Steam Engines

Steam engines were the first devices where the power was not dependent on the weather.

The most impressive characteristic of steam engines is their quiet, smooth operation:  even very powerful engines hardly made a noise.

The next important characteristic is that they can start under full power.  There is no running-up, no clutches and no gearboxes are needed.

Steam engines do not react quickly to changes in demand though.

It is often said that they were inefficient, but this is not true:  one should compute the total efficiency from the production of heat to the amount of mechanical work available at the end of the process.  An electric motor may convert 99% of the electric energy into mechanical work, but the electricity has to be produced by a power plant which converts heat into steam, runs it through a steam turbine which drives a generator, then the electricity has to be transformed to high voltage, transported over power lines, transformed back into low voltage before it finally arrives at the motor.  The total efficiency is therefore not much better, but the convenience is indisputably higher.

There is no way around the laws of thermodynamics, and for any cycling engine the highest possible efficiency is that of the theoretical Carnot cycle.  Petrol engines compete with steam engines, but their only advantage is in comfort:  they react quicker and need not carry water.

Turbines have a higher efficiency than piston engines because they can use higher pressures and temperatures, but their disadvantage is in controlling them, which is why they are used mostly in stationary set-ups such as power stations (steam) or large jet planes (kerosene).

For solar panels the efficiency achieved today is at most 25% and the production is unreliable.  Good steam locomotives achieved better than 45%.  Electric locomotives run of course in the end off the steam turbines in the power plant.  Apart from devices running from solar panels, wind turbines or dams, all electric and electronic devices still rely on steam somewhere down the line.

Steam engines also last a very long time.  Engine 2 in this page was put into service in 1850 and ran until 1970.

So it is fair to say that the disappearance of the reciprocating, piston steam engine is mostly due to convenience issues, which were considered more important than efficiency, longevity, noise, etc.

Engine 1: single cylinder double action

Schoolchildren count down to the start of the engine:

No noise… The clanging you hear is slack somewhere down the train of driven equipment, as the "explainer" explains:

Engine 2: double cylinder

Below a video of starting up this huge machine:  it is a two-cylinder, where the first cylinder uses the high pressure (9 atm.) and the second uses the lower pressure steam coming out of the first.  Both cylinders work on the same rod.  Again there is almost no noise; the badly damped valve controls are making the most noise.

There is a speed controller, which is a mechanical integrator:  it keeps adding the difference of the actual to the desired speed until the actual speed matches the set one.

Here is a closer look at the integrator:

These two girls are also "explainers" and love oiling engines:

The time during which steam is let into the cylinders is controlled by the integrator via several mechanisms including some eccentrics.  The principle is very similar to that of switched electronic power adapters, which suddenly break the the alternating voltage at a changing point in the cycle.

More integrator video:

Geometry Problems

This small vertical beam engine is virtually noiseless (what you hear are the noises of engine 1)

Observe how the beam that drives the crankshaft is suspended:  is the geometry indeed such that the top of the piston rod moves in a straight line?

Other stuff

A beautiful model:

A waterwheel:

An early electric generator, driven by a two-cylinder vertical steam engine (the cylinders are on top, on either side of the spinning disc)