2008

Jeff De Jong, Bethany Kortman, Jeena Velzen

Calvin College Engineering
12/12/2008
Re-Fueled
i


Executive Summary

The project goal is to design a simple low cost process to create fuel from waste material,
bringing justice to the people of Malawi by increasing the availability of fuel and reducing the
effects of deforestation. The fuel making process is low cost and simple to implement with the
intent of having wide adoption providing fuel, reducing waste, and creating jobs in developing
nations. Ideally, the design will be functional for paper products and other carbon based waste
such as agricultural waste.

The intended power source for this project is human work which incorporates design elements
such as gears and chains which can be scavenged from bicycles or other available materials in
the area, aiding in the cultural appropriateness of the design. By creating a people powered
process, the design will provide jobs for individuals within the context of the project with the
possibility of selling the fuel product for a profit.

As the feasibility study was carried out for this project, the device inputs were expanded past
waste paper to include a grass local to Malawi called sekera grass which is burned off the fields
at the beginning of each growing season. The initial design for the fuel processing device
implements human power transmitted through gears and chains to provide the power for
shredding the input materials, mixing the paper and grass with the binding agent, compressing
the materials into fuel briquettes, and drying the fuel product. The material shredding
component is a paper shredder, and the mixing component is a drum mixer. The compressing
component of the design is a screw extruder, and the drying component is a combination of a
solar heat collector and a blower.

Cost and process feasibility have been analyzed through research and experimentation for the
initial design and the project objectives. Through this analysis it was determined that the project
goals are feasible within the two budgets consideredthe Senior Design budget and the
Malawian budget. The design and construction of the prototype is expected to cost $225. The
product goals were also determined to be feasible in that a high quality fuel briquette can be
produced with the initial process and component design.

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Table of Contents

1 Introduction ............................................................................................................................... 1
1.1 Team Description ............................................................................................................... 1
1.2 Problem Statement .............................................................................................................. 2
2 Design Considerations ................................................................................................................ 3
2.1 Project Objectives ............................................................................................................... 3
2.1.1 Purpose of Design ....................................................................................................... 3
2.1.2 Cost ............................................................................................................................ 3
2.1.3 Reliability ................................................................................................................... 3
2.1.4 Scope .......................................................................................................................... 3
2.2 Design Norms ..................................................................................................................... 4
2.2.1 Stewardship ................................................................................................................ 4
2.2.2 Justice......................................................................................................................... 4
2.2.3 Cultural Appropriateness .............................................................................................. 4
2.2.4 Safety ......................................................................................................................... 4
3 Project Organization ................................................................................................................... 5
3.1 Schedule ............................................................................................................................ 5
3.1.1 List of Key Milestones, Fall Semester ........................................................................... 5
4 Feasibility Study ........................................................................................................................ 6
4.1 Fuel and Process Options .................................................................................................... 6
4.1.1 Material Input ............................................................................................................. 6
4.1.2 Fuel Product ................................................................................................................ 6
4.1.3 Process Options ........................................................................................................... 7
4.2 Components ....................................................................................................................... 8
4.2.1 Shredder ..................................................................................................................... 8
4.2.2 Mixer .......................................................................................................................... 8
4.2.3 Compressor ................................................................................................................. 9
4.2.4 Dryer .......................................................................................................................... 9
4.2.5 Burner ...................................................................................................................... 10
4.3 Power Source ................................................................................................................... 11
4.3.1 Internal Combustion Engine ....................................................................................... 11
4.3.2 Electricity ................................................................................................................. 11
4.3.3 Renewable Energy ..................................................................................................... 11
4.3.4 Human Power ........................................................................................................... 11
4.4 Transmission .................................................................................................................... 12
4.4.1 Hydraulic .................................................................................................................. 12
4.4.2 Linkage..................................................................................................................... 12
4.4.3 Gear and Chain.......................................................................................................... 12
4.5 Experiment ....................................................................................................................... 13
5 Preliminary Design ................................................................................................................... 14
5.1 Decision Matrices ............................................................................................................. 14
5.1.1 Process Decisions ...................................................................................................... 14
5.1.2 Component Decisions ................................................................................................ 15
5.1.1 Sensitivity Analysis ................................................................................................... 15
5.2 Description of Design ....................................................................................................... 16
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6 Budget ..................................................................................................................................... 19
6.1 Senior Design Budget ....................................................................................................... 19
6.2 Malawian Design Budget .................................................................................................. 19
7 Future Work ............................................................................................................................ 21
7.1 Component Design ........................................................................................................... 21
7.2 Communication ................................................................................................................ 21
7.3 Prototype Construction ...................................................................................................... 21
8 Conclusion .............................................................................................................................. 22



Table of Figures

Figure 4.1 Methods for Charcoal Creation: the (a) Direct and (b) Indirect Methods. ............... 10
Figure 4.2 Experiments of the (a) Direct and (b) Indirect Methods ........................................... 13
Figure 5.1 Preliminary Process Diagram .................................................................................... 17


Table of Tables

Table 5.1 Decision Matrix for Process Design Variables ........................................................... 14
Table 5.2 Decision Matrix for Component Design Variables ..................................................... 15
Table 5.3 Design specifications .................................................................................................. 17
Table 6.1 Preliminary Senior Design Budget.............................................................................. 19

1

1 Introduction

The country of Malawi is among the top 10 poorest countries in the world. Numerous
organizations invest time and effort into aiding the people of Malawimeeting their basic needs
such as water, food, shelter, healthcare, and many other essentials. Despite these efforts, the
country of Malawi is still in great need. Currently, deforestation is an increasing problem in
rural areas of Malawi, as the demand for charcoal fuel requires more resources than are
available. This is a very unsustainable, temporary, and environmentally damaging solution.

