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Stirling engine

1. STIRLING ENGINE
ME F315
Advanced Manufacturing Process
Fabrication Project Presentation

2. 1.Arghya Das - 2022A4PS1061H
2.Zahed Riyaz - 2021B5A43179H
3.Lakshmi Vaibhava Kollipara-2022A4PS1478H
4.Jyoteesh Kumar Gulla-2022A4PS1560H
5.D.Abhishek Paul-2022A4PS1476H
6.Pritam Debnath- 2022A4PS1670H
7.Alok Mohanty - 2022A4PS1666H
8.Nallabilli Sri Varun - 2022A4PS0871H
9.Abhilash Krishna S - 2022A4PS1109H
10.Venkata Siva Adithya Chokkapu - 2021B4A42472H
11.Arun Mitra - 2021B5A42443H
12.Kenche Trijal - 2022A4PS0735H

3. INTRODUCTION
The Stirling engine, first patented by Robert Stirling in 1816, is a type of
heat engine that operates on a closed thermodynamic cycle, converting
heat energy into mechanical work. Unlike internal combustion engines,
the Stirling engine is an external combustion engine, meaning it can
utilize a wide variety of heat sources, including renewable energies such
as solar power.
Among the different types of Stirling engines, the Alpha Stirling engine
stands out for its high power-to-volume ratio and efficient energy
conversion capabilities.
It consists of two separate cylinders: one heated (hot cylinder) and the
other cooled (cold cylinder). This design allows the engine to achieve
higher thermal efficiencies compared to other Stirling engine
configurations.

4. OBJECTIVE
The objective of this presentation is to provide a comprehensive overview of
the design, fabrication, and performance evaluation of an Alpha Stirling engine.
Through this presentation, we will explore the theoretical foundations, design
considerations in bills of materials, working and applications that were studied
during the project.
Additionally, we seek to highlight the engine's efficiency and its applicability in
sustainable energy solutions, offering insights into it.

5. APPLICATION
●Applications of stirling engine range from mechanical propulsion to heating
and cooling of electrical generation system
●The Stirling Engine could be well suited for underwater power systems where
electrical work or mechanical power is required on an intermittent or
continuous level
●A Stirling Engine can convert solar energy to electricity with an efficiency
better than non-concentrated photovoltaic cells and comparable to
photovoltaic cells
●A wide variety of smaller Stirling cryocoolers are commercially available for
tasks such as cooling of electronic sensors and sometimes microprocessors

6. Components of a Stirling Engine
●Air Valve

7. Components of a Stirling Engine
●Burner plate

8. Components of a Stirling Engine
●Connecting tube

9. Components of a Stirling Engine

●Cooler Bracket

10. Components of a Stirling Engine

●Cooler Cylinder

11. Components of a Stirling Engine

●Cooler Piston

12. Components of a Stirling Engine

●Crank

13. Components of a Stirling Engine

●Flywheel Bracket

14. Components of a Stirling Engine

●Flywheel

15. Components of a Stirling Engine
●Heater Bracket

16. Components of a Stirling Engine
●Heater Bracket

17. Components of a Stirling Engine

●Heater Cylinder

18. Components of a Stirling Engine

●Heater Piston Cap

19. Components of a Stirling Engine

●Inner Piston

20. Components of a Stirling Engine

●Linkage

21. Components of a Stirling Engine

●Piston Rod

22. Components of a Stirling Engine

●Rod connector

23. Components of a Stirling Engine
●Base

24. WORKING OF STIRLING ENGINE
A Stirling engine is a type of heat engine that operates on the Stirling cycle. It’s known for its efficiency and
quiet operation.
Basic Principle-The Stirling engine operates by cyclically compressing and expanding a gas (usually
air, helium, or hydrogen) at different temperature levels. This process converts heat energy into
mechanical work.
Operation Cycle
The Stirling engine operates in a closed loop and follows a four-stroke cycle:
❖Heating: The gas inside the hot cylinder is heated by an external heat source. As the gas heats
up, it expands.
❖Displacement: The displacer piston moves, pushing the hot, expanded gas from the hot cylinder
to the cold cylinder. This process doesn’t directly do work but helps move the gas through the
engine.

25. ❖Cooling: The gas in the cold cylinder is cooled by an external cooling source. As the gas cools, it
contracts.
❖Power Stroke: The power piston moves, driven by the pressure difference between the hot and cold
gases.This movement turns the crankshaft and produces mechanical work. After the power stroke, the
displacer piston moves again to push the gas back to the hot cylinder, and the cycle repeats.
❖ Cycle Repeats:After the power stroke, the displacer piston moves again to push the cooled gas back to
the hot cylinder. The cycle then repeats, with the engine continuously producing power.




