Thermoacoustic Refrigerationx - 123SeminarsOnly

roastdismalMechanics

Oct 27, 2013 (4 years and 13 days ago)

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THERMOACOUSTIC
REFRIGERATION



Introduction


Thermo acoustic combines the branches of
acoustics and thermodynamics together to
move heat using sound.


Acoustics is primarily concerned with the
macroscopic effects of sound transfer like
coupled pressure and motioned oscillation.


Thermo acoustic focuses on microscopic
temperature oscillation that is accompanied
by pressure changes.

Principle


It is based on the principle that sound waves
are pressure waves and they propagate
causing compression and rarefactions in the
medium.




In the region of compression pressure is low
and in the region of rarefaction pressure is
high.


As sound is adiabatic in nature thereby
applying first law of thermodynamics ,there is
high temperature in compression region and
low temperature in rarefaction region.

Components used:


Driver
-

It houses the loud speaker to produce



necessary sound .



Resonator
-
Houses the gas


Houses the stack



Houses hot and cold exchangers





Description of the components used

Moving coil loudspeaker


When the electrical current flows through the
electromagnetic wire coil it reverses the coil’s
polar orientation.


So positive end of electromagnetic attracted
towards the negative end of the permanent
magnet so when electric current signals are
passed through, the direction of attraction and
repulsion reverses making the cone to vibrate
back and forth and producing the sound waves.

STACK


It is the small parallel channels through which
pressure and velocity of waves changes.

Resonator


The resonator contains stack , gas and the
heat exchanger.


So it typically takes heat from the cold heat
exchanger and deposits it to the hot heat
exchanger and other stack locations

Working

W
orking


Sound of required frequency is produced from
loudspeaker.


Sound waves thus produced is allowed to pass
through the stack and resonator tube which
gets reflected back from reflecting surface
which is at the end of the resonator tube
creating standing wave


Thus due to the standing wave the helium
particles vibrate back and forth




Thus temperature gradient is created


Thus heat is removed from colder body and it
is maintained at the required temperature


Advantages


Harmful chemicals are not released into the
atmosphere .


More reliable as there are no moving parts


As the working fluid used is inert gas there is
no toxicity , flammability and other negative
environmental effects

Conclusion


Thermo acoustic refrigeration is an innovative
alternative for cooling that is both clean and
inexpensive. The refrigeration effect is
achieved by using sound waves and an inert
gas which will not cause any damage to the
atmosphere

THANK YOU