using stirling engine & TEG to convert waste heat into electricity

2.  Introduction
 Advantages
 Disadvantages
 Configuration
 Design conditions
 Material selection and dimensions
 Parts of the Stirling Engine
 Types of Thermoelectric Generator
 Calculation
 Efficiency
 Application
 Conclusion
 References

3. What is stirling engine?
A stirling is a heat engine that is operated by the cyclic
compression and expansion of air or other gas at different
temperatures, resulting in a net conversion of heat energy to
mechanical work.

5. ADVANTAGES
• The maintenance facility
• They are quieter engines
• Stirling engines offer better performance than alternative internal combustion
engines.
• Greater fuel versatility.
Advantages of Stirling engine:
Advantages of Thermoelectric Generator:
• Reliable source of energy
• Environment friendly
• Have high scalability, which means they can be applied to heat source of
any size
• Lower the production cost
• Recycle wasted heat energy.

6. DISADVANTAGES
• The stirling engine works best at
constant power.
• It has low starting torque.
• It has low power density.
• Reciprocating engine
Disadvantage of Thermoelectric Generator:
• Low energy conversion efficiency
rate.

7. Configurations

8. 2. The beta configuration has a single cylinder with a
hot end and a cold end, containing a power piston and
a 'displacer' that drives the gas between the hot and
cold ends. It is typically used with a rhombic drive to
achieve the phase difference between the displacer
and power pistons, but they can be joined 90 degrees
out of phase in crankshaft.

9. 3. The gamma configuration has two cylinders: one
containing a displacer, with a hot and a cold end, and one
for the power piston; they are joined to form a single
space, so the cylinders have equal pressure; the pistons
are typically in parallel and joined 90 degrees out of phase
on a crankshaft.

10. Design Conditions of Stirling Engine :
The characteristics required for this type of design are as given below
 The ratio of the swept volumes of the displacer to power piston
must be very high.
 The diameters of the displacer and displacer cylinder must be
large.
 The length of the displacer must be small.
 The heat transfer must be effective on the surface of both plate
ends of the displacer.

11. Material selection and dimensions :
1.Heat exchanging surfaces:-
The surfaces of heat exchanging is fixed by the available area at the heat rejection system & it
helps us to fix the displacer diameter and its height. In order to have high heat transfer rate from the
source to the system & from the system to atmosphere materials with high thermal conductivity must
be used. Some of the materials with above required features for heat exchanging surfaces are as
follows:
Eg: Copper, Aluminium, Mild steel, G.I (galvanized iron) Aluminium material
is used as a heat exchanging surface:
Thickness: 2mm
2.Displacer Cylinder:-
It must be having good resistance property to heat transfer which means a material of lower
thermal-conductivity. So that the heat flow cannot be done from hot end to the cold end of the
cylinder body. In this displacer-cylinder the displacer performs its stroke. The working medium gets
transferred from displacer cylinder to the power piston cylinder through regenerative pipes some of
the materials possessing the above property are: Wood, Concrete, Plastic, and Glass.
So we had selected an aluminium can as displacer cylinder.

12. 3.Displacer :-
Displacer must be resistant to heat transfer and light in weight. So we have to select a
material having lo thermal conductivity and lower density. The types of displacer materials
available are Wood, Thermocol, Iron wool, Reinforced plastic. It displaces the working
medium (air) in between cold and hot ends.
So we had selected Steel wool material as displacer.
Diameter of displacer: 5.92cm
Thickness of displacer: 4.0cm
Volume: 110.145 cm

13. S.No Working
Medium
Gas Constant(J
/kg.k)
Cp (J
/kg.k)
Cv (J
/kg.k)
Viscosity(N-
s/m2)
1 Air 287 1007 720 0.00003
2 Argon 208 523 315 0.00004
3 Carbon
dioxide
189 845 656 0.00002
4 Helium 2077 5200 3123 0.00003
5 Hydrogen 4120 14310 10190 0.000015
6 Nitrogen 296 1038 742 0.00003
4. Properties of working mediums:-
We used air as a working medium as it is easily available.

