This document provides an overview of a presentation on thermo-acoustic refrigerators. It discusses how thermo-acoustic refrigerators use sound waves in a pressurized gas tube to pump heat from one place to another to produce a refrigeration effect without lubricants. The document outlines the basic functioning of thermo-acoustic refrigerators including how a loudspeaker creates high amplitude sound waves that can compress refrigerant and allow for heat absorption. It also discusses advantages such as being environmentally friendly and having simple designs with few moving parts.

1. CORE JAVAPresentation Topic :- Thermo-acoustic Refrigerator
Presented By :- Anand Kumar (ME/13/710)

2. 2
Contents
 ABSTRACT
 INTRODUCTION
 BASIC FUNCTIONING
 THERMO ACOUSTIC EFFECT
 MERITS OF TECHNOLOGY
 APPLICATIONS
 CONCLUSION
May 23, 20172

3. 3
Abstract
 Thermo acoustic refrigeration is a phenomenon
that uses high intensity sound waves in a
pressurized gas tube to pump heat from one
place to other to produce refrigeration effect.
 This system completely eliminates the need for
lubricants and results in 40% less energy
consumption.
May 23, 2017

4. 4
Introduction
 Thermo acoustic devices take advantage of
sound waves reverberating within them to
convert a temperature differential into
mechanical energy or mechanical energy into a
temperature differential.
 Thermo acoustic devices perform best with
inert gases.
 They do not produce the harmful
environmental effects such as global warming
or stratospheric ozone depletion.
May 23, 20174

5. 5
Convention Refrigeration and Thermo acoustic Refrigeration
 Convention refrigerator
 Compressor
 refrigerants
 Thermo acoustic refrigerator
 Loudspeaker
 Inert gases
May 23, 20174

6. 6
Thermo-acoustic’s Benefit
 Environmental regulation
 No cfc emission
 Design
 Simple and robust design
 Production
 Cost efficient manufacturing
May 23, 20174

7. 7
Basic Functioning
 A thermo acoustic refrigerator uses acoustic
power to pump heat from a cool source to a hot
sink.
 These devices perform best when they employ
noble gases as their thermodynamic working
fluids.
 The principle can be imagined as a loud speaker
creating high amplitude sound waves that can
compress refrigerant allowing heat absorption.
 sound waves travel by compressing and
expanding the gas they are generated in
May 23, 20175

8. 8
Basic Functioning
 Suppose the wave is traveling through a tube, a
temperature gradient can be generated by putting
a stack of plates in the right place in the tube, in
which sound waves are bouncing around.
 Some plates in the stack will get hotter while the
others get colder
May 23, 2017

9. 9
Thermo Acoustic Effect
 Acoustic or sound waves can be utilized to
produce cooling.
 The pressure variations in the acoustic wave are
accompanied by temperature variations due to
compressions and expansions of the gas.
 As expansion and compression in an acoustic
wave are inherently associated with a
displacement, a net transport of heat results.
 To fix the direction of heat flow, a standing wave
pattern is generated in an acoustic resonator.
May 23, 2017

10. 10
Theoretical Basics
 Thermoacoustic refrigerator is a special kind of device
that uses energy of sound waves or acoustic energy to
pump heat from low temperature reservoir to a high
temperature reservoir.
May 23, 2017

11. 11
Main Prototype Components
 Two main parts are in the TAR
A. Driver
• Houses the Loudspeaker
A. Resonator
• Houses the gas
• The hot and cold heat exchangers
• Houses the Stack
May 23, 2017

12. 12
Loudspeakers
 A loudspeaker (or "speaker") is an
electroacoustic transducer that produces sound
in response to an electrical audio signal input.
 It was invented in the mid 1820’s by the scientist
Johann Philipp Reis.
 It is powered by electricity.
 The magnet or the coil in the speaker vibrates to
produce the waves of required frequency.
May 23, 2017

13. 13
Loudspeakers
 Consideration
 Power capacity
 Frequency response
 Choice
 10 inch
 Operating at low frequency
 400w max power
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14. 14
Gas Medium
 Consideration
 Physical properties
 Sealing
 Cost
 Choice
 Air
 Atmospheric pressure
May 23, 2017

