During the 19th century, the world ran on steam. However, it wasn't a perfect technology due to its heavy fuel consumption and the natural risk of boilers, which could cause serious accidents. The Stirling engine tried to establish itself in industry with promises of greater efficiency and safety, and by and large we can say it delivered, but it had a more complete presence in low-power applications, including fans and record players.
Today there's no doubt that oil and internal combustion devoured everything in their path, but steam was "the definitive solution" in its moment, and it also faced some competition in the form of the Stirling engine. Early in September we explained how to build a cheap and educational homemade version, and simply seeing the engine in action reveals its potential.
How the Stirling Engine Works
Essentially, the engine has the ability to convert a temperature difference into mechanical work, using a fluid (in this case air, but other gases are possible) through its expansion and compression. It all begins with a sealed cylinder filled with air. If we heat it, the pressure rises, and if we cool it, it drops. Now, if we place another cylinder with a small piston on top of that, the piston moves "up" with the increase in pressure, and "down" with its fall.
If we add a disc or displacer to the main cylinder that moves along with the pressure change, and connect the displacer and piston so they feed back into each other (with the help of a flywheel), the cycle will remain active as long as the temperature difference exists.
This is just one variant of the Stirling engine. Versions with a greater number of pistons have also been developed, always with the goal of optimizing their overall performance. But beyond those efforts, the Stirling engine failed to make its way into heavy industry, and by the early 20th century it ended up as a "domestic engine". What kind of devices adopted the Stirling engine? First, fans:
The model shown in the video was made by Hubertus Raab in Zeitz, Germany. A lamp that at first glance is not so small (charged with kerosene or similar fuel) serves as the heat source, while the fan blades are directly connected to the flywheel with a shaft. Its noise level is no higher than that of a sewing machine of the era (1909-1910), and its operation is impressive even after having removed the lamp.
A Phonograph Powered by Alcohol
Next we have a demo of the so-called "Paillard Maestrophone No. 205", a gramophone-record player launched on the market in 1910. At that time, the only two options were electricity (expensive, risky, and of limited availability), or the "spring-wound" models. The Maestrophone tried to position itself as a "third option", with a small alcohol burner and a casing that allowed the user to see both the movement of the mechanism and the flame.
Unfortunately, it didn't fare very well. While it was silent and efficient, some units ended up engulfed in flames despite its ventilation and asbestos plates (Fire + alcohol + wooden case = Bad idea). The Maestrophone was also very expensive, and it ceased production with the start of the First World War.
Music Boxes and DIY Projects
Music boxes with Stirling engines are not necessarily old. In fact, they have some popularity in the DIY space, and they are excellent projects for anyone willing to accept such a challenge. Some of the final designs are pure beauty, combining brass, crystal, and wood. One of the main objectives is to reduce noise, so that it doesn't interfere with the music playback.
And remember, you can buy a Stirling engine today and have it as a desk ornament. Available from 15 euros, in multiple configurations and sizes.
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