DESIGN OF PROTOTYPE THERMOACOUSTIC ENGINEPROJECT BY: Click to edit Master subtitle style PRASHANT KUMAR SRIVASTAVA (U08ME631) ANKIT SHARMA (U08ME632) SURYANS CHAMOLI (U08ME633) AKSHAY BHARGAVA (U08ME652)GUIDED BY: PROF. H.B. NAIK
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thermoacoustic devices which use highamplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves.Pre-requisite knowledge :-
THERMOACOUSTIC ENGINES Thermoacoustic engines are
1. Acoustics Sound Wave Pressure Oscillations 2.Standing Wave 4/26/12 3. Travelling Wave
HISTORY Earlier:It was found that when a hot glass
bulb was Attached to a cool glass tube tip, i. e. tube, some times emitted sound (singing). Byron Higgins discovered that acoustic oscillations in a pipe might be excited by suitable placement of a hydrogen flame inside. Sandhauss firstly studied the thermoacousticeffect happening in a hollow glass tube with one end closed and 4/26/12 the other open.
1777:
1850:
HISTORY (contd.) Earlier: Glass blowers found that when a hot glass
bulb was attached to a cool glass tube tip, i.e. tube, some times emitted sound (singing).
1777 : Byron Higgins discovered that acoustic
oscillations in a pipe might be excited by suitable placement of a hydrogen flame inside.
1850: Sandhauss firstly studied the thermo acoustic
effect happening in a hollow glass tube with one end closed and the other open.4/26/12
HISTORY 1949
:Taconis Oscillations
The phenomenon was discovered when the open and of a gasfilled tube was immersed in liquid nitrogen and cooled to cryogenic temperature. When the tube was removed from the coolant, it begin to vibrate and sing loudly.
1962
:Carter et al. greatly enhanced the thermo acoustic effect by placing suitable structures (stack of plates) in sandhauss tube.
27 W of acoustic power from 600 w of heat.
1979
:Ceperley proposed the concept of traveling wave thermo acoustic machines. 4/26/12
CLASSIFICATIONS
On basis of energy conversion :1 ) Prime mover 2 ) Heat pump
On basis of type of wave used :-
1 ) Travelling wave 2 ) Standing wave
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SOUND WAVESmechanical wave that is an oscillation of
pressure transmitted through a solid, liquid, or gas.
consists of :
-Traveling compressions and rarefactions - Longitudinal oscillations(in direction of propagation)Sound speed =4/26/12
INTERFERENCEphenomenon in which two waves
superpose to form a resultant wave of greater or lower amplitude.
Interference usually refers to the
interaction of waves that are correlated or coherent with each other.
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STANDING WAVEArise from the combination of reflection
and interference such that the reflected waves interfere constructively with the incident waves.
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STANDING WAVE (contd.)Displacement and pressure :-
A node for displacement is always an antinode for pressure and vice versa.When the air is constrained to a node, the
air motion will be alternately squeezing toward that point and expanding away from it, causing the pressure variation to be at a maximum.
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TRAVELLING WAVEHere change in gas pressure travels along
the path as a sound wave.
Observed when a wave is not confined to a
given space along the medium.pressure oscillations have alternate
compressions and
rarefactions.
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Converts heat into sound by creating a self
RIJKE TUBE
amplifying standing wave. of two motions :-
flow of air past the gauze is a combination
1) uniform upwards motion of the air due to aconvectioncurrent. 2)
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BASIC CONCEPTSReviewing the concept of standing waves in
columns of air. We have to solve
(wave equation hyperbolic.)since we are dealing with longitudinal pressure
waves in gas. = A cos (t kx) B sin (t kx) In order to produce standing waves, two waves
(1 & 2)
must be traveling in 4/26/12 opposite
BASIC CONCEPTS (contd.)In order to produce standing waves, two waves
(1 & 2) must be traveling in opposite directions with equal amplitudes, the sum of which is corresponds to zero displacement, corresponds to maximum displacement, depends on harmonic of standing wave and the boundary 4/26/12 condition.
= 2 [A cos (t) + B sin (t)] cos [kx] node
antinode
no. of nodes
We can have Combining with gives
kL = n/2
(A)
a = with = 2f, gives f = from first line It can be seen - f = g (n, v or a, L) - lower f
4L n = n = 1, 3,5 n (C)
with a = RT (B)
from (A) from (B) for constant4/26/12
higher acoustic velocity
STANDING WAVE ENGINE temperature gradient is established that
causes spontaneous acoustic oscillations . axis.
A typical parcel of gas oscillates along the During its travel it experiences changes in
temperature caused by compression and expansion of gas by the sound pressure and by heat exchange with solid wall. pressure is such that the gas moves towards hot junction while P is rising and towards cool junction when pressure is 4/26/12 falling.
Time phasing between gas motion and
STANDING WAVE ENGINE (contd.)
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STANDING WAVE ENGINE (contd.)
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How to decide the following dimenssions?
Resonator/Device
Length and Diameter
Stack
Position Length Plate Spacing/Channel Gap Plate Thickness
Heat Exchangers
Length
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Resonator Length and Diameterwith a = RT
L= 2
for half wave length resonator4/26/12
Stack Position Length Plate Spacing/Channel Gap Plate Thickness
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STACK DESIGN PARAMETERS2)The Stack Material Thermal conductivity: Ks Density: s Specific heat : CS Melting point, Geometry cost, easeLs Length: of processing, Stack center etc position Plate thickness: 2l Plate spacing:
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TERMS AND EXPRESSIONS1)Thermal penetration depth
2) Viscous Penetration depth
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OUR PROJECT MODELOur project mainly deals with the
construction of a proto type model of thermo acoustic engine that is actually Rijke Tube experiment inspired. shall be using the following materials: 1. Stainless tube ( length of tube: 47 cm) ( diameter of tube: 27 mm) 2. Steel grid (to act as stack)
Though he used glass tube material we
4/26/12 The material procuremet and construction
THANK YOU
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