development of Stirling

engines was severely hampered.

Sketch of Robert Stirling of his invent

FIGURE: 6

15

LITERATURE REVIEW

16

2. LITERATURE REVIEW

The Stirling Engine is one of the hot air engines. It was invented by Robert

Stirling (1790-1878) and his brother James. At this period, he found the

steam engines are dangerous for the workers. He decided to improve the

design of an existing air engine. He hope it wound be safer alternative.

After one year, he invented a regenerator. He called the “Economizer” and

the engine improves the efficiency. This is the earliest Stirling Engine. It is

put out 100 W to 4 kW. The Ericsson invented the solar Energy in 1864 and

did some improvements for after several years. Robert’s brother, James

Stirling, also played an important role in the development of Stirling

engines.

Earliest Stirling engine

FIGURE: 7

17

The original patent by Reverend Stirling was called the "economizer", for

its

Improvement of fuel-economy. The patent also mentioned the possibility of

using the device in an engine. Several patents were later determined by two

brothers for different configurations including pressurized versions of the

engine. This component is now commonly known as the "regenerator" and

is essential in all high-power Stirling devices.

During the early part of the twentieth century the role of the Stirling engine

as a "domestic motor" was gradually usurped by the electric motor and

small

Internal combustion engines until by the late 1930s it was largely forgotten,

only produced for toys and a few small ventilating fans. At this time Philips

was seeking to expand sales of its radios into areas where mains electricity

was unavailable and the supply of batteries uncertain. Philips’

Management decided that offering a low-power portable generator would

facilitate such sales and tasked a group of engineers at the company

research lab (the Nat. Lab) in Eindhoven to evaluate the situation. After a

systematic comparison of various prime movers the Stirling engine was

considered to have real possibilities as it was among other things, inherently

quiet (both audibly and in terms of radio interference) and capable of

running from any heat source (common lamp oil was favored). They were

also aware that, unlike steam and internal combustion engines, virtually no

serious development work had been carried out on the Stirling engine for

many years and felt that with the application of modern materials and

know-how great improvements should be possible.

18

2.1 PRESENTATION OF STIRLING ENGINES

2.1.1 STIRLING THERMODYNAMIC CYCLE

The Stirling engine cycle is a closed cycle and it contains, most commonly

a fixed mass of gas called the "working fluid" (air, hydrogen or helium).

The principle is that of thermal expansion and contraction of this fluid due

to a temperature differential.

So the ideal Stirling cycle consists of four thermodynamic distinct processes

acting on the working fluid: two constant-temperature processes and two

constant volume processes.

Each one of which can be separately analyzed:

Stirling thermodynamic cycle: FIGURE:8

19

Process Involved In Stirling Cycle:

1-2: isothermal compression process. Work W1-2 is done on the

working fluid, while an equal amount of heat Q1-2 is rejected by the

system to the cooling source. The working fluid cools and contracts

at constant temperature TC.

2-3: constant volume displacement process with heat addition.

Heat Q 2-3 is absorbed by the working fluid and temperature is raised

from TC to TH. No work is done.

3-4: isothermal expansion process. Work W3-4 is done by the

working fluid, while an equal amount of heat Q3-4 is added to the

system from the heating source. The working fluid heats and expands

at constant temperature TH.

4-1: constant volume displacement process with heat rejection.

Heat Q4-1 is rejected by the working fluid and temperature decrease

from TC to TH. No work is done.

20

2.2 ANALYSIS OF THE STIRLING-CYCLE

ENGINE

2.2.1 Work done by an ideal Stirling-cycle engine

The net work output of a Stirling-cycle engine can be evaluated by

considering the cyclic integral of pressure with respect to volume:

W=-∮

This can be easily visualized as the area enclosed by the process curves on

the pressure-volume. To evaluate the integral we need only consider the

work done during the isothermal expansion and compression processes,

since there is no work done during the isochoric processes, i.e.

W=-[ ∫

+∫

(4.1)

By considering the equation of state:

pV =mRT

and noting that T is constant for an isothermal process, and m is constant for

a closed cycle, then an expression for work done during an isothermal

process can be formulated:

∫ ∫

(

) (4.2)

so that by substitution of Equation 4.2 into Equation 4.1,we can evaluate

the work integral:

( ) (

) ( ) (

)

where the subscripts H and L denote the high and low temperature

isotherms respectively.

