One of the most interesting applications we can give to the concepts of heat exchange and pressure difference in aqueous media is that of making a STEAM ENGINE simple, taking advantage of a small heat source and a simple fluid flow, which will generate the movement of our assembly.
- A small candle with its metal holder.
- A glass of water.
- A 20cm long copper tube with a diameter of 2mm.
- An awl.
- A scissors or cutter.
- A pair of pliers.
- A small lighter or blowtorch.
To build our STEAM ENGINEFirst remove the candle from the metal support and with the punch make two holes of about 2 to 2.5 mm in diameter at the ends of the metal support, large enough for the copper tube to fit through and hold it in place.
Once this is done, we make a kind of coil with the copper tube. To make this coil, we use the burner or blowtorch. Copper is very malleable, we only have to heat it a little, make a small loop and direct the ends of the tube downwards.
We take the candle and make some cuts (with a scissors or cutter) on the sides, so that both sides of the copper tube are perfectly fixed to the candle. Once the sides of the copper tube are placed on the candle, we fix them to the metal base until the candle is completely inside its support and the two ends of the copper coil protrude.
With the help of a pair of pliers or tweezers, we direct each coil projection towards opposite sides of the metal base, in order to direct the water flow towards different sides and generate the movement of our steam engine.
Steam engine start-up
To start our steam engine, we fill the tube with fluid, in our case water. To do this, we can use a small vacuum pump. We must make sure that there are no air bubbles inside the tube. Then, we light the candle and wait a few minutes until we see the circular movement of our engine.
Steam engine operation
The operation of the STEAM ENGINE we have built is quite simple: a liquid flow is created, thanks to a pressure difference between the coil projections. This pressure difference has been created by the water vapour bubbles formed by the candle flame.
The pressure difference causes both sides of the tube projection to create a thrust. This thrust, we have directed it to opposite sides in order to harness its energy and generate a circular motion, i.e. to turn the heat energy at mechanical energy.