CRYOGENICS : Basics & Applications

Reading Time: 7 minutes





  • CRYO—-



  • Cryogenics – the study and use of materials at extremely low temperatures
  • Inputs from three major disciplines, namely PHYSICS , MECHANICAL ENGINEERING, CHEMICAL ENGINEERING
  •  Such low temperatures cause changes in the physical   properties of materials that allow them to be used in unusual engineering, industrial, and medical applications
  •  For example, in the cryogenic temperature range, air becomes a liquid—or even a solid—and living tissue freezes instantly



  •  SHALLOW CRYOGENICS, the objects are cooled down to temperature of approximately -85oC
  • FLOODING, first the object is taken to -85oC, then the chamber is flooded with liquid nitrogen to reduce the temperature furthur
  • DEEP CRYOGENICS TREATMENT, Subjects the objects to the temperature of approximately    -185oC



  • 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



  • HEAT CONDUCTION: When bodies are in contact, heat flows from the body with the higher temperature to the body with a lower temperature. Can occur between any and all forms of matter. It is essential in the production of cryogenic temperatures and environments.
  • EVAPORATIVE COOLING: Humans lose heat by this mechanism. Atoms and molecules in the gaseous state are moving faster than the atoms and molecules in the liquid state. Adding heat energy to the particles in a liquid makes them gaseous
  • THE JOULE-THOMSON EFFECT:  Allowing a gas to expand very rapidly causes its temperature to drop dramatically. Reducing the pressure on a gas accomplishes the same effect.
  • Ordinary house hold refrigerators and air conditioners operate on this principle.



  • Linde’s System also known as Hampson System
  • Claude’s 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





  • Claude’s System yields more efficient cycle than Linde’s System
  • The expansion through an expansion valve is an irreversible process.
  • In Claude’s 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 Claude’s System the gas is first compressed to pressure of the order 4 Mpa.


How Claude’s System is more efficient than Linde’s System

  • The advantage of the Claude’s System is, it operates at low compression ratio      compared with Linde’s process.
  • Secondly the temperature of air before coming to the expansion valve in Claude system is lower than the Linde system.


Cryogenic Devices









  •   Aerospace-cryogenic engines
  •  Medical Field
  •  Manufacturing field
  •  Electronics Field
  •  Fuels research
  •  Miscellaneous uses



  • First operational Cryogenic Rocket Engine is 1961 NASA designed  RL-10 LOX LH2 rocket engine
  • The 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 LPSC. The system involves materials working at 23K and pumps at speeds of 40,000 rpm. Complex metering, monitoring, integrating technologies involved. The engines required to fire for  700 seconds during the final stage of a launch providing 7 tones of thrust
  • Engine works on ‘Staged Combustion Cycle’ with an integrated turbo pump running at 42,000rpm. 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
  • Closed loop control of both thrust and mixture ratio, which ensures optimum propellant utilization for the mission
  • To know how cyrogenics plays vital role in space shuttle.. watch this video :




  • Cryosurgery- Use of extreme cold produced by liquid nitrogen (or argon gas) to destroy abnormal tissue.
  • 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.
  • Used since many years in the treatment of skin cancer



  • Cryogenic treatment works on Reamers, Tool bits, Tool punches, Carbide Drills, Carbide Cutters, Milling Cutters, Files, Knives, Reciprocating Blades, Dies and cutting tools
  • Stress relieved ferrous and non ferrous castings and forgings for enhanced dimensional stability and surface finish



  • 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

Nuclear Magnetic Resonance Spectroscopy (NMR)

Most common method to determine the physical and chemical properties of atoms by detecting the radio frequency absorbed and subsequent relaxation of nuclei in a magnetic field. Strong magnetic fields are generated by supercooling electromagnets. Liquid helium(BP  4K) is used to cool the inner coils. Cheap metallic superconductors can be used for the coil wiring. So-called high-temperature superconducting compounds can be made to superconduct with the use of liquid nitrogen(BP 77K)

Magnetic Resonance Imaging (MRI)  :

Complex application of NMR where geometry of the resonances is deconvoluted and used to image objects by detecting the relaxation of protons that have been perturbed by a radio-frequency pulse in the strong magnetic field. Mostly used in health applications

Electric Power Transmission:

  • Superconductors could be used to increase power throughput. Require cryogenic liquids such as nitrogen or helium to cool special alloy-containing cables to increase power transmission. Field is the subject of an agreement within the International Energy Agency.

