Submitted By :
Mech Engg. VIII sem
TECHNICAL SEMINAR ON
Prof. Vinaykumar m j
Dept. Of Mechanical
MEANING OF CRYOGENICS
Meaning of Cryogenics
Cryogenics originated from two Greek words “kyros”
which means cold or freezing and “genes” which
means born or produced
Cryogenics is the study of very low temperatures or
the production of the same
In physics, cryogenics is the study of the operations
at very low temperature (below −150 °C, −238 °F or
123 K) and the behavior of materials at these
Cryogenic technology in
o Cryogenic technology involves the use of rocket propellants at
extremely low temperatures.
o The combination:- Liquid Oxygen (LOX) & Liquid Hydrogen
(LH2) offers the highest energy efficiency for rocket engines.
o Oxygen remains at liquid only at temperatures below -183 ° C
and hydrogen below - 253 ° C.
Basically Rocket engines are reaction engines.
Use of cryogenic propellants (cryogenic fuel or oxidizer) to
Needs High mass flow rate of propellants.
The liquid oxygen (LOx) oxidizer and liquid hydrogen
(LH2) fuel combination is one of the most widely used.
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.
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
The first operational cryogenic
In a cryogenic propellant the fuel and the oxidizer are in the form
of very cold, liquefied gases.
Liquification done by cooling and compressing them below
we can vastly increase their density and make it possible to store
them in large quantities in smaller tanks.
The propellant combination used is that of LOx & LH2.
Liquid oxygen being the oxidizer and liquid hydrogen being the
The basic principle driving a rocket engine are:
(i) Newton 's third law of motion
(ii) Law of conservation of momentum
In principle, cryogenic rocket engines generate thrust like all other
rocket engines-by accelerating an impulse carrier to high speeds.
The chemical energy stored in the fuel is converted into kinetic
energy by burning it in the thrust chamber and subsequent
expansion in the nozzle, in the process creating thrust.
The major components of a cryogenic rocket engine are:
External fuel tanks
1.Rocket Engine Nozzle
A rocket engine nozzle is a propelling nozzle used in a rocket
engine to expand and accelerate the combustion gases produced
by burning propellants so that the exhaust gases exit the nozzle at
A pyrotechnic initiator (also initiator or igniter) is a device
containing a pyrotechnic composition used primarily to ignite
other, more difficult-to-ignite materials. Pyrotechnic initiators are
often controlled electrically (called electro-pyrotechnic
The thrust chamber is the key subassembly of a rocket engine.
Here the liquid propellants are metered, injected, atomized,
vaporized, mixed, and burned to form hot reaction gas
products, which in turn are accelerated and ejected at high
A rocket thrust chamber assembly has an injector, a combustion
chamber, a supersonic nozzle, and mounting provisions. All
have to withstand the extreme heat of combustion and the
various forces, including the transmission of the thrust force to
Regenerative cooling curtain cooling or film cooling, are employed
to give longer nozzle and chamber life.
A cryopump is a turbo pump powered by a flow of fuel
through gas turbines. Looking at this aspect, engines can
be differentiated into two:
i. Main Flow Configuration
ii. Bypass Flow Configuration
There are 5 propellant valves in a CRE. They are:
i. Oxidizer preburner oxidizer
ii. Fuel preburner oxidizer
iii. Main fuel
iv. Main oxidizer
v. Chamber coolant
Fuel and oxidizer from the external tank enters the orbiter
orbiter's main propulsion system feed lines the fuel and oxidizer each branch
out into three parallel paths, to each engine.
An Oxidizer system provides regular supply of LOX .A Hydrogen fuel system
provides regular supply of LH2.
Pre-burners and thrust control system
LH2 partially burnt with a little LOX in a gas generator. The hot gases drive a
turbo-pump and are then injected at high pressure into the thrust chamber
where the rest of oxygen is introduced and full combustion takes place.
Before going to the gas generator, the incredibly chilly liquid hydrogen is used
to cool the thrust chamber
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 vapour.
Use of oxygen and hydrogen as fuels is very economical, as
liquid oxygen costs less than gasoline.
Boil off Rate
Highly reactive gases
Zero Gravity conditions
As the world progress new developments are being made more
and more new developments are being made in the field of Rocket
Now a day cryo propelled rocket engines are having a great
demand in the field of space exploration.
Due to the high specific impulse obtained during the ignition of
fuels they are of much demand.
Semi-cryogenic engines, Hypergolic engines are being developed.
Hence Cryogenic Rocket Engine proves to be very promising for
the future in this world of technology.