WORKING OF STIRLING ENGINE

26. Some Key Features are:
●Separation of Hot and Cold Cylinders: In the Alpha Stirling engine, the hot and
cold cylinders are separate, which can simplify the design and construction of the
engine compared to other types.
●High Power-to-Weight Ratio: The Alpha Stirling engine is known for having a
high power-to-weight ratio, making it suitable for applications where weight is a
concern.
●Simple Design: The separation of cylinders can lead to a simpler and more
robust design, although it can also make it more complex to seal and maintain.


Fig- Alpha Stirling Engine

27. Design Conditions
The characteristics required for Stirling Engine are given below:
1)The ratio of the swept volumes of the displacer to power piston must be high.
2)The diameters of the displacer and displacer cylinder must be high.
3)The length of the displacer must be small.
4)The heat transfer must be effective on the surface of both plate ends of the displacer

28. Uses of each of the component in the Stirling
Engine
●Hot Cylinder:The cylinder where the working gas is heated. It’s connected to the heat source and designed to
withstand high temperatures. Materials such as copper alloys, aluminium etc. can be used as the cylinder material. We
use aluminium cylinder here because it is easy to procure.
●Cold Cylinder:The cylinder where the working gas is cooled. This component typically includes a cooling system to
effectively dissipate heat. The cooling cylinder is positioned on the opposite side of the hot cylinder, with the two
cylinders connected through the displacer piston and regenerator. We again use aluminium here for reasons stated
above.

●Power Piston:Located in the hot cylinder, this piston is driven by the expanding gas. It converts the gas’s thermal
energy into mechanical work. Here we are using steel wool for piston material.Power-piston is the critical part of the Stirling
engine, which produces the power stroke 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 coefficient must be as low as possible in
between the piston and cylinder, which also requires proper lubrication.
●Displacer Cylinder: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.

29. Uses of each of the component in 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 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. We can use
a CD
●Connectors:Here connecters are used as the connection between the crankshaft &
connecting rod.
●Connecting Rod:A mechanical device which is used in connecting between any two
moving parts, especially in between the crank shaft and the piston.
●Regenerator :A heat exchanger located between the hot and cold cylinders that
captures and reuses some of the heat from the working gas to improve the engine’s
efficiency. A wire mesh can be used as a regenerator here.

30. Uses of each of the component in the Stirling Engine
●Heat Exchanger:Facilitates the transfer of heat between the working gas and the
external heat source (hot cylinder) or cooling system (cold cylinder).

●Seals:Essential for containing the working gas within the cylinders and preventing
leaks, thus maintaining the engine’s efficiency.

31. Design Considerations
1. Thermodynamic Efficiency:Ensuring a significant temperature difference between the hot and cold sides to maximize
efficiency. The greater the temperature difference, the more efficient the engine. Optimize the design of heat exchangers
(both hot and cold sides) to ensure effective transfer of heat. High thermal conductivity materials and efficient designs are
crucial.so we are using aluminium.
2.Material Selection: Choosing materials that can withstand the high temperatures of the hot cylinder without degrading.
Stainless steel, high-temperature alloys, and ceramics are common choices. But we choose Aluminum. Select materials with
high thermal conductivity for components like the heat exchanger to improve heat transfer efficiency. Consider materials that
resist oxidation and corrosion, especially if the engine will be exposed to harsh conditions or combustion gases.

3.Cost Efficiency: Balancing material choices and design features with budget constraints. Using cost-effective materials
where possible without compromising performance.

4.Seals: Use high-quality seals to prevent gas leaks between cylinders and ensure efficient operation. Seals must withstand
high temperatures and pressure fluctuations
5.Clearances: Maintain precise clearances between moving parts to minimize friction and wear while ensuring proper gas
compression and expansion.


.

32. We have used the following materials for our fabrication. The selection of the appropriate steel
grade for each component depends on the specific operational requirements, including
temperature exposure, mechanical stresses, environmental conditions, and cost considerations.
However a few components can be made from other materials in case of unavailability of the
proposed items.
●Alloy steel (AISI 4340)
●Carbon Steel (AISI 1018)
●Carbon Steel (AISI 1045)
●Stainless Steel (AISI 316)
Later we approximated the volume and using the per kg price we estimated the billing cost of
the materials

Billing of materials

34. Conclusion
●Before we begin with the fabrication we have modelled the design of the stirling engine
and had the design analysis as wella s an estimated cost on the selected materials. In the
future we would try to go through the fabrication process and model the engine.
●The main challenges the we might face is the set up of the engine after the fabrication of
the parts and making sure it follows the thermodynamic processes as well as sticks to the
estimated efficiencies.
●Precision in Machining and Assembly:
Ensure tight tolerances during machining to prevent issues like increased friction or misalignment.
Maintain designed clearances during assembly to avoid energy losses and achieve the expected
efficiency.
●Thermal Management and Material Behavior:
Implement effective thermal management strategies to maintain designed temperature gradients.
Monitor material behavior during operation to ensure components expand and contract as expected,
optimizing performance.

35. THANK YOU