Frozen Food:

  • Transportation of large masses of frozen food. Food is freezed in war zones, earthquake hit regions, etc. Cryogenic food freezing is also helpful for large scale food processing industries

Forward looking infrared (FLIR)
Many infra-red cameras require their detectors to be cryogenically cooled


Blood banking
Certain rare blood groups are stored at low temperatures, such as −165 °C

Special effects
Liquid nitrogen and CO2 has been built into nightclub effect systems by Kryogenifex to create a chilling effect and white fog that can be illuminated with colored lights.




  • Inert Gases: Do not react chemically to any great extent. Do not burn or support combustion. Includes Nitrogen, Helium, Neon, Argon and Krypton
  • Flammable Gases: Some cryogenic liquids produce a gas that can burn in air. Includes Hydrogen, Methane and Liquefied Natural Gas
  • Oxygen: Many non-combustible materials can burn in the presence of Liquid Oxygen. Organic materials react explosively with Liquid Oxygen. Hazards and handling precautions of liquid oxygen is considered separately from other cryogenic liquids



  • Oil Diffusion Vacuum Pumping System with Measuring Guages, Trolley Heater & Oil
  • Dewar vessels ( Model T-26-A 0110 capacity – 25 Lt. ) ( Model T-55-A 0110 capacity – 50 Lt. )
  • VPF 100 Liquid Nitrogen variable temperature Dewar with Controller & Trolley
  • Servotronic Digital (6 digit) Temperature Indicator ( PT-100 -200C to 100C six channel 230 VAC )
  • Piezo-Electric Transducer with Accessories
  • Data Logger with Software for online display ( ModelNo: MICROLOG 6102 + CST 27)
  • Helium Compressor


Projects on Cryogenics


Teardown of Washing Machine

Reading Time: 3 minutes




  • Motor & counterweight
  • Cable –pulley support system
  • Vibration damping system
  • Plumbing system
  • Clutch & coupling
  • Drive mechanism
  • Control system



Motor & Counterweight

  • The concrete is used to balance the equally heavy electric motor, which drives a very heavy gearbox that is attached to the steel inner tub.





Cable –pulley support system

  • There are a total of three pulleys, so that if one side of the frame moves up, the other side moves down. This system supports the weight of the heavy components, letting them move in such a way as not to shake the entire machine.




Vibration damping system

  • In each of the four corners of the machine is a mechanism that works a little like a disc brake. The part attached to the washer frame is a spring. It squeezes two pads against the metal plate that is attached to the black frame.




Plumbing system
It comprises of the following parts:

  • Solenoid valve
  • Anti-siphon device
  • Water inlet & overflow port
  • Pump vanes






Clutch & Coupling

  • The coupling is needed because the motor and clutch are mounted to the frame, which can move freely with the inner tub, whereas the pump is mounted to the stationary outer tub.





Drive mechanism

  • The drive mechanism on a washing machine has two jobs:

To agitate the clothes, moving them back and forth inside the wash tub.

To spin the entire wash tub, forcing the water out.





Control & Coordination


  • Water level control switch
  • Temperature control switch
  • Speed control switch
  • Cycle switch



Front Loading Machines


  • This layout mounts the inner basket and outer tub horizontally, and loading is through a door at the front of the machine.
  • Front-loaders control water usage through the surface tension of water, and the capillary wicking action this creates in the fabric weave.
  • Front-loading washers are mechanically simple compared to top-loaders, with the main motor (usually a universal motor) normally being connected to the drum via a grooved pulley belt and large pulley wheel, without the need for a gearbox, clutch or crank.





  • Clothing can be packed more tightly in a front loader, up to the full drum volume if using a cottons wash cycle.
  • Front-loading washers are mechanically simple compared to top-loaders.





  • Extreme overloading of front-loading washers pushes fabrics towards the small gap between the loading door and the front of the wash basket, potentially resulting in fabrics lost between the basket and outer tub, and in severe cases, tearing of clothing and jamming the motion of the basket.



Top Loading

  • This design places the clothes in a vertically mounted perforated basket that is contained within a water-retaining tub, with a finned water-pumping agitator in the center of the bottom.
  • In most top-loading washers, if the motor spins in one direction, the gearbox drives the agitator; if the motor spins the other way, the gearbox locks the agitator and spins the basket and agitator together. Similarly if the pump motor rotates one way it recirculates the sudsy water; in the other direction it pumps water from the machine during the spin cycle of the basket.





