Test Tube Stirling Engine

In this page, we make a simple Stirling engine using a test tube and glass marbles. The pressure in the test tube changes with changing of the movements of the marbles. The test tube is connected to a cylinder, then the Stirling engine, which can run with the heat of an alcohol lamp, is completed.

Let's Experiment!

When the air is heated, the air becomes hot, and expands. First of all, we prepare a simple equipment, and experiment.

Step 1: A glass syringe connect to a test tube. And the bottom side of the test tube is heated by an alcohol lamp. You can see the syringe lengthens with the expansion of the air. Step 2: Put in marbles in the test tube. And heat the bottom side of the test tube.
Step 4: When you move the marbles in the test tube, the syringe becomes long and short with the moving of the marbles. Step 4: Because the air has temperature difference in the test tube. The marbles move the air through the hot- and the cold space.

Let's Make a Test Tube Stirling Engine!

When the air is heated, it expands. When it is cooled, it compressed. The hot air engine, called the Test Tube Stirling Engine, works using the characteristics of the air. CAUTIONS!

* Note that the test tube is too hot after the heating.
* Treat the test tube and the glass syringe politely.
* Don't touch the surface of the syringe. It has a big friction when it is stained.

Preopared Parts

(1) Test tube x1, (2) Syrinege x1, (3) Marbles x5, (4) Rubber cap with an aluminum tube x1, (5) Rubber tube x1, (6) Rubber seat x1, (7) Wood screws x8, (8) Base board x1, (9) Frames x2, (10) Reinforced board x1, (11) Rubber ring x1, (12) Alcohol lamp x1
Step 1: Put in five marbles in the testtube, and cover with the rubber cap. Step 2: Set the rubber tube to the rubber cap. Set the syringe to the rubber tube as shown in the following photograph.
Step 3: Assemble the frames and the reinforced board to the base board. Step 4: Paste the rubber seat with a both-faces-adhesive tape on the base board.
Step 5: Set the rubber ring to the frames. Step 6: Set the assembled test tube to the rubber ring as shown in the following ptograph.
Step 7: Install the syringe to the rubber seat with the both-faces-adhesive tape. Step 8: Put the alcohol lamp. And The engine is completed.

Let's Run the Engine!

When you heat the bottom of the test tube, and set the height of the test tube suitably, @the engine runs well.

Demonstration Movie of the Test Tube Stirling Engine (MPEG1, 3.7 MB)

You need to prepare the follows before the making of the engine.
The test tube has 14 mm of inner diameter. The glass syringe is 3 ml capacity, which has about 10 mm of diameter. Five marbles has about 12.5 mm of diameter. The rubber cap is inserted the aluminum tube, which has 5 mm of outer diameter, 3 mm of inner diameter and 30 mm of length. The rubber tube has 6 mm of outer diameter, 3 mm of inner diameter, and 30 mm of length, and it must be soft. The size of the rubber seat is 36 x 15 x 2 mm. The both-faces-adhesive tapes, whose size is 15 x 15 mm, are pasted the both sides of the rubber seat. The wood screws has 2.8 mm of diameter and 20 mm of length approximately. Nails are OK instead of the screws. The size of the base board is 280 x 90 x 14 mm, and it is made of lauan wood. The size of the frames is 170 x 30 x 14 mm. The size of the reinforced board is 90 x 30 x 14 mm. The big size of the rubber ring is better. The alcohol lamp is marketed.

[ Stirling Engine Dictionary ]