thermoacoustic engine and refrigerator

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Thermoacoustic Engine andRefrigerator

Advisor: Prof. Akiyoshi Iida

Assistant Prof. Hiroshi Yokoyama

Student: Subhan UllahStudent ID: M135117

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Contents

Introduction

Background

Previous research

Objective

Methodology

Results until now

Obtained knowledge until now To do until the final presentation

Plan until the final presentation

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Introduction

Thermal

(heat energy)

Acoustic

(sound energy)

Other forms ofenergy (electricormechanicaletc.)

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Thermoacoustic engines

main components

Regenerators

(made of porousmaterial)

Heat

exchangers(hot and cold)

Resonator

tube

Data

recordingdevices

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The thermoacoustic engine

convert thermal energy

to acoustic(sound) powerwhen the timing betweenthe pressure and velocity

oscillations is appropriatelyset in such interactions.

The regenerator or stacksandwiched between a pair of(hot and cold) heat exchangers

constitutes the so-called

thermoacoustic core,where the thermoacoustic

energy conversion from heat toacoustic power takes place.

The high density

acoustic wave can beused to produce cooling

power or to drive analternatorto generate

electricity.

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Background

Roughly one-thirdof the energy consumed by industry isdischarged as thermal losses

Most of this waste energy, however, is of low quality (i.e.,below 300 F (260 C) and is typically not practical oreconomical to recover with current technology

Multi-stage engine is seemed to recover low quality wasteheat to useful work

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Previous research

K. de Blok (ASMEFEDSM2010-ICNMM2010 August 2-4, 2010,Montreal, Canada)

Thermoacoustic cooking device, producing 17.6W output power

Four stage TA engine (the results are not confirmed yet)

Thermoacoustic power generator (TAP), this is under construction at

Netherland and it will make a power of 100kW from the paper drying

process

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Tijani et al.(ECN Paper presented at acoustics 08, Paris, France,August 1-5, 2010)

Torus shape engine with mechanical type

resonator

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Objective

Our first step is to setup the existing engine and takethe experimental data and analysis

The second step is to make our own engine keeping inmind the discrepancies of the previous work and makeeffective steps to improve the efficiency

Our goal is to make such an engine which will have anefficiency of 40% or more. If the efficiency reallyimproved then our next goal is to make a commercialdesign

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Methodology

The methodologyfor this project is

stemmed throughthe following phases

Information

(knowledge about theproject)

Setting and analyzing

the existing engine

Creativity(making our own design)

Evaluation

Development

Implementation

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Results until now

To know about the reality of thermoacoustics

we performed a simple experiment on a pipe

having a mesh working as a stack. Giving heat

to the mesh we observed a loud sound. It

gradually disappeared when the heat source

was removed

We also observed that the sound is louder at adistance of L/4 rather than L/2

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We are at the initial state and have no special

results yet regarding the project under

research, but we are struggling to get

experimental data soon.

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Obtained knowledge until now

As for as our project is concerned we are trying toget more knowledge as the more the knowledgethe more efficient will be our research

While studying about the current project, variousquestions also arises which needs furtherresearch e.g., What is the availability of the waste heatIs it

continuous, cyclic or intermittent? Does the temperature of the waste stream vary over

time?

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What is the composition of the waste stream?

Are there contaminants that may corrode or erode

the TA-engine?

What is the flow rate of the waste stream, and does itvary?

There may be added complexity and cost for

integrating the system controls with existing process

controls. Space limitations and equipment configurations may

make TA-engine systems difficult or impossible to site

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Plan until the final presentation

0% 50% 100%

Theory

Experiments and analysis

Results

Thesis

work done

work remaining

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To do until the final presentation

0% 20% 40% 60% 80% 100%

Theory

Experiments

Results and analysis

Thesis

Progress

Progress

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To achieve this goal I am studying to make such changes in designwhich are the key factors to efficiencye.g.,

The first and the most important thing is to decrease the value ofonsettemperature to reach quickly.

To reach to the onset temperature quickly we will surely increasethe number of stages but again the problem will be thecomplexity of the design.

We have also another option to use another gas e.g., Heliumtoovercome this problem but that will require other configurationsand deviceslike gas tank etc.

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The other option may be to pressurizethe air inside the resonator tubeso that the oscillations take place quickly to reach the onset temperaturesoon but it will also be difficult to overcome the leakages.

An option to overcome the same problem is to make some positive

changes in the regenerator design or size or position. Similarly we canalso observe some positive changes by increasing or decreasing thenumber of heat exchangers or the position of heat exchangers.

The second option to improve the efficiency is to overcome the losses.

So there are many factors which cause losses for example the length or

size of the resonator tube, the geometryof the resonator tube, theeffectivenessof the heat exchangers and other such factors which needsto be controlled.

The erectnessof the engine may also add the efficiency somehow.

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thermoacoustic engine and refrigerator

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