As a team of aspiring Christian engineers, Re-Fueled (one of fifteen Senior Design groups) has
taken on this design project based on a desire for addressing environmental problems and using
gifts and talents to aid the developing world. In working with Larry McAuley, a Malawi based
member of Christian Reformed World Relief Committee, the team will gain a more culturally
specific understanding of Malawi. The need for inexpensive fuel in Malawi requires a solution
which Re-Fueled has set out to define.

1.1 Team Description

Re-Fueled is composed of three senior Calvin College engineering students in the mechanical
concentration: Jeff De Jong, Bethany Kortman, and Jeena Velzen.



Jeff De Jong grew up in Glendale, California where he has worked as a
swim coach at the local country club. Jeff intends obtain a degree in both
engineering and business information systems. He enjoys working on his
computer as well as riding and repairing his two motorcycles. After
graduation, Jeff intends to return to California to pursue a career in
automotive engineering.

Bethany Kortman was raised in Grandville, Michigan where she attended
Calvin Christian High School. She has received an international
designation to her degree for her participation in an internship for Solvay
Pharmaceuticals in Weesp, Netherlands and an interim abroad. Bethany
plays lacrosse and enjoys cycling. She also enjoys outdoor recreation
including hiking, climbing, and camping. After graduation, Bethany hopes
to work abroad for a few years and then settle down at an architecture and
engineering firm in the West Michigan area.


Jeena Velzen was raised in Jenison, Michigan and worked for Gentex
Corporation, as well as participated as a leader for a Wilderness Orientation
Trip and resident assistant position for the Entrada Scholars Program.
Jeena is a member of the Calvin Swim and Dive Team as a 1 and 3 meter
springboard diver. After graduation, Jeena hopes to pursue a MBA in
international business while working internationally.

2

1.2 Problem Statement

Living requires fuel. Even in the most rustic and primitive areas of the world, fire is required to
cook food and to provide heat. In many developing countries where electricity is not widely
available and fossil fuels are too expensive, wood is the primary source of fuel. Malawi is a
country of particular interest which has been ravaged by its people, stripping its landscape of
forests to produce charcoal.

Malawi is a country the size of Pennsylvania in southeastern Africa, with a population slightly
largernearly 14 million. A large majority, roughly 85%, of Malawians are poor subsistence
farmers living in rural Malawi
1
. A very shocking comparison shows the per capita GDP of
Malawi is $800 compared to Pennsylvanias of greater than $40,000. Malawi is currently
experiencing massive deforestation to provide fuel for its people. Homemade charcoal from
trees is illegal because of the deforestation; however, the problem persists. These circumstances
present a need for an inexpensive fuel source which does not encourage the environmentally
damaging process of providing fuel which is currently destroying the Malawian landscape.

Re-Fueled seeks to design a process and mechanism which can provide an affordable fuel made
from materials which would otherwise be wasted. Keeping the Malawian people in mind as the
end users, the design will be bound by considerations for the culture and circumstances
surrounding Malawi.


1
CIA World Factbook (www.cia.gov)
3

2 Design Considerations

When confronting a stated problem, proposed designs must be fashioned from objectives which
are intrinsic to the problem statement. In addition, these designs are defined by norms which are
specific to the designer. The following sections will layout multiple objectives of this design
project.

2.1 Project Objectives

There are a number of objectives that have been deemed to be important to consider in the
design. These objectives are taken into account when making design decisions.

2.1.1 Purpose of Design

The purpose of this project is to use available scrap materials within Malawi for the
design and construction of a process to convert waste material to an inexpensive fuel
source for cooking and heating.

2.1.2 Cost

Minimal cost is a primary objective in the design of a functional mechanism for
producing fuel from waste in a developing country. The Senior Design budget is $300
per project; however, the Malawian salary is an average of $160 per year. The materials
needed to construct this mechanism will be chosen from recycled and previously used
scrap parts of bicycles and other parts that are available in Malawi. The intention of
reusing parts is to significantly reduce the cost of the machine, as well as helping waste
materials to serve another purpose.

2.1.3 Reliability

Reliability is an important objective because of the cultural differences between Malawi
and the United States. A fix it mentality cannot be assumed for the individuals who
will be the end users of the mechanism. Over time, if the mechanism breaks, the design
must be simple enough so a large range of people could repair it. The design of this
mechanism will focus on being very simple to understand, but also to be able to
withstand frequent use without breaking down or needing repair. Although the simplicity
of design aims to enable operators to repair the machine, reliability is of primary
importance.