This equation can then be further simplified by noting that V4 = V1 and V3

= V2 so that a final equation for work can be obtained:

21

(

)(TH -TL) (4.3)

The work done represents energy out of the system, and so has a negative

value according to the sign convention used here.

Inspection of Equation 4.3, therefore, shows that the work output for a

Stirling-cycle machine can be increased by maximizing the temperature

difference between hot and cold ends (TH-TL), the compression ratio

(V2/V1), the gas mass (and hence either the total volume of the machine

and/or the mean operating pressure), or the specific gas constant.

Material strength/temperature considerations and practicalities such as the

overall size of the machine usually limit the amount that the temperature,

volume, or pressure can be increased.

However, it is interesting to note that the specific work output (i.e. work

output per kilogram) can be dramatically enhanced in a Stirling-cycle

machine simply by selecting a working gas with a high specific gas

constant.

One of the reasons that hydrogen and helium are so often used as the

working gas in large Stirling-cycle machines can be deduced by inspection

of the values for specific gas constants given in Table 4.1. (another reason

is the lower flow losses that occur with smaller molecule gases).

Table: Specific gas constants for a variety of gases at 300 K

Gas Specific gas constant,

R (J/kgK)

Air

Ammonia

Carbon dioxide

Helium

Hydrogen

Nitrogen

Propane

Steam

319.3

488.2

188.9

2077.0

4124.2

296.8

188.6

461.5

Specific gas constants: TABLE: 2

22

2.2.2 Heat flow in an ideal Stirling-cycle engine

The heat flowing into and out of a Stirling-cycle engine can be evaluated by

considering the integral of temperature with respect to entropy:

∫

Since the isochoric heat transfers within the regenerator are completely

internal to the cycle, i.e. -Q2-3 = Q4-1, then to evaluate the heat flows into

and out of the system we need only consider the isothermal processes.

For the isothermal expansion process in a closed cycle (where T and m are

constant, and where the subscripts H and L denote the high and low

temperature isotherms respectively):

QH= ∫

H dS

This integral can be most easily evaluated by considering the First Law of

Thermodynamics in the form:

QH=∫

∫

and by considering the equation of state:

pV=mRT n be expressed in terms of volume and temperature, and (noting

that there is no change in internal energy during an isothermal process) the

integral can be easily solved:

QH=∫

∫

H dV = 0 + ∫

H dV

giving:

QH = mRTH ln (

) (4.4)

which is a somewhat convoluted (but hopefully instructive) method of

derivation. The same expression can, of course, be obtained much more

easily by simple inspection of Equation 4.3., since the heat and work

transfers for an isothermal expansion process are equal but opposite.

23

The isothermal compression process can also be readily evaluated (noting

that V4 = V1 and V3 = V2, and where the subscripts H and L denote the high

and low temperature isotherms respectively), giving:

QL = - mRTL ln (

) (4.5)

2.2.3 Efficiency of an ideal Stirling-cycle engine

The efficiency of any heat engine is defined as the ratio of work output to

heat input, i.e.

hence an equation for the efficiency of an ideal Stirling-cycle engine can be

developed by considering Equations 4.3. and 4.4., giving:

STIRLING=

which simplifies to:

STIRLING=

this demonstrates the interesting fact that the efficiency of an ideal Stirling-

cycle engine is dependant only on temperature and no other parameter. It is

worth recalling that the Carnot efficiency for a heat engine is:

CARNOT=

and so it will readily be observed that:

STIRLING = CARNOT

or, in other words, that the Stirling-cycle engine has the maximum

efficiency possible under the Second Law of Thermodynamics. However, it

should be noted that unlike the Carnot Cycle, the Stirling-cycle engine is a

practical machine that can actually be used to produce useful quantities of

work.

24

2.2.4 Actual Stirling Engine

Actual Stirling Engine: FIGURE: 9

In real life, it is not possible to have isothermal and isochoric process

because they are instantaneous. In stirling cycle heat addition and rejection

is assumed to be instantaneous which is not possible and because of some

internal losses in friction and other the actual graph is oval shape.

