When performing a hydrogen combustion test, can you see water flowing? Of course not! This is because the temperature during combustion is very high and water exists in the form of gas. At this point, the volume of water becomes very large, so there is a surge.
In fact, the hydrogen-oxygen engine should be called a hydrogen-oxygen fuel cell. It uses hydrogen and oxygen produced by electrolysis of water to combine again. The principle is equivalent to the original battery. the electrical energy generated causes the motor to rotate, thereby providing energy.
When a submarine sails underwater, there is no air and cannot be powered by a diesel engine. Currently, batteries are used to power the submarine. When the submarine is sailing on the water, the diesel engine not only provides power, but also drives the generator to charge the battery. THEHydrogen-oxygen fuel cells are currently the research area of underwater batteries. Because this type of battery is clean and environmentally friendly, unlike lead batteries, which are polluting.
The rocket's hydrogen-oxygen engine uses liquid hydrogen and liquid oxygen to burn to produce a large amount of high-temperature water vapor to provide thrust.
Hydrogen-oxygen engines are currently only used for launching a small number of spacecraft, as there is currently no efficient way to store hydrogen.
In addition to your question, let me explain it again. As mentioned above, the hydrogen and oxygen in the rocket engine are burned to form a gas at high temperature and high pressure. There is a formula in thermodynamics:
pV=nRT
Among them, p represents the pressure, V represents thevolume, nR can be considered as a constant and T represents the thermodynamic temperature.
It can be seen from this formula that the combustion temperature of hydrogen and oxygen is 3500 K, and the temperature of water vapor increases by almost 3000 K, that is, the original pV value of 10 times also increases by 10. times. When water vapor After being sprayed, the pressure decreases to about 1/10 of the original value. Therefore, the volume of water vapor at high temperature expands more than 100 times. But when liquid hydrogen and oxygen change to gaseous state, the temperature decreases, so the pV value also decreases. The storage pressure of liquid hydrogen and oxygen is only 50 atmospheres at most. When reduced to normal pressure, the volume increases up to 40 times, which is incomparable with water vapor at high temperatures. Is that clear ?