We review how a steam engine works, a type of engine that despite everything, is still relevant.
If I say steam engine, you probably think of old appliances and vehicles, from before combustion engines, electric and other alternatives became popular, not something that is used on a day to day basis.
However, that image given by steam engines could not be more wrong; Today, most of the energy we consume comes from machines that use steam in one way or another. Whether using coal, nuclear energy or solar energy, there comes a time in the process when you have to boil water, as they did three centuries ago.
How a steam engine works
And all that, with a concept as simple as boiling water, behind a steam engine there is only one source of heat, which boils water and produces steam that moves a piston. At least, it was one of the first steam engines, devised by ThomasNewcomen in 1712.
If the date seems early, it is because although Newcomen had managed to move a piston using steam, it really the machine itself was of little use because it was so inefficient. To understand why it is not so easy to get energy from steam (or at least not more than we spend creating steam), it is necessary to analyze how this first machine works, as pointed out in Real Engineering.
These were the first steam engines
The Newcomen machine is the simplest steam engine you can imagine. The fire, fueled by a fuel (coal), heats the water and forms steam, which passes to a piston, which, thanks to this thrust, greater than atmospheric pressure, is able to rise.
However, it is not this rise that activates the mechanism, since in reality this scheme can only pull, not push. To get the move it is necessary to put cold water in the cylinder so that it faces and the atmospheric pressure lowers it and so pull a chain.
Enough for the coal miner (thanks to the availability of fuel), but for little more. The amount of energy we lose with this method is too much, either because we cannot contain the heat and it escapes into the environment, or because we do not allow the steam to expand as much as it should. Also, by cooling the entire piston, we are making everything worse (although this was easily solved by adding a capacitor to the scheme).
Another setback was in the piston itself, or rather, in its manufacturing method. Remember that we are in the early years of the Industrial Revolution, and it wasn’t until the method for melting iron and creating cylinders was perfected that it really pistons that withstand higher pressures without leaks could be created and therefore, increase the performance of the steam engine.
A revolutionary concept that only needed to be polished
The other big problem with the Newcomen machine was that it was only able to pull a chain vertically, and that doesn’t do much good. Must convert this linear motion into a rotational motion, and for that we need a crank-crank mechanism.
That brings its own problems; By horizontally setting the mechanism, we can no longer rely on atmospheric pressure to return the piston to its initial position. That is solved by spending steam on make the piston move in the opposite directionAlthough this involves implementing inlet and outlet valves, which regulate the amount of steam that flows in and out of the cylinder.
We already have rotation movement! Except it is very irregular. Due to the movement of the connecting rod-crank mechanism, the force exerted is different and undulating, never constant; This is called engine torque, and getting stable, linear torque is absolutely necessary to maintain the mechanism and be able to use it, to say nothing of energy inefficiency.
The solution is a battery. Well, not an electric battery like the ones you have at home, but a flywheel, which is basically a mechanical battery, which stores the kinetic energy it receives and releases it linearly.
We may no longer travel from one place to another riding huge steam trains, but the only difference is that these machines have moved around and are now bringing us the power on cables.
The steam engine ushered in a new era of engineering that in some ways we still live in today, and now you know how it works.