25

2.3 ENGINE CONFIGURATIONS

Mechanical configurations of Stirling engines are classified into three

important distinct types: Alpha, Beta and Gamma arrangements.

These engines also feature a regenerator (invented by Robert Stirling). The

regenerator is constructed by a material that conducts readily heat and has a

high surface area (a mesh of closely spaced thin metal plates for example).

When hot gas is transferred to the cool cylinder, it is first driven through the

Regenerator, where a portion of the heat is deposited. When the cool gas is

transferred back, this heat is reclaimed. Thus the regenerator “pre heats”

and “pre cools” the working gas, and so improve the efficiency.

But many engines have no apparent regenerator like beta and gamma

engines configurations with a “loose fitting” displacer, the surfaces of the

displacer and its cylinder will cyclically exchange heat with the working

fluid providing some regenerative effect.

26

2.3.1 Alpha Stirling :

Alpha engines have two separate power pistons in separate cylinders which

are connected in series by a heater, a regenerator and a cooler. One is a

“hot” piston and the other one a “cold piston”.

Alpha Stirling: FIGURE: 10

The hot piston cylinder is situated inside the high temperature heat

exchanger and the cold piston cylinder is situated inside the low

temperature heat exchanger. The generator is illustrated by the chamber

containing the hatch lines.

Alpha type Stirling.

FIGURE: 11

27

Expansion: At this point, the most of the gas in the system is at the hot

piston and expands, pushing the hot piston down, and flowing through the pipe into the cold cylinder, pushing it

down as well.

Transfer: At this point, the gas has expanded. Most of the gas

is still in the Hot cylinder. As the crankshaft continues to turn the next 90°, transferring the bulk of the gas to the cold piston cylinder. As it does so, it pushes most of the

fluid through the heat exchanger and into the cold

piston cylinder

This type of engine has a very high power-to-volume ratio but has technical

problems due to the usually high temperature of the "hot" piston and its

seals.

Contraction: Now the majority of the expanded gas is shifted to the cool piston cylinder. It cools and

contracts, drawing both pistons up.

Transfer: The fluid is cooled and now crankshaft turns another 90°. The gas is therefore pumped back, through the heat exchanger, into the hot piston cylinder. Once in

this, it is heated and we go back to the first step.

28

2.3.2 Beta Stirling

The Beta configuration is the classic Stirling engine configuration and has

enjoyed popularity from its inception until today. Stirling's original engine

from his patent drawing of 1816 shows a Beta arrangement.

Both Beta and Gamma engines use displacer-piston arrangements. The Beta

engine has both the displacer and the piston in an in-line cylinder system.

The Gamma engine uses separate cylinders.

The purpose of the single power piston and displacer is to “displace” the

working gas at constant volume, and shuttle it between the expansion and

the compression spaces through the series arrangement cooler, regenerator,

and heater.

A beta Stirling has a single power piston arranged within the same cylinder

on the same shaft as a displacer piston. The displacer piston is a loose fit

and does not extract any power from the expanding gas but only serves to

shuttle the working gas from the hot heat exchanger to the cold heat

exchanger.

Beta Stirling: FIGURE: 12

29

Expansion: At this point, most of the gas in the system is at the heated end

of the cylinder. The gas heats and expands driving the power piston

outward.

Transfer: At this point, the gas has expanded. Most of the gas is still

located in the hot end of the cylinder. Flywheel momentum carries the crankshaft the next quarter turn. As the crank goes round, the bulk of

the gas is transferred around the displacer to the cool end of the

cylinder, driving more fluid into the cooled end of the cylinder.

Contraction: Now the majority of the expanded gas has been shifted

to the cool end. It contracts and the displacer is almost at the bottom of

its cycle.

Transfer: The contracted gas is still located near the cool end of the cylinder. Flywheel momentum

carries the crank another quarter turn, moving the displacer and transferring the bulk of the gas

back to the hot end of the cylinder. And at this point, the cycle repeats.