2.1.4 Scope

The scope of this design project is a very important objective which must be defined.
Although there are many possibilities for the production capacity of this design, the scope
must be limited to fuel a small community. The finished project could prove to be viable
for a small business, but the intent of the design is to produce enough useable fuel in one
operating period for a weeks worth of fuel for a single family.
4

2.2 Design Norms

In addition to typical project objectives, there are a number of design norms which tie into the
ethical, and more specifically Christian, perspective for the design of this project. Christian
engineers are called by God to adhere to higher standards, which they incorporate, by their faith,
into their design.

2.2.1 Stewardship

The team name, Re-Fueled, is derived from the teams desire to design a solution from
readily available materials that would otherwise be wasted. The current problems of
deforestation
2
within Malawi can be offset by this design which converts wasteusing a
machine made of re-used componentsto useable fuel. Reusing components and
reducing the damage caused by unsustainable deforesting are all aspects of being
Christian stewards of Gods creation and being responsible caretakers of the earth and its
resources.

2.2.2 Justice

There are many inequities within societies; this design seeks to bring justice to areas like
Malawi where individuals and families struggle to afford fuel to cook food and heat
homes. Everyone should have the right to a job in order to work hard and earn a living.
By aiming to supply jobs and provide safe inexpensive fuel, this design will work toward
justice on the very basic level of fulfilling some needs for Gods people.

2.2.3 Cultural Appropriateness

The design for this project must agree with the culture and environment of Malawi.
Considering materials that can be easily acquired for a low cost in the area will aid in
achieving this goal. Also, in order for the device to be accepted and easily adopted, the
machine must be very simple to assemble, use, and repair. By keeping the use of
materials limited to locally available scrap and making the device simple, this project will
make cultural appropriateness a priority. Larry McAuley will act as a liaison,
communicating the needs and concerns of the theoretical Malawian end users, to help the
team be as immersed as possible in the Malawian culture.

2.2.4 Safety

A device and process to bring cooking and heating fuel to homes would be obsolete if it
also brought harm to the people operating the device and using the fuel product. There
are many factors in this process that could cause harm to a person. All components must
be designed so there are no harmful features, or else safety precautions designed into the
mechanism. If input material is found as litter on the streets, it is important that possible
toxins are determined and taken into consideration for the design. Consistency of the fuel
is also necessary to avoid unpredictable burning, for the safety of the end user.

2
CIA World Factbook (www.cia.gov)
5

3 Project Organization

Planning is extremely important when undertaking any project. As this project spans two
semesters it was imperative to create a plan and work from that plan.

3.1 Schedule

A Gantt chart was used throughout the fall semester to schedule work to be completed
(Appendix A). This includes all deliverables required by Senior Design and additional steps
required for the preliminary design and feasibility test of the project.

3.1.1 List of Key Milestones, Fall Semester

The following is a list of significant project milestones that have been achieved in the
preliminary feasibility design process.

September 29 Initial Project Objectives Defined
October 13 Project Website Startup
October 24 First Class Presentation
November 17 Project Proposal and Feasibility Report Draft Due
December 5 Final Class Presentation
December 12 Project Proposal and Feasibility Report Due


6

4 Feasibility Study

The physical aspects of the process and the mechanism need to fit within the physical and project
constraints and consider the design objectives and norms. The potential input materials, output
products, conversion processes, and components are considered in this section.

4.1 Fuel and Process Options

4.1.1 Material Input

There are multiple materials to consider as an input to a useable fuel production design.
Other engineers have designed processes to produce fuel from waste paper, wood, sugar
cane, and other agricultural waste.

Other individuals proposing designs to meet the fuel needs of Malawi have used paper as
a potential waste material which can be converted to fuel. Paper littering is a problem in
Malawi, which means that it is an available resource which would otherwise be wasted.
Paper is made from trees which makes it a feasible option for cooking and heating. The
majority of Malawians live in rural areas, making paper a plentiful resource but possibly
only in urban areas. Other considerations for paper include a higher burning temperature,
faster rate of burning, and possible pollutants on the paper.

Agricultural waste such as grass are feasible sources for fuel because they are plentiful in
many areas of Malawi. The sekera grass of Malawi grows between 2-3 meters in height
and is burned to clear fields for planting. Sekera grass is only available in the dry season,
which limits the source of input material during this time. Burning grass only emits
alkaline gases, which help to mitigate acid rain.

4.1.2 Fuel Product

Charcoal is a very valuable resource for providing heating and cooking for domestic use.
The benefits of charcoal include the following: lower burning temperature, slower and
cleaner burn, fewer ash remains. Charcoal is currently being used in Malawi as the
primary fuel source. Despite its advantages charcoal production from trees is currently
illegal in Malawi.

