development of a new biomass stove integrated with a stirling engine952097/fulltext01.pdf ·...
TRANSCRIPT
Bachelor of Science Thesis
KTH School of Industrial Engineering and Management
Energy Technology EGI-2016
SE-100 44 STOCKHOLM
Development of a New Biomass Stove
Integrated with a Stirling Engine
Petra Näsström
Julia Kuylenstierna
Bachelor of Science Thesis EGI-2016
Development of new Biomass Stove with
integrated electricity generation
Petra Näsström
Julia Kuylenstierna
Approved
Examiner
Anders Malmquist
Supervisor
Catharina Erlich
Commissioner
UMSS
Contact person
Joseph Adhemar Araoz
Ramos
Abstract 1.2 billion people around the world, mainly in the developing countries, live without access to electricity. To increase the living standard for this people and make socio economic development possible, supplying rural areas with electricity is crucial.
In rural areas around the world 2.7 billion citizens use biomass through simple stoves or open fire for heating, lighting and cooking in the households. This leads to indoor pollution which both is unhealthy and dangerous to inhale and ultimately leads to the prematurely death of 4 million people every year. Bolivia is no exception since it is one of Latin Americas poorest country. 1.2 million Bolivians still have no electricity access and fuel wood accounts for 47 % of the energy used for cooking in the country.
One solution to minimize the premature deaths caused by pollutants is to improve the cook stoves to become cleaner and more efficient. A product that can contribute to both solve the problems with indoor pollution and no electricity access is an improved cook stove integrated with electricity generation. This thesis will present the first design approach in the development of a new biomass stove with an integrated Stirling engine, primarily adapted for rural Bolivians. The Stirling engine is an external combustion engine that can convert thermal energy to electricity.
Through literature survey and field studies information to formulate a requirement specification was collected. A Quality Function Deployment (QFD) was formulated to transfer the requirements into technical measurable qualities. This constituted the guidelines for the development which led to five different concepts. With support from a Decision Matrix, where the different concepts where compared to each other, it was shown that the best concept was MAYA, a stationary stove with capacity for two pots, one combustion chamber, an ash trap and an attached chimney.
Combustion and heat transfer processes appearing in a stove are complicated and depending on a number of different parameters. To evaluate a good stove design testing is required which is why the design approach was to look at successful improved stoves and to follow design principles and guidelines. The improved MAYA is a 70 cm high metal stove with a scaffold base constructed with double metal walls with insulation in between. The two pots can together fit 10 liters and are sunken down in the stove body. To create a good draft in the stove the combustion chamber, flue gas path and chimney are designed with a constant cross sectional area.
Three different placements for a 95 We Stirling engine prototype are suggested but the final placement has to be further investigated since it depends on the temperatures in the stove. To increase the accessibility of the produced electricity a battery is advisable connected to the engine. A battery with a capacity of 25 000 mAh is shown sufficient to store the daily produced electricity.
MAYA is a design draft based on design principles of wood burning cook stoves and can be further used in physical modeling and testing to create a final design.
Sammanfattning 1.2 miljarder människor runt om i världen, huvudsakligen i utvecklingsländer, har ingen tillgång till elektricitet. För att öka levnadsstandarden för dessa människor och möjliggöra socio-ekonomisk utveckling är det avgörande att försörja dessa områden med elektricitet.
I de rurala områdena runt om i världen använder 2.7 miljarder människor biomassa genom enkla spisar eller öppen eld för matlagning, belysning och värme. Detta leder till luftföroreningar inomhus vilka både är ohälsosamma och farliga att inhalera. I förlängningen leder det även till dödsfall i en för tidig ålder för 4 miljoner människor varje år. Bolivia är inget undantag då det är ett av Latinamerikas fattigaste länder. 1.2 miljoner bolivianer lever fortfarande utan tillgång till elektricitet och ved står för 47 % av energin använd för matlagning i landet.
En lösning för att minimera de för tidiga dödsfallen är att utveckla renare och effektivare spisar. En produkt som både kan lösa problemen med begränsad elektricitet och föroreningar inomhus är en utvecklad spis med integrerad elgenerering. Detta projekt kommer presentera första designförslaget i utvecklingen av en ny biomassaspis med integrerad Stirlingmotor, primärt anpassad till Bolivias rurala områden. Stirlingmotorn är en extern förbränningsmotor som kan konvertera termisk energi till elektricitet.
Genom litteratur- samt fältstudier insamlades information för att formulera en kravspecifikation. En Quality Function Deployment (QFD) utformades för att översätta kraven till tekniskt mätbara kvalitéer vilka gav riktlinjerna för fortsatt utveckling och ledde till att fem olika koncept genererades. Med hjälp av en Decision Matrix valdes det mest lovande konceptet av dem alla ut, detta var spisen MAYA: En stationär spis med plats för två kastruller, en förbränningskammare, ett askuttag samt en skorsten.
De förbrännings- och värmeöverföringsprocesser som sker i en spis är komplicerade och beror av många olika parametrar. Utvecklingen av en bra spisdesign måste ske via prototyptestning varför tillvägagångssättet för fortsatt design var att inspireras av lyckade utvecklade spisar och designprinciper. Detta resulterade i en 70 cm hög metallspis konstruerad med dubbla metallväggar med isolering emellan. De båda kastrullerna rymmer tillsammans 10 liter och är nedsänkta i spiskonstruktionen. För att skapa ett bra drag genom spisen har förbränningskammaren, rökgasgången och skorstenen samma tvärsnittsarea.
Tre olika placeringar föreslogs för en 95 We Stirlingmotorprototyp, slutgiltig placering måste utforskas vidare då den beror på temperaturerna i spisen. För att öka tillgängligheten på den producerade elektriciteten bör ett batteri kopplas till Stirlingmotorn. Ett batteri med kapacitet på 25 000 mAh visade sig vara tillräckligt för att lagra den dagligt producerade elen.
MAYA är ett designförslag baserat på designprinciper för vedspisar och kan användas i fysisk modellering för att utveckla en slutlig design.
Acknowledgement We wish to thank our supervisor Dr. Catharina Erlich. Her points, advice and review comments
helped us form this thesis from day one to the finishing day. We also want to extend our gratitude
to our supervisor in Bolivia, Dr. Joseph Adhemar Araoz Ramos for the help to get settled in
Bolivia as well as his support throughout the entire project.
The main people making our field studies possible, Mariana Butron Oporto and Ricardo
Billarroel Camacho from Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), we
want to thank you for the shared information that helped us understand rural cooking habits. Also
Marcelo Gorrity from the Stove Testing Center (CPC) in La Paz who contributed with
information about existing improved cook stoves.
We are grateful for the financial support from The Swedish International Development
Cooperation Agency (SIDA) through the exchange program Linnaeus-Palme and The ÅForsk
Foundation who both made this project possible.
Finally, we would like to extend our deepest gratitude to Dr. Lucio Alejo, Jerry Luis Solis
Valdivia, Ricardo Mendoza Sirpa, Pablo L. Cossio Rodriguez and Gabriela Peña Balderrama for
all the help we received with our everyday life in Cochabamba.
Julia Kuylenstierna, Petra Näsström
Lima, 2016-06-08
Nomenclature
CHP Combined heat and power
DFM Design for manufacturing
FP Free piston
GHG Greenhouse gas
GDP Gross domestic product
HDI Human development index
LHV Lower heating value [MJ/kg]
LPG Liquid petroleum gas
OECD Organization for economic co-operation and development
PAH Polycyclic aromatic hydrocarbons
PV Photovoltaic
QFD Quality function deployment
SE Stirling engine
TAG Thermoacoustic generator
TEG Thermoelectric generator
UNFCC United nations framework convention on climate change
Currencies used
1 USD (American dollars) = 6.89 BOB (Bolivianos) [1]
Table of Contents
Abstract ........................................................................................................................................... 1
Sammanfattning ............................................................................................................................. 2
Acknowledgement .......................................................................................................................... 3
Nomenclature ................................................................................................................................. 4
Table of Contents ........................................................................................................................... 5
1 Introduction ................................................................................................................................. 1
1.1 Background ............................................................................................................................ 1
1.2 Objective ................................................................................................................................ 4
Specific objectives for the final product are: ........................................................................... 4
1.3 University Cooperation .......................................................................................................... 4
1.4 Limitations ............................................................................................................................. 5
1.5 Methodology .......................................................................................................................... 5
2 Literature Survey ........................................................................................................................ 7
2.1 Biomass .................................................................................................................................. 7
Biomass in Bolivia ................................................................................................................... 8
2.2 Energy and Electricity in Bolivia ........................................................................................... 9
Electricity Need ..................................................................................................................... 10
2.3 Economy in Bolivia ............................................................................................................. 10
2.4 Microgeneration systems ..................................................................................................... 11
2.5 The Stirling Engine .............................................................................................................. 12
Technology ............................................................................................................................ 12
2.7 Cooking Habits .................................................................................................................... 14
2.8 Different Kinds of Stoves .................................................................................................... 15
The Rocket Stove Principle ................................................................................................... 16
Improved Cook Stoves ........................................................................................................... 17
2.9 State of the Art Cook Stoves Integrated With Electricity Source ........................................ 18
The µPower Cookstove .......................................................................................................... 18
The TEGSTOVE .................................................................................................................... 19
The BioLite CampStove ........................................................................................................ 19
Score Stove ............................................................................................................................ 20
3 Biomass Stove Design ............................................................................................................... 21
3.1 Requirement Specification ................................................................................................... 21
3.2 Quality Function Deployment .............................................................................................. 23
3.3 Concept Generation ............................................................................................................. 23
3.4 Concept Evaluation .............................................................................................................. 26
3.5 Further Design and Design Approach for MAYA ............................................................... 27
InStove ................................................................................................................................... 27
Uganda 2-pot .......................................................................................................................... 28
Rocket Stove .......................................................................................................................... 29
3.6 Stove Components ............................................................................................................... 30
Combustion Chamber, Grate and Ash Trap ........................................................................... 30
Insulation ................................................................................................................................ 31
Stove Body ............................................................................................................................. 33
Flue Gas Passage and Chimney ............................................................................................. 33
Outer Dimensions .................................................................................................................. 34
3.7 Stirling Engine Placement .................................................................................................... 34
3.8 Pricing for the stove ............................................................................................................. 36
4 Results and Discussion .............................................................................................................. 39
4.1 Dimensions of MAYA ......................................................................................................... 39
4.2 Pricing .................................................................................................................................. 44
4.3 Requirement specification ................................................................................................... 45
5 Conclusion and Further work ................................................................................................. 46
Conclusion ................................................................................................................................. 46
5.1 Further Work ........................................................................................................................ 46
References ...................................................................................................................................... 48
Appendix 1 ....................................................................................................................................... 1
Sustainable Development Goals .............................................................................................. 1
Appendix 2 ....................................................................................................................................... 2
Stove Testing Center (CPC) ..................................................................................................... 2
Appendix 3 ....................................................................................................................................... 6
Cook stoves integrated with electricity producing source ........................................................... 6
Appendix 4 ....................................................................................................................................... 9
Requirement Specification ........................................................................................................... 9
Time frame ................................................................................................................................... 9
Functional Requirements ............................................................................................................. 9
Requirements ........................................................................................................................... 9
Aspirations ............................................................................................................................... 9
Restrictive Requirements ............................................................................................................. 9
Requirements ........................................................................................................................... 9
Appendix 5 ..................................................................................................................................... 11
Decision Matrix ......................................................................................................................... 11
Appendix 6 ..................................................................................................................................... 12
Pictures of improved cook stoves .............................................................................................. 12
Appendix 7 ..................................................................................................................................... 13
Quality Function Deployment .................................................................................................... 13
1
1 Introduction This section presents the background information about traditional cooking and how energy is
connected to development. Furthermore, general and specific objective and methodology will be
presented together with the limitations for this study.
1.1 Background Because of cooking with bad equipped stoves 4 million humans worldwide die prematurely every
year of illnesses caused by polluted air [2]. Women additionally tend to suffer with these health
effects more than men [3]. Today, about 2.7 billion citizens in the rural areas around the world
use biomass as primary energy source through simple stoves or open fire for cooking [4]. It is
stated that a cleaner housing condition will reduce asthma, rhino conjunctivitis and eczema
symptoms in school aged children [5].
About 1.2 billion of the world’s population has no access to electricity and the majority of these
lives in developing countries [7]. In a developing country the majority of the population lives on
far less money with much fewer basic public services compared to the population in the
industrialized countries [8]. The Human Development Index, a composite statistics of life
expectancy, education and income per capita, is also in comparison low in these countries [9]. In
estimations 550 million humans will live without access to electricity by 2040. During the same
time the electricity demand will increase with 70 % because of the industrialized countries needs
[10]. Figure 1 below shows the links between energy and poverty and how these factors are
connected.
2
Figure 1. The links between energy and poverty [7]
Figure 1 only offers a rough description of the key components for sustainable development.
Therefore Figure 2 below offer a deeper explanation of the key concepts.
Figure 2. The links between energy and the connections to environment, income, education and
health [7]
3
Education is a main factor for changing people’s behavior, as shown in Figure 1 and Figure 2, it
is also important in order for the society to develop. It is shown that education about
sustainability at all levels is crucial if the citizens should embrace sustainable development in
their everyday lives [13]. It is therefore essential to integrate the education possibility in rural
areas to reach a sustainable development and reduce poverty already from the beginning [7].
Students in ages between 6 to 18 years old study 14 minutes longer per day if they have
electricity. It is also shown that the children doing well in school are more likely to stay in school
longer which further is another reason why energy access is crucial for a sustainable development
[14].
The links between electricity access and advancement in socio-economic conditions can be seen
in Figure 3. One can also notice that electrification will directly reduce the respiratory illnesses
because the reduction of pollutants used for heating and lighting with dirty fuel. This will benefit
the society due to reduction of health care costs, both private and public [14].
Figure 3. Electricity access and its impact on development [15]
Sustainable development through an environmental, social and economic perspective is crucial
for humanity and the planet [11]. For sustainable development and poverty reduction access to
affordable and modern electricity is vital [12]. It is therefore important, in order to develop rural
areas and reduce poverty, to make electricity more accessible. Further, develop improved
cooking devices to avoid the pollution that today’s traditional stove emits.
