CRYOGENICS - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

CRYOGENICS

Description:

CRYOGENIC ENGINES IN AEROSPACE The first operational Cryogenic Rocket Engine is the 1961 NASA design the RL-10 LOX LH2 rocket engine. The upgraded cryogenic second- ... – PowerPoint PPT presentation

Number of Views:1991
Avg rating:3.0/5.0
Date added: 22 July 2020
Slides: 22
Provided by: SARA142
Learn more at: http://rajtherock7.files.wordpress.com
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: CRYOGENICS


1
CRYOGENICS
  • PRESENTED BY
  • RAJKUMAR.G
  • VASUDAVEN.S

2
ABSTRACT
  • Cryogenic Treatment is a material science and
    involves the process of reducing the temperature
    of components over an extended period of time to
    extreme cold levels, usually slightly below
    -250C. The use of vapour compression circuit is
    to provide pre-cooling emphasis the dependence of
    cryogenic cooling technology on refrigeration and
    the synergy between the two technologies. It is
    apparent that gas compression and reduction in
    temperature as a result of throttling are common
    to both systems. The differences are the
    thermodynamic properties of the working fluid and
    the temperature range of cycle. The significance
    of critical temperature is also apparent. In the
    vapour compression cycle shows all the processes
    occur below the critical temperature, as it
    typical for such cycles, and therefore
    condensation of the working fluid is possible
    simply by rejecting heat to a sink at a lower
    temperature. By contrast, in the cryogenic cycle
    the temperature of the working fluid only falls
    below the critical value in the throttling
    process. By this method, cryogenic treatment
    helps to reduce the temperature very low.
  • Keywords
  • Absolute zero, Linde-Hampson system, Claude
    system, various applications.

3
INTRODUTION
  • Cryogenics stems from Greek and means "the
    production of freezing cold" however the term is
    used today as a synonym for the low-temperature
    state. It is not well-defined at what point on
    the temperature scale refrigeration ends and
    cryogenics begins. Cryogenics typically involves
    a deep-freezing process, usually one that takes
    object down below 240 degrees Fahrenheit and
    changes the molecular alignment of the material
    structure. This change creates the new property.
    Cryogenic process has been researched and
    developed by universities and NASA since the
    mid-sixties after NASA discovered that deep space
    exploration vehicles had improved their
    structural integrity due to extended exposure to
    cryogenic temperature.
  • The terms cryogenics, cryobiology are
    frequently confused and given below
  • Cryogenics
  • The branches of physics and engineering that
    involve the study of very low temperatures, how
    to produce them, and how materials behave at
    those temperatures.
  • Cryobiology
  • The branch of biology involving the study of
    the effects of low temperatures on organisms
    (most often for the purpose of achieving
    cryopreservation).

4
  • TYPES OF CRYOGENIC TREATMENT
  • SHALLOW CRYOGENICS, made the objects to
    temperature of approximately -120o F.
  • FLOODING, takes the component to -120o F, then
    the chamber is flooded with liquid nitrogen.
  • DEEP CRYOGENICS TREATMENT, Subjects the objects
    to the temperature of approximately -300o F.
  • ABSOLUTE ZERO
  • Absolute zero is a temperature marked by a 0
    entropy configuration. It is the coldest
    temperature theoretically possible and cannot be
    reached by artificial or natural means.
    Temperature is an entropically defined quantity
    that effectively determines the number of
    thermodynamically accessible states of a system
    within an energy range. Absolute zero physically
    possesses quantum mechanical zero-point energy.
    Having a limited temperature has several
    thermodynamic consequences for example, at
    absolute zero all molecular motion does not cease
    but does not have enough energy for transference
    to other systems, it is therefore correct to say
    that at 0 Kelvin molecular energy is minimal. In
    addition, any particle with zero energy would
    violate Heisenberg's Uncertainty Principle, which
    states that the location and momentum of a
    particle cannot be known at the same time. A
    particle at absolute zero would be at rest, so
    both its position, and momentum (0), would be
    known simultaneously.
  • By international agreement, absolute zero is
    defined as precisely 0 K on the Kelvin scale,
    which is a thermodynamic (absolute) temperature
    scale, and -273.15 on the Celsius scale.1
    Absolute zero is also precisely equivalent to 0 R
    on the Rankine scale (same as Kelvin but measured
    in Fahrenheit intervals), and -459.67 on the
    Fahrenheit scale.

5
  • PRODUCTION OF LOW TEMPERATURE
  • The following methods are involved to produce
    the low temperature in cryogenics
  • Heat conduction It is a relatively simple
    concept to understand. When two bodies are in
    contact, heat flows from the body with the higher
    temperature to the body with a lower temperature.
    Conduction can occur between any and all forms of
    matter, whether gas, liquid, or solid. It is
    essential in the production of cryogenic
    temperatures and environments.
  • Evaporative cooling Humans are familiar with
    this process because it is a mechanism in which
    our bodies lose heat. Atoms and molecules in the
    gaseous state are moving faster than the atoms
    and molecules in the liquid state. Add heat
    energy to the particles in a liquid and it will
    become gaseous.
  • The Joule-Thomson effect It was discovered by
    the English Physicist James Prescott Joule,
    William Thomson and Lord Kelvin, in 1852. They
    found, for example, that allowing a gas to expand
    very rapidly causes its temperature to drop
    dramatically. Reducing the pressure on a gas
    accomplishes the same effect.
  • The Joule-Thomson effect is an important part of
    our lives today, even though we may not be aware
    of it. Ordinary house hold refrigerators and air
    conditioners operate on this principle. First a
    gas is pressurized and cooled to an intermediate
    temperature by contact with a colder gas or
    liquid. Then the gas is expanded, and its
    temperature drops still further. The heat needed
    to keep this cycle operating comes from the
    inside of the refrigerator or the interior of a
    room, producing the desired cooling effect.
  • METHODS OF LIQUIFICATION OF AIR
  • Lindes system also known as hampson system.
  • Claudes system.

