A REVIEW PAPER ON THERMO ACOUSTIC REFRIGERATION

SYSTEM

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INTRODUCTION • Thermo acoustic refrigerator is a device that operates

efficiently by using sound waves to produce a low

temperature.

• Thermo acoustic devices use inert gases as the working

fluid.

• They do not produce the harmful environmental effects

such as global warming or stratospheric ozone depletion.

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WORKING • Customized loudspeakers attached to cylindrical chambers

filled with inert pressurized gases such as xenon and helium.

• At the opposite end of the tubes are tightly wound "jelly rolls" made of plastic film.

• When the loudspeakers blast sound at 180 decibels, an acoustic wave resonates in the chambers and the gas molecules begin dancing frantically in response to the sound.

• They are compressed and heated, with temperatures reaching a peak at the thickest point of the acoustic wave where the super hot gas molecules crash into the plastic rolls.

• After transferring their heat to the stack, the sound wave causes the molecules to expand and cool and cold temperatures can then be tapped for useful application.

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CLASSIFICATION

• Standing-wave thermo acoustic devices

• Travelling-wave thermo acoustic devices

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Standing wave thermo acoustic device

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Standing wave thermo acoustic device • The main components are a closed cylinder, an acoustic driver, a

porous component called a ‘‘stack”, and two heat-exchanger systems.

• Application of acoustic waves through a driver such as a loud

speaker, makes the gas resonant.

• As the gas oscillates back and forth, it creates a temperature difference

along the length of the stack.

• The temperature difference is used to absorb heat from the cold side

and reject it at the hot side of the system.

• The temperature change comes from compression and expansion of

the gas by the sound pressure and heat transfer between the gas and

the stack. 6

Travelling-wave thermo acoustic device

Sounds Cool! The Ben & Jerry’s Project, 2005

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Travelling-wave thermo acoustic device • In the travelling-wave device, the pressure is created with a

moving piston and the conversion of acoustic power to heat

occurs in a regenerator rather than a stack.

• The regenerator contains a matrix of channels which are much

smaller than those in a stack and relies on good thermal

contact between the gas and the matrix.

• The design is such that the gas moves towards the hot heat

exchanger when the pressure is high and towards the cold heat

exchanger when the pressure is low, transferring heat between

the two sides.

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APPLICATIONS • the Space Shuttle

• Navy warship

• Liquefaction of natural gas

• Chip cooling

• Upgrading industrial waste heat

• In Automobiles

• In food industry

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Performance of the TAR system

• The experimental system in general can be broken down into

(a) the thermoacoustic refrigerating system

(b) the test section

(c)the data acquisition system.

• The refrigerating system consists mainly of the resonator tube

or resonator, the stack, the acoustic driver and the heat

exchangers.

• An electrical resistance heater arrangement was located at the

cold side of the resonator to supply the variable load for the

refrigerating system.

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• The test section involves specific parts of the system were the

measurements were made.

• The data acquisition system includes thermocouples , pressure

transducer , oscilloscope , flow meter, data acquisition board

and a personal computer for the data display.

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Experimental setup

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• For each frequency, the temperature increased at the beginning

of the experiment and then stabilized after a time.

• The experiment was performed for various constant pressure

and cooling load values and it was found that the stabilization

time increased as the pressure was increased.

• The results also confirm that the higher the cooling load

required, the higher the desired hot side temperature at the

resonator should be.

• The average coefficient of performance for the system was

calculated to be 0.65.

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The recently completed thermoacoustic refrigerator (TAR).

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BENEFITS IN USING TAR SYSTEM • Environmentally friendly working fluid is used

• Simple design

• Continuous cooling capacity control

• Less moving parts

• ODP and GWP is very less

• The performance is not influenced by the implementation in a

vehicle

• Very low temperature can be attained in a single stage when

compared to VC system

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• 1996-Martin Wetzel and Cila Herman made a systematic design

approach for initial design calculations of thermo acoustic refrigerators. A separate optimization of the four main modules of a thermo acoustic refrigerator:

(i) thermo acoustic core, (ii) resonance tube, (iii) heat exchangers and (iv) acoustic driver.

• 2001-Tijani, Moulay El Hassan of Eindhoven: Technische Universite made an experimental study on Loudspeaker-driven thermo-acoustic refrigeration.