30

2.3.3 Gamma Stirling

A gamma Stirling is simply a beta Stirling in which the power piston is

mounted in a separate cylinder alongside the displacer piston cylinder, but

is still connected to the same flywheel. The gas in the two cylinders can

flow freely between them and remains a single body. This configuration

produces a lower compression ratio but is mechanically simpler and often

used in multi-cylinder Stirling engines. Gamma type engines have a

displacer and power piston, similar to Beta machines, but in different

cylinders. This allows a convenient complete separation between the heat

exchangers associated with the displacer cylinder and the compression and

expansion work space associated with the piston.

Gamma engine’s configuration

FIGURE: 13

Furthermore during the expansion process some of the expansion must take

place in the compression space leading to a reduction of specific power.

Gamma engines are therefore used when the advantages of having separate

cylinders outweigh the specific power disadvantage.

The advantage of this design is that it is mechanically simpler because of

the convenience of two cylinders in which only the piston has to be sealed.

The disadvantage is the lower compression ratio but the gamma

configuration is the favorite for modelers and hobbyists.

31

TECHNICAL COMPLEXITY OF TOPIC

The Stirling cycle is a highly advanced subject that has defied analysis by

many experts for over 190 years. Highly advanced thermodynamics are

required to describe the cycle. Professor Israel Urieli writes: "...the various

'ideal' cycles (such as the Schmidt cycle) are neither physically realizable

nor representative of the Stirling cycle" [

The analytical problem of the regenerator (the central heat exchanger in the

Stirling cycle) is judged by Jakob to rank 'among the most difficult and

involved that are encountered in engineering '.

Piston motion variations

A model of a four-phase Stirling cycle

FIGURE:14

32

MODEL DESCRIPTION

33

3.1 DESIGN AND DRAWING

MATERIAL LENGTH

(mm)

DIAMETER

(mm)

THICKNESS

(mm)

CYLINDER 1 TIN 200 80 1

2 TIN 105 50 1

PISTON

(HOLLOW)

1 HARD FIBRE 25 78 3

2 HARD FIBRE 15 48 1

LINK 1 ALUMINIUM 250 3 SOLID

2 ALUMINIUM 300 3 SOLID

3 ALUMINIUM 270 3 SOLID

4 WOOD 300 25* 8

BEARING STAINLESS

STEEL

6000z

(Note: * Represents rectangular section width)

DESIGN: TABLE: 3

Clearance volume, V1= (D1)2 L1 = 1.231 x 10

(-5) m

3

V2 = D2 L2

=2.155 x 10(-5)

m3

Heat given (through wax i.e. candle) = m x C.V.

= x V x C.V.

=0.93(g/cm3) x 3.53(m

3) x 10

(-5) x 10

6 x 7.8(kJ/g)

=253.8 kJ

Work done , TH -TL)

Assuming TH = 120 0C (Temperature of hot air)

TL = 40 0C (Temperature of cold air)

W = 5.358 x m kJ

Hence, efficiency, = = 0.328=32.8 %( on assumed conditions)

CRANKSHAFT MATERIAL CRANK RADUIS

1 (mm)

PLASTIC 22

34

PRO-ENGINEEER DESIGN & SPECIFICATION

3.1.1 STAND & CYLINDER

Criteria: Good thermal

conductivity

Easy machinable

Material preferred: Wood, Tin

Processing: Mig welding

For sealing ,M-Seal

Internal grinding through

Sand paper

FIGURE:15

HINGED SUPPORT: FIGURE:16

LINK: FIGURE: 17

35

3.1.2 PISTON

Criteria: Light weighted

Material preferred: Hard fiber

Processing: Sealing on

both side Turning on surface

Finishing by lathe

machine

FIGURE:18

3.1.3 FAN ACTING AS CRANK

Criteria: Light weighted

Material preferred: Fiber

Processing: Bending to the required

crank radius

FIGURE:19

36

3.1.5 ASSEMBLY IN PRO-Engineer software:

ASSEMBLY: FIGURE: 21

3.1.4 CONNECTING ROD & LINK

Criteria: Light weighted ,

Fatigue resistance

Material preferred:

