Diy stirling engine Project: Stirling engines have a high efficiency compared to steam engines,being able to reach 50% efficiency. They are also capable of quiet operation and can use almost any heat source. The heat energy source is generated external to the Stirling engine rather than by internal combustion as with the Otto cycle or Diesel cycle engines.
Stirling engines are compatible with alternative and renewable energy sources, since it could become increasingly significant as the price of conventional fuels rises, and also in light of concerns such as depletion of oil supplies and climate change.
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In this project, we will give you simple instructions to make a very simple DIY Stirling engine using test tube and syringe. You can make this simple Stirling engine at home. At the end of this project, we will discuss the importance of concentrated solar thermal power in the future of Stirling engine technology.
How to make a Simple Stirling engine Video
Components and Steps to make Simple Stirling engine
1. A Piece of ACP or hardwood
This is the base for your Stirling engine. So it should be hard and stiff enough to cope up with the movements of the engine. Then, make three small holes as shown in the figure. You can also use plywood, wood etc.
In Stirling engine, these marbles perform an important function. In this project, the marbles act as a displacer of hot air from the warm side of the test tube to the cold side. When marbles displace hot air, it cools down.
3. Sticks, fishers, and Screws
Sicks and screws are used to hold the test tube in a convenient position to move freely in any direction without any interruptions. Watch the video- how can it be fixed on the Base.
4. Rubber Pieces
Buy an eraser and cut it into the following forms. It is used to hold the test tube tightly and to keep the test tube airtight. There should not have any leakage in the mouth part of the test tube. If so the project wouldn’t be a success.
The syringe is one of the most important and moving parts in a simple Stirling engine. Add some lubricants inside the syringe so that the piston can move freely inside the cylinder. When Air get expanded inside the test tube, it pushes the piston downward. As a result, Syringe cylinder moves upward. At the same time, marbles roll to the hot side of the test tube and displaces the hot air and causes it to cool down(decrease volume).
6. Test TubeThe test tube is the most important and working component of the simple Stirling engine. A test tube is made up of some special type of glasses (ex.borosilicate glass) that has a high heat resistant capacity. So it can be heated to high temperatures.
How a Stirling engine Work?
Above is a short video clip of a simple test tube stirling engine using glass marbles as the displacer and a glass syringe as the power piston.
This simple Stirling engine was built from materials that are available in most school science labs and can be used to demonstrate a simple heat engine.
Pressure-volume diagram for the cycle
Process 1→2 Expansion of working gas on the hot end of the test tube, heat is transferred into gas and gas expands thus increasing volume and pushing syringe piston upwards.
Process 2→3 As marbles move to the hot end of the test tube gas is displaced from the hot end of the test tube to the cold end, as gas moves it gives up heat into the test tube wall.
Process 3→4 Heat is removed from the working gas and volume decreases, the syringe piston moves downwards.
Process 4→1 Completes the cycle working gas moves from the cold end of the test tube to the hot end, as the marbles displace it, acquiring heat from the test tube wall as it moves thus increasing the gas pressure.