Thermal engines. Types of thermal engines
A heat engine is an apparatus thataccomplishes work by using fuel energy. A machine running on such an engine converts thermal energy into a mechanical one and applies the dependence of the expansion of matter on the temperature value.
The first heat engine appeared in the Romanempire. It was an external combustion turbine, working on steam. But because of the poor development of technology, this invention has not been developed. On the progress it had no effect 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, the rocket missile was not a thermal engine, but from the point of view of physics it was a heat engine. Already in the 17th century, scientists tried to invent a thermal engine on the basis of a gun powder.
Types of thermal engines
Thermal engines of external combustion:
1. The Stirling engine is a thermal apparatus in which a gaseous or liquid working medium moves in a confined space. This device is based on periodic cooling and heating of the working fluid. In this case, energy is extracted, which arises when the volume of the working fluid changes. The Stirling engine can operate from any heat source.
2. Steam engines. Their main advantage is simplicity and excellent traction qualities, which are not affected by the speed of work. At the same time, you can do without a reducer. This steam engine differs for the better from the internal combustion engine, giving out at low speeds an insufficient amount of power. For this reason, the steam engine is convenient to use as a traction motor. Disadvantages: low efficiency, low speed, constant consumption of water and fuel, high weight. Previously, steam engines were the only engine. But they demanded a lot of fuel and were frozen in winter. Then they were gradually replaced by electric motors, ICE, steam turbines and gas, which have compactness, higher efficiency, versatility and efficiency.
Thermal engines of internal combustion:
1. ICE (deciphered as an internal combustion engine) is an engine in the process of which part of the combustion fuel is converted into mechanical energy. Reciprocating internal combustion engines differ in the type of fuel (gas and liquid), in the working cycle (two- and four-stroke), according to the method of preparation of the working mixture (carburetor, diesel engines), in the type of energy conversion (turbine, combined, piston and reactive). The first DVS was coined and created by E. Lenoir in 1860. The duty cycle consists of four cycles, for this reason this engine is also called a four-stroke cycle. Currently, this engine is most often found on cars.
2. Rotary internal combustion engines. An example is an electric thermal station operating in the base and peak modes. This kind of engine is relatively simple and can be created in any size. Instead of the pistons, a rotor is used, rotating in a special chamber. It has inlet and exhaust ports, as well as an ignition plug. With this type of construction, a four-cycle cycle is carried out without a gas distribution mechanism. In a rotary engine, cheap fuel can be used. Also it practically does not create vibrations, it is cheaper and more reliable in manufacture, than piston thermal engines.
3. Missile and reactive thermal engines. The essence of these devices is that the thrust is created not by means of a screw, but by the return 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 are turboprop thermal engines. The creation of energy is due to the screw and due to the return of exhaust gases.