Experimental analysis of thermoacoustic refrigeration with combination of different gases and stack material

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1 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: Experimental analsis of thermoacoustic refrigeration with combination of different gases and stack material Parbadia Amjadali Habibbhai, Mandhata Yadav, Kumel Nagori 3 Student MED, Hansaba College of Engineering & Technolog Mehsan, Gujarat, India Assistant Professor, MED SPIT Mehsasna, Gujarat, India 3 Assistant Professor, MED, Hansaba College of Engineering & Technolog Mehsan, Gujarat, India *** Abstract - This project focuses on fundamental stud and experimental analsis of thermoacoustic refrigerator. This research project considers the different variables that directl or indirectl affect the performance and reliabilit of thermoacoustic refrigeration. The variable parameter that is considered for analsis is working gases (helium, neon, argon, nitrogen), stack material and stack position. The efficienc of thermoacoustic refrigeration b finding the best combination of stack material, stack position and working gases for creating maximum temperature gradient across the stack. Ke Words: TAR, Resonator, Heat Exchanger, Stack & Loudspeaker. INTRODUCTION Thermo acoustic is the stud of an elegant engineering field that involves both acoustics and thermodnamics - in other words, the stud of fields that involve both acoustic waves and the conversion of one form of energ into another, such as heat into motion. Thermoacoustic thus describes energ conversion processes initiated b the interaction of the temperature oscillation accompaning b the pressure oscillation in a sound wave with solid boundaries. The significance of the term thermoacoustic, according to Nicholas Routt (who laid much of the theoretical foundation for the field) is fairl self-explanator. As its name suggests, Thermoacoustic is a science that is concerned with the interactions between heat (thermo) and pressure oscillations in gases (acoustics)[].this field can be broken into two subcategories. The first is the forward effect which is concerned with the production of pressure oscillations from heat. This result is primaril used to create engines that are widel referred to as thermoacoustic engines in the literature. The second subcategor or reverse effect is concerned with using acoustic waves to pump heat. This reverse effect is primaril used to create refrigerators known as thermoacoustic refrigerators which are the topic at hand. Advantages of thermoacoustic refrigerator are that it is environmental friendliness, potentiall high reliabilit due to simple structure and minimum number of moving parts, and realistic efficienc. These characteristics could lead to low manufacturing and maintenance expenditure.. Working Principal of Thermoacoustic Refrigeration Sstem. Theor of Thermoacoustics The continuit equation expressed above as equation (.) is repeated once again as follows ( V ) t (.) This equation is a function of the densit and the velocit of the fluid. These two variables are expressed in difficult notation using the assumptions from the previous section as follows [] ( x,, z, t) ( x) ( x.. z) e j t (.). Thermoacoustic Work m m Now, we will proceed to develop an expression for the timeaveraged acoustic power dw used (or produced in the case of a prime mover) in a segment of length in the stack. This power is the difference between the average acoustic power at x+ and x, [3] dw A [ p u p u ] (.3) g x x Here over bar indicates time average, brackets h i indicate averaging in the direction, and Ag is the cross-sectional pu area of the gas within the stack. Expanding x in a Talor series and p being independent of, Eq (.3) can be written [ dp u dw A ] g (.4) The time average of the product of two complex quantities such as p and u is given b, p u R [ p u ] (.5) e x Where the star denotes complex conjugation and Re signifies the real part. Using Eq. (.4) and intensifing the derivatives in Eq.(.3) as, 8, IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page

