A heat engine is a device that does the job through the use of fuel energy. A machine running on such an engine converts thermal energy into mechanical energy and applies the dependence of the expansion of the substance on the temperature value.
The first heat engine appeared in the Roman Empire. It was a steam turbine of external combustion. But due to the low development of technology, this invention was not developed. It had no effect on progress and was soon forgotten. Later in China, a powder gun and a powder rocket appeared. It was a relatively simple device. From the point of view of mechanics, a powder rocket was not a heat engine, but from the point of view of physics it was a heat engine. Already in the 17th century, scientists tried to invent a heat engine based on a powder gun.
Types of heat engines
Thermal engines of external combustion:
1. The Stirling engine is a thermal apparatus in which a gaseous or liquid working fluid makes movements in a confined space. This device is based on periodic cooling and heating of the working fluid. In this case, energy is extracted, which occurs when the volume of the working fluid changes. The Stirling engine can be powered by any heat source.
2. Steam engines. Their main advantage is simplicity and excellent traction qualities, which are not affected by the speed of work. In this case, you can do without a gearbox. This steam engine differs for the better from the internal combustion engine, which produces an insufficient amount of power at low speeds. For this reason, it is convenient to use a steam engine as a traction engine. Disadvantages: low efficiency, low speed, constant consumption of water and fuel, high weight. Previously, steam engines were the only engine. But they required a lot of fuel and froze in the winter. Then they were gradually replaced by electric motors, internal combustion engines, steam turbines and gas, which have compactness, higher efficiency, versatility and efficiency.
Thermal internal combustion engines:
1. ICE (stands for internal combustion engine) - this is an engine in the process of which, part of the burning fuel is converted into mechanical energy. Piston ICEs differ in type of fuel (gas and liquid), in the duty cycle (two- and four-stroke), in the method of preparation of the working mixture (carburetor, diesel), in the type of energy conversion (turbine, combined, piston and jet). The first ICE was invented and created by E. Lenoir in 1860. The duty cycle consists of four cycles, for this reason this engine is also called four-stroke. Currently, such an engine is most often found on cars.
2. Rotary engine. An example is an electric thermal station operating in the base and peak modes. This type of engine is relatively simple and can be created in any size. Instead of pistons, a rotor rotating in a special chamber is used. It has inlet and outlet openings, as well as a spark plug. With this type of design, a four-stroke cycle is carried out without a gas distribution mechanism. In a rotary engine, you can use cheap fuel. Also, it practically does not create vibrations, cheaper and more reliable in production than piston heat engines.
3. Missile and jet heat engines. The essence of these devices is that the thrust is created not with the help of a screw, but by means of the exhaust gases of the engine. Can create traction in space without air. There are solid fuel, hybrid and liquid).
And the last subspecies is turboprop heat engines. The creation of energy occurs due to the screw and due to the return of exhaust gases.