Study on a high efficiency thermoacoustic engine...Temperature field Temperature distribution around the engine F=60 degs F=120 degs F=180 degs F=240 degs F=300 degs F=360 degs HEX

International Workshop on Construction of Low-Carbon Society Using Superconducting and Cryogenics Technology (March 7-9, 2016)

Study on a high efficiencythermoacoustic engine

• Shinya Hasegawa• Hideki Kimura• Kota Fukuda • Shun Takahashi• Kazuto Kuzuu• E. M. Sharify (Presenter)• Mariko Senga

Tokai University ( Dep. of Prime Mover Engineering )( Dep. of Electrical & Electronic Eng. )( Dep. of Aeronautic & Astronautics )( Dep. of Prime Mover Engineering )( Dep. of Prime Mover Engineering )( Dep. of Prime Mover Engineering )( Graduate School of Engineering )

3D FunktionIntroduction

The thermoacoustic engine (TE) is an energy-conversion device which converts heat and acoustic power and has no moving parts!

Thermoacoustic engine with high efficiencywas first realized in 1999. （SWIFT, NATURE, 1999)

＋

ーHeat source

Power

Acoustic wave

Power generation

2

3D Funktion

Maintenance-free: absence of moving parts and simplicity of the components

High efficiency: changes the heat flow to the acoustic power based on the Carnot cycle.

Low-cost structure: extremely simple structure that works through the pipe and does not require special parts.

3

Introduction

3D Funktion

High efficiency at low temperature: Regenerator with high thermal efficiency could be obtained when :

I. the phase difference between the pressure and the mean velocity is close to zero.

II. hydraulic radius much less than thermal penetration depth

III. to reduce viscous losses in the regenerators, z value be sufficiently large

102

1

10-2

10-4 010

2030

z/ρmcωτ

比カルノー効率

[%]

0

20

40

60

80

100

Multiple heat sources: Generally in the factory the waste heat is generated in different location rather than one place. While, the waste heat device can recover heat from single location of the heat source.

4

Introduction

3D

To overcome this problem : I. Low temperature operating TA engine with high efficiency: Using

multistage thermoacoustic engines with high acoustic impedance that operate by multiple heat sources is used.

II. Reducing the non-linear effects: Using PIV, LIF and numerical methods to suppress the minor loss and mass flow.

III. Compact, high-output linear generator:

Aco

ust

ic P

ow

er

ハイスピードYLFレーザKANOMAX DYLF-L300 デジタルハイスピードカメラKANOMAX HSS-7

Compact High-output linear

generator

Local high acoustic impedance

Reducing the non-linear effects5

Introduction

3

To overcome this problem :

I. Low temperature operating TA engine with high efficiency:

II. Reducing the non-linear effects:

III. Compact, high-output linear generator:

𝜼 =∆𝑾

𝑸𝒑𝒓𝒐𝒈 +𝑸𝒔𝒕𝒂𝒏𝒅+𝑸𝑫

6

In order to evaluate the TE more quantitatively.

Total heat

𝑸𝒊𝒏𝟎 = 𝑸𝒑𝒓𝒐𝒈 + 𝑸𝒔𝒕𝒂𝒏𝒅+𝑸𝑫 +𝑸𝜿

Thermal efficiency of oscillating flow

Introduction

3D Funktion

音響パワー

① Local high acoustic Imp.

The energy conversion with high efficiency is realized by using multiple regenerators with high acoustic impedance.

By controlling the acoustic field, high local acoustic impedance inregenerator area are achieved, which was more than 5 times ofthe acoustic impedance of the acoustic waves propagating inoutside of regenerator area.

The cascade thermoacoustic engine

7

3

The acoustic power increase as the absolute temperature ratio TH/TR increase:

C

Hinout

T

TWW P. H. Ceperley, J. Acoust. Soc. Am., 66, 1508-1513, 1979.

T. Biwa et.al., J. Acoust. Soc. Am., 129, 132-137, 2011.

By using multiple regenerator :

n

C

Hinout

T

TWW

Therefore, it is possible to increase the power gain for a low temperature

ratio as well.

8


3

The engine unit

FOSTEX® FW108N

JTEKT PD104K

Flow channel diameter :0.48mm, 30mm

Waveguide (φ14)

9


3

Aco

ust

ic p

ow

er

More than 50% of the Carnot efficiency

The high efficiency thermoacoustic engine

More than 50% of the Carnot efficiency achieved when the temperature of the cold and hot heat exchangers were around 300K and 600K, respectively.

10

3D Funktion

In 1979, Ceperley proposed a traveling-wave thermoacoustic engine in which the acoustic power was amplified by traveling-wave propagation through a differentially heated regenerators

*P. H. Ceperley, J. Acoust. Soc. Am., 66, 1508-1513,(1979).

In 1985, Ceperley realized the relationship between the specific acoustic impedance z (= p / u) and thermal efficiency

Acoustic impedance z=10ρmc

Specific Carnot efficiency η2=79％

*P. H. Ceperley, “Gain and efficiency of a short traveling wave heat engine”, J. Acoust. Soc. Am. 77 (3), 1239-1244 (1985).