A fuel briquette is an option which comes from the compression of an input material and
binding agent, which is then dried and subsequently used as fuel. The process to make a
fuel briquette is simpler than the process needed to turn the input material into charcoal.
This method saves time; unfortunately it increases the burning temperature of the fuel
and leaves more ash. However, the excess ash from this fuel briquette could be returned
to the earth and used to fertilize the soil. In addition, a fuel briquette could be made of
mixed inputs such as paper and grass. Consistency is important in a mixed fuel briquette
in order to provide a product with a consistent heat output and burning temperature.
Consistency is also important in the intermediate steps to assure reliable and long lasting
operation of the components used in the design.
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4.1.3 Process Options

Many options were considered for the conversion of waste material to a useable fuel
product. The ideas for the design process were formulated concurrently with fuel product
feasibility testing (section 4.5).

There are many different potential components to incorporate into the optimal design.
Despite the selected fuel product, there are optional components such as a feeder or
hopper for material inputs to be inserted into the process. A shredding component may
be necessary to provide a more consistent fuel product. A mixing unit would be
incorporated if a binding agent is added to the process and greater consistency was
needed to combine the fuel product into a burnable product. A dryer and compressing
unit would also be necessary to produce dense, compact product that burns easily.

Assuming a charcoal fuel product, the process requires a burner component. Both the
direct and indirect burning methods were considered (section 4.2.5). Possible charcoal
specific processes are shown below:

1. feeder mixer compressor dryer (in)direct burner compressor
dryer
2. shredder (in)direct burner mixer compressor
3. (in)direct burner compressor

Assuming a compressed fuel briquette, a burner component is not required. However,
many similar components are necessary, which can be powered manually or
mechanically. Fuel briquette processes are shown below:

1. mixer compressor dryer
2. shredder mixer compressor
3. shredder mixer compressor dryer
4. shredder dryer mixer compressor

The first listed briquette making process is the most commonly used process. There are
small manually powered compressing units available that compress a paper-water
mixture into briquettes that are dried and burned. A more complex process is required for
a higher production capacity.

The processes are very similar with subtle differences, but the selected components and
order of those components will determine the quality of the product and the ease of
production.

8

4.2 Components

Each process option is comprised of a number of individual components. Many viable options
for each of the individual components are examined and analyzed to make informed design
decisions.

4.2.1 Shredder

There are many advantages for a shredding component. Smaller shredded inputs require
less power for a drying component due to an increase in surface area of the inputs. There
are various options for a shredding mechanism including a blender or food processor
blade, a lawn mower blade, or a paper shredder design.

A blender or food processor blade mechanism may not work depending on the weight of
the input material. Although salvaging these components would be ideal, food processor
parts are not available in Malawi. Also, the blades are very small for the desired
production capacity of this design, which would require a large number.

A lawn mower blade would be a large enough component for the desired production
capacity for the design; however, feasibility of cutting paper with this blade is
questionable. The types of lawn mower blades commonly used in the U.S. are a rare find
in Malawi. The possibility exists for construction of a spinning blade similar to a lawn
mower blade using more available cutting devices (like a scythe).

A paper shredder design, two parallel rotating drums covered in blades, would cut paper
into useable strips, however a commercial sized paper shredder may be difficult to
acquire and a domestic-use sized shredder may be too small. Feasibility for this
component will depend on the ease of constructing an adequate substitute.

4.2.2 Mixer

Using a mixing component provides a stage at which to add a binding agent. In addition,
a mixing component assures the intermediate product is consistent in both composition
and coverage of the binding agent.

A paddle or blade mixer stirs the intermediate product in order to achieve the required
consistency. The stirring implement could vary from being a set of paddles to being a set
of blades. A major obstacle to this design is scaling the mixer to the necessary size for
the specified task.

A drum mixer consists of a rotating drum in which the intermediate products and the
binding agent are mixed. The drum can include vanes on the inside of the drum to
increase agitation during the mixing process. This type of mixer design is much easier to
scale for different sized applications.

9

A starchy binding agent is necessary to join the materials for a homogenous product. A
number of food starch options include wheat, corn, potato, and cassava. Availability of
the food type will determine the selection of a particular binding agent.

4.2.3 Compressor

A compressing unit is necessary to compact the products so that the fuel can be
distributed in a solid form without crumbling and also to slow the burn.

A screw drive compressor using a power screw to compress material is an option,
however it lacks in range of motion. The screw drive compressor requires rotational
force to compress effectively while also requiring force to unscrew to compress again,
which takes time and effort.

Currently, linkage compressors can be purchased which use leverage to compress a fuel
mixture. This type of compression requires significant human powered input and must be
repeated frequently to produce a large amount of compressed briquettes.

Hydraulic compression, like that used in automobile braking systems, is an effective
method for compression but requires hydraulic fluid and is a complex system for the
developing world, which is an added complexity to the design.

A screw extruder method of compression is an appropriate option because it serves as a
continuous method for compressed product extrusion. The cost of creation and
complexity of an extruder will determine its feasibility.

4.2.4 Dryer

A drying component is necessary for the design because a fuel product of high moisture
content will not burn adequately. Moisture in the product could be due to input material
of high water content, the moisture from the selected binding agent, or both. Forced
convection of ambient or warmed air and solar radiation are all methods of drying
material.