4
1.2 Objective The 2030 Agenda for Sustainable Development by the United Nations states 17 development
goals for economic, social and environmental sustainable development, which are presented in
Appendix 1 [11]. Eradicating poverty is seen as the greatest global challenge and an
indispensable requirement for sustainable development. The importance of healing and securing
the planet and shift the world to a resilient and sustainable path is pointed out. Particularly
relevant in this context is development goal number three and seven and follows [11]:
“Ensure healthy lives and promote well-being for all at all ages”
“Ensure access to affordable, reliable, sustainable and modern energy for all“
A step towards these goals could be to develop alternative electricity sources and sustainable
cooking equipment for rural populations with deficient grid connection. One solution is a
combined heat and power plant for the final consumer [16].
The overall objective for this project is to develop a new biomass stove design of household scale
that is sustainable from an economic, health and environmental perspective. This stove shall also
be integrated with a Stirling engine for electricity production using the waste heat of the biomass
fuel used for cooking.
Specific objectives for the final product are:
1. Design a biomass stove that satisfies the rural cooking habits
2. The combustion process in the developed stove shall be complete
3. The electricity generating source shall cover basic electricity need for an average Bolivian
family
4. Formulate a requirement specification with requirements respecting the rural population
5. Investigate the economical limitation for the stove in order to make it accessible
1.3 University Cooperation This project has taken place in Cochabamba, Bolivia, since there is a research cooperation
between the universities Royal Institute of Technology (KTH) and Universidad Mayor de San
Simon (UMSS). The Research Cooperation Program works to educate Ph.D. students for UMSS
to get a better foundation of knowledge. Students from both universities also get the possibility to
write bachelor or master thesis at the other university. This project is a bachelor thesis following
the guidelines of the ongoing Linnaeus Palme program [17].
5
1.4 Limitations This project will focus its study on Bolivian rural cooking, although the results will be valid in
other rural areas with similar difficulties regarding electricity and cooking. The design of the
stove will be custom for biomass fuel and the size will be for a family household and indoor use.
The wanted Stirling engine is not available for commercial use which is why the biomass stove
will be designed to become a reality in 5-10 years from now.
Production analysis, design details and final material decision are suggested for complementary
future work.
1.5 Methodology The four phases in a product design process is investigation, planning, implementation and
inspection and this project followed these steps as well [18]. The project was organized into four
phases as seen in Figure 4. As showed in the figure the difference between the described process
and this project was that the planning was made before the investigation phase, number one in the
figure. Further the implementation phase was divided in two, phase two and three, because of its
workload.
Figure 4. The methodology used in the project
The planning phase included time, logistic and project planning and was made before phase one
and two started. All the phases will be described accordingly.
6
The study began through phase one where existing stove solutions and today’s situation for the
rural population in Bolivia were studied. The literature study also consisted of deepening the
knowledge concerning Stirling engines, biomass stoves, rural cooking habits and stove design
principles. The investigation regarding the subject was also made through a field study. This
consisted of meetings and interviews with local manufacturers in Cochabamba to see the further
possibilities of manufacturing a stove. Parallel with this work a collaboration with the German
Cooperation, Deutsche Gesellschaft für Internationale Zusammenbeit, (GIZ) took place where
ideas and experiences were exchanged. To understand rural cooking habits and traditions an
improved cook stove was inspected through a field study with GIZ. Additionally The Stove
Testing Center (CPC) in La Paz was visited to receive information about stove testing and to see
different models of improved cook stoves. As seen in Figure 4, phase one progressed throughout
the entire project; this because planning difficulties with field studies and also the need to deepen
the information throughout the entire project.
The second phase, and first part of the implementation phase of the project, was to gather the
collected data and turn it into technical requirements through a requirement specification and a
Qualify Function Deployment (QFD). The work at this stage contained divergent designing
techniques through different concept generating processes. The aim was to create a variety of
concepts.
The second part of the implementation, and third phase, was into convergent designing methods
where the most successful concepts were individually evaluated. The final overall concept was
selected at this stage of the project. The decision was made through a Decision Matrix.
The project got to its fourth phase and also the inspection phase regarding the product
development methodology. This consisted of material analysis, dimensioning suggestions and a
realization in Solid Edge [105]. Finally the further work was analyzed.
All of these phases were successive documented in this thesis and can be read accordingly.
7
2 Literature Survey This section will analyze biomass, energy and economic aspects to lay a foundation for future
development. The chapter also contains a review of stoves used in rural areas as well as basic
facts about the Stirling engine and combined heat and power systems. Lastly the chapter will
display a state of the art regarding stoves integrated with an electricity producing source.
2.1 Biomass Biomass includes all organic materials that are made from the photosynthesis. It is a natural
method of storing solar energy in form of chemical energy in a plant. In terms of energy biomass
is defined as organic material that can be converted to fuel and is therefore regarded as a potential
energy source [19]. Wood, agricultural residues and dung are examples of traditional biomass
[20].
Today, biomass represents 10 % of global annual primary energy supply, mostly traditional
biomass used for cooking and heating which also constitutes the largest proportion of renewable
energy [21][22]. For rural energy supply in developing countries, biomass often accounts for
more than 90 % and is generally used with very low efficiency of about 10 - 20 % [23][24]. From
2010 to 2030, the number of people using traditional biomass is estimated to increase with over
100 million [25].
If the combustion of biomass is complete the fuel is classified as a sustainable energy source
regarding CO2-footprint since it returns the same amount of CO2-molecules to the atmosphere
when burned as it holds during its lifetime. Other advantages are low cost of growing, low level
of technology for growing and using and can be considered a renewable energy source [26].
In case of incomplete biomass combustion it releases pollutants that are harmful for both
environment and health such as carbon monoxide (CO), nitrous oxide (N2O), methane (CH4) and
polycyclic aromatic hydrocarbons (PAHs) [27]. Residential sources, mainly from cook stoves,
represent more than 25 percent of the global inventory of black carbon emissions [28].
Irresponsible and negligence biomass use can cause deforestation, a problem that occurs when
forests are replaced with faster growing crops or fuel wood is used without re-plantation.
Deforestation is in conflict with the United Nations Framework Convention on Climate Changes
(UNFCCC) as well as United Nations (UN) 2030 agenda [29]. It is contributing to extermination
of plants and animals, increased flooding and climate changes [30][11].
8
Depending on firewood species, zone of harvesting and dried or not the moisture content value in
the wood differs. As seen in Table 1 below, the lower heating value (LHV) increases when the
moisture content decreases. The lower heating value is defined as the heat amount of a fuel
portion evolved when a unit weight of the fuel is completely burnt and water vapor leaves with
the combustion products without being condensed [32].
Table 1. Lower heating value for firewood with different moisture rate [33]
Firewood, different
properties
[-]
Moisture Rate
[ %]
LHV
[MJ/kg]
Firewood (wet, fresh out) 40 10.4
Firewood (air dried, humid
zone)
20 14.6
Firewood (air dried, dry zone) 15 15.6
Firewood (oven dry) 0 20.0
After ignition, the moisture in the fuel requires energy in the evaporating process. First when the
fuel is dried the temperature rises and the combustion can be fully developed. The residual ash
outcome is correlated with the initial fuel moisture rate. Ash content for firewood with moisture
rate between 10 - 60 % varies between 0.25 - 1.70 % [33]. A low moisture rate and a low rate of
ash content are most preferable. There is a correlation between efficient biomass fuel and a high
level of heating value which is why low moisture rate is important for the efficiency [33].
Biomass can hence be sustainable if used correctly but at the same time harmful for humans and
environment if used incorrectly. Modern biomass based cooking options such as improved
biomass-, biogas- and producer gas-/red stoves can potentially play an important role in
mitigating greenhouse gas (GHG) emission [27][31].
Biomass in Bolivia
Due to Bolivia’s variety in topography the accessibility and availability of fuel sources differ
within the country. In Figure 5 the annual biomass production in different areas of Bolivia is
displayed. In the tropical zone of the country primary firewood as fuel is chosen, because of the
forest´s easy access. Dung is a common fuel source and liquid petroleum gas (LPG) is frequently
used for long time cooking or during rainy season [6]. As seen in Figure 5 the biomass
production is equal to zero in the mountainous south-western parts, despite this firewood is the
9
most common fuel source over all in rural Bolivia [35]. Year 2009 wood accounted for 47 % of
fuel used for cooking in the country and it is said that fuelwood gives the food more of a
character and is therefore preferred. Fuelwood is in general easy accessible in Bolivia and the
most frequent used fuel source of today [6].
Figure 5. Map of the annual biomass productivity in Bolivia in the year of 2012 [34]
Even for the rural population in the fertile areas the collection of firewood can be both time
consuming and dangerous. Therefore a fuel efficient and health promoting stove should make
everyday life easier. To achieve the good consequences with this new biomass stove it has to
match cooking habits and stove utilization of today. This leads to a number of criteria for the
stove and the use of biomass concerning combustion, reforestation and smoke emission.
2.2 Energy and Electricity in Bolivia Bolivia does not have many big manufacturing industries and therefore, the country is not a big
electricity consumer. In the country with only 493 kWh per capita yearly compared to the 8795
kWh per capita and year consumed by OECD Countries [41].
In the rural areas of Bolivia 66 % of the inhabitants have access to electricity compared to 99 %
in the cities. In 2012 1.2 million Bolivians had no electricity access and traditional biomass was
an important fuel for heating and cooking. For those who have access to electricity, natural gas-
fired plants and hydropower are the dominant sources of Bolivia’s electricity supply [36].
10
The governmental plan for Bolivia is to access electricity for all citizens by the year 2025 [37].
Electrifying the rural areas of Bolivia has been proven to be more expensive and time consuming
than originally considered, which is why the plan to electrify the entire country by 2025 can be
seen as unreasonable [38].
The energy demand in different topographical zones has been investigated and the result showed
that the average daily energy demand was 32 kWh for rural households, of which 30.5 kWh was
used for cooking [6].
Electricity Need
Daily electricity use in rural households connected to the grid varies between 1.7 - 4.2 kWh in
existing studies [6][42]. In addition the wanted devices in rural households has been investigated.
Even though the number of households in the study were few one can see a pattern; illumination,
a refrigerator and the possibility to charge a cellphone were highly desirable. When looking at the
economical assets in the same study it was seen that a fridge is a big investment for the rural
population [6].
With today’s fuel-efficient devices both illumination and cellphone charging can be achieved
with low electrical consumption. A simple cellphone has a battery capacity around 800 mAh and
3.7 V, which is equal to 2.96 Wh [44]. A LED light bulb with a power of 7 - 8.5 W is
illumination wise equivalent to a 40 - 60 W incandescent bulb. The LED light of today also has a
long lifetime of 30 000 - 50 000 hours [40].
2.3 Economy in Bolivia Bolivia is one of the poorest Latin American countries. It has no big manufacturing industries and
depends in many sectors on foreign import. The economy of the country is traditionally based on
subsistence farming, the production of hydrocarbons and mining [41]. Bolivia owns one of the
biggest fields of natural gas in the world, it also contributes to 8 % of Bolivia’s Gross Domestic
Product (GDP) and the export of the fuel accounted for 54 % of the country’s total export in 2014
[36]. Except natural gas Bolivia also has great mineral and oil reserves [36][39]. Due to
increased mineral and natural gas exports the economic growth in Bolivia was in average 4.9%
per year between 2004 -2014 [43].
Despite great natural resources about 39 % of the population 2013 lived, because of inequalities
and a weak institutional framework, under the national poverty threshold [41][45].
Poverty can be described as:
11
“Poverty is associated with the undermining of a range of key human attributes, including health.
The poor are exposed to greater personal and environmental health risks, are less well
nourished, have less information and have a higher risk of illness and disability” [48]
2.4 Microgeneration systems Microgeneration systems are small scale decentralized energy generation of heat and/or
electricity. These can be categorizes in the three following groups [71];
1. Microheat based on heat pumps (air, water and ground source), biomass or solar thermal
2. Microelectricity based on solar photovoltaic (PV), microwind turbines and microhydro
3. Micro combined heat and power (micro-CHP) or cogeneration systems based on internal
combustion engines, Stirling engines or fuel cells
Where the third category micro-CHP based on Stirling engines is applicable for the biomass
stove.
The combined heat and power (CHP) arrangement combines two forms of energy, thermal
together with electrical or mechanical. The CHP is therefore able to use fuel in a way that is more
efficient compared to conventional separate electric and thermal energy technologies [71]. The
CHP arrangement appears in different scales. The micro - CHP is defined as a unit with a
maximum capacity below 50 kWel which suits the individual households and thus the target
group [79].
Small Stirling engines with a power output less than 1 kW barely exist in prototype or research
stage and the same situation applies for Micro-CHP systems of a household scale. Some small
Stirling engines or CHP-SE for military applications have been reported [80][81].
Bigger CHP-SE systems for commercial use seem to be more common. Cleanergy offers
solutions powered on either biogas or solar power. Those have an electrical peak efficiency of
25-30 % and a power output of 9 - 11 kW, the life expectancy for the systems are 25 years [83].
Qnergy has though invented a CHP solution fueled on natural gas or propane. The free piston
Stirling engine generates a power output between 3 - 6.5 kW [84]. However, the electrical
efficiency for biomass driven CHP-SE systems is low, around 10 - 15 % [85][63]. The
thermodynamic total efficiency is reported to vary between 59 - 73 % [65].
12
2.5 The Stirling Engine In the new biomass stove, fuelwood will be used for cooking and a Stirling engine will take
advantage of waste heat to produce electricity which will increase the efficiency.
The first Stirling engine (SE) was patented in 1816 by Robert Stirling, who also gave the engine
its name. [64]. Even if the engine has been relatively efficient and promising has the development
has been slow. Literature from the last decades report a number of Stirling Engine applications,
mostly for heat and power generation, which might be seen as the revival of the technology
[67][68][69] [83][84]. Today the engine is hardly commercial but some can be found like the
biofuel compatible Stirling engines of 1 respective 3 kWe that can be bought for 16 500 and
19 300 USD [136].
The engine is quiet running and fuel flexible, it can theoretically achieve high electrical
efficiency. These are properties that make the Stirling engine suitable for combined heat and
power arrangements. It does not require special infrastructure and suits therefore rural
environment [71].
