sound wave moving producing Refrigeration process Thermo acoustic refrigeration systems operate by using sound waves and a non-flammable mixture of inert gas (helium, argon, air) or a mixture of gases in a resonator to produce cooling.. The temperature difference is used to remove heat from the cold side and reject it at the hot side of the system. Thermo acoustic refrigeration (TAR) 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

1. THERMOACOUSTIC
REFRIGERATION
Presented by
JISHNU U
S5 Mechanical
Roll No : 35

2.  ABSTRACT
 INTRODUCTION
 BASICS OF REFRIGERATION
 DISADVANTAGES OF CONVENTIONAL REFRIGERATOR
 BASICS OF THERMO ACOUSTIC REFRIGERATION
 COMPONENTS
 HOW IT WORKS
 MERITS OF TAR
 DEMERITS OF TAR
 IMPROVEMENTS MADE
 APPLICATIONS
 CONCLUSION
CONTENTS

3. Thermo acoustic refrigeration (TAR) is a phenomenon that uses high
intensity sound waves in a pressurized gas tube to pump heat from one
place to other to produce refrigerationeffect.
This System completely eliminates the need for lubricants and
results in 40% less energy consumption.
ABSTRACT

4.  Thermo acoustic devices take advantage of sound waves
reverberating within them to convert a temperature differentialinto
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
INTRODUCTION

5. STEVEN L GARRETT
 Leading Researcher
United TechnologiesCorporation
Professor of Acoustics, The
Pennsylvania State University
 He invented the thermo acoustic
refrigerator in the year 1992 and
that TAR was used in the space
shuttle Discovery(STS-42).

6. BASICS OF REFRIGERATION
• In refrigeration heat is not created, it is converted andtransferred

7. • The compressor is the heart of the system. It compresses the low pressure
refrigerant vapour into high pressure refrigerantvapour.
• The condenser removes heat from the refrigerant, it changes state intohigh
pressure liquid.
• Metering devices are small thin copper tubes (thermal expansion devices). It
regulates the amount of refrigerant going into theevaporator.
• The evaporator absorbs the heat in the system, the low pressureliquid
changes into low pressure gas.
• The low pressure vapour pulled into the compressor and the cyclestarts
over….

8. DISADVANTAGES OF
CONVENTIONAL REFRIGERATOR
 Uses harmful refrigerants like ammonia, CFC’s and HFC’s
 Refrigerants if leaked causes the depletion in the ozone layers.
 Refrigerants are costly.
 The moving parts like the compressors require lubrication.
 Leakage of refrigerant may result in adverse human health effects
including cancers, immune system deficits, and respiratory effects.

9. BASICS OF THERMO ACOUSTIC
REFRIGERATION
 Thermo acoustics combines the branches of acoustics and thermodynamics
together to move heat by using sound.
 While acoustics is primarily concerned with the macroscopic effects of sound
transfer like coupled pressure and motion oscillations, thermo acoustics focuses
on the microscopic temperature oscillations that accompany these pressure
changes.
 Thermo acoustics takes advantage of these pressure oscillations to move heat
on a macroscopic level.
 This results in a large temperature difference between the hot and cold sides of
the device and causes refrigeration.

10. THERMO ACOUSTIC REFRIGERATOR

11. COMPONENTS
The purpose of the resonance tube in a
TAR is to contain the working fluid and
to cause it to have a desired natural
frequency
RESONANCE TUBE:

12. ACOUSTIC LOUD SPEAKER:
 A loudspeaker is an electro acoustic
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

13.  The most important piece of a thermo acoustic device is the stack.
 The stack consists of a large number of closely spaced surfaces that are
aligned parallel to the resonator tube.
 In a usual resonator tube, heat transfer occurs between the walls of cylinder and
the gas.
 However, since the vast majority of the molecules are far from the walls of the
chamber, the gas particles cannot exchange heat with the wall and just oscillate in
place, causing no net temperature difference.
 The purpose of the stack is to provide a medium where the walls are close
enough so that each time a packet of gas moves, the temperature differential
is transferred to the wall of the stack
REGENERATOR STACK:

14. • Most stacks consist of honeycombed
plastic spacers that do not conduct
heat throughout The stack but rather
absorb heat locally.
• With this property, the stack can
temporarily absorb the heat transferred by
the sound waves

15.  Heat exchangers are devices used to
transfer heat energy from one fluid
to another.
 The media maybe separated by a solid
wall, so that they never mix.
 They are widely used in space heating,
refrigeration, air conditioning, power
plants, Chemical plants.
HEAT EXCHANGER:

16.  Acoustic or sound waves can be utilized to produce cooling.
 The principle can be imagined as a loud speaker creating high amplitude
sound waves that can compress refrigerant allowing heat absorption.
 The pressure variations in the acoustic wave are accompanied by temperature
variations due to compressions and expansions of the gas.
 For a single medium, the average temperature at a certain location does not
change. When a second medium is present in the form of a solid wall, heat is
exchanged with the wall.
 An expanded gas parcel will take heat from the wall, while a compressed parcel
will reject heat to the wall.
HOW IT WORKS?

17. Experimental Setup

18.  No moving parts for the process, so very reliable and a long lifespan.
 Environmentally friendly working medium (air, noble gas).
 Use of simple materials with no special requirements, which are commercially
available in large quantities and therefore relatively cheap.
 The technology could represent a major breakthrough using a variety of
refrigerants, and save up to 40% in energy.
 Thermo acoustic refrigeration works best with inert gases such as helium and
argon, which are harmless, non-flammable, nontoxic, non-ozone depleting or
global warming and is judged inexpensive to manufacture.
MERITS OF TAR

19.  Thermo acoustic refrigeration is currently less efficient than the traditional
refrigerators.
 Lack of suppliers producing customized components.
 Lack of interest and funding from the industry due to their
concentration on developing alternative gases to CFCs
DEMERITS OF TAR

20. To overcome the drawbacks, some improvements were made:
 In order to improve the efficiency, regenerators are used. The function of a
regenerator is to store thermal energy during part of the cycle and return it later.
This component can increase the thermodynamic efficiency to impressive
levels.
 Increasing the level of temperature gradient setup thereby
providing more refrigeration effect.
IMPROVEMENTS MADE

21.  Liquefaction of natural gas.
 Chip cooling.
 Electronic equipment cooling on naval ships.
 Electricity from sunlight.
 Upgrading industrial waste heat.
APPLICATIONS OF TAR

22.  Thermo acoustic engines and refrigerators were already being considered
a few years ago for specialized applications.
 Their simplicity, lack of lubrication and sliding seals, and their use of
environmentally harmless working fluids were adequate compensation for
their lower efficiencies.
 In future let us hope these thermo acoustic devices which promise to
improve everyone’s standard of living while helping to protect the planet
might soon take over other costly, less durable and polluting engines and
pumps.
CONCLUSION