A blower, such as a spinning fan, is an option for drying the material using forced
convection of ambient air. Fan blades are available from urban Malawi. This design
would be simple to implement because a hand crank or foot peddling method could easily
drive this device.

A hot air blower would be an effective method of drying the material; however it requires
an input of fuel to create hot air to blow on the damp materials. This increases cost and
decreases the overall efficiency of the entire process when comparing input and output
fuels.

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Solar drying is a readily available option for drying the fuel product because it is free,
however the weather determines when drying can be done using solar radiation resulting
in an unpredictable variable.

4.2.5 Burner

A burner is required for a charcoal producing process. There are two methods to convert
inputs such as wood or sugar cane to charcoal: the direct and indirect method.

The direct method involves igniting the material being converted and sealing the burning
material in an oxygen-deprived environment. This allows some of the input to burn up,
but produces charcoal from the material remnants. Amy Smith, a former MIT professor
who undertook a project to convert sugar cane waste to charcoal
3
, used the direct method
(Figure 4.1a). This method can result in a product with an inconsistent composition (i.e.
all of the input material may not be fully converted to charcoal).

The indirect method (Figure 4.1b) cooks the input material in an oxygen-deprived
environment which is heated. In this method, an exhaust piping system can recycle the
noxious gases emitted from the input materials, which are combustible and can be used to
provide heat to aid the process. The use of the noxious gases increases the efficiency of
the burner and indicates the process is finished when no further noxious gases are emitted
from the burner. This creates a more consistent product and is generally more efficient
than the direct method.



(a) (b)
Figure 4.1 Methods for Charcoal Creation: the (a) Direct and (b) Indirect Methods.



3
CNN (www.cnn.com)
11

4.3 Power Source

A power source is necessary for this machine in order to operate the different stages of the
process. Some of these potential power necessities include compression, transport of materials,
drying of product, and other possibilities. To meet the power needs of the machine, four
different options are compared.

4.3.1 Internal Combustion Engine

An internal combustion engine is a gas powered option which could prove problematic
since Malawi does not have any of its own fossil fuel sources, so petroleum is expensive
and not readily available. An internal combustion engine also has many parts increasing
the chances of necessary and difficult maintenance, while also increasing the difficulty of
the initial assembly. These parts can also be quite expensive which is important to
consider because 53% of the population of Malawi lives below the poverty level
4
.

4.3.2 Electricity

Electricity from the local power grid is an option for the design if only focused on urban
users; other users would not have access to an electricity source. Problems lie in the
reliability of the electricity since many African countries experience rolling blackouts as
a method of load shedding on a regular basis.

4.3.3 Renewable Energy

Renewable energies such as solar, wind, and hydro power are alternative power options
for this design. These options are environmentally friendly and not wasteful, but also
harbor many potential problems. The materials necessary for renewable energy are very
costly and not readily available in Malawi. Additionally, the assembly and maintenance
tasks for these systems are expensive and complex, requiring significant instruction and
down time.

4.3.4 Human Power

Human power is an available energy source which can be harnessed to power multiple
components of the fuel conversion process. This option could include hand cranks,
bicycles, and levers. By using human powered devices, cost and complexity can both be
greatly reduced. Also, jobs can be created with the process. Safety considerations are
very important when incorporating human operators in a mechanical process.


4
CIA World Factbook (www.cia.gov)
12

4.4 Transmission

The transmission moves the power generated from the power source to the individual
components in order to complete a given task. A number of options that vary in complexity,
flexibility, and simplicity were considered in the project design.

4.4.1 Hydraulic

A hydraulic transmission allows for a great deal of flexibility regarding the placement of
components relative to the power source. It can also provide mechanical advantage
easily through the use of master and slave cylinders. Using hydraulics, power output can
be scaled up to do very impressive tasks using a relatively small power source. Hydraulic
transmissions add a level of complexity due to the use of a working fluid. There are a
number of specific parts needed to maintain proper system operation and pressure. The
availability of parts could be an issue as the only cheap and available resource for
hydraulic parts would be automotive and construction machinery.

4.4.2 Linkage

Linkages are very simple and easy to construct. It can provide a reliable and effective
form of power transmission as well as being made from a variety of available materials.
One major downside to linkages is the difficulty in placing the transmissions relative to
the power source and component. Two dimensional linkages are typically the most
common and the easiest design and construct. Another downside to linkages it can
potentially take a very large or complex linkage to generate a significant mechanical
advantage or transmit power in a three dimensional plane. Linkages are a simple and
reliable solution for simple operations that can be completed in a two dimensional plane.

4.4.3 Gear and Chain

Gears and chains offer the ability to transmit power easily and efficiently in two or three
dimensions. Typically gear and chain parts are easily scavenged from other machines
such as bicycles and automobiles. They are a simple solution for mechanical advantage
and power transmission between planes. They offer some spatial flexibility without the
added complexity of a working fluid. Some issues that may arise with gear and chain
transmissions can be mounting and alignment as they will affect the proper operation and
reliability of the machine.