Technology
The Stirling engine is an external combustion engine. It is based on the Stirling cycle, a closed
thermodynamic cycle where the working gas is compressed in a cold cylinder volume or
expanded in a hot cylinder volume [67]. The engine is working due to a temperature difference
between a hot and a cold end of the engine where thermal energy is transformed to mechanical
energy. The hot side is pictured in red and the cold in blue in Figure 6. The heat to the engine´s
hot side is transferred through a heat exchanger, unlike the internal combustion engine where heat
is supplied to the cycle by combustion of fuel inside the cycle [67].
13
Figure 6. A drawing of the Stirling engine with the hot side in red and the cold side in blue [72]
The Stirling engine appears in three different types of cylinder couplings α, β and γ shown in
Figure 7. The alpha engine has two pistons in separate cylinders; those are connected in series
with heater, regenerator and cooler. As shown in Figure 7 the Beta engine has a displacer and the
power piston in the same cylinder. The gamma configuration has, as the beta, a displacer and a
power piston but in two different cylinders. The engine can also be categorized based on piston
coupling that can either be rigid-, gas-, or liquid coupling [76]. One of the gas coupling engines is
the free piston engine. It has gas dynamically, instead of mechanical, linkage for the piston and
the displacer. Advantages with this type are reduction of maintenance and possibilities to develop
more compact engines [65]. These qualities make it suitable for the combined heat and power
arrangement [77]. A well-made free piston SE can achieve 50 % and above of the ideal Carnot
efficiency [78].
Figure 7. The different cylinder couplings appearance in Stirling engines [66]
14
The free piston Stirling engine has a lifetime of about 10 years and the maintenance interval for
small engines (capacity > 20 kW power) are 5000 - 8000 hours. This is low compared to internal
combustion engines [65].
A battery will increase the accessibility of the electricity produced in the Stove. This means that
the electricity can be used when needed and not only when the stove is running. The average
daily time for cooking in rural households was estimated to be 130 min [6]. With a power output
from the engine of 95 W the daily energy production in the households would be 206 Wh. A 12V
and 25 000 mAh battery, only discharged to 70 %, would be sufficiently to store all daily
produced electricity [86][87]. Further, Bolivia has great natural resources in lithium which is a
component in the lithium battery. This may contribute to future industry and economic
development.
2.7 Cooking Habits For a successful stove implementation cooking habits in a cultural and social perspective are
crucial to consider. The technology is obliged to be customized for the user. A number of projects
have failed tried to implement new stove-concepts in rural areas not considering these aspects
[53][54]. Technology adoption is influenced by perceived difficulty, adoptive experiences,
supplier’s commitment, perceived benefits, compatibility and enhanced value [55]. For a
successful implementation of the new biomass stove it is therefore important to educate in
maintenance and provide support during the lifetime of the stove, declare the advantages with the
stove and make a new stove that allows the user to have the same cooking habits as today.
The economic situation is foundational for the possibility to cook and determine what families in
general cook. This makes the cooking habits throughout rural Bolivia diverse. One can though
see some similarities if the cooking habits are studied. One of them is that it is most common to
eat three cooked meals a day and the biggest out of all of these three meals is the lunch. This
lunch often consists of two dishes, first a soup and then a dish consisting of meat with rice,
potatoes or quinoa. Total average daily cooking time was determined to be 130 minutes [6].
A long-lived tradition in the rural areas of Bolivia is to drink a maize beverage called Chicha, a
socially important drink [56]. To make this traditional drink one has to boil the water together
with spices and then add the maize flour and let the drink boil minimum 2 hours [57]. In Bolivia
it is also mostly common to cook all of these meals in a standing position [58].
15
2.8 Different Kinds of Stoves The term stove means a device that burns fuel or uses electricity in order to heat a specific place
[59]. As already stated, most of rural cooking is through simple biomass stoves and Bolivia is no
exception. The rural citizens often use different kinds of fuels depending on the accessibility in
the area. Therefore the stoves also vary in design [6].
The most common stoves in Bolivia are the open fire stove and the U-type stove which Figure 8
and Figure 9 shows. It is possible to see design changes for the stoves throughout the country
because of the altitude changes [6].
Figure 8. The open fire stove [6]
For example on higher altitude, it is more common to have well-constructed stoves with a small
risk of heat waste; this difference can be seen when comparing Figure 8 and Figure 9. But
throughout Bolivia it is not common to see a chimney attached to the stove. It is also common to
have the stoves located in the house, especially in the areas in high altitude where the temperature
is lower and the need for heating is bigger [6]. This makes the problem with indoor pollution
even more important to solve.
16
Figure 9. The open fire U-type stove that is one of the most common in Bolivia [6]
The Rocket Stove Principle
There have been many projects where the firewood cooking stoves have been improved and new
concepts developed. The rocket stove principle is one of the most successful new designs of a
improved cooking stove [60]. As shown in Figure 10 the stove is integrated with a large
combustion chamber. This chamber behaves a bit like a chimney which is good regarding the
pollution problem previously discussed since the smoke removed from inside the house. The
internal walls are isolated which reflects all the heat back into the chamber instead of warming up
the stove body. The heat makes the chemical combustion complete which is why many of the
improved fuel wood cook stoves follow the rocket stove principle [49].
17
Figure 10. The rocket stove principle [49]
This principle is successful because of the stack effect. The hot air is lighter, less dense, than the
cold air [46]. The hot air wants to rise and out which creates a diminished air pressure where cold
air gets sucked in to the combustion chamber. These thermal forces create a draft throughout the
construction, which formulates higher temperatures, and further a complete combustion [47].
Improved Cook Stoves
To discover and investigate different kinds of improved cook stoves a field study was made to
Stove Testing Center (CPC). These stoves design principles and thermal efficiency can be seen
fully in Appendix 2. The discovery of the outer design was that there were two categories of
stove designs on the market. One was a portable stove design and one was a stationary stove
design in a standing height. There were also discoveries about the stove characteristics such as
stoves with or without chimney, with or without fan, sunken down pots or not.
In addition to the different design categories analyzed during the visit to CPC an interesting
implementation for an improved cook stove with traditional design named Malena was
discovered. Knowledge about this stove and the way it is implemented was gathered during a
field study with GIZ. The implementation regarding its sustainable way to introduce the Malena
stove to the rural areas in Bolivia [63]. The users prepare the clay mix beforehand and then
18
locally trained stove builders construct the stove. After the stove is constructed there is also
follow up monitoring of the installation [61]. The construction of the stove does not need any
other tools than available in the house [62]. A principle sketch of the Malena stove can be seen in
Figure 11.
Figure 11. Principle sketch of the Malena cook stove [62]
2.9 State of the Art Cook Stoves Integrated With Electricity Source There have been several projects where cooks stoves also have been working as an electricity
source. Four improved cook- or camping stoves that follows this principle are presented below.
The µPower Cookstove
An engineering team from Trinity College Dublin has developed a low cost, locally made
biomass cook stove [92]. The µPower Cookstove can be seen in Figure 12 together with all its
components. This stove can also produce electricity through locally made thermoelectric
generator (TEG) devices [93]. TEG is a technology that converts heat into electrical energy
without moving parts as in an engine [94].
19
Figure 12. The µPower Cookstove with all its components [93]
The TEGSTOVE
This is a portable gas stove which transforms the energy from the heat to electrical energy
through TEG technology. As seen in Figure 13 the TEGSTOVE is integrated with a battery so
that the electrical energy can be stored for later use. The TEG device consists of two ceramic
plates connected with two different materials. The temperature difference between these two
plates it used to generate electrical energy [95].
Figure 13. The TEGSTOVEs complete design [95]
The BioLite CampStove
The BioLite CampStove is a camp stove that also generates electricity. The camp stove is made
of metal and can be seen in Figure 14. This stove uses fuelwood and has smokeless flames [96].
20
The smokeless flames are possible because of an integrated fan that leads to complete
combustion [97]. The BioLite CampStove uses TEG technology to convert heat power into
electrical power, this electricity can be used at the same time as the fire is burning [98].
Figure 14. The BioLite CampStove [96]
Score Stove
The Score stove is a biomass stove integrated with thermoacoustic generator (TAG) to create
electrical power. As seen in Figure 15 the stove is accompanied with a chimney to avoid indoor
pollution [99]. The TAG itself has only one moving part and uses the temperature difference to
induce high amplitude sound waves [100]. Compression and expansion is driven by a gas which
is motioned by these sound waves [101]. The display of the Score stove can be shown in Figure
15 together with description of the different stove parts.
Figure 15. The Score stove displayed together with all is stove parts [102]
To create a deeper understating of material and usage for the stoves described above, pictures can
be seen in Appendix 3.
21
3 Biomass Stove Design This section will describe the procedure to get to the final stove design through concept
generation and evaluation based on the requirement specification. It also includes material
suggestions for the different stove components and suggestions for placement of the Stirling
engine. Lastly a price investment for the stove will be made.
3.1 Requirement Specification A requirement specification is a list of requirements which are independent of solutions [103].
All the requirements, wishes and needs formulated in the literature survey through field studies,
observations and literature research, were summarized and formulated into the requirement
specification for the further design of the stove. The complete requirement specification can be
found in Appendix 4.
The aim and prerequisites for a successful stove were formulated into a design that avoids indoor
pollution, makes complete combustion and provides easy removal of ashes. The literature survey
showed that fuel wood is the most common fuel source for cooking in rural Bolivia why the stove
shall be adapted for fuelwood burning. Further the size of the stove should be customized for a
family of five persons since it is the average in Bolivia [62]. This also applies for the Stirling
engine that should have a power output of minimum 100 W. This will cover the electricity that
lightning and cell phone charging requires, stated in the literature survey as wanted devices
likable for the rural population to get.
A central objective, and therefore a crucial requirement, was to develop a stove that satisfies the
rural culture and cooking habits. Due this objective requirements of two pots, stove height for an
average Bolivian woman and stove adopted for fuel wood were formulated.
The airflow inside the stove should be ideal in the sense of not cooling the fire with unnecessary
air neither too little air for complete combustion. Further the importance of the flames not
reaching the pot or plate to avoid a burned bottom was pointed out. In Table 2 all the functional
requirements are displayed.
Table 2. Functional requirements from the requirement specification
Functional Requirements
The size of the stove shall be customized for a family of five persons [62]
22
The combustion in the stove must be complete [5]
The stove shall have a solution for easy removal of ashes
The air flow inside the stove shall be ideal [60]
The fire shall not be in direct contact with the pot [60]
The stove shall have minimum two pots
The stove shall be designed for a standing position for an average woman in Bolivia [2]
An electricity generating engine shall be integrated in the stove
The engine shall be integrated with a battery
The stove shall satisfy the rural culture and cooking habits [54]
The stove shall be adapted for burning fuel wood [35]
To solve the problem with indoor air pollution the emission levels of the stove are essential.
Maximum emission levels for PM10, PM2.5 and CO are set with respect to WHO and European
Commission´s guidelines and can be seen Table 3 together with the other restrictive
requirements. Many of these requirements are impossible to evaluate without a physical model of
the stove and will therefore not be evaluated in this project.
Table 3. Restrictive requirements from the requirement specification
Restrictive Requirement
The lifetime of the entire stove concept shall be minimum of 10 years
The stove shall boil 5 liter of water in maximum 30 minutes [58]
The minimum thermal efficiency shall be 25 % [58]
Stirling engine shall maintenance interval of minimum 5000 hours [77]
Dimensions of the stove shall not be bigger than 3x1 m [62]
Not emit more than 0.035 µg/m3 per minute of PM10 to the indoor air [149]
23
The Stirling Engine shall have the capacity of minimum 100 W
The stove will need maximum 20 000 kJ to boil 5 l of water [58]
Emission rates from fuel combustion should not exceed 0.80 mg/min of PM2.5 (fine
particles) [148]
Emission rates from fuel combustion should not exceed 0.59 g/min of CO [148]
The outer temperature of the stove body shall not exceed 52 °C [150]
3.2 Quality Function Deployment A Quality Function Deployment (QFD) was made to systematically transfer the customer
requirements and wishes into measurable technical qualities. In this way, the most important
stove qualities could be identified for the coming design decisions [104]. The customer
requirements and wishes used in the QFD were collected from the requirement specification.
These wishes and requirements together with measurable product qualities formulated the
foundation of the QFD. The customer requirements were weighted according to the customer
experience of what was seen as most important. Further these requirements were weighted
towards the product qualities given a number 1, 3 or 9 depending on how strong they were
correlated. This weighting was, for respective product quality, summarized into a technical
weight. The quality with the highest technical weight was the most important one to focus on in
the design aspect.
This analysis showed that the most important product quality was thermal and overall efficiency
in the stove. Another highly weighted quality was the stove´s height and that the stoves surface
area could not be too warm. It is possible to find the full QFD in Appendix 7 together with all
customer requirements and product qualities.
3.3 Concept Generation A first concept generation followed the feasibility research. At this stage the aim was to create a
great variety of solutions and see the possibilities in them. Focus on the stoves fulfilling the
requirement specification was not prioritized during the generation when the aim was the
diversity. The concept generation was made after a field study to CPC discussed earlier. The
characteristics were studied from the successfully tested stove design and furthermore a design
concept from each of the discovered successful stove characteristics was formulated. From these
discoveries two families of stove solutions were shaped, one portable and one stationary. The
24
most interesting solutions were three portable and two stationary stoves all sketched in Solid
Edge and can be seen with description [105]. The different concept generated were named
afterwards so it would be easier to separate them in further work.
An assumption was made that the integrated engine does not affect the basic stove design why a
decision was made to first develop the fuel wood stove and then investigate the optimal
placement for the engine.
The portable stoves were formulated in three different appearances and can all be seen in Figure
16. The first concept shown in Figure 16 a) named SOLAN is a portable stove with an integrated
oven close to the combustion chamber. There are two hobs for two pots and the darker material
seen in the figure is made of a conductive material. The rest of the stove consisted of a heat
resistant metal combined with an insulating material.
Next portable stove is named IDA and can be seen in Figure 16 b). IDA also has a chimney but
only place for one bigger pot. The pot has a skirt for potential reduction in fuel use and emissions
[89]. The body of this stove was metal based with an insulating material around the pot and
combustion chamber.
The third and last portable stove named ULLA can be seen in Figure 16 c) and is like the others,
mainly made of metal and insulation. This stove does not have a chimney but instead a fan. The
Stirling engine driven fan boosts the air flow and enables complete combustion. In general,
improved stoves with a fan have a fuel efficiency of 60 % compared to improved cook stoves
without a fan which has a fuel efficiency of 25 - 30 % [58].