14. 5. Design of Cylinder & Power-piston:-
Power-piston is the critical part of the Sterling engine, which produces the power stoke by the
expansion of the air in it. The friction between the cylinder and the power piston is very less and the
power stroke must be as same as the stroke of the displacer. Friction co- efficient must be as lo low as
possible in between the piston and cylinder, which also requires proper lubrication.
The materials which requires the above requirement as follows:
S.No Piston Material Cylinder Material
1 Steel Wool Aluminum
2 Steel Steel
3 Epoxy Resin Glass or Steel
4 Brass Brass

15.  Parts of the Stirling engine :-
• Crankshaft:
Crankshaft is the mechanical device which converts linear motion into rotary motion
which also supports the flywheel. It’s made up of stainless steel with diameter of 0.2 cm and length of
16.4 cm which has the phase angle difference of 900
• Flywheel:
A heavy mechanical device which is used in the increase of machine’s momentum and
also to provide greater stability. Here it is made of plastic, with the dimensions of 0.2 cm in
thickness and 12.2 cm in diameter.

16. • Connectors:
Here connecters are used as the connection between the crankshaft & connecting rod.
Here it is made up of brass, with 2.5 cms in length & 0.5 cms in width.
• Connecting Rod:
A mechanical device which is used in connecting between any two moving parts,
especially in between the crank shaft and the piston.

17.  FINAL ASSEMBLY OF STERLING ENGINE

18. 18
0
1
3
2
4
6
5
800 1200 1600 2000 2400 2800
OUTPUT
VOLTAGE
RPM
EFFECTS OF RPM TO OUTPUT
VOLTAGE OF STIRLING
OUTPUT
VOLTAGE
1000
500
0
3000
2500
2000
1500
50
RPM
(Wm)
80 110 140 170
200 230 260
290
TEMPERATURE (°C)
EFFECTS OF TEMPERATURE TO
RPM STIRLING ENGINE
RPM

19. GENERATOR
Schematic diagram showing components and arrangement of a
typical single-stage thermoelectric power generator

20. 13
Types of experiment for thermoelectric power
generator
⮚ Thermoeletric without water

21. 14
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
30 40 50 60 90 100
110
OUTPUT
VOLTAGE
70
8
0
TEMPERATURE
OUTPUT VOLTAGE VS
TEMPERATURE

22. 16
GENERATOR
0
0.005
0.01
0.015
0.02
0.025
0.035
0.03
30 40 50 80 90 100
POWER
(WATT)
60 70
TEMPERATURE (°C)
⮚ Aluminum Plate as the Agent to Transfer Hot Temperatures to
Thermoelectric
EFFECTS OF TEMPERATURE TO
THE POWER OF TE1, TE2, TE3,
TE4
POWER
TE 1
POWER
TE 2
POWER
TE 3
POWER
TE 4

23. A p-V diagram of the Stirling cycle is depicted in below fig It consists of four
processes: isothermal compression with heat removal 1 → 2, isochoric heat
addition 2 → 3, isothermal expansion with heat addition 3 → 4, and
isochoric heat removal 4 → 1. Thus, we have
T1 = T2, V2 = V3, T3 = T4, and V4 = V1. The thermal efficiency of the Stirling cycle is the same as the
Carnot efficiency. Hence,
Using the relation p1V1/T1 = p3V3/T3, can be expressed as η=1−p1V1p3V3
The compression and pressure ratios for the Stirling cycle are CR = V1/V3 and PR = p3/p1.
may now be represented in terms of CR and PR.
η=1−CRPR
Denote TR = Tmax/Tmin as the ratio of the maximum-to-minimum temperature of the
cycle, where Tmax = T3 and Tmin = T1, it can be inferred from Eqs. and that PR = CR · TR.
Calculations
 FOR STIRLING ENGINE:-

