Working of Cryogenic Propellants
For using cryogenic propellants, special insulated containers and vents are used to prevent gas from the evaporating liquids to escape. The liquid fuel and oxidizer are fed from the storage tank to an expansion chamber. Then it is injected into the combustion chamber. In this chamber, they are mixed and ignited by a flame or spark. The fuel expands as it burns and the hot exhaust gases are directed out of the nozzle to provide thrust.
Cryogenic propellants have many advantages, which enable them to be used as propellants for space vehicles. Some of the advantages are:
High Energy per unit mass
Propellants like oxygen and hydrogen in liquid form give very high amounts of energy per unit mass due to which the amount of fuel to be carried aboard the rockets decreases.
Hydrogen and oxygen are extremely clean fuels. When they combine, they give out only water. This water is thrown out of the nozzle in form of very hot vapor. Thus the rocket is nothing but a high burning steam engine.
Use of oxygen and hydrogen as fuels is very economical, as liquid oxygen costs less than gasoline.
Cryogenic propellants suffer from certain drawbacks. Let us see what these drawbacks are and how they can be overcomed.