25
Figure 16. a) SOLAN the portable stove with a chimney, oven and place for two pots
b) portable stove IDA with chimney and pot skirt
c) portable one-pot stove with an integrated fan, ULLA.
The two stationary stoves named KARIN and MAYA can be seen in Figure 17. They are more
traditionally designed and inspired by the Malena cook stove [62]. Both of them have submerged
pot holders to preserve the heat and also a chimney to carry away the gases. They are also both
integrated with a combined ash trap and air intake. The first version KARIN seen in Figure 17 a)
have perpendicular gas flow compared to the pots and the second stationary stove, MAYA seen
in Figure 17 b) have a parallel flue gas flow to the pots.
26
Figure 17. a) Stationary stove KARIN with a chimney, ash trap and two settled pot holders b) Stationary stove MAYA with two settled pot holders, chimney and ash trap
3.4 Concept Evaluation A Decision Matrix was formulated to evaluate the generated concepts accordingly. The method
scores each concepts relative in order it meets the given criteria [104]. Each concept from the
concept generation phase was evaluated and assimilated to an ideal concept. The highest scoring
concept was the most interesting concept for further development and the complete matrix can be
seen in Appendix 5.
The highest scoring overall design concept in the Decision Matrix, with respect to the
requirement specification, was MAYA seen in Figure 17 b. This is the traditionally and stationary
designed stove with two pots.
What was decided to keep out of MAYA in the further development was two sunken down pots,
keep it stationary, a chimney and that the stove should be made out of metal. This because it is
advisable to use thin low density material in the stove construction due to reduced heat transfer
through the walls [106]. For the surface area not being too warm and wall insulation should be
used. Further the design with a high technical Stirling engine will look inhomogeneous if a metal
material were not chosen. Furthermore, since reduction of materials contributes to lower material
costs it was decided to only cover the necessary parts of the stove body. The further work
regarding MAYA contained additional development of the stove design, material parameters,
inner design and components.
27
3.5 Further Design and Design Approach for MAYA A number of different factors affect the fuel efficiency of which the key factors found are
described below.
1. Combustion Efficiency, formulates how much energy in the fuel that releases as heat.
2. Heat Transfer Efficiency, percentage of generated heat that transfers, through conductive,
convective and radiative heat transfer processes, to the contents of the pot.
3. Control Efficiency: adjustment so only as much heat as needed for cooking is generated.
The thermal efficiency is the combustion and heat transfer efficiency together. These two with
the control efficiency is named the stove efficiency [108].
However the actual combustion process taking place in the stove is too complicated, highly
interdependent and variable to be modeled within this project. Because the complex processes a
physical model must be tested to determine the inner design parameters which correlates to the
stove efficiency. The complexity in the combustion process formulated a design approach where
successfully improved stove designs were analyzed and adapted to the final concept. Some
successfully tested stoves will be displayed together with important data and how these can be
adapted in the MAYA stove.
InStove
This institutionally used stove adapted for pot sizes 60 or 100 liters has a high thermal efficiency
[109]. The MAYA concept is inspired of its high performance combustion chamber.
InStove has the best grading regarding efficiency and indoor emission and second best grading
when it comes to emission and safety in Global Alliance for Clean Cookstoves third part testing
[109]. A principle sketch of the stove can be seen in Figure 18.
28
Figure 18. A principle sketch of InStove, an institutional cook stove
The combustion chamber is made out of high-temperature 310 stainless steel and 601 nickel
alloys. The operating temperature rises to 1100 °C which is why the stoves emission grading is
good. The stove can be bought for 850 - 995 USD depending on the size [110].
Uganda 2-pot
The two pot stove with a chimney showed in Figure 19 boils water fast and is considered fuel
efficient. Compared to open fire the carbon monoxide and the particulate matter are low, 2
respective 3 %. Tests regarding the Uganda 2-pot stove declares that the first pot in the flue gas
passage needs to be smaller than 25 cm in diameter if the second one is 23 cm in diameter if both
of the pots should be able to boil [111].
29
Figure 19. A drawing of Uganda 2-pot with outer dimensions [111]
The combustion chamber is of rocket type made with insulated firebricks. Hot flue gases are
forced to pass in a narrow insulated channel around the sunken pots before exiting the chimney.
In the sheet metal tops are the pots fitted tightly to prevent smoke in the kitchen. This stove is
available for 40 USD [111].
Rocket Stove
For the rocket stove, combustion chamber diameter and area are given together with different gap
dimensions for respective pot diameters. These dimensions can be seen in Table 4 for different
pot diameters.
Table 4. Given gap sizes, combustion chamber area and diameter for pot diameters [106]
Pot
Diameter
[cm]
Combustion
Chamber
Diameter
(D)
[cm]
Chamber
Area
[cm2]
K=D/2
[cm]
H=K+D
[cm]
Pot Skirt
Gap
(L)
[cm]
< 21 12.0 113 6.00 18.00 1.6
21 - 27 14.0 154 7.00 21.00 1.5
28 - 30 16.0 201 8.00 24.00 2.0
31 - 35 16.0 201 8.00 24.00 1.5
30
The description of where these gaps are located in the rocket stove can be seen in Figure 20.
Figure 20. The described gaps inside the Rocketstove [106]
To understand Uganda 2-pot and Instove more deeply regarding material, usage and looks can
pictures of them be seen in Appendix 6.
3.6 Stove Components After studying the improved cook stoves together with their dimensions and materials the
information was adapted to the MAYA concept. Respective component will be analyzed and
discussed accordingly. Potential materials are presented for each part, final decision should be
considered in further work where the price aspect of the materials should be considered as well.
In further work technical resistant, exact dimensions, assembly, installation and a secure solution
for the stove not tipping also should be taking in account.
Combustion Chamber, Grate and Ash Trap
The pot diameter and combustion chamber size are highly connected to each other. Therefore to
determine the combustion chamber size, the pot diameter needed to be identified. Uganda 2-pot
stated that the pot diameters for guaranteed boiling was 25 cm for the first pot and 23 cm for the
second. These dimensions were guidelines when the pot dimensions should be determined for
MAYA. Suggested pot size for MAYA is two pots with 24 cm in diameter [112]. The pot bottom
area for two 24 cm in diameter pots are roughly the same, with a difference in area of 1.4 cm2, as
two pots with diameter 25 and 23 cm respective. This means, if the pot height is the same, the
31
total pot volume is roughly the same for the two options. Boiling in both pots can therefore be
assumed. Pots with 24 cm in diameter and the height of 16 cm fit 5 liters [112]. Two of these pots
should correspond to the cooking need in a family of five, which is required in the requirement
specification.
When the pot sizes were determined a dimensioning suggestion for the combustion chamber
could be made. The suggested combustion chamber area is 154 cm2 and the diameter is
determined to be 14 cm according to Table 4. The combustion chamber is shaped in a cylinder
form because smaller mantel area leads to smaller heat losses through the walls.
It is crucial in the means of create complete combustion to have high temperatures in the
combustion chamber. The high temperature formulates strict material requirements. In the
combustion chamber the temperatures can rise to over 1100 °C which is why the material needs
to function in these temperature rates. Analyzing the InStove materials their solution for the high
temperature problem in the combustion chamber was to integrate 301 stainless steel and nickel
alloy [110].
Type 301 is an austenitic chromium nickel stainless steel which is often for example applied in
aircrafts trailer bodies and sinks [114]. The nickel alloy covering material around the stainless
steel which makes it more heat resistant [115].
It was advisable to have a pot to grate distance of no less than 0.4 times the pot diameter [107].
Because of the combustion chamber diameter and the stove insulation this distance was set to 145
mm.
For air to pass under the burning wood sticks and make the combustion more complete a grate
should be placed in the combustion chamber. It is even better if the air passes through the fuel
first to get preheated [60]. Since the grate will be exposed to high temperatures it needs to be
made in a heat resisting material. This is why the suggested grate material is the same as in the
combustion chamber, 301 stainless steel and nickel alloy. Ash will fall down from the grate to the
bottom of the combustion chamber which constitutes an ash trap. Minimizing components in this
way is also advisable regarding DFM [104].
Insulation
14 - 42 % of total energy input goes into the stove body though conduction which accounts for
the biggest energy losses [106]. This is why it is essential to select proper material for the
insulation. Insulation will also reduce the surface temperature which leads to safer use. Relevant
32
material properties in stove design are thermal conductivity, specific heat and density. Specific
heat (cp) is a measure of a material's ability to store thermal energy. Thermal conductivity (k) is a
measure of a material's ability to conduct heat where a higher value equals faster conduction
[116].
It was advisable to use thin, low density material in stove construction. A thick and dense stove
body material with low thermal conductivity and high specific heat will conduct less heat from a
fire than a thin material under steady state conditions but this will most likely not compensate for
the heat required to warm the body during transient conditions, which implies when the stove is
getting warm [106].
Double metal walls with an insulated material in between have been proven a good solution for
the improved cook stove [107]. This insulation material needed to consider specific factors such
as melting temperatures, thermal conductivity, strength and also costs of materials [117]. The
lower the thermal conductivity, the lower heat transfer and therefore a good insulating material
[118]. Different insulating materials suitable for the stove construction will be presented below.
Fiberglass can be a good alternative. It is one of the most used insulation materials in modern
times because of its reduction of heat transfer but also because of its low cost [119]. Fiberglass
with a thickness of 25.4 mm, a density of 64.0 kg/m3 and with a thermal conductivity of 0.036
W/mK are available on the market [120].
Vermiculite is a lightweight, cheap and fireproof material and another alternative for the
insulation [113]. It is for example used in open fireplaces, high temperature insulation and
fireproofing of structural steel. Vermiculite is a hydrated magnesium, aluminum and silicate
mineral [121]. To formulate this into an insulated material vermiculite should be mixed with
water and clay. It is possible to find vermiculite in various parts of the world, closest producing
country to Bolivia is Brazil [122]. A vermiculite mix with 85 % vermiculite and 15 % clay has a
thermal conductivity of 0.120 W/mK and a density of 559 kg/m3 [106].
Perlite is an amorphous volcanic glass that has high water content [123]. The perlite is light
weight, fireproof and insulating and is used for example as insulation and in constructions. This is
why perlite was jet another alternative for insulation material [124]. Perlite is available both
inexpensive and plentiful in countries close to where it is produced. Closest producing country to
Bolivia is Mexico [123]. The perlite needs, for best insulated property, be made into a graded mix
33
before combined with clay and formed into bricks [113]. A perlite mix of 85 % perlite mix and
15 % clay has a thermal conductivity of 0.128 W/mK and a density of 439 kg/m3 [106].
Stove Body
As mentioned it is advisable to use thin, low density material in the stove construction. These
ideas also adapts to the stove body. Sheet metal is a flat and thin metal processed industrial
though roll slitters. The metals are possible to find in different thicknesses and metals such as
aluminum, brass, copper, steel and tin. Sheet metal is used for car bodies, airplane wings and
medical tables and is easy to form into desired geometrics [125]. Different possible stove body
materials will be presented below.
Stainless steel is iron alloys with minimum 10.5 % chromium where other elements can be added
to formulate the desired material properties but stainless steel is commonly corrosion resistant
[126]. The chromium formulates a film surrounding the steel and is good for high temperatures
since it protects the steel [127]. High temperature stainless steel are available at different qualities
and often used in high temperature tubes. In the stove construction Sanicro 31HT and Sandvik
253MA could be suitable because they both have a good resistance for combustion gases and are
structurally stable at high temperatures [128][129][130].
Aluminized steel is often used in water heaters, ovens and heat exchanger and is therefore good
applicant for the high temperatures inside the stove. The outside level consists of aluminum oxide
and the inside is a mixture of aluminum, silicone and steel [131]. ASTM A463 is a low cost
aluminized steel that is possible to formulate into steel sheet. The type of metal is used in ovens,
firewalls and heaters and is therefore working in high temperatures [132]. ASTM A463 reflects
up to 80 % of the radiant heat below temperatures of 427 °C [133]. Therefore, the suggested
aluminized steel material was ASTM A463.
Flue Gas Passage and Chimney
The cross sectional areal where the flue gases pass with hot air are suggested to be the same size
throughout the entire stove. This helps to keep good draft throughout the stove which further
keeps the fire hot and helps the air transfer its heat to the pot [60]. It is also stated that a constant
cross sectional area will not slow down the draft inside the stove. The goal is to keep gases as hot
as possible and flowing as quick as possible [134]. Since the combustion chamber diameter was
determined to be at least 14 cm the cross sectional area turned out to be minimum 154 cm2 which
also includes the chimney. To avoid rainwater in the chimney and to make cleaning easier a
34
detachable hood was advisable. This type of chimney can typically be constructed of metallic
steel [62].
Outer Dimensions
Women are often in charge of cooking in Bolivia as around the world [6]. The average height of a
Bolivian woman is 142 cm [135]. Standing height is roughly half of the full length why around
70 cm is a good stove height. This is also confirmed by the Malena stove which has an average
height from 70 - 80 cm [62].
A scaffold was needed in the construction to assembly the entire stove. This formulated the base
for the construction and gave the stove its height of 70 cm. To minimize the cost, it was
determined to construct the stove in a steel profile, and to further minimize the cost and weight it
was determined to work with a square hollow steel profile. These profiles are also known to be
firm construction wise. The suggested dimensions for the steel profiles in MAYA were
determined to 40 x 40 mm with a 2 mm thickness and can either be made in aluminum or iron
[137][138]. The density for aluminum is 2.7 kg/m3 and costs about 0.66 USD/ kg [139]. Iron on
the other hand costs 0.036 USD/kg and has a density of 7860 kg/m3 [140].
3.7 Stirling Engine Placement To get realistic dimension when determine possible placements for the Stirling Engine in the
stove, a prototype was chosen. Technical data for the engine in the stove has been taken from
Sunpower’s prototype free piston Stirling engine EE-80-H as shown in Figure 21. This prototype
does not fulfill all requirements for the wanted Stirling engine but it was the only free piston
Stirling engine prototype with technical information found. The power output of 95 We is slightly
less than the minimum of 100 We, stated in the requirement specification, and the engine is sun
and not biomass driven. However the size of the prototype will give a good indication of the size
of the required engine.
Figure 21. Free Piston Stirling engine from Sunpower [82]
35
The technical information for the prototype can be seen in Table 5. The temperature ratio
displays the difference in temperatures between the hot and the cold side.