• 2004-Fathi Jebali, Jean Valentin Lubiez and Maurice-Xavier Francois conduct an experimental study to find the response of a thermoacoustic refrigerator to the variation of the driving frequency and loading

REVIEWS

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• 2005- Bamman T.C , Howard C.Q and Cazzolato B.S made a

review on the flow through designs of thermo acoustic

refrigeration systems.The review shows that the system is

overall efficient as the vapour compression system.

• 2006-Insu Paek, James E. Braun, and Luc Mongeau conduct a

design optimization program based on the thermo acoustic

simulation known as DELTAE was developed.

• 2007-Emmanuel C. Nsofor, Serdar Celik, and Xudong Wang

conduct an experimental study on the heat transfer at the heat

exchanger of the thermo acoustic refrigerating system. The

study identified significant factors that influence this heat

transfer as well as the construction of the system.

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• 2008-Emmanuel C. Nsofor and Azrai Ali conducted performance test on Thermoacoustic Refrigeration system under various operating conditions

• 2009-Florian Zink, Jeffrey S. Vipperman and Laura A. Schaefer conduct a study to illustrate the benefit of this technology with a consideration of its Total Equivalent Warming Impact (TEWI) compared to conventional cooling in vehicles

• 2010- S.A. Tassou a, J.S. Lewis , Y.T. Ge , A. Hadawey , I. Chaer in the review of emerging technologies for food refrigeration applications they define thermo acoustic refrigeration system as a better alternative for refrigeration in food industry.

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FUTURE WORK • Thermo acoustics can be considered as being in the ‘‘tube”

stage, but it can be significantly advanced by improving

simple components.

• The efficiency and refrigeration capacity has to be increased in

order for TARs to become a feasible replacement for current

technology.

• To achieve useful incorporation in engine compartments, a

straight resonator may not be a feasible solution, thus requiring

curvature to be incorporated in the resonator.

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CONCLUSIONS • 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.

• Due to the developments in the design of high power, single frequency loud speakers and reciprocating electric generators it is suggests that thermo acoustics may soon emerge as an environmentally attractive way to power hybrid electric vehicles, refrigerate food, air condition buildings, liquefy industrial gases and serve in other capacities that are yet to be imagined.

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REFERENCES • Environmental motivation to switch to thermoacoustic refrigeration

Original Research Article Applied Thermal Engineering, Volume 30, Issues 2-3, February 2010, Pages 119-126 Florian Zink, Jeffrey S. Vipperman, Laura A. Schaefer

• A review of emerging technologies for food refrigeration applications Review Article Applied Thermal Engineering, Volume 30, Issue 4, March 2010, Pages 263-276 S.A. Tassou, J.S. Lewis, Y.T. Ge , A. Hadawey, I. Chaer

• Experimental study on the performance of the thermoacoustic refrigerating system Original Research Article Applied Thermal Engineering, Volume 29, Issue 13, September 2009, Pages 2672-2679 Emmanuel C. Nsofor, Azrai Ali

• Geometric optimization of a thermoacoustic regenerator Original Research Article International Journal of Thermal Sciences, Volume 48, Issue 12, December 2009, Pages 2309-2322 Florian Zink, Hamish Waterer, Rosalind Archer, Laura Schaefer

• Design and optimization of thermoacoustic devices Original Research Article Energy Conversion and Management, Volume 49, Issue 12, December 2008, Pages 3585-3598 Hadi Babaei, Kamran Siddiqui

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• Experimental study on the heat transfer at the heat exchanger of the

thermoacoustic refrigerating system Original Research Article Applied

Thermal Engineering, Volume 27, Issues 14-15, October 2007, Pages 2435-

2442 Emmanuel C. Nsofor, Serdar Celik , Xudong Wang

• Evaluation of standing-wave thermoacoustic cycles for cooling applications

Original Research Article International Journal of Refrigeration, Volume

30, Issue 6, September 2007, Pages 1059-1071 Insu Paek, James E. Braun,

Luc Mongeau

• Evaluation of standing-wave thermoacoustic cycles for cooling applications

International Journal of Refrigeration 30 (2007) 1059-1071Insu Paek,

James E. Braun, Luc Mongeau

• Review of flow-through design in Thermo acoustic refrigeration

Proceedings of ACOUSTICS 9-11 November 2005, Busselton, Western

Australia Bammann T. C. , Howard C. Q. , Cazzolato B. S.

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THANK YOU

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