How does machine movement come about and how does it affect our daily lives?

Machines relieve human labour and are usually powered by an engine or motor. The principles and development of the heat and internal combustion engines have played an important role in the development of human civilisation.

 

We live in more machines than you might think. If you ask the average person to think of an object that they consider a machine, most people think of a car or a washing machine. In the film The Three Stooges, Rancho, the main character, is asked by his professor to define a machine, and he replies that anything that saves human labour, even a nib or a trouser zip, is a machine.
My guess is that the things we think of as machines are things that work and move with the power of an engine or motor rather than human power. Machines such as washing machines and cars, which are powered by engines or motors, are considered to be machines because they save a lot of “human labour”. Before the 18th century, humans harnessed the power of human or animal muscles, so livestock were important as a means of transport and production. Later, natural power sources such as water wheels and windmills were used. With the development of the coal-fired steam engine in the 1790s, this new prime mover increased the speed of movement and production beyond anything possible with primitive or natural power. The steam engine was later replaced by the internal combustion engine and electric motors, which are smaller and more controllable motors for different applications, and are used as sources of power in our daily lives.
The aforementioned steam and internal combustion engines are typical thermal engines. A heat engine is a machine that converts heat energy, which is the micro-movement of molecules, into kinetic energy, which is the macro-movement of objects. In other words, it is a machine that burns fuel to make it hot and then uses the heat to move. All heat engines receive heat energy from a high-temperature heat source and transfer some of it to the working fluid inside the engine. As the temperature of the working fluid rises with the heat energy, its pressure increases and its tendency to expand pushes against the mechanical parts of the engine, creating force and motion. To keep the engine moving, the remaining heat energy is dumped into the lower temperature air.
Nowadays, steam engines are used as heat engines to generate most of the electricity in power plants. Steam engines use the heat energy from burning fuel to boil water, the working fluid, to produce high-temperature, high-pressure water vapour, which is discharged into a turbine, where it pushes against the turbine blades and loses pressure, creating the force and motion to turn the turbine shaft. The rotating shaft is wound with coils and around the shaft are stationary magnets, which generate electricity by electromagnetic interaction. And an electric motor is a surrogate for a heat engine in that it converts some of the work of a heat engine that produces work on one side into partial work on the other side.
Unlike steam engines, internal combustion engines burn fuel in the working fluid, that is, inside the heat engine, so they are smaller in size than steam engines, which, with some exceptions, have a combustion chamber separate from the working fluid. Also, while steam engines need to be preheated until room temperature water boils, internal combustion engines do not need to be preheated; they can be started immediately by applying a spark, such as an electric spark, to the working fluid mixed with fuel. Their small size and quick start made internal combustion engines popular for transport. They were also used in aeroplanes before the development of jet engines.
The heat engine allowed humans to consume fossil fuels, which are concentrated solar energy: about four litres of petrol gives off the heat energy of about 90 tonnes of vegetable matter, which is the same amount of energy as all the rhizomes of wheat grains in a field of about 160,000 square metres. This enormous amount of energy made it possible for humans to harness faster and stronger power. John Smeaton, one of the pioneers of the steam engine, estimated that a human being generates about 100 watts of energy when working long hours, meaning that a million slaves couldn’t get sugar from the West Indies or Brazil to Europe faster than a sailing ship. Even if a million people made candles, they wouldn’t produce enough light for a night game in the Colosseum. Heat engines gave rise to the Industrial Revolution, increased population and longevity, and are still the backbone of human civilisation.
Since the commercialisation of the steam engine in the 19th century, the overriding theme in heat engine development has been efficiency. The quest for greater kinetic energy using less fuel continues to this day. Thermodynamics is a discipline that has been established from the experience gained in the development of heat engines and provides the criteria for the ideal efficient heat engine.
In 1834, an engineer named Emile Clapeyron published a reformulation of Sadi Carnot’s arguments under the title Force Motrice de la Chaleur. Carnot proved that an idealised cycle of four processes – isothermal expansion, adiabatic expansion, isothermal contraction, adiabatic contraction, and adiabatic contraction – is the most efficient, with the following efficiency (The unit of temperature is absolute temperature).

Efficiency = 1 – (low heat source temperature / high heat source temperature)

Thus, unless the heat engine is operating at -273 degrees Celsius, or absolute zero, its efficiency is always less than one, proving that perpetual motion is impossible. Carnot’s process of deriving this result was the basis for the later formulation of entropy and the second law of thermodynamics.
There are many reasons why a real heat engine uses more fuel to produce the same amount of work than an idealised heat engine. These include heat escaping through the vessel, losses due to friction as the working fluid or engine moves, and interactions between the molecules of real gases as opposed to ideal gases. Many engineers are struggling to reduce this energy loss.
Humanity has harnessed thermal energy as a power source for the past 200 years, and we live in a way that has never been possible before. It is expected that we will continue to use fossil fuel-burning heat engines to sustain and advance human civilisation for many years to come. Despite the development of alternative energy sources, the use of fossil fuels is here to stay. According to the International Energy Agency (IEA), consumption of oil, coal, and natural gas accounted for about 81% of total energy consumption in 2006 and is expected to remain at this rate through 2030. Research and development of heat engines, the foundation of human civilisation, is still needed to ensure that we leave more of this supposedly finite source of concentrated solar energy to our descendants.