Table 5. Technical data for free piston Stirling engine [82]
Temperature
Ratio
[Th/Tc]
Mass
[kg]
Dimensions
Diameter x Length
(nominal)
[mm]
3.0 1.0 65 x 186
To display forbidden placements of the engine red areas have been marked in stove pictures. The
Stirling engine will be damaged if it is placed in direct contact with flue gases why the flue gas
channel is red shown in Figure 22. The top of the stove is another forbidden area to place the
Stirling engine when this area is intended for pots and cooking. As other improved stove reports
has presented, the combustion chamber temperature can rise above 1100 °C [110]. The warm side
of the engine is for the chosen prototype three times warmer than the cold side (Th/Tc = 3) why
the combustion chamber most likely will be too hot. It is crucial to have the combustion chamber
well insulated, which is why it was not preferable to place the engine inside.
Figure 22. Inside of the stove with forbidden areas for the Stirling Engine
36
Dimensional good placements for the engine seen in Figure 23. The temperatures for these
placements have to be further investigated when the final stove design and testing is made. As
seen in Figure 23 the cold side of the red engine (placed to the right) might disturb the user
depending on the stove placement in the house. Weather the blue or green engine is best
positioned must be determined when the temperatures in the stove are known. Sealing between
flue gas path and the stove body where the engine will be placed must be further investigated to
secure the lifetime of the engine.
Figure 23. Three different Stirling engine placements in the stove
3.8 Pricing for the stove Two types of pricings can be made where the first option is market based pricing where the
markets assets determine the price and what the costumers are willing to pay. The second option
is cost based pricing, which is the price of the produced product correlated to the company’s
expenses and profit margins. To determine a final price of the stove, the list price, regarding cost
base pricing one needs to know the direct and indirect cost. The direct cost is the cost that can be
directly linked to a specific component, assembly or product. The indirect cost is every other cost
regarding production of a product such as, for example, selling expenses and profit marginal. To
evaluate the cost of each component, and determine the expenses of the machined component one
needs to know [104]:
37
- Material cost for the raw material and the value of the scrap produced
- Type of machine used
- Component dimensions since it determines the size of the needed machine
- Surfaced areas, the more the longer time will it take to produce
- Number of components made
- Tolerance and surface finish
- Labor rate of the used machine
Therefore, regarding the price of the stove a similar approach was made where the already
analyzed stoves got compared to each other so that a price estimation could be determined for the
MAYA stove. Since the price is an estimation will it be presented within a range. Firstly the price
for the stove itself will be analyzed and afterwards the cost together with the Stirling engine and
also different batteries.
As seen in Appendix 2 and in Section 3.5, the price of the improved cook stoves can vary
between 40 - 995 USD. The cheapest of the once compared was the Uganda 2-pot and the most
expensive one was the InStove. The InStove will not be included in pricing of MAYA since it is
institutional and also far away from the other stoves in price.
The MAYA stove was similar to Uganda 2-pot in its outer design, a simple metal construction
with two pots and a chimney but with brick insulation. MAYA was designed with a different
combustion chamber material and insulation technics meaning the price of the stove would
increase. This indicates that the price range more likely will reach something similar to
GAMMA11411 with the price 60 - 80 USD or Philips HD4012 priced 89 USD resulting in a
price range for MAYA of 60 - 89 USD, Stirling engine excluded.
The purchasing power of the people living in rural areas needed to be investigated. Since the
stoves used today were cheaply built in the villages the budget for the rural people to invest in a
new stove was limited [6]. The price of the Malena stove was 45 USD, which was showed a
possible amount to overcome for many rural people, even if some needed economic assistance
[62][151]. Using the MAYA stove leads to decreased costs regarding monthly electricity use and
also saved grid connection expenses that could vary between 22 - 726 USD [6].
As seen the assets of the possible consumers are very limited why some form of financial support
is needed for the stove implementation. Since the governmental plan to electrify all the citizens in
Bolivia by 2025 seem to be difficult for the government economic support to projects like this
can be a solution [37][38].
38
Household scaled Stirling engines driven on biomass fuel was only produced as prototypes and
the price could therefore not be determined. Prices for larger output Stirling engines of 1 kW are
about 16 500 USD and therefore too expensive to integrate in rural households.
The price of any technology product decreases with time because inter alia technology
advancement and competition. Nothing indicated these economical decreases would not happen
to the Stirling engine. Stirling engines of the wanted size will hopefully be accessible for a
reasonable price in a 5 – 10 years period from now when the CHP will be further developed
[136].
Lithium-ion batteries could be found at the wanted size for circa 350 USD [79], lithium iron
batteries could be found in the same size for 203 USD [88][89]. Another solution could be
batteries known as power banks. A 25 000 mAh and 12 V lithium- ion rechargeable power bank
could be found for 130 USD [90]. Car batteries of the wanted size were accessible and could be
bought for about 92 USD [91]. To mention is that these prices are not wholesale prices why the
prices can be expected to be lower.
39
4 Results and Discussion Here the full design of MAYA will be displayed together with dimensions, material and the flue
gas passage. The stove construction, as already discussed, is a draft that has to be tested and
further developed before production. Physical resistance must be calculated and the stove
material and design needs further development and optimization as well the assembly and
manufactory analysis. The dimensions displayed are suggestions as well as the materials.
4.1 Dimensions of MAYA The design of the new stove, MAYA, and its inside can be seen in Figure 24. As seen in the
figure the pots are tightly fit in the stove body making the only possible escape for the flue gases
through the chimney.
Figure 24. Design for MAYA where also the inside is displayed.
The dimension of the flue gas path and combustion chamber was based on the dimensions of the
pots. In Table 6 one can see the pot dimensions together with its material.
40
Table 6. Dimensions for the pot [112]
Pot diameter
[cm]
Pot height
[cm]
Total volume
[liter]
Material
[-]
24 16 5 Stainless steel
The MAYA pot sizes was inspired from the Uganda 2-pot where total bottom pot area for both
pots to boil was < 906.4 cm2 [113]. The total pot area for MAYA was defined as 904.8 cm2,
which results in an area difference between the stoves of 1.6 cm2. Since the total pot area in
MAYA is slightly smaller both pots was assumed to boil. The pot diameter gave information
about the combustion chamber. The combustion chamber can be seen in Figure 25.
Figure 25. The combustion chamber
The dimensions for the combustion chamber can be seen in Table 7 together with the material
suggestion.
Table 7. Combustion chamber dimensions [106]
Area
[cm2]
Diameter
[cm]
Material
[-]
154 14 301 stainless steel and nickel alloy
41
Even though the combustion chamber dimensions was fetched from the rocket stove, which has
one pot instead of two, the size will probably be sufficient. As seen in Table 4 the combustion
chamber size does not increase drastically with bigger pot diameters. Uganda 2-pot has a smaller
combustion chamber size of 12 cm in diameter and two pots that both could boil for the diameters
given earlier [113].
To reduce wall losses through the stove body it was discovered that a thin and low density
material was preferable in stove construction. Advised for the stove wall construction was to use
two metal sheets with insulation between to reduce heat losses [107]. The suggested materials for
the insulation which will be located in between the walls, can be seen in Table 8.
Table 8. Material and material properties for the insulation material [120][106]
Materials
[-]
Thickness
[mm]
Thermal conductivity
[W/mK]
Density
[kg/m3]
Fiber glass 25.4 0.036 64.0
Vermiculite - 0.120 559
Perlite - 0.128 439
In this application, fiber glass is considered to be the best material and in an isolative perspective
but it is also indicated in Table 8 by its light weight and good thermal conductivity which is
desirable [107]. Fiberglass with a thickness of 20 mm in between metal walls could provide up to
50% more radiant heat flux to the pot than a bare metal wall [107]. Additional, a well insulated
stove body will reduce the risk of the stove surface being unsafely warm. This is highly weighted
in the requirement specification and crucial for safety. The reason why both vermiculite and
perlite is not excluded from further investigations is because of the economic advantages which
also is an important perspective regarding a successful improved cook stove [54].
As seen in Figure 26 the sheet metal and insulation material of the stove body was built with
layers on each other. First layer of sheet metal (A in figure) had a thickness of 6 mm, the
insulation material (B) has a thickness of 25.4 mm and the last layer of sheet metal (C) has a
thickness of 3 mm.
42
Figure 26. The walls with steel sheet and insulation in between.
A ductile, cheap, thin and flat metal is suitable to use in the stove body which is why sheet metal
is advisable [106]. The suggested materials for the stove body, which implicate the walls of the
stove, can be seen in Table 9.
Table 9. Material suggestion for the stove body
Stainless steel
[-]
Aluminized steel
[-]
Sanicro 31HT Sandvik 253MA ASTM A463
Both these materials could function in the walls. Both of them are good heat resistors, for
example used in heat exchangers [128][132].
A highly weighted quality in the QFD was that the construction should be made in a standing
height which, for an average Bolivian woman, was determined to be 70 cm [135]. The scaffold in
the construction constitutes the base for the assembly and gives the stove its correct height.
MAYA is designed with a 40 x 40 mm square profile with a 2 mm thickness. The suggested
materials and material qualities can be seen in Table 10.
43
Table 10. Suggested materials for the scaffold construction together with material qualities [139] [140]
Material
[-]
Density
[kg/m3]
Price
[USD/ kg]
Iron 7860 0.036
Aluminum 2.7 0.66
In order to create a light stove construction aluminum seemed to be the best solution for the
scaffold material. On the other hand to create a cheaper solution iron might be interesting. This is
why the materials need to be further investigated in a later stage. The physical resistance
calculations are of highest importance for the scaffold.
The flue gas passage can be seen in Figure 27. Air enters the combustion chamber, passes
through the flue gas path, where the pots are placed, and leaves through the chimney. To create a
good draft throughout the construction the aim was to maintain a constant cross sectional area
[113]. This means the area should be the same throughout the combustion chamber, flue gas
passage and chimney, independent on the geometrical form. For MAYA this cross sectional area
was determined to be is 154 cm2 [106].
Figure 27. The inner design of MAYA with combustion chamber, flue gas passages, pot holes and chimney
Maintaining constant cross sectional area throughout the entire flue gas passage resulted in the
gap size, pot to pot hole, to be 34 mm. This can be seen in Figure 28 and also applies on the
44
distance between the pot bottom to bottom of the pot hole. Further the passages between the two
pot holes and pot hole to chimney also needed to be included in the constant cross sectional area
which formulated this to a rectangular passage with the dimensions 109 x 141 mm. The aim, as
said before, was to maintain this area constant. In MAYA the cross sectional area is in the
interval of 153.7 - 155.7 cm2 which makes the assumption of a good draft valid.
Figure 28. The dimensions of the flue gas path and gap size to maintain the cross sectional area constant
It was shown that Bolivia had a good posibility to manufacture a stove because their well equiped
workshops, for example the existing UMSS workshop visited by the authors March 2016. The
production volume capacity and their possibilities to assembly should be investigated in further
work.
4.2 Pricing The suggested price of the MAYA stove without the SE could possibly be around 60 - 89 USD
when looking at other improved cook stoves. Comparing this with the price for Malena of 45
USD the price could be considered as possible to overcome for at least some rural people since
the grid connection cost as well as monthly electricity cost will be excluded. The produce and
sale the product for this price the production volumes has to be optimized and Design for
Assembly (DFA) have to be seriously regarded.
The big problem with the price is connected to the Stirling engine since the wanted one is not on
the market and bigger ones are in a price ranges far away from the price reasonably to pay the
given electricity outcome for a rural family. Due to this the development of the Stirling engine is
fundamental for how the realization of the stove is possible.
45
4.3 Requirement specification The MAYA is a design needed to be tested and can therefore not be truthfully evaluated to the
requirement specification. The restrictive requirements need to be further investigated but the
functional requirements can be analyzed and the following requirements are fulfilled with the
current MAYA design:
The size of the stove shall be customized for a family of five.
The stove shall have a solution for easy removal of ashes.
The fire shall not be in direct contact with the pot.
The stove shall have minimum two pots.
The airflow inside the stove shall be ideal.
An electricity generating engine shall be integrated in the stove.
The stove shall be adapted for burning fuel wood.
The stove shall satisfy the rural culture and cooking habits.
The stove shall be designed for a standing position for an average woman in Bolivia
Dimensions of the stove shall not be bigger than 3 x 1 m.
The QFD showed that the safety for the user is a highly weighted and then important
requirement. For the stove surface to not exceed 52 °C testing and modeling whit insulation
thickness is necessary. With the right insulation material and thickness the construction can fulfill
this requirement. Another highly weighted quality regarding the QFD, is the stove having the
right height for a Bolivian woman to use it. As seen in the list above this is fulfilled. Regarding
that the Stirling engine should have the capacity of 100 W and the chosen engine has a capacity
of 95 W is one of the restrictive requirements MAYA does not achieve. Finding the right engine
for the stove depends on the development and commercialization of free piston Stirling engines
with electrical output around 100 – 200 We.
The thermal- and overall efficiency cannot be evaluated without a physical model and are further
crucial for the stove to be successful or not, both regarding the QFD but also WHO and Global
Alliance for Clean Cookstoves. Due to this the efficiencies shall play a central role in further
development.
46
5 Conclusion and Further work This final chapter presents conclusion and further work.
Conclusion Cooking with traditional stoves occupy a large amount of time in families of the developing
world’s everyday life. Not only time spending on cooking food because of the stoves bad thermal
efficiency but also the time it takes to collect the fuel. These factors together with the pollution
the stoves emit that contributes to health issues and even premature deaths creates an obstacle for
the families to be integrated in the developed world. Electricity access is another crucial aspect in
order for a country to develop. Therefore existing improved cook stoves with integrated
electricity source can be seen successfully implemented in developing countries, most frequently
in Africa. These cook stoves usually use TEG technology and are good indicator that a market
exist for a biomass stove integrated with a Stirling engine.
The difficulties in designing an improved cook stove are the complex calculations regarding
combustion processes, flue gas passages and the economic aspects. These factors determine the
complexity of cook stove design and must be tested through a physical model via trial and error.
This does, understandably, formulate difficulties in the early design process since it is only
possible to formulate qualified guesses. Therefore the specific objective number 2, combustion
process in the developed stove shall be complete and the objective number 5, to investigate the
economical limitation for the stove in order to make it accessible, needs to be investigated in
further work after the model testing has been done.
