Aveneu Park, Starling, Australia

ABSTRACT spatial distance decides region of heat flux

 

ABSTRACT

 

Generally,
Cooling is achieved with vapour compression system that uses a specific
refrigerant. In recent years, it has been discovered that conventional
refrigerants affect the environment adversely. For the safety of the
environment, it is necessary to avoid the use of environmentally hazardous
refrigerants by developing new alternative refrigeration technologies such as thermoacoustic
Refrigeration System.

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       In this project a thermoacoustic
refrigeration device (TAR) is designed, which includes an acoustic wave
generation device arranged directed to the channel of a hollow tube, and a
stack provided at a predetermined position in the channel of the tube. A
temperature gradient is obtained across the stack by an acoustic wave emitted
from the acoustic wave generation device.

KEYWORDS: Thermoacoustic refrigeration, Stack, Acoustic resonator tube,
Thermocouple, Temperature indicator

INTRODUCTION

Over
the past few decades, physicists and engineers have been working on a class of
heat engines and compression-driven refrigerators that use no oscillating
pistons, oil seals or lubricants. These so called 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. Such materials thus can be used, for example, to generate
electricity or to provide refrigeration and air conditioning. Because thermo
acoustic devices perform best with inert gases as the working fluid, they do
not produce the harmful environmental effects such as global warming or
stratospheric ozone depletion that have been associated with the engineered
refrigerants such as CFCs and HFCs.

Thermo
acoustics deals with the conversion of heat energy to sound energy and vice
versa. There are two types of thermo acoustic devices: thermo acoustic engine
(or prime mover) and thermo acoustic refrigerator. In thermo acoustic engine,
heat is converted into sound energy and this energy is available for useful
work. In this device, heat flows from a source at higher temperature to a sink
at lower temperature. In a thermo acoustic refrigerator, the reverse of the
above process occurs, i.e., it utilizes work (in the form of acoustic power) to
absorb heat from a low temperature medium and reject it to a high temperature
medium. Loudspeakers or
electro-dynamic shakers convert electrical power into acoustic power. Besides,
heat can be produced from sound waves. This technology utilizes sound effect to
pump heat across a temperature gradient.

Fig : Sound
Wave Thermoacoustic Refrigerator

 

A
thermoacoustic device uses a fluid medium (gas) to accomplish work within the
stack (stack in standing wave devices or regenerator in travelling wave
devices). A stack is a compartment by means of various linear sub-chambers
associated to both ends, heat exchangers are there; one for to cool and the
other used for hot thermal energy. The sub-compartments are separated through
plates whose spatial distance decides region of heat flux caused through the
functioning fluid. Working fluid experience expansion and compression since it
move along these channels as an effect of the passing of acoustic waves. By
providing the accurate wavelength and frequency of acoustic wave, cold heat
energy transferred to one surface of stack and hot heat to another, which
permit for refrigeration process.

DESIGN OF THERMOACOUSTIC
REFRIGERATOR

Fig :
Schematic Diagram Thermoacoustic Refrigeration

 

The list of
materials used for the fabrication of the thermo acoustic refrigeration system
is shown in the table. The resonator is a glass tube of 60 mm diameter. The
stack is made of polyester film

S.no

Item Name

Size

Qty

Material

1

ACRYLIC TUBE

L=60cm,D=6cm

1

Acrylic

2

    TEMPERATURE INDICATOR

12 SWITCHES

1

 

3

THERMOCOUPLES

 

6

 

4

SPEAKER & AMPLIFIER

15 Watts 

1

 

5

STACK

 

1

Polyester Film

6

SUPPORTING FRAME

80 X 40 X 10

1

 Mild Steel

 

 

 

 

Fig :
Experimental setup of Thermoacoustic refrigerator

RESULTS

From the
experimental  setup analyzed  the performance of thermo acoustic refrigeration system and
got the temperature difference of 7 degree Celsius (avg) between the two ends
of the Resonator tube. The values of experimental setup and the graph as
follows

 

 

TABLE

 
THERMOCOUPLE
            
NO.

    
     
1

     
     
2

      

     
3

     
     
4

      

     
5

    
     
6
 

DISTANCE FROM
ACOUSTIC RESONATOR (cm)

 
     2

 
    
12

 
    
23

 
    
35

 
    
48

 
    60
 

    TIME (MINUTES)

               TEMPERATURE IN (0
C)

             5

     30

       32

      33

      34

       35

       35

           10

     29

       33

      34

      35

       37

       37

           15

     29

       36

      38

      39

       38

       38

 

GRAPH

From the table
values drawn the graph between the temperature and distance from the acoustic
driver and are as follows

CONCLUSION

Thermo acoustics is
a promising area, which if properly explored, could serve as a good
refrigeration system. However, the performance of these device is currently
very low. The main motivation for the present work was to develop a simple
thermo acoustic refrigerator that is completely functional. This paper reports
on the design and fabrication of a simple thermoacoustic refrigeration system
with inexpensive and readily available material.

The characteristic of the fabricated refrigerator and
its performance were analysed experimentally and the results are noted. For the
given operating condition a temperature gradient of 7 degree Celsius could be
established across the stack. This device worked as a proof of concept device
showing that a thermo acoustic device is possible and is able to cool air, for
only a short period of time. If we were able to build the device with better
materials, such has a more insulating tube, we might have been able to get
better results.

REFERENCES

1  Mattew. E. 
Poese & Steven. L.Garrett “Performance measurement of thermo
acoustic    refrigerator.” Journal of the
Acoustical Society of America, June 2008.

2 Richard raspet & Henry. E. Bass
“Element interaction in thermo acoustic heat engine.”International Journal of
Thermal Science, Nov 2003.

3 Nathan thoman weiland, Ben. T. Zinn
“Design of thermo acoustic engine in internal combustion”, March 2003.

4 D.A.Geller & W.A.Swift
“Thermoacoustic enrichment of isotopes of neon.” Jan 2004.

 5
Mark. P. Telez “Design and Testing of thermoacoustic power converter.” May
2006.

 6
Byram Arman, John Henry Royal “thermoacoustic cogeneration system.” Applied
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7 Bryan .O. Maqury & Steve .M. Cole
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 9
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Thermoacoustic  refrigeration system.” Jun 2011.

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Compact thermo acoustic array energy generator.” Aug 2011

11 Garrett S.T., Adeff J.A., and Hofler
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12 Tijani M.E.H., Zeegers J.C.H., and De
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Cryogenics, 42(1): 59-66, 2001.

13 Sakamoto S. “The experimental studies
of thermoacoustic cooler.” Ultrasonics, 42(1):53-56, 2004.

14 Wetzel M, and Herman C. “Experimental
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