Whether fuel with more heat or less heat is used to build a satellite launch vehicle

You kid!

You can think about what happens when a rocket burns coal!

Let’s say that the basic principle of a rocket is recoil, that is, outward movement After the gas is ejected, if the rocket wants to take off, a basic condition must be met, that is, the recoil force must be greater than gravity. The recoil force is entirely obtained by ejecting gas. According to the momentum theorem, momentum depends on speed and mass, so it usually needs to be considered comprehensively. Depending on the quality of a fuel, in order for the rocket to gain enough momentum, the momentum of the reflected gas must be reached, so the speed of the injected gas must be very high. The fuel burns and releases its own internal energy, and the internal energy is released by changing the volume of the gas. Work is done, that is, the gas expands, so the gas will be ejected outward. What determines the rate of expansion is, of course, the amount of heat released per unit mass, unit volume, unit time, that is, the specific heat. Furthermore, the mass of the rocket required to lift off is As small as possible, in this case, although the combustion value of some fuels is greater than that of hydrogen, quality reasons restrict its use.

In fact, hydrogen is rarely used as fuel in rocket fuel, and more The fuel is hydrazine, that is, N2H4, which has a stronger comprehensive ability.