If the MAYA stove should be able to fulfill its purpose the Stirling engine must be available to a
reasonable price. The price limitation also applies to the stove construction and the battery.
5.1 Further Work MAYA is a design draft, which is why further work and most central physical model testing needs to be done before the stove can become reality. Vital parts of the further work are described in a list below.
- Experimental testing of the flue gases path inside the stove together with a full evaluation
of the heat losses
- Formulate exact dimensions for the stove components
- Decide exact placement of the Stirling engine after thermal testing is done
- Investigate the need and possibilities to integrate an oven in the stove
- Investigate the possibility to integrate a fan to improve the combustion
47
- Optimize material thicknesses and investigate the most suitable material including
insulation materials, scaffold materials and stove body materials
- Analyze the stove price
- Investigate the information and integration program for the stove
- Optimizing the construction assembly of the stove and investigate the manufacturing
possibilities
48
References [1] Conversor Monidas – “ Conversor de monedas gratuito y preciso” [Online] Available: http://conversormonedas.co/ [Accessed: 30-05-2016]
[2] World Health Organization (WHO), “Household air pollution and health, Fact sheet No. 292” [Online]. Available: http://www.who.int/mediacentre/factsheets/fs292/en/ [Accessed: 2015-09-24] 2016
[3] Heltberg “Factors Determining Household Fuel Choice in Guatemala.” Environment and Development Economics 10 (03): 337-36120052005.
[4] International Energy Agency (IEA), “Modern energy for all” [Online] Available: http://www.worldenergyoutlook.org/resources/energydevelopment/[Accessed: 2016-02-29] 2016
[5] María Teresa Solis-Soto, Armando Patiño, Dennis Nowak, Katja Radon, “Association between environmental factors and current asthma, rhinoconjunctivitis and eczema symptoms in school-aged children from Oropeza Province – Bolivia: a cross-sectional study” Solis-Soto et al. Environmental Health, 12:95 [Pg 4-7] October 2013.
[6] Maria Hallberg, Elin Hallme, “Energy demand in different topographical zones: A field study about the domestic energy demand in the rural areas of Bolivia“ Bachelor of Science thesis, Department of Energy Technology, Royal Institute of Technology, Stockholm, Sweden [Pg. 11-12; 16-20; 22-25; 27-29; 31-35; 38-64; 66] July 2015. Available: http://www.diva-portal.org/smash/get/diva2:838985/FULLTEXT01.pdf
[7] Makoto Kanagawa, Toshihiko Nakata ”Analysis of the energy access improvements and its socio-economic impacts in rural areas of developing countries” Management of Science and Technology Department, Tohoku University, Aoba-Yama 6-6-11-815, Sendai, 980-8579, Japan. [Pg. 319-321, 326-328] July 2006.
[8] The World Bank “About Development” [Online] Available:http://web.worldbank.org/WBSITE/EXTERNAL/EXTCHINESEHOME/EXTFAQSCHINESE/0,,contentMDK:20147486~pagePK:283622~piPK:3544780~theSitePK:3099031,00.html[Accessed: 2016-04-06] June 2012
[9] Sullivan, Arthur; Steven M. Sheffrin “Economics: Principles in Action”, Upper Saddle River, New Jersey 07458: Pearson Prentice Hall. [Pg 471]. ISBN0-13-063085-32003.
[10] International Energy Agency (IEA), “World Energy Outlook 2015 Factsheet: Global energy trends to 2040” 2015.
[11] United Nations General Assembly“ Resolution adopted by the General Assembly on 25 September 2015: Transforming our world: the 2030 Agenda for Sustainable Development” [Pg. 1, 14] October 2015.
49
[12] The United Nations’ inter-agency mechanism on energy (UN-Energy Knowledge Network), “Energy access” [Online] Available: http://www.un-energy.org/cluster/energy_access[Accessed 15-03-2016]
[13] Bhawani Venkataraman, “Education for Sustainable Development” Environment: Science and Policy for Sustainable Development, 51:2, 8-10, DOI: 10.3200/ ENVT.51.2.08-10 [Pg 8-10] August 2010.
[14] Peter Meier, Voravate Tuntivate, Douglas F. Barnes, Susan V. Bogach, Daniel Farchy, “Peru: National survey of rural household energy use”, Energy and poverty: Special report 007/10 [Pg. 19-21; 49; 54] August 2010
[15] Makoto Kanagawa, Toshihiko Nakata, “Assessment of access to electricity and the socio-economic impacts in rural areas of developing countries” Department of Management Science and Technology, Graduate School of Engineering, Tohoku University Aoba-Yama 6-6-11-815, Sendai 980-8579, Japan. [Pg. 2016: 2026-2027] April 2008
[16] Suani T.Coelho, José Goldemberg, “Energy access: Lessons learned in Brazil and perspectives for replication in other developing countries” CENBIO, National Reference Center on Biomass, Institute of Eletrotechnics and Energy, University of São Paulo. [Pg. 1088-1091; 1094-1095]. June 2013
[17] Universitets- och högskolerådet ”Linnaeus-Palme Partnerskap” [Online] Available: http://www.utbyten.se/sv/Program/Program-A---O/Linnaeus-Palme-partnerskap/ [Accessed 28-03-2016] September 2015
[18] Bangchun Wen, Xuejun Wang, Jishuang Dai, Xingguo Ma, Zhaohui Ren, Xiaopeng Li, Xiaomei You, Jie Liu, Yang Liu, “New development of product design methodology” Advanced Materials Research Trans Tech Publications, Switzerland ISSN: 1662-8985, Vols. 308-310, [Pg. 148-149] August 2011
[19] Naturvårdsverket,”Naturvårdsverkets föreskrifter om utsläpp till luft av svaveldioxid, kväveoxider och stoft från förbränningsanläggningar med en installerad tillförd effekt på 50 MW eller mer” Konsoliderad version av NFS 2002:26 October 2002.
[20] International renewable energy agency (IRENA) “The importance of modern bioenergy for meeting global renewable energy targets” Remap 2030 [Pg. 1]
[21]World Energy Council, “World Energy Resources - 2013 Survey” ISBN: 978 0 946121 29 8 [Pg. 287]
[22] The United Nations’ inter-agency mechanism on energy (UN-Energy Knowledge Network), “Target 7.2 – Renewable Energy” [Online] Available: http://www.un-energy.org/cluster/renewable_energy[Accessed: 15-03-2016]
[23] The Energy and Resources Institute (TERI)“TERI Energy Data Directory Yearbook 2009”ISBN: 978-81-7993-243-8 [Pg. 392] 2009
50
[24]International Renewable Energy Agency (IRENA), International Energy Agency (IEA), Energy Technology Systems Analysis Programme (ETSAB),“Biomass for Heat and Power: Technology Brief “ [Pg. 5] January 2015
[25] International Energy Agency (IEA), “World Energy Outlook 2010” ISBN: 978-92-6408-624-1, 2010
[26] Efstathios E. (Stathis) Michaelides “Alternative energy sources” Green energy Thechonology ISBN: 978-3-642-20950-5 [Pg. 287, 289] 2012
[27] S.C. Bhattacharya, P. Abdul Salam, “Low greenhouse gas biomass options for cooking in the developing countries” Energy program, Asian Institute of Technology, School of environment, Resources and Development, [Pg. 305-306] January 2002
[28] Global Alliance for Clean Cookstoves, “Igniting Change : A Strategy for Universal Adoption of Clean Cookstoves and Fuels” November 2011
[29] United Nations Framework Convention on Climate Change “Adoption of the Paris Agreement- proposal by the President” [Pg. 22] December 2015
[30] Michael Gane, “Forest strategy - Strategic Management and Sustainable Development for the Forest Sector” ISBN: 978-1-4020-5964-3 [Pg. 5] 2007.
[31] World Energy Council “World Energy Resources: 2013 Survey” ISBN: 978-0-946121-29-8 [Pg. 287] 2013
[32] Energy KTH CompEdu “S4 Combustion and Fuel Conversion” [Online] Available: http://www.energy.kth.se/compedu/webcompedu/WebHelp/S4_Combustion/B1_Combustion_Basics/C1_Introduction_to_Combustion/ID35_files/Lower_calorific_value.htm [Accessed: 04-05-2016]
[33] Erika Johnels, Sara Murray, “Performance Evaluation of the Fire Pipe Cookstove with focus of its Product Development” KTH School of Industrial Engineering and Management [Pg. 18] 2013
[34] Energética, ONUDI, “Cambio Climático Agua y Energía en Bolivia” [Pg. 23] September 2012
[35] Thomas E, Douterlungne D, Vandebroek I, Goetghebeur P, Van Damme P, “Human impact on wild firewood species in the Rural Andes community of Apillapampa, Bolivia” Laborator [Pg. 1]
[36] U.S Energy Information administration (EIA) “Analysis, Bolivia” [Online] Available: http://www.eia.gov/beta/international/analysis.cfm?iso=BOL [Accessed: 20-02-2016] July 2015
[37] Ministerio de hidrocarburos & Energía “Rendición Pública de Cuentas Final 2013 e Inicial 2014” [Pg. 3]
51
[38] Programa Electricidad para Vivir con Dignidad “Programa de Electrificación Rural (PER-BID)” http://www.pevd.gob.bo/pevd/resultados/programasyproyectosenejecucion [Accessed: 23-05-2016] May 2016
[39] Susan Wacaster, “The mineral industry of Bolivia” United States Geological Survey (USGS) [pg 3.1] January 2016
[40] European Commision “EUROPEAN LED QUALITY CHARTER - An initiative promoted by the European Commission Joint Research Centre” Renewable Energy Unit [Pg. 4] February 2011
[41] Mario Pansera “Renewable energy for rural areas of Bolivia” University of Exeter Buisiness School [Pg. 6695] October 2012
[42] Fernández, M. “Energías Renovables para el Acceso Universal a la Electricidad, de la Población Rural Dispersa de Cochabamba” Energética, March 2013
[43] The World Bank “Bolivia Overview” [Online] Available: http://www.worldbank.org/en/country/bolivia/overview#1[Accessed: 24-02-2016] September 2015
[44] Doro AB “Doro PhoneEasy 609” [Online] Avalible: http://www.doro.se/mobile-devices/easy-phones/doro-phoneeasy-609.html [01-05-2016] 2015
[45] The World Bank “Poverty headcount ratio at national poverty lives (% of population)” [Online] Available: http://data.worldbank.org/indicator/SI.POV.NAHC[Accessed: 19-02-2016] 2016
[46] Green building advisor “The stack effect: When buildings act like chimneys” [Online]
Available: http://www.greenbuildingadvisor.com/stack-effect-when-buildings-act-chimneys [Accessed: 23-05-2016] October 2015
[47] Fönster Fukt & Innemiljö – SP Sveriges Tekniska Forskningsinstitut “Luftrörelser: Temperaturens inverkan - skorstensverkan” [Online] Available: http://energy.extweb.sp.se/ffi/luftrorelser.asp [Accessed 23-05-2016] December 2011
[48] World Health Orgaization (WHO), “Health Topics: Poverty” [Online] Available: http://www.who.int/topics/poverty/en/[Accessed: 22-02-2016] 2016
[49] GIZ HERA, “Cooking Energy Compendium: Cooking with firewood” [Online] Available: https://energypedia.info/wiki/Cooking_with_Firewood Cooking energy Consumption [Accessed: 24-02-2016] September 2015
[50] Youssef Boulkaid, “Quantifying the Potential Impact of Improved Stoves in Nyeri County, Kenya ” Master of Science thesis, Department of Renewable Energy Technologies, Royal Institute of Technology, Stockholm, Sweden, [Pg. 1, 2, 5, 9, 13, 22, 24, 34] Available: http://www.diva-portal.org/smash/get/diva2:784198/FULLTEXT01.pdf
52
[51] Miranda, V. “Cooking, Caring and Volunteering: Unpaid Work Around the World” OECD Social, Employment and Migration Working Papers, No 116 [Pg. 30] February 2011
[52] Paul H. Riley“Affordability for sustainable energy development products” The University of Nottingham, Department of Electrical and Electronic Engineering [Pg. 309] July 2014
[53] J-Pal Abdul Latif Jameel, Poverty Action Lab “Up in Smoke” Policy Briefcase [Pg. 3] July 2012
[54] Karin Troncosco, Alicia Castillo, Omar Masera, Leticia Merino, ”Social perceptions about a technological innovation for fuelwood cooking: Case study in rural Mexico” Uniersidad Nacional Autónoma México [Pg. 0-1] January 2007
[55] Alan Kai-ming Au, Peter Ederwick, “A cognitive model on attitude towards technology adoption – Enderwick” The Open University of Hong Kong, Waikato University [Pg. 267-271] June 1999
[56] Amanda L. Logan, Christine A. Hastorf and Deborah M. Pearsall “Let’s drink together: Early ceremonial use of maize in the Titicaca basin” Society for American Archaeology Vol. 23, No. 3 [Pg. 236] September 2012
[57] Cocina Boliviana “Chicha de Maiz” [Online] Available: http://www.cocina-boliviana.com/recetas/5_entradas/173_chicha-de-maiz [Accessed: 18-03-2016]
[58] Gorritty, Marcelo Ing. at Stove Testing Center La Paz, Universidad Mayor de San Andrés (UMSA). Personal contact: 2016-03-22
[59] Cambridge dictionaries online, “Stove” [Online] http://dictionary.cambridge.org/dictionary/english/stove[Accessed: 4-03-2016] 2016
[60] Dr. Mark Bryden, Dean Still, Peter Scott, Geoff Hoffa, Damon Ogle, Rob Bailis, Ken Goyer, “Design Principles for Wood Burning Cook Stoves” Aprovecho Research Center Shell Foundation Partnership for Clean Indoor Air [Pg: 5, 12, 14-15]
[61] Kavita Rai, Jeveta McDonald, “Cookstoves and Markets: Experiences, Successes and Opportunities: Accelerating access to energy” GVEP international [Pg 24-25] December 2009.
