Cryogenic rocket engines use liquid oxygen and liquid hydrogen propellants, which are cooled to extremely low temperatures below their freezing points. This allows them to be stored densely in rocket fuel tanks. The first operational cryogenic engine was developed by NASA in 1961. Cryogenic engines work by pumping the liquid propellants into a combustion chamber where they ignite and expand, producing thrust through a nozzle. They offer high energy efficiency but also technical challenges due to boil off and leakage risks at very low temperatures. Future rocket technologies may use alternative propulsion methods like ion engines or nuclear thermal rockets.

1. CRYOGENIC ROCKET ENGINE
By :
Satyajit S Patil
BE Mechanical
Roll No. 141

3. Meaning of Cryogenics
 In physics, cryogenics is the study of the production of
very low temperature(below −150 °C, −238 °F or 123 K)
and the behavior of materials at those temperatures .

4. Cryogenic technology
o Cryogenic technology involves the use of rocket propellants at
extremely low temperatures.
o The combination of liquid oxygen and liquid hydrogen offers the
highest energy efficiency for rocket engines that need to
produce large amounts of thrust.
o Oxygen remains a liquid only at temperatures below minus 183
° Celsius and hydrogen at below minus 253 ° Celsius.

5. Brief history
 Space travel was mainly developed by the
Russians and the Americans.
The Russians were the first to reach into space.
 Solid-fuel rocket engines were the first engines
created by man.
 All the current Rockets run on Liquid-propellant
rockets.
 The first operational cryogenic rocket engine was
the 1961 NASA design the RL-10 LOX LH2 rocket
engine, which was used in the Saturn 1 rocket
employed in the early stages of the Apollo moon
landing program.

6. SPACE PROPULSION SYSTEM
 Spacecraft propulsion is any
method used to accelerate
spacecraft and artificial satellites.
 Rocket Engines
 Interplanetary vehicles mostly
use chemical rockets as well.
 Cryogenic Engine is also in use.

7. Classification Of Space Propulsion System

8. CRYOGENIC FUELS
 Cryogenic propellant - the fuel and the oxidizer
 super cooled gases -temperature lower than the freezing
point.
 To store them is difficult task
 cooling and compressing them into liquids, we can vastly
increase their density and make it possible to store them
in large quantities in smaller tanks.
 Nitrogen, hydrogen, oxygen, helium argon, neon, etc,
 Liquid oxygen being the oxidizer and
liquid hydrogen being the fuel.
 Liquid oxygen boils at 297oF and liquid hydrogen boils
at 423oF.

9. The first operational cryogenic engine

10. Construction
The major components of a cryogenic rocket engine are:
 Thrust chamber or combustion chamber
 Igniter
 Fuel injector
 Fuel turbo-pumps
 Valves
 Regulators
 Fuel tanks
 Rocket engine
 Nozzle

12. Position Of Various Parts In Shuttle

13. Working of 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.

14. ROCKET ENGINE POWER CYCLES
1. Gas pressure feed
system

15. 2. Gas-Generator Cycle

16. 3. Staged Combustion Cycle

17. COMBUSTION IN THRUST CHAMBER

18. Advantages
 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.
 Clean Fuels
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
 Economical
Use of oxygen and hydrogen as fuels is very
economical, as liquid oxygen costs less than

19. Drawbacks:
 Boil off Rate
 Highly reactive gases
 Leakage
 Hydrogen Embrittlement
 Zero Gravity conditions

20. The next generation of the Rocket Engines
 All rocket engines burn their fuel to generate thrust . If
any other engine can generate enough thrust, that
can also be used as a rocket engine
 There are a lot of plans for new engines that the
NASA scientists are still working with. One of them is
the “ Xenon ion Engine”. This engine accelerate ions
or atomic particles to extremely high speeds to create
thrust more efficiently. NASA's Deep Space-1
spacecraft will be the first to use ion engines for
propulsion.
 There are some alternative solutions like Nuclear
thermal rocket engines, Solar thermal rockets, the
electric rocket etc.
 We are looking forward that in the near future there
will be some good technology to take us into space

22. THANKS