Interesting knowledge: Micro gas turbines are hot-fried. Is this engine suitable for cars?

Limitation of gas turbine range extender and practical value of gas turbine turbojet engine.

Thermal efficiency is a word that chemical engines will inevitably discuss. Its concept is the ratio of energy produced by the combustion of an energy source to mechanical energy. Although the law of conservation of energy is the same cognition, there are many factors that will "consume energy" in the process of energy transformation; For example, the internal combustion engine will consume power because of the antifreeze coolant, the cooling of the engine body and the intake and exhaust gas, and the operation of the piston connecting rod valve and other structures. Only about 35% of the total heat energy generated by combustion can be converted into mechanical energy, and the rest is wasted. Can gas turbines replace internal combustion engines?

The most famous gas turbine is the "jet engine" (turbofan engine). The structure of the aircraft includes inlet, compressor, combustion chamber and tail nozzle (integration and integration). Its working principle is actually very simple, and the positive pressure intake effect of the huge intake port will be ideal. A large amount of compressed air reaches the standard of "absolute oxygen enrichment", and after mixing with aviation fuel, it produces extremely high temperature and kinetic energy, and the jet air is used to realize the reverse thrust (interaction force) to push the plane to take off.

Learning point

1: Oxygen-enriched combustion is the basic knowledge in the industrial field. Combustion is a redox reaction process of hydrocarbons. During the reaction process, there will be violent movement of molecules to produce an energy. This energy will not only become the driving force of piston, turbofan, rotor and other structures, but also produce extremely high flame temperature due to movement.

2. Oxygen-enriched combustion can improve the reaction intensity of the same amount of fuel. To put it bluntly, the torque increases. The higher the oxygen concentration, the greater the torque will be. This is the meaning of compressor (supercharger), which is the oxygen concentration increased by compressed air. The following figure shows the combustion flame temperature difference of the same amount of fuel under different oxygen concentration ratios, that is, the performance difference. (Torque × speed = power)

Obstacles to the popularization of gas turbines

As a range extender, it is an ideal choice, but it cannot be popularized.

The discussion about turbofan as a range extender has never stopped, even our technicians have discussed it with the R&D team of a car company, but there is basically no result. Because the turbofan engine can achieve 50%~60% high thermal efficiency with this simple structure, but it also has a very high working temperature! At the same time, it is impossible to use the tail jet to drive the turbofan in the car to generate electricity, and the structure is too limited to bear the temperature; All ideal ways should be "shaft drive, shaft power" to generate electricity. Even so, the tail nozzle still has about 5% power loss, and combined with the loss of high standard cooling system, the actual efficiency is not high.

Naturally, turbofan direct drive cannot be considered. How many meters of "safe distance" does this huge thrust and high temperature need? How to use this thrust drive to release thrust during emergency braking? You know, complicated roads are not as free as the sky, and there will be no traffic jams in the sky. Therefore, "turbojet" can only appear on the track, and it is a simple concept car test. Of course, there are other reasons why this machine has no use value in cars, because there are more ideal ways to obtain electricity.

Summary &; Note: Clean energy must not consume traditional conventional energy, whether it is coal, oil or natural gas, because these resources are non-renewable. Therefore, power generation must find "inexhaustible" energy sources, such as "wind, light, water, electricity and heat" endowed by nature. It seems to be the most ideal way to use these resources to generate electricity, and then use motors with "thermal efficiency" (energy conversion efficiency) as high as 95%.

Secondly, as a range extender, there is an electromagnetic piston reciprocating mode. In the research and development process, the reciprocating operation of large compressors can achieve higher power generation efficiency than turbofan engines. If this machine can be mass-produced, commercial vehicles will be the first batch of electric-driven vehicles with extended range, and the traditional internal combustion engine has no potential to be tapped.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.