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3D Funktion

S. Backhaus and G. W. Swift, “Athermoacoustic stirling engine,”Nature (London) 399, 335–338 (1999).

In 1999, Backhaus built a quarter-wavelength mode prototype traveling-wave thermoacoustic engine and introduced a resonator in a looped tube and with high acoustic impedance ( z=30 ρmc) in the regenerator area, they achieved 42% of the Carnot eff.

Following the concept of Backhaus and Swift et al, Tijani built thermal efficiency with 49% of the Carnot efficiency in 2011.

However, due to the lack of the boundary condition, it is difficult to install the regenerator at exactly peak acoustic impedance for a quarter-wavelength mode.

Reduction in the efficiency

12


3D Funktion

By the driver, the acoustic field at the regenerator area are controlled.

Installing linear motor on the left and right side and controlling the phase and amplitude by function generator, the specific acoustic impedance can be changed at the end of the unit such as 10𝜌𝑚𝑐，5𝜌𝑚𝑐，2𝜌𝑚𝑐，1𝜌𝑚𝑐.

Linear motor

Unit

:Pressure transducers

RegeneratorAmbient HX Hot HX

HX:Heat exchangers

Power

amplifierFunction

generator

Linear motor

6.01m

The zero phase difference between pressure and velocity amplitude at downstream part

20 W acoustic power at downstream part.

Operating frequency: 35Hz

Working gas: helium 10 atm

𝑇𝐻: 300 ℃

𝑇𝐶: 20 ℃

13


3

Materials: Etched stainless steel mesh

length ：30mm

diameter ：40mm

Flow channel ：0.3mm

ωτ: 0.0758

porosity ：77.85%

Heat exchanger (Tapered fin) Plate thickness : 1.0mm gap between each plate:2 .0 mm

14


3D Funktion

To convert high frequency (50-200) acoustic power with small strokes into the electric power, new linear generator is required which is capable of switching rapidly between the magnetic poles of the generator.

Compacted and High-output linear

generator

Outer yoke(axis)Coil

Permanent magnetMover

Outer yoke(cover)

The thermoacoustic electrical generator

Through analysis of dynamic magnetic field, the prototype of linear power generator is designed which generates the output power of 200W with 80% eff.

15

3

16

Moving-coil linear generator

2004，S. Backhaus 120Hz => 58WS. Backhaus, E. Tward and M. Petach: Applied Physics. Lett. ,85, pp. 1085-1087(2004).

Moving-magnet type linear generator

2014，Z. Wu 64Hz => 1043WZ. Wu, L. Zhang, W. Dai and E. Luo: Investigation on a 1 kW traveling-wave thermoacoustic electrical generator, Applied Energy, 124, pp.140-147(2014).

Moving-coil type Moving-magnet type

the mover

output

light Heavy

Low High

The thermoacoustic electrical generator

16

3D FunktionEnergy flow around the engine core plates

17

To construct the optimized regenerator and exchangers, it is essential to realize the energy flow around the regenerator and heat exchanges. PIV, LIF, and CFD are the basic tools.

3

Work Flow Q = Tm s=Aρm Tm 〈〈S・u〉t〉r

The enthalpy flow can be driven from the temperature and velocity.

H = Q+I = AρmCp〈〈T・u〉t〉rEnthalpy Flow

I = A〈P 〈u〉r〉tHeat Flow

18

Energy flow around the engine core plates

3D Funktion

MeasuringTemperature variation (T)

LIF(Laser-induced fluorescence)

Measuringvelocity amplitude (u)

PIV (particle imagevelocimetry)

The enthalpy flow in the core can be measured19


3D

Measuring oscillatory flow in the vicinity of a parallel plates placed in a traveling-wave thermoacoustic

using the PIV

PIV YAG Laser

Function

Generator

Power

Amplifier

X=0

Loud Speaker

PIV

Controller

PIV High speed Camera

3.71 m

1.815 m

1.77 m

45mm

4mm

3mm

45mm

20


3D

Measurement of velocity amplitude distribution by PIV

PIVanalysis

Measuring the velocity distribution in the parallel plate 21


3D

Comparison of the PIV and analytical results

velocity amplitude distribution in the parallel plate

Future Plan: measuring the temperature and enthalpy flow by LIF

Comparison of experimental and analytical results

22


3

Governing equations were two-dimensional compressible Navier-Stokes equations:

y

F

x

E

y

F

x

E

t

Q vv

yyyyx

yy

yx

v

xxyxx

xy

xx

u

Tvu

F

Tvu

E

vpe

pv

vu

v

F

upe

uv

pu

u

E

e

v

uQ

0

,

0

,

)(

,

)(

, 2

2

The pressure 𝑝 is related to the total energy 𝑒 per unit mass by the equation of state:

22

2

1

1vu

pe

The temperature T in the energy equation was estimated using the specific heat at constant pressure Cp based on the ideal gas law:

22

2

1vu

peTCp

23


3

Kazuto Kuzuu, Shinya Hasegawa, 3rd International Workshop on

Thermoacoustics 26-27 Oct. 2015 Enschede 24


3


Thermoacoustics 26-27 Oct. 2015 Enschede

Temperature field

Temperature distribution around the engine

F=60 degs F=120 degs F=180 degs

F=240 degs F=300 degs F=360 degs

HEX REG CEX-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 30 60 90 120 150 180 210 240 270 300 330 360 390-20

-15

-10

-5

0

5

10

15

20

Uav

e (m

/s)

Dis

plac

emen

t (m

m)

phase (degrees)

F01

F02

F03

F04

F05

F06

F07

F08

F09

F10

F11

F12

u-velocityobserved phase u

observed phase disp

25


3D

-9

-6

-3

0

3

6.3 6.4 6.5 6.6 6.7-1500

0

1500

3000

4500

-9

-6

-3

0

3

6.3 6.4 6.5 6.6 6.7-1500

0

1500

3000

4500

-18

-12

-6

0

6

2.05 2.1-3000

0

3000

6000

9000

-18

-12

-6

0

6

2.05 2.1-3000

0

3000

6000

9000

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

0 1 2 3 4 5 6 7-3000

-2000

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

u (

m/s

)

P (

Pa

)

time (sec)

u-velocity

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

0 1 2 3 4 5 6 7-3000

-2000

-1000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

u (

m/s

)

P (

Pa

)

time (sec)

u-velocitypressure

Reproduction of a self-sustained oscillation

Time variation of velocity and pressure amplitudeat (x,y) = (1.04,0.0)Closed end Open end


Thermoacoustics 26-27 Oct. 2015 Enschede 26


3D



Comparison of velocity profiles

-1.5

-1

-0.5

0

0.5

1

1.5

-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

y (

mm

)

U (m/s)

F01F02F03

F04F05F06

F07F08F09

F10F11F12

F01F02F03

F04F05F06

F07F08F09

F10F11F12

-19.5

-19

-18.5

-18

-17.5

-17

-16.5

-16

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

y (

mm

)

U (m/s)

F01F02F03

F04F05F06

F07F08F09

F10F11F12

F01F02F03

F04F05F06

F07F08F09

F10F11F12

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 30 60 90 120 150 180 210 240 270 300 330 360 390-20

-15

-10

-5

0

5

10

15

20

Ua

ve (

m/s

)

Dis

pla

cem

en

t (m

m)

phase (degrees)

F01

F02

F03

F04

F05

F06

F07

F08

F09

F10

F11

F12

u-velocityobserved phase u

observed phase disp

Phase variation of section average velocity and displacement amplitude at x=1.045

Lines : CFD Symbols : Linear analysis

x = 1.045 m (middle section of REG) x = 2.00 m (section of resonance tube)

Closed end Open end

Verification of the simulation

27


3D

E.M. Sharify, Shinya Hasegawa, 3rd International Workshop on


i. Pressure: 0.1Mpa

ii. Working Fluid: Air

iii. Frequency: 10 -50 Hz

iv. Displacement amplitudes : 25%, 50%, 75%, 100%, 125%, and 150% ofthe regenerator length

The temperatures of cold and hot heatexchanges are set 300K and 600K,respectively

Schematic of the computation domain

Impedance-matching Boundary condition

Impedance-matching Boundary condition

1.5mm4mm

300K

67.5mm

180mm

15mm

600K

X

T

1.5mm300K 600K

15mm15mm67.5mm

A.W

28


3D

E.M. Sharify, Shun Takahashi, Shinya Hasegawa, 3rd International

Workshop on Thermoacoustics 26-27 Oct. 2015 Enschede

The acoustic load is defined by a linear system consisting of mass, springand damper components with the periodic input force p’=Psin(ωt+φ) andperiodic output velocity u’=Usin(ωt):

ΦU

Pc

ΦU

Pkm

pdtukucdt

udm

cos

sin

Parameters m, c and k for each system are determined:

L

LL

LL

U

Pc

km 0

F

F

R

R

RR

R

R

RRR

U

Pc

U

Pkm

cos

sin

Schematic of the IMB condition

29


3D

E.M. Sharify, Shun Takahashi, Shinya Hasegawa, 3rd International Workshop on Thermoacoustics 26-27 Oct. 2015 Enschde

c) Oscillation amp. 150% of the regenerator length (10 Hz)

b) Oscillation amp. 100% of the regenerator length (10 Hz)

a) Oscillation amp. 50% of the regenerator length (10 Hz)

Temperature

300K 600K

300K

600K

X

T

A. wave

Temperature

Temperature

30


3D

10Hz 30Hz

40Hz 50Hz

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Documents

Study on a high efficiency thermoacoustic engine...Temperature field Temperature distribution around the engine F=60 degs F=120 degs F=180 degs F=240 degs F=300 degs F=360 degs HEX