2 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: dw [ ] A R p d u u d p g e (.6) d p To calculate this expression, the derivatives and d u d p are essential The expression for is obtained as below, j dp u ( fv) m (.7) After substituting the values, dw I ( f ) ( ) I ( f ) dt f f ( ) ( ( )) a a f m m v m k m k v Ag u p Ag Re p u f m ( s) ( )( s) ( v) v.3 Thermoacoustic Energ Flow This assumption must be removed for the energ flow since there are no first order terms involved. The centre of this section will be on second order terms and all variables that are second order. It is eas to see that the energ flux or total power flux E is the following: E K T v ( h V ) V (.8), The second order power flow across the cross sectional area of a duct can then be written down as below, T E ( K V hu) da, (.9) Rott s acoustic approximation can now be used to simplif this equation. since all the terms inside the integral are time averaged, the first order parts of all the variables are zero. Keeping this in mind and examining the first term which is because of thermal conduction, it is assumed that the second order part is much less than the first order part, allowing the following generalization T dtm ( k ) da ( Ak Asolid ksolid ) (.).4 Boundar laer and short-stack Approximations The thermoacoustic expressions got in the previous section are complex to interpret. In this section we will use two assumptions, to simplif these expressions. First, we make use of the boundar-laer approximation: [>> δk, l >> δs] so that the hperbolic tangents can be set equal to unit. Second, we make the short-stack approximation, Ls<<< λ; where the stack is considered to be short enough that the pressure and velocit in the stack does not var appreciabl. Finall, we will consider standing-wave sstems, which are more related to the experimental work in this thesis. The standing wave acoustic pressure in the stack, ps, can be taken as real and is given b [4] s p cos( ) p p kx (.) And the mean gas velocit in x direction is, [4] i p u j( ) sin( kx) j u (.) s ma p The superscript s refers to standing waves, is the pressure amplitude at the pressure antinodes of the standing i ( ) wave and k is the wave number. The factor is used because of the continuit of the gas volumetric velocit at the boundar of the stack, which involve that the velocit inside the stack must be higher than that i ( ) Outside b the cross-sectional area ratio The Rott s function f in the boundar laer approximation is given b [5] f ( j) (.3) Using these assumptions and Ag = Π, As = Π; the approximate expressions for W And E are obtained [3] s s ( ) ( p ) m u W k Ls ( ) vls 4 ma ( s) ( ) 4 (.4) T p u dt W k lk s s, m s v m k k [ ( )] [ s] 4 ( ) ( s) ( ) Where, v v (.5) (.6) Ls is stack length, π is total perimeter of the stack plate and (π δk Ls) is the volume of gas within concerning a thermal penetration depth from the plates. 3. Instrumentation Setup 3. Resonator The resonator tube is the hollow component of the resonator sstem. It is placed between the reducer and the buffer volume. To ensure low thermal conductivit, high strength, and light weight, the resonator tube was fabricated out of a 8, IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page

International Research Journal of Engineering and Technolog (IRJET) e-issn: 395-56 Volume: 5 Issue: 4 Apr-8 www.irjet.

The resonator tubes consist of a small diameter tube, reducers, stack holder and buffer volume 3.

We decided to construct the holder out of the material Nlon. The Holder is shown in Fig.5.

It has two flanges for links to the taper and hot heat exchanger flange.

A rubber O- ring, mounted into the flange of the hot heat exchanger is used for sealing because this junction is at

is attached to the square flange of large diameter tube with circular buffer created with six inch inner diameter pipe

It has a volume of one liter, a wall thickness of mm and a length of 7 cm. It is welded to the small diameter tube.

At the end of the cone pipe bowl was welded to make a buffer volume and on the other side small diameter tube was

3 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: Aluminum. The resonator tubes consist of a small diameter tube, reducers, stack holder and buffer volume 3. Large Diameter Tube or Stack Holder The necessities for the stack holder are stiffness and low thermal conductivit. We decided to construct the holder out of the material Nlon. The Holder is shown in Fig.5. It has inner diameter of 38 mm, a wall thickness of 5 mm and a length of 85 mm. It has two flanges for links to the taper and hot heat exchanger flange. The holder is coupled to the flange of the hot heat exchanger via six M5 bolts. A rubber O- ring, mounted into the flange of the hot heat exchanger is used for sealing because this junction is at room temperature. 3.4 Driver housing Fig. 3. buffer Volume of TAR Safet is must required to the drives, so one more square flange [3 mm*3 mm] with eight bolts [M] is attached to the square flange of large diameter tube with circular buffer created with six inch inner diameter pipe as shown in fig.3.3 below. 3.3 Buffer volume Fig. 3. Stack holder TAR The buffer volume is also made of aluminum. It has a volume of one liter, a wall thickness of mm and a length of 7 cm. It is welded to the small diameter tube. A taper angle of 9 is used to reduce irreversibilit. At the end of the cone pipe bowl was welded to make a buffer volume and on the other side small diameter tube was welded to the buffer volume as shown in fig.3.. Fig. 3. Driver housing TAR.4 Stack The stack (Length- 85 mm) is manufactured from Mlar film (Thickness-75 micron), PVC (Thickness- micron) and Lather (Thickness- 8 micron) and fishing lines (Material- Nlon, Thickness- acc. To thermal penetration depth) are used as spacers. B considering easiness in manufacturing we decide spiral geometr for the stack. The distance between two adjacent spacing lines is 5 mm throughout the cross section. This particular spacing ensured that the two laer of stack film do not touch other and the gas passage channels are uniform 8, IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page 3