24.  For Thermoelectric power generator:-
In order to analyse and perform the computational data of the voltage generator module, some
parameters have to be considered, which includes the coefficient of Seebeck and the total
amount of thermoelectric module coupled together, and this results to
α: Coefficient of Seebeck of a single thermoelectric module N: Total number
couples.
Therefore, based on parameters collected from TEC1-12706 datasheet, Coefficient of
Seebeck for p-type is 270μV/K
Coefficient of Seebeck for n-type is -270μV/K (- sign mean n-type)α
Seebeck Coefficient of a thermoelectric single couple
270μV/K + 270μV/K
total number of couples used as generator, it will now be necessary to compute voltage
produced by overall combination of thermoelectric device forming a single voltage generator
module
V = ×T
Where V is voltage
∆T Is the temperature difference between T-hot and T-cold

25. Thot= 600
c + 273 = 333 K
Tcold= 240
c + 273 = 297K
To calculate a multiple cascade voltage of thermoelectric module
Vtotal=V × n
V total is the total voltage produced, V is the produced voltage from each module and thermoelectric
module number is n.
Where,
Where I and V are the total current and total voltage produced respectively
The specific volume is obtained using the formula,
V1 = RT/
“R” is the gas constant ( KJoule ⁄Kg*K)
Output Power = I*V

26. Further, the mass of flow of the gas can be calculated using the
volumetric of flow rate over the specific volume and the volumetric flow
rate can be obtained
m = V1/V
Total power can be calculated by multiplying the mass of the gas
flow with the difference of temperatures as mentioned below:
W = [m(h(hot)-h(cold))]

27. EFFICIENCY OF STIRLING ENGINE
AND THERMO ELECTRIC
GENERATOR
They could have the highest efficiency attainable by
any heat engine.The efficiency is also linked to the
environmental temparature
•But the efficiencies of the stirling engine and the
thermoelectric generator drop, if the temparature
difference between the hot and cold end
decreases.

28. Stirling engine:
Applications of the Stirling engine range from mechanical
propulsion to heating and cooling to electrical generation
systems like-
• Mechanical output and Propulsion
• Electrical power generation
• Solar power generation
• Heating and Cooling
• Heat pump
Application
Thermoelectric generator:
Thermo electric generators are the other way of converting
rejected heats to electricity.It can be applied in-
• Road lamps
• Alarm system etc

29. Figure : Snapshot of the Constructed Circuit together with the
Cylindrical TEG System

30. The stirling engine is the interesting alternative
way to commercialize the waste heat.
And the thermoelectric generators are the
intriguing way to generate renewable energy
directly from waste heat.
• So to reduce the GLOBAL WARMING, it is
necessary to reuse the exhausted heat by
using these two.

31. References
https://en.wikipedia.org/wiki/Thermoelectric_generator
https://en.wikipedia.org/wiki/Stirling_engine
https://www.youtube.com/watch?v=w2iTCm0xpDc&t=507s
https://youtu.be/BG8LYEqNmqk
Thermodynamics an advanced course with problems and solutions-RYOGO
KUBO(University of Tokyo)
Nightingale, Noel P. (October 1986). "Automotive Stirling Engine: Mod II Design Report" (PDF).
NASA. Archived (PDF)
from the original on 29 April 2017.
Mcconaghy, Robert (1986). "Design of a Stirling Engine for Model Aircraft". IECEC: 490–493.
T. Finkelstein; A.J. Organ (2001). Air Engines. Professional Engineering Publishing. ISBN 1-86058-
338-5.
C.M. Hargreaves (1991). The Philips Stirling Engine. Elsevier Science. ISBN 0-444-88463-7.
T. Finkelstein; A.J. Organ (2001). Air Engines. Professional Engineering Publishing. ISBN 1-
86058-338-5.

32. THANK YOU