Aluminum

FIGURE: 20

37

3.2 METHODOLOGY

3.2.1 ASSEMBLY AND PROCEDURE

a. Firstly we have designed our stirling engine model on the software

Wildfire Pro- Engineer designing software 5.0; We have calculated

our Dimensions requirement on the software. All the analysis taken on

the software taken into consideration for the fabrication of our project.

b. As per the requirement we have gathered our parts from various places

from the market.Both the cylinders are connected perpendicularly via a

small diameter pipe through welding & M-seal .

c. For the assembly of our project our workshop was the better place for

the fabrication as we get all the facilities at the same place.

d. For the piston cylinder arrangement. We have used Tin Cylinders for

vertical position and PVC Pipe for Horizontal cylinder. For the

fabrication of piston for vertical we buyed solid hard fiber of cylindrical

shape.than by using LATHE machine available in workshop. By the

operations turning on that fiber with a small clearance of 2mm.

e. As per cylinder diameter is considered.Reciprocation of piston in the

cylinder is quiet freely. On piston a aluminium link has been

attached..(LENGTH AND DIAMETER SPECIFICATION IN TABLE 3) By

cutting the upper portion of cylinder for placing the horizontal cylinder

of varying dia.and upper portion for the air movement.All this parts were

arranged than fixed by M-Seal making the arrangement air tight.

f. Our Fan which is Acting as crank for both the arrangement is fixed on

the bearing which is fixed by us on the wood frame fabricated by

us in Carpentry shop. Rest of the assembly was done by us at our

home.

g. Crank and links are connected. Now this whole model is placed on

rigid structure and clamped by strips to make It rigid while

working.Hinged support for the vertical cylinder piston & FAN

arrangement is done by cutting a PVC pipe and providing wood rip

between the PVC and Attaching both the arrangement on the hinged

support. than fabricating horizontal piston & connecting rod and

attaching it to the crank.

38

h. Our model is ready to work by providing Heat BY candle. Than by

providing sufficient heat so that expansion of air takes place by which

the reciprocation of piston takes place easily which will help to rotate

our crank easily. Every arrangement in the engine is so light weighted so

that reciprocating motion can be achieved easily in both the cylinders.

i. Working: Through the expansion of air inside the cylinders piston

moves vertically upwards and which helps in moving the cold air above

the piston to the horizontal cylinder by reciprocating the piston

backwards, the link and the connecting rod arrangement is done in such

a way that the reciprocation of piston in respective cylinders helps in the

rotation of fan by the hinged support.

This process is continuous and thus fan rotates by small amount of heat.

and this cycle is ecofriendly and thus providing pollution free

environment.

j. Future Aspects of our project: Continuous rotation of fan can be used

for the generation of electricity ,by providing Dynamo at the shaft of

fan .

39

3.2.2 OUR STIRLING ENGINE MODEL

FIGURE: 22

CONTINOUS ROTATION OF FAN with small amount of

HEAT by CANDLE.

BY THE use of STIRLING Cycle concept.

Fan Acting as

Crank

Cylinder 1

Cylinder 2

Flame

Hinged

support

40

3.3 EXPENSES SPEND ON OUR PROJECT

EXPENSES: TABLE: 4

QUANTITY PRICE

CYLINDER 2 50

PISTON 2 130

CONNECTING ROD 2 40

FAN 1 50

WOOD RIPS 1 10

M-SEAL(PACKETS) 3 75

CANDLES 3 25

WOODEN STAND 1 200

PVC PIPE 1 10

NAILS 20 10

BEARING 45

OTHER - 50

TOTAL 695/-

41

ADVANTAGES

42

4. ADVANTAGES

There are several reasons to use a Stirling Engine:

1. Inside the pistons can be used air, helium, nitrogen or hydrogen and you

don’t have to refill it because it uses always the same body of gas.

2. To produce heat you can use whatever you want: fuel, oil, gas, nuclear

power and of course renewable energies like solar, biomass or

geothermal heat.

3. The external combustion process can be designed as a continuous

process, so the most types of emissions can be reduced.

4. If heat comes from a renewable energy source they produce no

emissions

5. They run very silent and they don’t need any air supply. That’s why they

are used a lot in submarines. E.g. in the Royal Swedish Navy.