Result of combination N and Lather. 37. 37...5 36. 37.5.3. 35.6 37.9.3.5 35. 38. 3.. 34.3 38.3 4.5 33.7 38.6 4.9 3. 33. 38.6 5.6 3.5 3.6 38.

4 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: Fig 4. Time Vs Temperature profile N with PVC 3.5 Experimental Setup Fig. 3.3 Stack Material & Design Fig 4. Temperature difference profile N with PVC 4. N with lather stack 4. Result & Discussion 4. N with PVC stack Fig. 3.4 Experimental Setup TAR Table 4. Result of combination N and Lather Table 4. Result of combination N and PVC Fig 4.3 Time Vs Temperature Profile N with Lather 8, IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page 4

5 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: He with Lather stack Fig 4.4 Temperature difference profile N with Lather He with PVC stack Fig 4.7 Time Vs Temperature Profile Helium with Lather Fig 4.5 Time Vs Temperature Profile Helium with PVC Fig 3.8 Temperature difference profile Helium with Lather 5. Performance analsis of TAR The coefficient of performance of the device normalized b COPc = Tc/(TH Tc) (the Carnot coefficient of performance) has been calculated as Here we compare the COP of N & He gas with stack material which produce the highest temperature gradient with others stack materials Fig 4.6 Temperature difference profile Helium with PVC , IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page 5

6 International Research Journal of Engineering and Technolog (IRJET) e-issn: Volume: 5 Issue: 4 Apr-8 p-issn: Table 5. Result of combination N and PVC thermoacoustic stack Frontiers in Heat and Mass ransfer,,436() [4] Samir Gh. Yaha, Xiaoan Mao, Artur J. Jaworski Experimental investigation of thermal performance of random stack materials for use in standing wave thermoacoustic refrigerators, Jan-7 [5] Ahmed I. Abd El-Rahman, Waleed A. Abdelfattah, Mahmoud A. Fouad A 3D investigation of thermoacoustic fields in a square stack Dec-7 [6] Raffaele Dragonetti, Marialuisa Napolitano, Sabato Di Filippo Modeling energ conversion in a tortuous stack for thermoacoustic applications Apr-6 Fig 5. COP of TAR performed with N & He gas with PVC stack material 6. CONCLUSION The proposed design help to analse the cooling effect of various combinations of stack material and gases. B this research work, one can easil make the comparative stud of the same and choose the best combination. B experiments, we conclude that qualit of driver (Speaker) also had effect on performance of thermoacoustic refrigerator. From the result which was shown in Chapter 6 we can conclude that from all combinations of different gases and different stack materials, nitrogen as working gas and PVC stack gives highest temperature gradient and cooling effect. Proper heat transportation between the stack and heat exchanger and minimization of heat loss ma enhance the performance of the thermoacoustic refrigerator. REFERENCES [] M.E.H. Tijani, J.C.H Zeegers, A.T.A.M. de Waele, Construction and performance of thermoacoustic refrigerator, crogenics4(), PP [] Ikhsan Setiawan and Agung Bambang Setio Utamo The influence of the Length and position of the stack on the performance of a Thermo acoustic refrigerator,phsics Dep. Gadjah Mada Uni.Sekip Ultra BLS Yogakarta 558,Indonesia [3] Channarongwantha, Kriengkrai Assawamarbunlue The impact of the resonance tube on the performance of a 8, IRJET Impact Factor value: 6.7 ISO 9:8 Certified Journal Page 6

Mathewlal T 1, GauravSingh 2, Chetan Devadiga 3, Nehal Mendhe 3, 1 Mechanical Engineering Department, Fr CRIT, Vashi, Mumbai.

Demonstration of Thermo Acoustic Refrigeration by Setting up an Experimental Model Mathewlal T 1, GauravSingh 2, Chetan Devadiga 3, Nehal Mendhe 3, 1 Mechanical Engineering Department, Fr CRIT, Vashi,