Multistage thermoacoustic engine by Subhan Ullah

Embed Size (px)

Citation preview

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    1/25

    MULTI-STAGE TRAVELING WAVE

    THERMOACOUSTICS

    IN PRACTICE(Kees de Blok, 19th International Congress on Sound and

    Vibration, Vilnius, Lithuania, July 8-12, 2012)

    Student: Subhan Ullah

    Advisor: Prof. Akiyoshi Iida

    Assistant Prof. Hiroshi Yokoyama

    11/10/2013 1

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    2/25

    Table of contents

    Introduction Background

    Previous research

    Objective

    MethodologyMain components of TA-engine

    Acoustic resonators

    Regenerators

    Heat exchangers

    Results

    Conclusions

    11/10/2013 2

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    3/25

    Introduction

    Background

    Previous research

    Objective

    11/10/2013 3

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    4/25

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    5/25

    Simple TA-engine(Prime mover) and

    TA-Refrigerator(Heat pump)

    11/10/2013 5

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    6/25

    Multi-stage TA-engine

    Red = Heat in at Thigh

    Blue = Heat out at Tlow

    Green = Acoustic loop power

    In this case the mutual distance between

    the regenerator units is L

    There are four loads attached

    with each stage

    11/10/2013 6

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    7/25

    Cont

    An option to increase thermoacoustic power gain at medium

    and low operating temperatures is to use multiple

    thermoacoustic units or cores, changing the size of

    regenerators, or adding an acoustic load per stage

    A special configuration suggested by de Blok is, when an even

    number (typically two or four) of equally spaced regenerators

    is inserted inside the feedback loop, so that the distance fromone regenerator to the other is half of the wave length in the

    case of a two-stages engine, and a quarter of the wavelength

    in the case of a four-stages engine

    11/10/2013 7

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    8/25

    Thermoacoustic power (TAP)

    TAP was designed for converting 100 kW of thermal power of

    flue gas at 150-160C into 10 kW electricity with an exegetic

    efficiency of > 40%.

    Basically it is also a 4-stage traveling wave feedback system

    using helium at a mean pressure of 750 kPa as working gas

    The 1.64 kW output power is reached with helium at a meanpressure of 750 kPa and at only 1.7% drive ratio.

    11/10/2013 8

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    9/25

    Previous research

    1777, Dr. Bryan Higgins

    In 1859, Rijke (open ends, air, and 1/4L)

    11/10/2013 9

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    10/25

    Cont

    Sondhauss in 1850 (earliest known predecessor to todays

    standing wave thermoacoustic engines )

    Can work horizontally

    No ascending air current is required for oscillations

    11/10/2013 10

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    11/25

    Cont

    Carter in 1962, introduced a stack of parallel plates inside the

    tube which made it easier to exchange heat with the working

    gas

    11/10/2013 11

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    12/25

    Cont

    In 1979, Peter H. Ceperley:

    Toroidal geometry

    acoustic Stirling engine

    The high and low temperature heat exchangers and the stack

    or regenerator altogether are sometimes referred to as astage.

    11/10/2013 12

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    13/25

    Thermoacoustic power (TAP)

    TAP was designed for converting 100 kW of thermal power of

    flue gas at 150-160C into 10 kW electricity with an exegetic

    efficiency of > 40%. Basically it is also a 4-stage traveling wave

    feedback system using helium at a mean pressure of 750 kPa

    as working gas

    At an input of 99 C and heat rejection at 20 C this

    corresponds with 38% effeciency.

    11/10/2013 13

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    14/25

    Objectives

    Emphasis in this document is on acoustic loss in the acoustic

    resonance and feedback circuitry which has turned out to be

    the major issue in the design of useful integral

    thermoacoustic systems.

    To test an integral system of a low temperature

    thermoacoustic engine driving a thermoacoustic refrigerator.

    Practical reasonable application of Thermoacoustics.

    11/10/2013 14

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    15/25

    Methodology

    Main components of TA-engine

    Acoustic resonators:

    A: Standing-wave resonators

    B: Helmholtz type resonators

    C: Acousto-mechanical resonators

    D: Traveling wave or loop resonators

    Regenerators

    Heat exchangers

    11/10/2013 15

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    16/25

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    17/25

    Cont

    C: the Acousto-mechanical resonator The mass is acting like a resonator.

    D: The traveling wave feedback loop

    The load is connected to the acoustic source by one wavelength long feedback tube.

    11/10/2013 17

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    18/25

    Regenerator

    Sample of the material for the ceramic regenerator: general view (left); close

    up of the channel structure(right)

    11/10/2013 18

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    19/25

    Heat exchangers

    There are two types of heat exchangers

    Hot (left) and cold (right) heat exchanger assemblies

    11/10/2013 19

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    20/25

    Results

    Ranking of resonator tubes

    Coupling efficiency = P(Acoustic load) / P(Acoustic source)

    11/10/2013 20

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    21/25

    There are less losses in mechanical resonator

    but in practice it is difficult to make it.

    The travelling wave resonator has the lowest

    loss and also it is more compact.

    11/10/2013 21

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    22/25

    Table 1: Performance of the integrated system measured at increasing engine

    input temperature

    ENGINE

    TH_EHot hex inputtemperature C 169 211 239

    TC_ECold hex inputtemperature C 12 13.2 13

    QE Thermal input power W 1041 1300 1728

    Qstat Static heat loss W 235 296 340

    TH_regRegenerator high

    temperature C 138 178 199

    TC_regRegenerator low

    temperature C 32.1 38.8 47

    Pac1Acoustic power at

    refrigerator input (#1) 134 192 274

    Pac2Acoustic power atengine input (#2) W 73.0 91.4 121

    WfbAcoustic loss

    feedback W 21.4 30.8 44

    Wout_E

    Acoustic output

    power (Pac1Pac2+

    .Wfb) W 76.6 124 187

    T_E

    Thermal efficiency

    (Wout_E/ QE) - 0.10 0.14 0.15

    2_E

    Exegetic efficiency

    relative to TH_E - 0.29 0.34 0.35

    2_E_reg

    Exegetic efficiency

    relative to TH_reg - 0.42 0.48 0.5011/10/2013 22

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    23/25

    Table 2 shows the results for three engine input temperatures

    and the lowest cold hex temperature obtained after the system

    becomes thermally stable

    REFRIGERATOR

    dr Drive ratio at cold hex % 1.33 1.53 1.78

    Win_R

    Acoustic input power

    (Pac1

    Pac2

    .Wfb) W 55.2 93.4 143

    Tc_R Cold hex temperature C -33.7 -40.5 -45.5

    QC_R Net cooling power W 78.2 95.1 95.4

    TH_RAfter refrigerator

    temperature C 19.2 24.2 18.8

    QH_R Heat rejected W 135 182 253

    COP ( QC_R/ Win_R) - 1.42 1.02 0.67

    2_R

    Exegetic efficiency

    relative to TC_R - 0.32 0.29 0.19

    11/10/2013 23

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    24/25

    The performance of the engine is strongly affected by the

    temperature drop across the heat exchangers.

    In this paper only the overall integral system results are

    presented.

    The working gas is helium at 2.7 Mpa and frequency is 95 Hz.

    Performance of the integral system is measured at three

    different engine input temperatures.

    11/10/2013 24

  • 8/13/2019 Multistage thermoacoustic engine by Subhan Ullah

    25/25