Breeding a Better Stove

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22 Φεβ 2014 (πριν από 3 χρόνια και 1 μήνα)

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1

Breeding a Better Stove

the use of Genetic
Algorithms and
Computational Fluid
Dynamics to Improve
Stove Design



H Burnham
-
Slipper

MJ Clifford

SJ Pickering




Introduction

Appropriate and Inappropriate Stoves

Experimental Work

Computer Modelling


CFD


Genetic Algorithm

Results

Conclusions

Outline

Global problem


half the world cooks on wood
burning stoves


Indigenous stoves can be inefficient, dangerous,
smoky, hazardous to health


Introduced stoves can be unpopular


Our approach is to combine local indigenous
knowledge and preferences with advanced
computer modelling techniques to develop an
improved stove for use in Eritrea

Introduction / Motivation

Appropriate and Inappropriate
Stoves

Classic Eritrean mogogo


smoky,
inefficient, but free

Eritrea Research and Training Center
Mogogo
-

$40

Appropriate and Inappropriate
Stoves

MIRT


improved efficiency, but developed
in Ethiopia. “The stove of our enemies”

Appropriate and Inappropriate
Stoves

Aprovecho design


improved efficiency,
but heavy use of material and poor
thermal distribution

Appropriate and Inappropriate
Stoves

CleanCook alcohol stove


unfamiliar
technology and materials. Unsuitable for
cooking injera

Appropriate and Inappropriate
Stoves

9

Experimental Set
-
up

Experimental aim:


mass
-
rate data


temperature data

Apparatus:


regular wood cribs


mass balance


K
-
type
thermocouples


extractor hood


a tiny bit of fire
-
lighter


10

Experimental Results

11

Numerical Model
Formulation

Assume:


char combustion
limited by diffusion
of oxygen through
species boundary
layer


volatile release
limited by
conduction of heat
through char layer


volatiles burn in air,
limited by turbulent
mixing


12

Numerical Model Formulation

Fluent 6.2 CFD code:


buoyancy
-
driven
flow


k
-
ε turbulence
model


species transport


DO radiation model


UDF fuel model


lumpiness

function



13

Numerical Model Results

Fluent 6.2 CFD code:


burn
-
rate agrees with
experimental


temperature & velocity
fields agree with
experiment & literature



14

Stove Modelling

15

Stove Characterisation

Aprovecho rocket, HBS rocket,

mogogo, 3
-
stone fire

with & without grate

Stoves have evolved over
hundreds (maybe thousands) of
years


There may be good reasons why
stoves are the way they are


A genetic algorithm can speed up
the natural evolution of stove
design

Genetic Algorithm

Genetic Algorithm

Take two stoves

Allow the stoves to mate

Define ten children (new stoves) using randomly
selected genes from parent stoves

Test the efficiency of the new stoves using CFD

Discard all but the best two stoves

Repeat

(The method can be adapted to include genetic
abnormalities / random mutations)

Genetic Algorithm

Genetic Algorithm Progress

Genetic Algorithm Result

Conclusions and Further Work

Engineers need to take many factors into account when
designing stoves

Respecting local stoves and building on indigenous knowledge
is vital if a new design is to be successful

Combining genetic algorithms and CFD represents a novel
approach to stove design, mimicking the natural evolution of
stoves

It remains to be seen if the new design can be manufactured
and tested, we also have a lot of field work to do