[62] Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), “Malena Stove Sheet: Bolivia”
[63] Energising Development “Energy to Cook” [Online] Available: http://www.endev-bolivia.org/en/cook-stoves [Accessed: 11-04-2016]
[64] Stirling International “Stirling Engine: Inventor” Available:http://www.stirlinginternational.org/docs/presentations/robert_stirling.asp [Accessed: 2-02-2106]
[65] Joseph Adhemar Araoz Ramos, “Thermodynamic analysis of Stirling engine systems: Applications for combined heat and power”KTH School of Industrial Engineering and Management ISBN: 978-91-7595-498-1 [Pg. 8-9, 19, 22, 23] 2015
53
[66] Carlos Gaitan, “Rural electrification in Bolivia through solar powered Stirling engines” KTH School of Industrial Engineering and Management [Pg. 8] 2014
[67] I. Obernberger, H. Carlsen, F. Biedermann, “State of the art and future developments regarding small-scale biomassCHP systesm with a special focus on orc and Stirling Engine technologies” International Nordic Bioenergy Conference 2003, 2003
[68] Rolj Öberg, Fredrik Olsson, Magnus Pålsson,“Demonstration Stirling Engine based Micro-CHP with ultra-low emissions” Svenskt Gastekniskt Center Mars 2004
[69] Erich Podesser, “Electricity Production in Rural Villages with a Biomass Stirling Engine” Joanneum Research, Institute of Energy Research 1998.
[70] F. Formosa, G. Despesse, “Analytical model for Stirling cycle machine design”Laboratorie SYMME Université de Savoie, Laboratoire Capteurs Actionneurs et Récupération d’Energie [Pg. 1855] March 2010
[71] Nicolae Badea, “Design for Micro-Combined Cooling, Heating and Power Systems – Stirling Engines and Renewable Power Systems” Green Energy and Technology ISBN: 978-1-4471-6253-7 [Pg. 4, 39, 71] 2015
[72] Ohio University “Stirling Cycle Machine Analysis: Chapter 2b - Beta Type Stirling Engines” [Online]
Avalible: https://www.ohio.edu/mechanical/stirling/engines/beta.html [Accessed: 06-05-2016]
[73] Me Mechanical “Stirling Cycle” [Online] Available: http://me-mechanicalengineering.com/stirling-cycle/ [Accessed: 24-03-2016] 2016
[74] Hans Havtun, “Applied Thermodynamics – Collection of Formulas” ISBN: 978-91-633-7727-3 [Pg. 11-13] March 1997
[75] Stirling Engine “The Operating Principles of a Stirling Engine” [Online] Available:http://www.robertstirlingengine.com/principles.php [Accessed: 3-02-2016]
[76] D.G. Thombare, S.K. Verma “Technological developmet in the Stirling cycle engines” Department of Mechanical Engineering, Rajarambapu Institute of Technology, Babasaheb Ambedkar Technological University [Pg. 27-29] July 2006
[77] Dr. Joseph Adhemar Araoz Ramos, Universidad de San Simon (UMSS), Cochabamba. Personal contact: 22-02-2016
[78] Maxwell H. Briggs“Improving Free-Piston Stirling Engine Specific Power”Glenn Research Center, Cleveland, Ohio. NASA [Pg. 1] June 2015.
[79] Günter R. Simader, Robert Krawinkler, Georg Trnka, “Micro CHP systems: state-of-the-art” European Commission [Pg. 2] March 2006
[80] Aerospace Research Central (ARC) “160 W Dual Opposed Stirling Engine Power Source for Military Applications” [Online] Available: http://arc.aiaa.org/doi/abs/10.2514/6.2006-4039 [Accessed: 29-02-2016] 2015
54
[81] Sunpower “Military Portable Power” [Online] Available:http://sunpowerinc.com/engineeringservices/applications/military/ [Accessed: 29-03-2016] 2016
[82] Sunpower “High Performance Free-Piston Stirling Engines- Experience the Benefits of Unique Free-Piston Stirling Technology” Sunpower Inc 2005 [Pg. 2-3]
[83] Cleanergy “Stirling CSP Systems” [Online] Available: http://cleanergy.com/solutions/#csp-systems [Accessed: 29-03-2016] 2015
[84] Qnergy, “Micro-CPC System” [Online] Available: http://www.qnergy.com/-micro-chp-system[Accessed: 29-03-2016]
[85] Vollrad Kuhna, Jíri Klemesb, Igor Bulatovb,“MicroCHP: Overview of selected technologies, products and field test results” Berliner Energieagentur GmbH, Centre for Process Integration CEAS, The University of Manchester [Pg. 2041] February 2008
[86] Solpaneler.nu ”Dimensionering” [Online]
Available: http://www.solpaneler.nu/?q=node%2F4 [Accessed: 15-04-2016] 2012
[87] Lego Elektronik ”Dimensionering av solenergianläggning” [Online] Available: http://www.legoelektronik.se/dimensionering-solenergi [Accessed: 15-05-2016] 2011
[88] Smart Battery Power by Lithium “Products: 12V 25AH Lithium Ion Battery” [Online] Available: http://www.lithiumion-batteries.com/products/12v-25ah-lithium-ion-battery/ [Accessed: 14-04-2016] 2015
[89] Amazon “Battery Tender BTL35A480C Lithium Iron Phosphate Battery” [Online] Available: http://www.amazon.com/Battery-Tender-BTL35A480C-Lithium-Phosphate/dp/B00F9LPL5E/ref=sr_1_7?ie=UTF8&qid=1464021540&sr=8-7&keywords=lithium+ion+battery#productDetails [Accessed: 23-05-2016] January 2015
[90] AliExpress “12V 25000MAH 25AH Lithium ion Rechargeable Batteries for Power Bank with Free Charger,5V USB Buck Converter,DIY Connector“ [Online]
Available: http://www.aliexpress.com/item/Universal-Power-Bank-25000MAH-Li-polymer-12V-25AH-Lithium-ion-Batteries-Pack-Portable-with-Free-Charger/32363638287.html [Accessed: 23-05-2016]
[91] The Battery Shop UK Ltd “52515 Yuasa Motorcycle Battery 12v 25Ah” [Online] Available: http://thebatteryshop.co.uk/52515-yuasa-motorcycle-battery-12v-25ah-1393-p.asp [Accessed 24-05-2016]
[92] Trinity College Dublin, Department of Mechanical and Manufaturing Engineering “The µPower stove generator ”[Online] Available: http://www.tcd.ie/mecheng/research/fluids-heat-transfer/projects/stove.php [Accessed: 7 March 2016]
55
[93] Indiegogo “The µPower cookstove” [Online] Available: https://www.indiegogo.com/projects/the-power-cookstove#/story [Accessed: 7-03-2016]
[94] Zhiqiang Niu, Shuhai Yu, Hai Diao, Qianshan Li, Kui Jiao , Qing Du, Hua Tian, Gequn Shu, “Elucidating modeling aspects of thermoelectric generator” State Key Laboratory of Engines, Tianjin University, 92 Weijin Rd, Tianjin 300072, China [Pg. 12-13] February 2015
[95] TEGSTOVE by Tegology [Online]
Available: http://www.tegology.com [Accessed: 8-03-2016] 2016
[96] BioLite “CampStove” [Online] Available: http://www.bioliteenergy.com/products/biolite-campstove [Accessed: 15-03-2016] 2016
[97] The New York Times Blog Gadgetwise “Dead phone battery? Just burn something” [Online] Available: http://gadgetwise.blogs.nytimes.com/2012/11/06/biolite-stove/?_r=0 [Accessed: 15-03-2016] November 2012
[98] Kayake Dave “BioLite Camp Stove Rewiev” [Online] Available: http://kayakdave.com/2012/12/03/biolite-camp-stove-review/ [Accessed: 15-03-2016] December 2012
[99] Score research “How it works” [Online] Available: http://www.score.uk.com/research/default.aspx [Accessed: 14-03-2016]
[100] Peter H. Ceperley “A pistonless Stirling engine—The traveling wave heat engine”, Department of Physics, George Medson University, Virginia 22030 [Pg. 1508] May 1979.
[101] Kees de Blok, “On the design of near atmospheric air operated thermoacoustic engines: Blue print for a simple, reliable and low cost heat driven thermoacoustic generators for rural areas producing 20-50W electric power” ASTER thermoacoustics [Pg. 4-6] December 2013
[102] Researchgate “Cross section view of a single TAE design” [Online] Available: [https://www.researchgate.net/figure/257043121_fig4_Figure-4-Cross-section-view-of-a-single-TAE-design [Accessed: 27-4-2016] September 2013
[103] KTH intranät “Att skriva en kravspecifikation” [Online] Available: https://intra.kth.se/administration/upphandling/upphandlingar-over-direktupphandlingsgransen/att-skriva-kravspecifikation-1.533512 [Accessed: 23 may 2016] January 2015
[104] David G. Ullman, “The Mechanical Design Process” Oregon State University ISBN: 978-0-07-297574-1 [Pg. 149, 222, 315-317, 321, 322, 328] 2010
[105] Solid Egde ST7, 2015, Siemens PLM Software [Software]
[106] Nicholas H. Schreiner, “Performance characteristics and design recommendation for biomass-burning stoves using earthen construction materials” Michigan Technological University [Pg. 6, 29] 2011.
56
[107] Baldwin, Samuel F. “Biomass Stoves: Engineering Design, Development, and Dissemmanations” Center for Energy and Environmental Studies, Princeton University, ISBN 0-86619-274-3 [Pg. 44, 55, 79-81] 1987
[108] Milind P. Kshirsagar, Vilas R. Kalamkar St Vincent Pallotti “A comprehensive review on biomass cookstoves and a systematic approach for modern cookstove design”. College of Engineering and Technology, Visveswaraya National Institute of Technology [Pg. 587]. November 2013
[109] Clean Cooking Catalouge ”100 liter institutional cook stove” [Online] Available: http://catalog.cleancookstoves.org/stoves/1[Accessed: 25-04-2016]
[110] InStove ”60 and 100 liter institutional cook stove” [Online] Available: http://www.instove.org/60-100-liter-cookstove [Accessed: 13-05-2016]
[111] Partnership for Clean Indoor Air ”Test Results of Cook Stove Performance” Aprovecho Research Center [Pg 26-27]
[112] IKEA“IKEA 365+ gryta med lock, rostfritt stål, glas” [Online] Avaiable: www.ikea.com/se/sv/catalog/products/10256750/ [Accessed: 30-05-2016] 2016.
[113] Dr. Mark Brydeen, Dean Still, Damon Ogle, Nordica MacCarty “Designing improved wood burning heating stoves” Aprovecho Research Center, Advanced studies in Appropriate Technology [Pg. 5-6, 55-56]
[114] AK steel cooperation “301 Stainless steel: Product data bulletin” West Chester Revision 12.20.12 [Pg. 1]
[115] Nickel alloys “Nickel alloys – stainless steels, nickel copper alloys, nickel chromium alloys, low expansions alloys and magnetic alloys” [Online] Available: www.nickel-alloys.net/nickelalloys.html [Accessed: 21-05-2016)
[116] Yunus A. Cengel, Afshin J. Ghajar “Heat and Mass Transfer – Fundamentals and Applications” Mc Graw Hill Education Fourth Edition ISBN: 978-1-259-25377-5 [Pg. 20] 2011
[117] Dragon heater blogg “Burning wood - Insulation Material Choices” [Online] Available: http://blog.dragonheaters.com/burning-wood-insulation-material-choices/ [Accessed: 5-05-2016] July 2013
[118] The Engineering ToolBox “Thermal Conductivity of some common materials and gases” [Online] Available: http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html [Accessed: 5-05-2016]
[119] Thermaxx Jackets “5 most common thermal materials” [Online] Available: http://www.thermaxxjackets.com/5-most-common-thermal-insulation-materials/ [Accessed: 5-05-2016] June 2011
[120] Bulding Component Library “Glass fiber - Organic Bonded 1 in” [Online] Available: https://bcl.nrel.gov/node/34590 [Accessed 4-05-2016]
57
[121] The vermiculite association “What is vermiculite” [Online] Available: http://www.vermiculite.org/resources/vermiculite [Accessed: 23-05-2016]).
[122] Arnold O. Tanner “Vermiculite” U.S. Geological Survey, Mineral Commodity Summaries [Pg.178-179] January 2015
[123] Minerals educations cationcoalition “Perlite” [Online] Available: https://www.mineralseducationcoalition.org/minerals/perlite [Accessed: 23-05-2016]
[124] The Perlite Institute “Home” [Online] Available: https://www.perlite.org [Accessed: 23-05-2016]
[125] Vista Industrial Products, INC “Sheet metal” [Online] Available: www.vista-industrial.com/sheet-metal.php [Accessed: 17-05-016] May 2016
[126] British stainless steel association “The basics about stainless steel” [Online] Available: http://www.bssa.org.uk/about_stainless_steel.php [Accessed 17-05-2016] 2007
[127] Azo Materials “Stainless steels – introduction to the grades and families” [Online]
Available: http://www.azom.com/article.aspx?ArticleID=470 [Accessed: 17-05-2016] February 2015
[128] Sandvik "High-temperature stainless steels" [Online] http://smt.sandvik.com/en/products/tube-pipe-fittings-and-flanges/high-performance-materials/high-temperature-stainless-steels/ [Accessed 24-05-2016]
[129] Sandvik "Sanicro 31HT high-temperature stainless steel” [Online] Available: http://smt.sandvik.com/en/products/tube-pipe-fittings-and-flanges/high-performance-materials/high-temperature-stainless-steels/sanicro-31ht/ [Accessed 24-05-2016]
[130] Sandvik "Sandvik 253MA high-temperature stainless steel " [Online] Available: http://smt.sandvik.com/en/products/tube-pipe-fittings-and-flanges/high-performance-materials/high-temperature-stainless-steels/sandvik-253-ma/ [Accessed 24-05-2016]
[131] Atlas Steel ”Look no further for the world’s best source for aluminized steel” [Online] Available: http://www.atlassteel.com/products/aluminizedSteel.aspx [Accessed: 17-05-2016] 2016
[132]Oneal Steel “ASTM A463 Aluminized steel” [Online] 2016 Available: http://www.onealsteel.com/carbon-steel-sheet-aluminized-a463.html[Accessed: 17-05-2016] 2016
[133] AK steel cooperation “Aluminized type 1 steel” West Chester 06.18.14 [Pg. 1-3] June 2014
[134] Dean Still, Nordica MacCarty “Cooking with less fuel: Breathing with less smoke” Aprovecho Research Center, Advanced Studies in Appropriate Technology Laboratory (pg. 19).