6
LINDES SYSTEM
7
LINDES SYSTEM
  • Clean dry air is taken from the atmosphere and is
    compressed up to 200 bar.
  • The high pressure enters into counter flow air to
    air heat exchanger and is then throttled to atm -
    pressure.
  • The J-T cooling up to expansion causes a lowering
    of temperature and this cool air is passed
    through heat exchanger where it cools the
    incoming high section.
  • Thus the temperature at the valve is
    progressively lowered until the liquefaction
    temperature is reached.

8
T-S DIAGRAM (Lindes system)
PROCESS 1-2 Compression 2-3 Pre-cooling of
air by pre cooling circuit 3-4 Pre-cooling of
air by Heat exchanger 4-5 Throttling
process 5-6 Process in evaporator
9
CLAUDES SYSTEM DIAGRAM
10
CLAUDES SYSTEM
  • Claudes system yields more efficient cycle than
    Lindes system
  • The expansion through an expansion valve is an
    irreversible process.
  • In Claudes system energy is removed from the gas
    stream by using an expansion engine or expander.
  • The expansion process is isentropic and much
    lower temp is attained then isenthalpic expansion
  • In Claudes system the gas is first compressed to
    pressure of the order 4 Mpa.

11
T-S DIAGRAM (Claudes system)
How Claudes system is more efficient than
Lindes system The advantage of the
Claudes system is, it operates at low
compression ratio compared with lindes
process. Secondly the temperature of air
before coming to the expansion valve in Claude
system is lower than the Linde system.
12
APPLICATION OF CRYOGENICS
  • Aerospace-cryogenic engines
  • Medical Field
  • Manufacturing field
  • Electronics Field
  • Fuels research.

13
CRYOGENIC ENGINES IN AEROSPACE
  • The first operational Cryogenic Rocket Engine is
    the 1961 NASA design the RL-10 LOX LH2 rocket
    engine.
  • The upgraded cryogenic second-stage Pratt
    Whitney RL10B-2 engine is based on the 30-year
    heritage of the reliable RL10 engine.
  • At Mahendragiri in Tamil Nadu, is the Liquid
    Propulsion System Centre LPSC. Here work on
    developing Indias own cryo - engines has been
    quietly moving. The system involves materials
    working at 250 deg below zero and pumps at speeds
    of 40,000 rpm. There are also complex metering,
    monitoring, integrating technologies involved.
    The engines are required to fire for about 700
    seconds during the final stage of a launch
    providing 7 tones of thrust..
  • The Engine works on Staged Combustion Cycle
    with an integrated turbo pump running at around
    42,000 rotations per minute (rpm). It is also
    equipped with two steering engines developing a
    thrust of 2 kN each to enable three-axis control
    of the launch vehicle during the mission. Another
    unique feature of this engine is the closed loop
    control of both thrust and mixture ratio, which
    ensures optimum propellant utilization for the
    mission.

14
CRYOGENICS IN MEDICAL FIELD
15
  • CRYOSURGERY
  • Cryosurgery (also called cryo therapy) is the use
    of extreme cold produced by liquid nitrogen (or
    argon gas) to destroy abnormal tissue.
  • Cryosurgery is used to treat external tumors,
    such as those on the skin.
  • For internal tumors, liquid nitrogen is
    circulated through a hollow instrument called a
    cryoprobe.
  • Cryosurgery has been used for many years in the
    treatment of skin cancer
  • BENEFITS OF CRYOSURGERY
  • Cryosurgery is very effective and is less
    expensive than other treatment. It can be done in
    your health care providers office and an
    anesthesia is not necessary.
  • The treatment can be safely repeated and may be
    used along with standard treatments such as
    surgery, chemotherapy, Harmon therapy and
    radiation.
  • It can be used for patients who are not good
    candidates for conventional surgery because of
    their age or other medical condition.
  • It is used to treat skin lesions such as freckles
    (for cosmetic reasons), hemorrhoids and some skin
    cancers

16
CRYOGENICS IN MANUFACTURING FIELD
  • Cryogenic treatment works on Reamers, Tool bits,
    Tool punches, Carbide Drills, Carbide Cutters,
    Milling Cutters, Files, Knives, Reciprocating
    Blades, Dies and cutting tools.
  • Stress relives ferrous and non ferrous castings
    and forgings for enhanced dimensional stability
    and surface finish upon finish machining.

17
CRYOGENICS IN ELECTRONICS FIELD
The super conducting electronic devices like
SQUID (Super conducting quantum interference
device) are used in sensitive digital
magnetometers and voltmeters. Zero friction
bearings use magnetic field instead of oil or
air, derived from the Meissner effect associated
with super conductivity. Super conducting
electric motors are constructed approaching zero
electric loses.
18
CONCLUSION
  • Refrigeration and cryogenic cooling
    technology share a common history and there are
    many similarities in the underlying
    thermodynamics. The significant differences lie
    in the temperature range of interest and the
    properties of the working fluids.
  • Whilst it is most unlikely that cryogens
    can ever replace more familiar refrigeration
    technology for high temperature cooling, there
    may be niche applications where they can offer an
    interesting alternative.

19
REFERENCES
  • Cryogenic engines, http//en.wikipedia.org
  • Cryogenic engines, www.astronautix.com
  • Cook P. Richatdson R.N., Cryogenic safety
    manual, see www.ior.org.uk
  • GIST (Previously BOC Transhield), see
    www.gistworld.com

20
QUERIES??!!.......
21
THANKING YOU..
About PowerShow.com