6. They can run for a very long time because the bearings and seals can be

placed at the cool side of the engine → they need less lubricant and they

don’t have to be checked very often ( longer period between the

overhauls ).

43

DISADVANTAGES

44

5. DISADVANTAGES

5.1 PROBLEMS AND ITERATION

1. Initially we have made crankshaft using separate flywheel for both

cylinders, in which link-crankshaft assembly functioning is not proper.

Hence it is replaced by crankshaft made by bending the rod.

2. Firstly we have used large links, this increases weight and vibration.

Therefore we have reduced their length.

3. Due to the large clearance between piston and cylinder, it is not able to

displace by hot air. Hence for decreasing clearance small diameter

cylinder is used and reassembling of the model has done.

5.2. CAUSES OF FAILURE

1. Required precision between the crankshaft and link arrangement is not

achieved. High precision equipments are costly.

2. Proper clearance between piston and cylinder is not provided.

3. Weight of the link is more.

4. Improper welding, machining and surface finishing.

45

6. ANALYZE FROM ECONOMIC POINT

As said above the Stirling engine is a kind of external combustion engine,

and it can use a variety of fuels. It can be estimated that combustible gases

are the best material, including gasoline, diesel, propane, sunshine and salad

oil; even cow dung can be run on as fuels.

A cup of coffee cannot become a cup of gasoline, but it can be also used as

a

Stirling engine driver. There is a famous experiment that a Stirling engine

can easily run on a cup of coffee. The Stirling engine is a kind of piston

engine. In the external heating sealed chamber, the expansion of gases

inside the engine promotes the pistons work. After the expanded gases

cooling down in the air –conditioned room, next process is taking on. As

long as a certain value of the temperature difference exists, a Stirling

Engine can be formed.

Stirling Engine working on a cup of coffee

FIGURE: 23

46

This experiment shows that only a very small power operation can carry out

a Stirling engine, which contributes a lot to energy conservation. This

characteristic especially shows out on economy point. The benefits obtained

from the Stirling engine are definitely far beyond the costs.

So once solar is used to produce energy for the Stirling engine, the cost

would surely be cut down for quite a lot. As long as there is sunshine, the

Stirling engine will run on and on. Of course it costs much to manufacture a

Stirling engine, as it requires a high level of the materials and

manufacturing processes.

Some engines cause a lot of pollution, so much is cost for pollution control

and government. On contrast, Stirling engine exhausts cleanly and avoid

this type of matter. Development and utilization of solar will not pollute the

environment, as solar is one of the cleanest energy. While the

environmental pollution is becoming more and more serious today, this

characteristic is extremely valuable. It saves the cost for a lot while making

sustainable development.

Nowadays, more and more countries have recognized that a society with

sustainable development should be able to meet the needs of the community

without endangering future generations. Therefore, use clean energy as

much as possible instead of the high carbon content of fossil energy is a

principle which should be followed during energy construction. Vigorously

develop new and renewable sources of energy utilization technology will be

an important measure to reduce pollution. Energy problem is a worldwide

one, and it is sooner or later to get into the transition-to-new-energy period.

Because of its sustainability, renewably and efficiency, the Stirling engine

is just the very one being consistent with the requirements of the times.

47

APPLICATIONS

48

7.APPLICATIONS OF THE STIRLING POWER

7.1. Cars

In the ages of 1970s and 1980s several automobile companies like “General

Motors” or “Ford” were researching about Stirling Engine. This device is

good for a constant power setting, but it is a challenge for the stop and go of

the automobile.

A good car can change the power quickly. One possibility to obtain this

important characteristic is design a power control mechanism that will turn

up or down the burner. This is a slow method of changing power levels

because is not enough to accelerate crossing an intersection.

7.2. Submarine

“Kockums”, a Swedish defense contractor, produce Stirling Engines for the

Navy making the quietest submarines in the world.This high-technology is

named air-independent propulsion (AIP). There are

four submarines equipment with Stirling AIP. The models are HMS Näcken,

which was launch in 1978 and after ten years 1988 became the first

submarine equipped with AIP system, by means of a cut and lengthened by

an intersection of a Stirling AIP section, which before the installation is

equipped by two Stirling units, liquid oxygen (LOX) tanks and electrical

equipment.

