Why we need magnetic refrigeration AND what is the magnetocaloric effect?
- Magnetic cooling technology could make fridges and air conditioners quieter, safer, and more environmentally friendly. It might also help scientists run experiments at temperatures lower than the extreme chill of outer space without using expensive cryogenic liquids.
- To avoid damage to the environment. Magnetic Refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by the magneto-caloric effect (MCE).
How does it work?
- The magnetic refrigeration system works by applying a magnetic field to a magnetic material causing it to heat up.
- The excess heat can remove by using water.
- After cooling the material again come to the original temperature.
- The material will demagnetised.
- Magnetic cooling relies on materials called magnetocaloric, which heat up when exposed to a powerful magnetic field.
- The conventional vapor compression system makes use of a compressor, two heat exchangers – an evaporator and a condenser, a throttling device.
- The heat will converter into a vapor state in the evaporator
- The vapor will enter into a compressor and increase the pressure and temperature
- Then refrigerant will emits its heat into a condenser and will convert into a liquid in the magnetic system.
- Then the throttling device will reduce the refrigerant pressure to the evaporator pressure.
- The use of magnets, either permanent or superconducting, change occur in the magnetic field.
- After that CFC or HFC refrigerant will convert into a working substance i.e. a magneto-caloric material.
- Then the magneto-caloric effect will increase its temperature and the material will magnetize.
- The Magnetocaloric effect may be a magneto- thermodynamic phenomenon during which a reversible change in temperature of an appropriate material is caused by exposing the material to a changing magnetic flux.
- this is often also referred to as adiabatic demagnetization
- therein a part of the general refrigeration process, a decrease within the strength of an externally applied magnetic flux allows the magnetic domains of a selected (magnetocaloric) material to become disoriented from the magnetic flux by the agitating action of the thermal energy (phonons) present within the material.
- If the fabric is isolated so that no energy is allowed to (e)migrate into the material during this point (i.e. an adiabatic process),
- the temperature drops because the domains absorb the thermal energy to perform their reorientation.
- The randomization of the domains occurs during a similar fashion to the randomization at the Curie temperature, except that magnetic dipoles overcome a decreasing external magnetic flux while energy remains constant, rather than magnetic domains being disrupted from internal ferromagnetism as energy is added.
- one of the foremost notable samples of the magnetocaloric effect is within the element gadolinium and a few of its alloys.
- Gadolinium temperature is observed to extend when it enters certain magnetic fields.
- Gadolinium and its alloys are the simplest material available today for magnetic refrigeration near temperature
- since they undergo second-order phase transitions that haven’t any magnetic or thermal hysteresis involved.
ALSO CHECK- https://forgottentheory.com/maximum-efficiency/