13

4.5 Experiment

An experiment to determine the feasibility of converting paper to charcoal was of primary
importance. The methods for creating charcoal from wood were tested to verify the feasibility of
creating charcoal from paper.

The conducted experiment tested the conversion of paper into charcoal using the direct and the
indirect method. Steel cans with tight fitting lids were used as the containers in which the paper
was sealed in to create an oxygen-deprived environment. For the direct method, a can was
packed with paper which was ignited and sealed within (Figure 4.2a). The intent was for the
paper to continue burning and smoldering in the oxygen-deprived environment, converting the
paper into charcoal. For the indirect method, a can was packed with paper and sealed. Paper
was burned around the can, heating it. This method intends to heat the paper within the can in an
oxygen-deprived environment, converting the paper into charcoal.

Based upon the experimental data it was decided that paper conversion to charcoal was not a
suitable product. Either method produced an unsatisfactory product. Using the direct method
the paper would light and be consumed quickly, but once the can was sealed the flame
immediately went out and the paper would not continue to burn or smolder as needed. This
produced an unsatisfactory product consisting of mostly paper with burned edges and a small
amount of ash from the consumed paper. It was not even possible to create charcoal from the
paper using the direct method. Using the indirect method charcoal was successfully from the
paper; noxious gases were also produced from this conversion process. Unfortunately the
product was extremely light and brittle as well as inconsistent and difficult to light (Figure 4.2b).
The information gathered from this experiment was used in the decision to no longer pursue
charcoal as the fuel product.



(a) (b)
Figure 4.2 Experiments of the (a) Direct and (b) Indirect Methods

14

5 Preliminary Design

The design variable options were assessed using a decision matrix which prioritizes certain
design criteria. The decision matrix then presents weighted numbers for determining the most
suitable options for the design. A description of the preliminary design follows (section 5.2).

5.1 Decision Matrices

5.1.1 Process Decisions

The decision matrix for process design variables was completed to determine the best
choice for each set of options (Table 5.1). The primary design variables assessed using
the matrix were the product, power source, and transmission for the paper to fuel process.

Aspects of the project objectives and design norms were included in the matrix with
varying importance based on the variable being evaluated. The weighting is shown as a
number between 1 and 5; 5 being of greatest importance and 1 being of least importance.
Cost determination was based not only on an assessment of the cost of materials, but also
the profit from fuel product value. For example if the process produced a better fuel
product it would offset the increased cost of the equipment. The other categories were
scored where benefits have higher ranking.

Table 5.1 Decision Matrix for Process Design Variables


By completing the process variables decision matrix, the team was able to determine the
appropriate process options. These decisions are as follows: The final product will be
paper briquettes; human power will be the only power source; and a gear and chain
transmission will be used.

Cost Availability
Maintenance &
Reliability
Efficiency Simplicity
Environmental
Impact
Safety Totals
5 4 3 3 2 3 3
Paper Briquettes 4 4 5 3 5 3 4 91
Charcoal Briquettes 3 3 3 4 2 3 2 67
4 3 4 5 3 2 2
Human 3 5 4 3 5 5 4 91
Internal Combustion 2 4 3 4 2 2 3 68
Electricity 2 3 4 4 3 3 5 78
Other Renewable 1 2 2 2 1 5 4 49
4 3 4 3 5 2 3
Hydraulic 2 1 3 4 2 2 2 55
Linkage 5 4 4 2 3 3 4 87
Gear & Chain 4 4 4 4 4 3 3 91
Design Variables
P
r
o
d
u
c
t
P
o
w
e
r

S
o
u
r
c
e
T
r
a
n
s
m
i
s
s
i
o
n
Weighting
Weighting
Weighting
15

5.1.2 Component Decisions

The decision matrix for the design components (Table 5.2) follows the same format as
the matrix for the process options with varying weights according to the importance of
the design consideration. The components discussed in the decision matrix are the
shredding, mixing, compressing, and drying components of the device.

Table 5.2 Decision Matrix for Component Design Variables


Through this analysis it was determined that the preliminary design shall consist of the
following components: a paper shredder to increase the surface area of the input
material; a solar dryer or combination of solar and blower for removing moisture from
the fuel product; a screw extruder for compressing the material into briquettes. The
implementation of the process and component design decisions can be found in the
preliminary design (section 5.2).

5.1.1 Sensitivity Analysis

Depending on the weightings and scores assigned to the design variables, the design
decisions can change drastically. Because of this, it is important to do a sensitivity
analysis of the decision matrices and discuss the results.

