Cryogenics-An introduction

1. Cryogenics
The coolest thing ever!

2. What is cryogenics?
• The word cryogenics stems from Greek
word cryos and means "the production
of freezing cold“, the term is used today
as a synonym for the low-temperature
state.
• Cryogenics is the study of the
production of extremely cold
temperatures. This field of science also
looks at what happens to a wide variety
of materials from metals to gases when
they are exposed to these temperatures

3. 1) The development of cryogenics as a low
temperature science is a direct result of
attempts by nineteenth century scientists
to liquefy the permanent gases.
2) Michael Faraday, had succeeded, by
1845, in liquefying most of the gases
then known to exist.
3) His procedure consisted of cooling the
gas by immersion in a bath of ether and
dry ice and then pressurizing the gas until
it liquefied.

4. • The use of cryogenics or freezing technique seems to
have it’s roots way back.
• Here’s how-
 Starting back about 150 years ago Swiss
watchmakers gave birth to cryogenics. They would
bury their watch parts in the snow for a winter because
they noticed that it would make them more durable
and therefore keep better time.
 Tool and die makers of the 1930’s that noticed that
freezing tool steel would help it hold an edge better
than tool steel that hadn’t been frozen

5. Applications
Magnetic resonance imaging
Electric power transmission in big cities
Frozen food
Forward looking infrared (FLIR)
Blood banking
Rocket engines
To make metals durable

6. How do we use it?
• Magnetic Resonance imaging(MRI)
a. MRI is a method of imaging objects that uses a strong
magnetic field to detect the relaxation of protons that have
been perturbed by a radio-frequency pulse.
• Electric power transmission in big cities
• It is difficult to transmit power by overhead cables in big
cities, so underground cables are used.
• But underground cables get heated and the resistance of the
wire increases leading to waste of power.
• Superconductors are frequently used to increase power
throughput, requiring cryogenic liquids such as nitrogen or
helium to cool special alloy-containing cables to increase power
transmission.

7. • Frozen food
a. When very large quantities of food must be transported to regions like war
zones, earthquake hit regions, etc., they must be stored for a long time, so
cryogenic food freezing is used.
• Forward looking infrared (FLIR)
a. Many infra-red cameras require their detectors to be cryogenically
cooled.
• Blood banking
a. Certain rare blood groups are stored at low temperatures, such as -
165 degrees C.

8. What cryogenics is and what it is
not.
• People generally confuse cryogenics with
cryonics..
• Cryonics is one of the applications of cryogenics or
• cryogenics is the tree and cryonics the branch!
• Let’s see the difference between their definitions
• Cryogenics
• The branches of physics and engineering that involve the study
of very low temperatures.
• Cryonics
• The emerging medical technology of preserving humans and
animals with the intention of future revival.

9. Relation between cryogenics
and cryonics
Cryonics
Cryogenics

10. Cryogenics and NASA
• Astronomers at the Goddard Space Flight Center are working to develop
ever more sensitive sensors to catch even the weakest signals reaching
from the stars. Many of these sensors must be cooled well below room
temperature to have the necessary sensitivity. Here are some examples of
how cooling helps:
• Infrared Sensors: infrared rays, also called "heat rays" are given off by all
warm objects. Infrared telescopes must be cold so that their own radiation
doesn't swamp the weak infrared signals from faraway astronomical objects.
• Electronics: all sensors require electronics. Cooling electronics reduces the
noise in the circuits and thus allows them to study weaker signals.
• X-rays: the sensors for XRS, the X-Ray Spectrometer measure temperature
changes induced by incoming x-rays. When the sensors are colder, the
induced temperature changes are larger and easier to measure.

11. Cryogenics in rocket
engines

12. Cryogenics in rocket engines
• A cryogenic rocket engine is a rocket engine that uses a
cryogenic fuel or oxidizer, that is, its fuel or oxidizer (or both)
are gases liquefied and stored at very low temperatures.
• Notably, these engines were one of the main factors of the
ultimate success in reaching the Moon by the Saturn V rocket.
• During World War II, the warring countries discovered that
rocket engines need high mass flow rate of both oxidizer and
fuel to generate a sufficient thrust. At that time oxygen and low
molecular weight hydrocarbons were used as oxidizer and fuel
pair.

13. • At room temperature and pressure, both are in gaseous
state. Hypothetically, if propellants had been stored as
pressurized gases, the size and mass of fuel tanks
themselves would severely decrease rocket efficiency.
• Therefore, to get the required mass flow rate, the only
option was to cool the propellants down to cryogenic
temperatures (below −150 C, −238 F), converting them
to liquid form.
• Hence, all cryogenic rocket engines are also, by
definition, either liquid-propellant rocket engines or
hybrid rocket engines.

14. Cryogenic processing in industries
• The process is based on what is placed in the chamber.
• It starts with placing the parts in a controlled cryogenic chamber and the
ramp down starts with ultra-cold nitrogen gas. The materials are slowly
cooled with nitrogen gas only and then slowly introduced to liquid nitrogen
for the duration of the “soak” period. (20+ hours depending on what is being
treated)
• The liquid phase provides the most efficient and uniform deep cryogenic
soak at a consistent temperature of –320 deg. F (impossible to do with gas
alone).
• With cryogenics two factors that make for a better end product are
temperature (the colder the better) and time (the longer the better). Materials
are then allowed to return very slowly to room temperature. At that time,
those materials that specifically require post-cryo tempering are moved into
a tempering oven to complete the tempering procedure.

15. • Some cryogenic companies use gas only treatment
methods and only reach.
• The use of precisely controlled temperature profiles
avoids any possibility of thermal shock and thermal
stress that is experienced when a part is subjected to
abrupt or extreme temperature changes.
• Though liquid nitrogen is used, no part is introduced
to the liquid until it has been slowly cooled to
cryogenic temperatures by the ultra-cold nitrogen gas.
By eliminating the need for circulation fans and on-
board heating elements are chambers remain 100%
moisture free during the entire process.