  • The top-loader’s spin cycle between washing and rinsing allows an extremely simple fabric softener dispenser, which operates passively through centrifugal force and gravity.
  •  Another advantage to the top loading design is the reliance on gravity to contain the water, rather than potentially trouble-prone or short-lived front door seals.
  • Top loaders may require less periodic maintenance since there is no need to clean a door seal or bellows, although a plastic tub may still require a periodic “maintenance wash” cycle.





  • Clothing should not be packed tightly into a top-loading washer. Although wet cloth usually fits into a smaller space than dry cloth, a dense wad of cloth can restrict water circulation, resulting in poor soap distribution and incomplete rinsing.
  • Extremely overloaded top-loading washers can either jam the motion of the agitator, overloading or damaging the motor or gearbox, or tearing fabrics.



Flow Boiling

Reading Time: 2 minutes



Boiling is classified as pool boiling or flow boiling, depending on the presence of bulk fluid motion.


Pool Boiling and Flow Boiling

  • Boiling is called pool boiling in the absence of bulk fluid flow and flow boiling (or forced convection boiling) in the presence of it. In flow boiling, the fluid is forced to move in a heated pipe or over a surface by external means such as a pump or from height. Therefore, flow boiling is always accompanied by other convection effects.


Sub-cooled Boiling and Saturated Boiling

—        Boiling is said to be sub cooled (or local) when the temperature of the main body of the liquid is below the saturation temperature Tsat (i.e., the bulk of the liquid is sub cooled) and saturated (or bulk) when the temperature of the liquid is equal to Tsat (i.e., the bulk of the liquid is satu

Void fraction in a Gas-Liquid Flow


—        The fraction of the channel volume that is occupied by the gas phase.

—        The fraction of the channel cross-sectional area that is occupied by the gas phase.

—        Quality Profile :-  Vapour Quality is the percentage of mass in a saturated mixture that is vapour i.e. saturated vapour has a “quality” of 100%, and saturated liquid has a “quality” of 0%.



—  This type of boiling take place in Nuclear reactors and Aerospace Engines.

—  Flow boiling is also used in the cooling of Electronic Circuit Boards using Micro channels.

—  All the refrigeration cycles are based on flow boiling.

—  Cooling systems in various industries comprise of Flow boiling.





















Application Of Electronics in Automobiles

Reading Time: 2 minutes



Automotive electronics or automotive embedded systems are distributed systems and according to different domains in the automotive field they can be classified into:

}        Engine Electronics

}        Transmission Electronics

}        Chassis Electronics

}        Active Safety

}        Driver assistance

}        Passenger Comfort

}        Infotainment systems


Engine Electronics

}        One of the most demanding electronic part of an automobile is the engine control unit. Engine controls demand one of the highest real time deadlines, as the engine itself is very fast and complex part of the automobile. Of all the electronics in any car the computing power of the engine control unit is the highest, typically a 32-bit processor.


In a Diesel Engine

}        -Fuel injection rate

}        -Emission control, Nox control

}        -Regeneration of oxidation catalytic converter

}        -Turbocharger control

}        -Cooling system control

}        -Throttle control


In a Gasoline engine


}        OBD OnBoard diagnosis

}        -Cooling system control

}        -Ignition system control

}        -Lubrication system control (only few has electronic control)

}        -Fuel injection rate control

}        -Throttle control


Transmission Electronics

}        This controls the transmission system; mainly it controls the shifting process of the gears. For a better shift comfort, lower torque interrupt while shafting -these electronics are used in a manual transmission. Many semi automatic transmissions which have a fully automatic clutch or a semi-auto clutch (only declutching) use electronics for its operation and control. Also fully automatic transmissions use controls for their operation.


Chassis Electronics


}        ABS – Anti-lock braking system

}        TC – Traction control system

}        EBD – Electronic brake distribution

}        ESP – Electronic Stability Program



Active Safety

}        Air Bags

}        Hill Descent Control

}        Emergency Brake assist system


Driver assistance

}        Lane assist system

}        Speed assist system

}        Blind spot detection

}        Park assist System

}        Adaptive Cruise Control System


Passenger Comfort

}        Automatic Climate control

}        Electronic seat adjustment with memory

}        Automatic wipers

}        Automatic Headlamps



}        Navigation system

}        Music system

               Information access






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