Cost Availability
Maintenance &
Reliability
Efficiency Simplicity Safety Totals
4 5 3 3 4 4
Food Processor 5 2 2 2 4 4 74
Lawn Mower Blade 4 3 4 3 4 3 80
Paper Shredder 3 4 5 5 2 3 82
4 4 4 3 4 4
Paddle/Blade 3 4 4 4 4 3 84
Drum 4 5 5 5 4 4 103
4 3 4 3 5 3
Screw Drive 5 5 2 2 4 3 78
Linkage 5 4 3 4 3 4 83
Hydraulic 3 3 4 5 3 3 76
Screw Extruder 3 3 5 5 4 4 88
4 4 3 5 3 4
Solar 5 5 5 4 5 5 112
Blower 4 4 3 5 4 3 87
Hot Air Blower 2 3 3 5 3 3 71
S
h
r
e
d
d
e
r
Design Variables
Weighting
C
o
m
p
r
e
s
s
o
r
Weighting
D
r
y
e
r
Weighting
M
i
x
e
r
Weighting
16

For process options, sensitivity analyses were done for each section of the study. Due to
the potential higher selling price for charcoal, the matrix value for this option could have
been increased. However, it was important to keep in mind the added costs necessary for
the burning mechanism required for charcoal production. In this case, the extra
component and safety costs outweigh the selling price benefits for this option. When
considering the power source options for the process design, consideration must be given
to the time needed to run the machine components. Keeping in mind the adage, Time is
money, time spent with human power can add to the price of this option. However, the
next most feasible option is electricity, which is an unpredictable and unreliable energy
source in Malawi. Finally, the sensitivity analysis for the power transmission portion of
the design indicates that the linkage and gear and chain options are quite close. Although
it may be argued that linkages require less difficulty with assembly and maintenance, the
flexibility that can be achieved with the application of gears and chains outweighs the
simplicity of linkages.

For the design components, sensitivity analyses were done on the shredding and drying
components to help determine the strengths and weaknesses of each design. The
sensitivity analysis of the shredding component was completed because the paper
shredder and mower blades were both considered good choices. The efficiency variable
for this component was based on how well the device shreds large amounts of paper.
Since it was determined that the mower blades would require frequent sharpening in
order to efficiently shred paper, the paper shredder, already designed to shred the input
material, was considered the best choice for the preliminary design. However, if testing
proves the mower blade to be an acceptable alternative, this option will still be
considered. A sensitivity analysis was also done on the drying component of the design.
Because using the sun requires the least possible complexity and added costs, it is shown
as the best possible option. However, since there is a significant rainy season in Malawi
a combination of a blower and solar dryer might be the best year-round solution while
keeping cost and complexity to a minimum. If the main decision was based on drying
speed and reliability alone, forced hot air convection would be the appropriate design
choice. However, since making the air hot would require a large energy input, this option
does not lie within the design criteria.

5.2 Description of Design

The preliminary design is the combination of the selected input materials, fuel product, process
type, necessary components, power source, and transmission (Table 5.3). The preliminary
design has proven to be theoretically feasible based on the following: thoughtful analysis of
various options (section 4), decision matrices (section 5.1), experimentation, and incorporation
of design norms.


17

Table 5.3 Design specifications
Design Variables Design Specifications
Input Material Waste paper / Sekera grass
Fuel Product Fuel briquette
Process Type shredder mixer compressor dryer
Shredding Component Paper shredder
Mixing Component Drum mixer
Compressing Component Screw extruder
Drying Component Solar heat collector / Blower
Power Source Human power
Transmission Gear and chain

Waste paper and sekera grass are readily available resources in Malawi, whether focusing in
urban or rural areas of the country. These materials will serve as input materials for this fuel
conversion process. The process will produce compressed fuel briquettes, made of a mixture of
paper, grass, and cassava starch. Larry McAuley, the team contact in Malawi, has indicated a
prominent availability of cassava and a cassava starch extraction factory in his area.

The preliminary process includes four components: shredder mixer compressor dryer.
This process could be completed in a continuous or batch process, as well as four individual
components or a single multicomponent mechanism. The design will utilize a batch process for
simplicity in both operation and design of components. A single multicomponent mechanism
would provide transport between each component (Figure 5.1); this eliminates operator energy
and time, and the potential for intermediate product loss.


Figure 5.1 Preliminary Process Diagram

18

The first component is the input material shredder. The shredder consists of two parallel drums
covered in blades, which paper and grass are fed through, resulting in a more homogenous and
manageable sized intermediate product. The shredded material will be collected into a hopper,
separate from the mixer, so that the shredding and mixing components can be operated
independently.

The drum mixer component is the location for the addition of binding agent to the intermediate
products. The drum is rotated to ensure a more homogenous mixture, which produces more
consistent coverage of the binding agent. This is important because a more consistent
intermediate product will place a predictable load on subsequent components. This stage also
determines the final consistency of the product; which should burn in a safe and dependable
manner.

Mixed intermediate products are deposited into the screw extruder. The extruder consists of an
auger within a cylinder where the auger rotates and pushes the mixture down the cylinder,
compressing at the extrusion point. The compressed and extruded product can then be cut at
regular intervals producing a final briquette.

The final component of the design is the dryer where the damp fuel briquettes are placed to cure.
The preliminary dryer design is a box with metal grating shelves for the briquettes to be placed,
and solar heat is trapped in the box. Fans will produce air flow within the box to displace
moisture through vents, increasing the drying rate. Dry briquettes are ready to be burned.