7.3. Nuclear power

Steam turbines of a nuclear plan can be replaced by Stirling engine thus

reduce the radioactive by-products and be more efficient. Steam plants use

liquid sodium as coolant in breeder reactors, water/sodium exchanger are

required, which in some cases that temperature increase so much this

coolant could reacts violently with water.

NASA has developed a Stirling Engine known as Stirling Radioisotope

(SRG) Generator designed to generate electricity in for deep space proves

in lasting missions. The heat source is a dry solid nuclear fuel slug and the

cold source is space itself. This device converter produces about four times

more electric power from the plutonium fuel than a radioisotope

thermoelectric generator.

49

7.4. Solar Energy

Placed at the focus of a parabolic mirror a Stirling engine can convert solar

Energy to electricity with efficiency better than non-concentrated

photovoltaic cells.

In 2005 It is created a 1 kW Stirling generator with a solar concentrator, this

was a herald of the coming of a revolutionary solar, nowadays It generates

electricity much more efficiently and economically than Photovoltaic (PV)

systems whit technology called concentrated solar power (CPS). Nowadays

the company Infina Applications has development a 3 kW Solar Stirling

Product.

By a mirror to focus the sun’s rays on the receiver end of a Stirling engine.

The internal side of the receiver then heats hydrogen gas, which expands.

The pressure created by the expanding gas drives a piston, crank shaft, and

drive shaft assembly much like those found in internal combustion engines

but without igniting the gas. The drive shaft is connected to a small

electricity generator.

This solar application is called concentration solar power (CSP) and is

significant potential grid for water pumping or electrification.

7.5. Aircraft engines

Stirling engines may hold theoretical promise as aircraft engines, if high

power density and low cost can be achieved. They are quieter, less

polluting, gain efficiency with altitude due to lower ambient temperatures,

are more reliable due to fewer parts and the absence of an ignition system,

produce much less vibration (airframes last longer) and safer, less explosive

fuels may be used.

50

CONCLUSION

51

8. CONCLUSION

Our Stirling engine model has a good point that they can be constructed in a

way that they produce no emissions. That means, in combination with solar

or geothermal heat, they can be used as a renewable energy source to

produce electricity by means of dynamo.

The real renewable energy is the solar application for this device because

the

other ways to produce the heat source are burning something. It is possible

to decrease the emissions of CO2 or other toxic gases but not eliminate

completely this problem for the earth and therefore for humans. This

application could be one of the different ways to solve the problem of

greenhouse gas emissions and to continue and also to develop our comfort.

No high-tech materials are needed.

Future Aspects of our project: Continuous rotation of fan can be used for

the generation of electricity ,by providing Dynamo at the shaft of fan .

52

REFERENCE

53

9. REFERENCE

http://www.kockums.se/News/photostock/photo.html

http://www.moteurstirling.com/alpha.htm www.stirlingenergy.com/solar_overview.htm

www.stirlingenergy.com/images.asp?Type=solar

54

10. LIST OF FIGURES

S.NO.

FIGURE NAME

Page

no.

1. Heat Flow 6

2. P-v diagram of a thermodynamic cycle

8

3. Ideal stirling cycle 10

4. Actual and ideal overlaid, showing difference in work output

10

5. Actual performance 11 6. Sketch of Robert Stirling of his invent 14

7. Earliest stirling engine 16 8. Distinct processes 18 9. Actual stirling engine 24

10. Alpha stirling 26

11. Alpha type stirling 26 12. Beta stirling 28 13. Gamma engine’s configuration 30 14. A model of a four-phase Stirling cycle 31

15. Stand & cylinder 34 16. Hinged support 34 17. Link 34

18. Piston. 35 19. Fan acting as crank. 35 20. Connecting rod 36 21. Assembly in pro-engineer software 36

22. Our stirling engine model 39 23. Stirling engine working on a cup of

coffee 45

55

11. LIST OF TABLES

S.NO.

NAME

Page no.

1 Well-known thermodynamic

cycles

13

2. Specific gas constants for a

variety of gases at 300 k

21

3 Design 33

4. Expenses spend on our

project

40