[135] Avg.Heigh “Average female height by country” [Online] Available: http://www.averageheight.co/average-female-height-by-country/ [Accessed: 14-05-2016]
58
[136] Isabelle Gadré, Johanna Maiorana, “Price model of the Stirling engine” Bachelor of Science thesis, Department of Energy Technology, Royal Institute of Technology, Stockholm, Sweden [Pg. 18, 22] 2014 Available: http://www.diva-portal.org/smash/get/diva2:735271/FULLTEXT01.pdf [137] Sapa “Profiles in stock: Standard catalogue” Sapa profiles [Pg. 6] 2016
[138] Alfer “5. Profiles for DIY and professional purposes: Hardware catalogue” [Pg. 5.32] October 2008
[139] Sapa group ”Aluminiums egenskaper” [Online] Available: www.sapagroup.com/sv/common-information/sections-in-top-of-all-pages/den-grona-metallen/aluminiums-egenskaper/ [Accessed: 25-05-2016]
[140] Sälja skrot “Skrotpriser – metaller och metallpriser” [Online]
Available: http://www.säljskrot.se/metaller/ [Accessed: 25-03-2016]
[141] Clean Cookstove Catalog “Philipd HD4012” [Online]
Available: http://catalog.cleancookstoves.org/stoves/47 [Accessed: 30-04-2016]
[142] Clean Cookstove Catalog “Gamma1411” [Online]
Available: http://catalog.cleancookstoves.org/stoves/391 [Accessed: 30-04-2016]
[143] Burnstoves “Jikokoa” [Online]
Available: http://www.burnstoves.com/stoves/ [Accessed: 5-05-2016]
[144] Clean Cookstove Catalog “Jikokoa” [Online]
Available: http://catalog.cleancookstoves.org/stoves/214 [Accessed: 30-05-2016]
[145] Clean Cookstove Catalog “Prakti Double Pot Woodstove” [Online]
Available: http://catalog.cleancookstoves.org/stoves/214 [Accessed: 30-05-2016]
[146] Biomass Stove Testing Lab, “Research on stove for cooking, refrigeration and electricity (Score) Sofo Project” [Online] Available: http://ku.edu.np/bstl/?p=172 [Accessed: 14-03-201]
[147] Clean Cookstove Catalog “Malena” [Online]
Available: http://catalog.cleancookstoves.org/stoves/431 [Accessed: 30-05-2016]
[148] World Health Organization (WHO) “WHO Guidelines for Indoor Air Quality: Household Fuel Combustion” World Health Organization. ISBN 978 92 4 154888 5. [Pg. 34] 2014
[149] European Commission “Air Quality Standards” [Online]
Avalible: http://ec.europa.eu/environment/air/quality/standards.htm [Accessed: 29-03-2016] November 2015
59
[150] omBoende.se “Varmvattnets temperatur” [Online] Available: www.omboende.se/sv/Hyra/Varmvattnet-ska-vara-5060-C/ [Accessed: 29-03-2016] March 2013
[151] Ricardo Billarroel Camacho, Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), Cochabamba. Personal contact:09-03-2016
Appendix 1 Sustainable Development Goals
Goal 1. End poverty in all its forms everywhere
Goal 2. End hunger, achieve food security and improved nutrition and promote sustainable agriculture
Goal 3. Ensure healthy lives and promote well-being for all at all ages
Goal 4. Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all
Goal 5. Achieve gender equality and empower all women and girls
Goal 6. Ensure availability and sustainable management of water and sanitation for all
Goal 7 Ensure access to affordable, reliable, sustainable and modern energy for all
Goal 8. Promote sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all
Goal 9. Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation
Goal 10. Reduce inequality within and among countries
Goal 11. Make cities and human settlements inclusive, safe, resilient and sustainable
Goal 12. Ensure sustainable consumption and production patterns
Goal 13. Take urgent action to combat climate change and its impacts*
Goal 14. Conserve and sustainably use the oceans, seas and marine resources for sustainable development
Goal 15. Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
Goal 16. Promote peaceful and inclusive societies for sustainable development, provide access to justice for all and build effective, accountable and inclusive institutions at all levels
Goal 17. Strengthen the means of implementation and revitalize the Global Partnership for Sustainable Development
*Acknowledging that the United Nations Framework Convention on Climate Change is the primary international, intergovernmental forum for negotiating the global [11].
Appendix 2 Stove Testing Center (CPC)
La Paz, 22 March 2016
A comparison of the successfully tested stoves in CPC. Some of the qualities is marked as “-”
which means information could not be found.
Name: Philips HD4012
Type: Portable
Fuel type: wood
Hot start thermal efficiency: 40.5 %
Cold start thermal efficiency: 36.2 %
Air flow: Fan
Pot: 1 pot placed on top
Cost: USD 89 [141]
Name: Gamma11411
Type: Portable
Fuel type: Wood
Hot start thermal efficiency: 41 %
Cold start thermal efficiency: 29 %
Air flow: Open ashtray
Pot: 2 pots placed on top
Cost: 60-80 USD [142]
Name: Jikokoa
Type: Portable
Fuel type: wood
Hot start thermal efficiency: 43 %
Cold start thermal efficiency: -
Air flow: Open trap
Pot: 1 pot placed on top
Cost: 40 USD [144]
Figure: [143]
Name: Prakti Double Pot Woodstove
Type: Portable
Fuel type: wood
Average thermal efficiency: 30.26 %
Air flow: Open ash trap
Pot: 2 pots placed on top
Cost: - [145]
Name: Malena
Type: Non portable, traditional
Fuel type: wood
Hot start thermal efficiency: 28 %
Cold start thermal efficiency: 22 %
Air flow: Open ash trap + chimney
Pot: 2 pots sunken in
Cost: 45 USD [147] [62]
Name: 60 liter institutional cookstove
Type: Non portable, institutional
Fuel type: Wood
Hot start thermal efficiency: 48.69 %
Cold start thermal efficiency: 48.09 %
Air flow: Open ash trap + chimney
Pot: 1 pot, sunken in [109]
Figure: [110]
Appendix 3 Cook stoves integrated with electricity producing source Pictures of improved cook stoves integrated with electricity source
µPower Cook stove
[92]
TEGSTOVE
[95]
BioLite
[96]
Score stove
[146]
Appendix 4 Requirement Specification Version 5, April 2016
Time frame This project is limited from 18th of January to 1th of June 2016.
Functional Requirements
Requirements
The size of the stove shall be customized for a family of five persons [62]
The combustion in the stove must be complete [5]
The stove shall have a solution for easy removal of ashes
The air flow inside the stove shall be ideal [60]
The fire shall not be in direct contact with the pot [60]
The stove shall have minimum two pots
The stove shall be designed for a standing position for an average woman in Bolivia [2]
An electricity generating engine shall be integrated in the stove
The engine shall be integrated with a battery
The stove shall satisfy the rural culture and cooking habits [54]
The stove shall be adapted for burning fuel wood [35]
Aspirations
The stove can handle different biomass fuel
Restrictive Requirements
Requirements
The lifetime of the entire stove concept shall be minimum of 10 years
The stove shall boil 5 liter of water in maximum 30 minutes [58]
The minimum thermal efficiency shall be 25 % [58]
Stirling engine shall maintenance interval of minimum 5000 hours [77]
Dimensions of the stove shall not be bigger than 3x1 m [62]
Not emit more than 0.035 µg/m3 per minute of PM10 to the indoor air [149]
The Stirling Engine shall have the capacity of minimum 100 W
The stove will need maximum 20 000 kJ to boil 5 l of water [58]
Emission rates from fuel combustion should not exceed 0.80 mg/min of PM2.5 (fine particles)
[148]
Emission rates from fuel combustion should not exceed 0.59 g/min of CO [148]
The outer temperature of the stove body shall not exceed 52 °C [150]
Appendix 5 Decision Matrix
Appendix 6 Pictures of improved cook stoves
[110]
Instove
Uganda2pot [111]
Appendix 7 Quality Function Deployment
Quality Characteristics
(a.k.a. "Functional
Requirements" or
"Hows")
Demanded Quality
(a.k.a. "Customer
Requirements" or
"Whats")
1 9 5,5 9,0
2 9 1,8 3,0
3 9 5,5 9,0
4 9 5,5 9,0
▼ Objective Is To Minimize
▼ Strong Negative Correlation
▲ Objective Is To Maximize
x Objective Is To Hit Target
┼
Ro
w #
Max
Relat
ions
hip
Valu
e in
Row
Relativ
e
Weigh
t
Weigh
t /
Import
ance
ΘEasy to install
▼
2
┼┼ ┼┼
▲
4
▼
┼
Θ
Boiling
time of
5 liter
water
Number
of pots
Column #
Direction of Improvement:
Minimize (▼), Maximize (▲), or Target (x) ▼
▲
Total
volume
Θ
Surface
area
temerat
ure
┼
┼┼
Θ
Ο
Ο
3
┼
Θ
▲
Number
of
remova
ble
parts
▼
1
Number
of
screwes
in the
stove
Easy to remove pots
Ο ΘEasy to maintain
▲Θ
▲
ΘEasy to clean ▲
▲
┼
5 6
▼▼
Title: House of Quality, Stove
Julia Kuylenstierna, Petra NasstromAuthor:
2016-03-18Date:
Notes:
Moderate Relationship
Weak Relationship
▬
┼
▲
3
9
Positive Correlation
Strong Positive Correlation
1
Negative Correlation
Θ
┼┼
Legend
Ο
Strong Relationship
┼
5 9 5,5 9,0
6 9 5,5 9,0
7 9 5,5 9,0
8 9 5,5 9,0
9 9 0,6 1,0
10 9 1,8 3,0
11 9 5,5 9,0
12 9 5,5 9,0
13 9 5,5 9,0
14 9 5,5 9,0
15 9 1,8 3,0
16 9 1,8 3,0
17 9 1,8 3,0
18 9 1,8 3,0
19 9 5,5 9,0
20 9 5,5 9,0
21 9 5,5 9,0
22 9 5,5 9,0
23 9 5,5 9,0
24
25
9
99,4
2,1
1
500
Easy to light the fire
Relative Weight
Target or Limit Value
Max Relationship Value in Column
Difficulty
(0=Easy to Accomplish, 10=Extremely Difficult)
Weight / Importance
Enough electricity output
▲
Θ
Ο
ΟΘ
ΟΘ
▲
▲
Ο
Accessable to buy for rural population
▲
Θ
44 cubic
meters 200%
4,9 5,83,96,15,6
2
9
262,0
9
2
9
226,4182,2
9
3
283,4
9
76
270,6
52
Celcius
30
minutes
Easy to take out ashes
Θ
Θ
Ο
▲
Ο
ΘΘ
ΟΘ
Standing cooking height
Ergonomic cooking position
Θ
Θ ΟΘ
▲
Ο Ο
Θ
▲ Ο
Room for two pots
The stove will not tip
Θ
Complete combustion
Minimisze indoor pollution
Easy to refuel firewood
Safe and accessable to stir in pots
Reliable electricity
Satisfy rural cooking habits
▲
Ο
Ο
Surface area will not be too hot
Inexpencive to buy
An oven
Θ
▲
▲
Efficient use of fuel wood Θ
Ο
ΘInexpencive to own
Ο Θ
▼
┼
┼
┼ ┼┼
┼┼
┼┼
┼
┼
▬
┼┼
┼
┼
┼┼
▬
┼
▼
▬
┼┼
┼┼
┼┼
┼ ▬
98 10
CO
emissio
n rate
7
▲
┼┼
┼┼
Stove
lifetime
┼┼
┼┼┼┼
Size of
the pots Price
13
▲ ▼
11 12
▲
Θ
┼┼┼
Θ
Θ
Surface
area
temerat
ure
Ο
▲
▲
Ο
▲
┼┼
6
▼
▲
Ο
Mass
centrum
in
centere
d
position
Θ
x
▲ Ο
Ο
▲
Hight of
the
stove
Θ
Ο
┼┼
15
┼
┼┼
▼
Size of
the
engine
Output
from the
engine
▲
Ο
Θ
Thermal
efficienc
y
14
┼ ┼┼
PM2.5
emissio
n rate
PM10
emissio
n rate
1918
Constan
t cross
sectiona
l area
for flue
gases
▼x
Stirling
engine
mainten
ance
interval
Ο
┼┼
┼┼
┼┼┼┼
┼┼
┼┼
┼┼
┼┼┼┼
20
▼
21
▲
17
┼┼
┼┼
▲
▲
Θ Ο ΘΟ
Ο
▲
16
x
Battery
capacity
Overall
efficienc
y
Θ
Ο
5,8 6,94,3
9
6,9
2
9
5,5 6,8
3 2
9
116,0322,7 314,7 198,8
4
322,7
99
254,0
Ο
Ο
Θ
Ο
Ο
4,3
Ο
Θ Θ
▲
Θ
6
0.035µg
/m3min
6
Θ
2,5
50000h
4,3
9
198,8
Θ
▲ ▲
▲
Θ
Θ
TRUE0.59
g/min
66
9
7
270,6
10
years
52
Celcius
9 9
▲
Θ
Θ
7
Θ
Ο
Ο
Θ
Θ
Ο
Ο Θ
Θ
▲ Θ
Ο
Ο
154 cm225%
0.80
mg/min35%
▲
▲
Θ
Θ Θ
▲
ΘΟ
ΘΘ
Θ Θ
265,0
5,7
Θ
Θ
20 dm3
198,8176,7
3,8
308,0
6,6
2
9
4,6
215,3
9
2
9
3
100 W70 cm200
USD
9
9
Θ
Θ
▲
Ο
25 000
mAh
3
Ο
Θ
▲ Θ Ο
▲
ΘΘ Θ
Θ
Θ
Θ
▲
Θ
Ο
Ο ▲
Θ
198,8110,4
2,4 4,3
▲
128,8
2,8
▲
9
▲
Θ
Ο
Θ
Θ
Θ
Θ
4
9
Θ
Ο
Θ
9
3 liters
Θ
ΘΟ
Θ Ο
Θ
Θ
Θ
▲
Ο
Ο
Θ
Θ
Θ
Θ
▲ ▲
Θ
Θ Ο ▲Ο
Θ
▲
0 1 2 3 4 5
22
Stirling
engine
mainten
ance
interval
21
▲
Θ
25
Competitive Analysis
(0=Worst, 5=Best)
23 24
0,8
1
1,2
2
9
116,0
Θ
Powered by QFD Online (http://www.QFDOnline.com)2,5
50000h
▲
▲
▲
0
0,2
0,4
0,6
0 1 2
Serie1
Serie2
Serie3
Serie4
Serie5
Serie6