All process components are powered by human power which incorporates many design norms:
justice, by providing jobs and inexpensive fuel products; stewardship, by reducing cost, utilizing
available labor, and use green energy. The human power will be harnessed for the process by
bicycles, transmitted using gears and chains.
19

6 Budget

Since the context for this project is assembly and implementation in a developing nation, there
are two different budgets to take into consideration. The first is the budget for the prototype
determined by the Senior Design class. This includes expenses for feasibility testing, materials,
research, tools, etc. The Senior Design budget is defined to be an average of $300 per project.
The second budget to consider for this project is the budget for implementation in Malawi. This
budget must cover all start up costs involved with the machine and process including
construction materials, tools, and labor. The budget for implementation in Malawi is based on
the national average salary of about $160 per year while keeping in mind the aid provided by
relief missions like CRWRC.

6.1 Senior Design Budget

The Senior Design budget analysis was done according to the initial process and component
designs, also including extra materials for testing and possible part failure. The part prices were
found by researching used part costs (Table 6.1). The budget analysis was also done on a worst-
case basis assuming that some parts will be found in scrap yards for a much lower cost and some
others may be donated.

Table 6.1 Preliminary Senior Design Budget
Component Amount
Price
Per
Total
Price
Single Speed Bicycle 4 $20 $80
Consumer Grade Fan Blade 2 $10 $20
Consumer Grade Paper Shredder 1 $15 $15
20 in. Lawn Mower Blades 2 $15 $30
6 in. Auger 1 $30 $30
6 in. x 4 ft PVC Piping 1 $40 $40
1 lb. Cassava Starch 5 $2 10
Various Scrap Metal 1 $0 $0
Preliminary Total $225

The preliminary total of $225.00 lies within the budget allotted to senior design groups. This
determines that the testing and initial prototype is economically feasible in this context. Lying
within the teams emphasis on stewardship, however, it is important to keep the project costs to
an absolute minimum so that the funds and materials are used in the most efficient way possible.

6.2 Malawian Design Budget

In order for the design to be culturally appropriate, it is immensely important consider the final
product costs in the context of Malawi. Through communication with Larry McAuley from
CRWRC, the team was able to determine a rough financial feasibility estimate of the project
according to the initial design materials in the context of the financial restrictions in Malawi.
The exact budget, however, is difficult to determine because the final design has not been
20

decided on, and the cost of all materials cannot be identified completely. However, since the
testing and designing processes will be completed in the U.S. under the Senior Design Budget,
only the final design materials and labor costs need to be considered in the Malawian Budget.
Because of the lack of cost data for materials in Malawi, the total project cost as it applies to
Malawi will be analyzed in more detail during the design process. There is also the possibility of
finding the materials for no cost in trash piles and through donations from local aid sources,
emphasizing the goals of stewardship and caring.

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7 Future Work

The Project Proposal Feasibility Study is only the beginning of the design and implementation
process. As the year continues, progress must be made to meet the final goals of the Senior
Design project.


7.1 Component Design

Specific components of the machine need to be designed. For example, the human-powered
devices need to be studied further so they can be implemented in the safest and most effective
way possible. Also, the components need to be designed to withstand repeated use, weather, and
potential misuse.


7.2 Communication

As there is hope for this machine and process to be adopted by Larry McAuley and his
colleagues at CRWRC, continuous communication must be maintained in order to keep all
parties involved updated with changes and progress.


7.3 Prototype Construction

As a final product of the Senior Design project, a working prototype must be built to demonstrate
the process of creating fuel briquettes from waste materials. The design process must be iterative
and coincide with construction of the prototype. Materials must be gathered from local scrap
yards and other sources. This prototype will be displayed at the Senior Design Open House at
the end of the Spring semester.

22

8 Conclusion

This project seeks to design a simple low cost process to create fuel from waste material. The
fuel making process is low cost and simple to implement with the intent of having wide adoption
providing fuel, reducing waste, and creating jobs in developing nations. This design is
functional for both waste paper and sekera grass.

The material inputs include waste paper and a grass local to Malawi called sekera grass. The
product is a mixed fuel briquette consisting of the two inputs and a starchy cassava binding
agent. The power source for the design is human power and incorporates a gear and chain
transmission which can be scavenged from bicycles. The current process design calls for a
shredder, mixer, extruder, and dryer in series to complete the task. The shredder is a drum type
which will slice the inputs. From the shredder the intermediate products are placed in the mixer,
this is a rotating drum and adds the binding agent to the intermediate products. The extruder is a
screw extruder that will compress and form the briquette shape. From there the shaped
briquettes are placed in the dryer which uses solar heat and a blower to dry the final product.

The preliminary project design is feasible for the physical and financial limitations present. The
design also takes into account the design considerations and norms laid out. Based upon these
findings is feasible to have a process and a mechanism that produces a high quality fuel briquette
from waste material that will operate in Malawi.




Table of Appendices


Appendix A: Project Gantt Chart
Appendix B: Emails from Larry McAuley (CRWRC, contact in Malawi)
Appendix C: Project Market Price Research





Appendix A: Project Gantt Chart












Appendix B: Emails from Larry McAuley (CRWRC, contact in Malawi)




Appendix C: Project Market Price Research