15. 15
Tube
 Considerations
• Length
• Diameter
• Sound reflection
• Low acoustic losses
• Sound transmission
 Choice
• 1.5” PVC tube
• Flat end
May 23, 2017

16. 16
Stack
 It is also called as regenerator.
 The most important piece of a thermoacoustic device is
the stack.
 The stack consists of a large number of closely spaced
surfaces that are aligned parallel to the to the resonator
tube.
 In a usual resonator tube, heat transfer occurs between
the walls of cylinder and the gas.
 The different materials used in the Stack are
 Paper
 Alluminium
 Lexan
 Foam
May 23, 2017

17. 17
Stack
 Considerations
 Gap size
 Material properties
 Material thickness
 Location
 Length
 Does not impede wave
 Choice
 Paper
 Aluminum screen
May 23, 2017

18. 18
Heat Exchangers
 Heat exchangers are devices used to transfer heat
energy from one fluid to another.
 A heat exchanger is a piece of equipment built for efficient
heat transfer from one medium to another.
 The media may be separated by a solid wall, so that they
never mix, or they may be in direct contact.
May 23, 2017

19. 19
Heat Exchangers
 Considerations
 Material
 Type
 Choice
 Aluminum
 Water Circulated
May 23, 2017

20. 20
Thermo-acoustic Cycle
 The figure traces the basic
thermo-acoustic cycle for a packet
of gas, a collection of gas
molecules that act and move
together.
 Starting from point 1, the packet
of gas is compressed and moves
to the left.
 As the packet is compressed, the
sound wave does work on the
packet of gas, providing the
power for the refrigerator.
May 23, 2017

21. 21
Thermo-acoustic Cycle
 As the packet is
compressed, the sound
wave does work on the
packet of gas, providing the
power for the refrigerator.
 When the gas packet is at
maximum compression, the
gas ejects the heat back
into the stack since the
temperature of the gas is
now higher than the
temperature of the stack.
May 23, 2017

22. 22
Thermo-acoustic Cycle
 This process results in a net
transfer of heat to the left
side of the stack.
 Finally, in step 4, the
packets of gas reabsorb
heat from the cold reservoir.
 And the heat transfer
repeats and hence the
thermoacoustic refrigeration
cycle.
May 23, 2017

23. Advantages 23
May 23, 201718
 The working fluid is typically helium or other inert,
benign gases such as air which are environment-friendly
unlike common refrigerants.
 The simplicity of the design makes it robust, small, and
lightweight.
 It has almost no moving parts, which translates into a
longer working life with fewer repairs. In turn, this makes
the system less expensive.
 The loudspeaker is TAR’s only moving part which is
more durable than a compressor.
 It has the ability to attain a higher level of the limiting
Carnot efficiency than current refrigeration methods.

24. Disadvantages 24
May 23, 201719
 The downside of the TAR is that these failed to achieve
efficiencies as high as those of standard refrigerator
units.
 The coefficient of performance of most advanced TAR is
only 1 when compared to 3-4 of modern refrigerators.
 Another major problem of TAR is that it is either fully on
or off.
 It leaked an incredible amount of sound that causes ear
pain but produces only a small temperature gradient.
 These refrigerators were able to cool the air for a short
amount of time before the cooled air started raising its
temperature.

25. Improvements 25
May 23, 201719
 Insulate the sound leaks by isolating the system.
 Replace the closed cap with a speaker to increase the
efficiency by co-generation.
 If both ends of a stack are connected to a heat
exchangers thus coupling the stack to a heat source and
sink, the transfer of heat would be more efficient.
 Use conductive material for hot section of resonator.
 Widen the resonator and use a cone to reduce the
losses due to rapid area change.
 More practical and efficient reliable temperature sensors
such as thermostats should be used.
 The composition of stack material may also be changed
to any conducting materials like gold, silver or copper.

26. Conclusion 26
May 23, 201719
 A Thermo Acoustic Engine Studies In The
Combined Thermo Acoustic Engine Refrigerator
Systems Area Are Only A Handful
 This Work Is Only One In Open Literature To
Use Standing Wave Thermo Acoustic
Refrigerator Systems To Cool High
Temperatures
 Analysis Of Tar Can Be Obtained By Software
Delta Which Is Used To Investigate Parameters
Like Pressure, Type Of Gas Frequency

27. CORE JAVA
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