Peter Coutts

Phase 3 Lab Write Up

P15484 Essential Oil Distiller

10/28/14

Solar Assisted Essential Oil Distiller – Solar Tracking Feasibility & Design

Project Background:

Our team’s goal is to design and build a working prototype of an essential oil distiller that utilizes

the suns energy as a sustainable energy source. The fragrant oils distilled from locally grown plant

matter could potentially serve as a source of income to farmers in Borgne, Haiti who currently have no

monetary income at all.

We broke down the overall system into several sub-systems that have to operate together to

distill the oils using the suns energy. One of the most important sub-systems is our solar trough, which

is a type of a solar energy collector that concentrates the solar energy onto a tube of water and causes

the water to boil. Because the sun changes angle throughout the day and our solar trough system

needs to operate for two full days of sun, a tracking mechanism is essential to ensure the available

solar energy is being fully used to distill the oils.

My Feasibility Question: What type and design of a solar tracking mechanism could help our solar

trough be more efficient while complying to the system Engineering Requirements (ER’s)?

My Assigned Sub-System: Solar Tracker

System Assumptions:

1) Force required to rotate solar trough is small because the centroid of the trough is also located

at the axis of rotation of the trough

2) Rotational friction is present but insignificant (in some cases)

a. Friction can be reduced

3) Overall cost should be less than $100 to fit within budget

4) Materials that can be obtained in Haiti

a. Scrap metal

b. Ply wood, 2x4 type wood

c. Basic screws, nuts, bolts

d. Tools:

i. Wrenches

ii. Wood saw

iii. Screwdriver

iv. Small measuring cup

e. Methanol

5) Haitian operators are capable of performing small, intuitive fixes

6) Haitian people will not have circuitry knowledge

7) There will be a possibility of the tracking mechanism left out in the rain/ wind

Solar Tracker Sub-System Engineering Requirements:

Most sub-system requirements track back to the overall parent Engineering Requirement(s).

Solar Tracker Feasibility Analysis:

1) Benchmarking

Several different solar tracking mechanisms were researched and benchmarked as

possibilities for our project. Tracking concepts as a whole were considered, not individual

components to build a novel system. Our goal was not to innovate, but to utilize and improve

upon existing and proven concepts. The different technologies found are as follows:

We looked for concepts that were feasible for our project and required little to no electrical

components. We were also only interested in tracking mechanisms that would rotate a single parabolic

trough for an entire day’s worth of sunlight.

We quickly found out that in order to select a solar tracking technology, some more formal

method of selection was going to be necessary. A few different methods were used to choose the best

tracking technology.

a. Pugh Matrix Iterations

Three different Pugh Matrix Iterations were performed, each time moving the datum as our

comparison point. A ‘+’ sign meant that the corresponding technology was better or more preferred

than the datum, a ‘-‘ sign meant that the corresponding technology was not as good or as preferred

than the datum, and a ‘S’ meant that the corresponding technology was the same or relatively similar to

the datum.

After all the technologies were assigned signs based on the selection criteria in comparison to

the datum, the totals were summed and the highest total received the highest rank for that iteration. ‘S’

did not contribute to the total score.

The Pugh Matrix ‘Selection Criteria’ with desired states in parentheses are as follows:

1) Cost (low) 2) Design complexity (low) 3) Further design time required (low) 4) Availability of replacement parts in Haiti (high) 5) Difficulty of repairs (low) 6) Video proof of concept (present) 7) Number of electrical components (low) 8) Water resistance (high) 9) Durable (high) 10) Manual labor required (low) 11) Level of torque it can produce (sufficient/high) 12) Reliability under occasional cloud cover (high) 13) Adapting needed for solar trough (low)

It was decided that further iterations were not necessary, because a clear winner and runner-up

were evident in each iteration. The Solar Flower Tracker came out on top in every iteration, and the

Solar Cell Tracker was the next best.

b. Pros & Cons List

A short pros and cons list was created to make sure nothing important was missed by

the Pugh Matrix iterations:

Clearly, the Solar Flower Tracker had many beneficial pros that help make the option more

desirable.

Concept Selection:

Our selected solar tracking concept is the Solar Flower Tracker and if this device fails in some

way during the protyping phase (or any phase), we can easily resort to more reliable solar tracking

methods (which may cost more and require further purchasing). Specific reasons for selection include:

Solar Flower Tracker Selected Because:

All Pugh Matrix iterations led to Solar Flower Tracker

Already designed

Plans to build available

Low cost

Risks have low severity

o Little time spent on designing

o Low monetary risk

Parts are mostly ‘up-cycled’ and could potentially be found/replaced in Haiti

Does not require any type of electricity

o No electrical maintenance/protection required

Video proof of concept

o https://www.youtube.com/watch?v=Lva3bm3psyI

o https://www.youtube.com/watch?v=xHl-

nuBpe5c&list=UUyjzaMkXTTp9P20UZbxDH6w

Can revert to a plan “B” if prototyping fails

Ultimate reasons other tracking devices were not selected because:

1) Pendulum Tracker

Lots of moving parts that could potentially break and not be available in Haiti

Not dependent on sun to control (ie: passive tracking)

Unknown cost (lots of components to find/ purchase)

Build intensive

2) Solar Battery Tracker

Requires a solar battery

Not as resistant to weather (electrical components)

3) Photodiode Battery Tracker

Requires a battery that needs to be charged

Not as resistant to weather (electrical components)

4) Solar Cell Tracker

Not as resistant to weather (electrical components)

Solar cells may be hard to find in Haiti to replace

5) Secondary Fluid with Mass Transfer

Uses either anti-freeze or butane as the secondary fluid- could be hard to

replace in Haiti and both are potentially dangerous

Only very crude designs available

Drawbacks of Solar Flower Tracker to keep in mind:

High complexity

o May be hard for Haitian farmers to fix if it breaks

Requires secondary working fluid: ethanol or other alcohol based fluid

o Adds in another level of difficulty

Maintaining fluid levels

Reusability

Reliability

Although some of the other methods are more widely used and tested in solar tracking than the

Solar Flower method, they are more expensive and many would require further design to make a reality.

We will continue to further investigate the abilities and limits of the Solar Flower tracker through

prototyping and through contact with the Solar Flower creator.

Our “Plan B” is the Solar Cell Tracker because it is simple, proven, and not highly design or build

intensive. It also had the next best results from the Pugh Matrix iterations. There is a concern that

wiring the solar cells directly to the motor may short out the cells and cause damage to the cells over a

long period of time. Further investigation must be done in order to know how to avoid this problem. A

simple circuit with diodes that only allow current to run in one direction may be necessary. A subject

matter expert will be needed for the completion of this design. Because the Solar Flower Tracker has

the potential to be very cheap, there should be money in the budget to purchase the components for

the Solar Cell Tracker.

Now that a solar tracking mechanism was selected, we will focus on the design of the solar tracking

sub-system.

Solar Flower Tracker – [Broken into 3 Sub-Sub Systems]

The following link gives a video break-down of how the Solar Flower tracker works in conjunction with a

parabolic trough solar collector:

https://www.youtube.com/watch?v=WrMltEp-dcw

The Solar Flower tracking device is broken down into three sub-sub systems:

1. The Box Collector

2. The Wheel

3. The Gearing

Sub-System Level Drawing:

Sub-Sub System Drawings:

1. Box Collector (Sub-Sub System 1 of 3) (Pictured in red)

2. The Wheel (Sub-Sub System 2 of 3) (Pictured in purple)

3. The Gearing (Sub-Sub System 3 of 3) (Pictured in green)

Critical Interfaces:

There are a few different interfaces that are important to the overall success in the operation to

the Solar Flower tracking device. With each interface comes a list of risks and concerns that need to be

addressed and mitigated.

1) Gearing / Trough End

2) Gearing/ Frame

3) The Wheel/ Gearing

4) Box Collector/ Trough

Risks:

Calculations:

No mathematical calculations were required in the design of this sub-system so far. Only

ballpark cost estimates were determined for each benchmarked tracking device.

I did not do any calculations for the amount of force required to turn the trough after talking to

the creator of the Solar Flower, Daniel Connell. Daniel confirmed that the center of gravity and the axis

of rotation are at the same point on the cross section of the trough, meaning very little force is required

to turn the trough. Only the inertia of the trough must be overcome in order to move the trough. In

Daniel’s words, “it takes tens of grams on the rim to turn. This then in turn means pretty much zero

friction on the worm drive, so practically no force [is] needed from the tracker.” For the full email

conversation (so far) between me and Daniel Connell, see “Solar Flower Contact Emails” under Project

Management-Correspondence. I also received video proof of concept that the Solar Flower tracking

mechanism can turn the trough with the sun throughout the day.

If I did need to calculate the force required to turn the trough, I would first need the final

geometries of the trough to calculate the moment of inertia, which is still being designed.

Conclusions:

I will begin looking at the design of the Solar Flower Tracker and possibly start prototyping and

making improvements. Many of the materials can be found from recycling, so I will start to look for and

accumulate materials to help reduce the cost of the tracking system.

I will also look deeper into our “Plan B” solar cell option. I will need to get in contact with either

Dr. Stevens or a circuits professor to ask them about the potential short circuit problem.

Expert Feedback:

Dr. Stevens was receptive to the idea of the Solar Flower Tracking device. He was initially

hesitant upon hearing how it operated, but when he heard that there was video proof of it successfully

operating, he was more open to the idea. He did also want us to look into the thermal expansion piston

(secondary fluid mass transfer) and photovoltaic systems.

We considered Dr. Stevens’ advice and benchmarked the two systems he suggested. However,

we are still moving forward with the Solar Flower tracking system because of its low cost and low design

time required. We will come back to the photovoltaic option if the Solar Flower system fails.

Bill of Materials:

The estimated cost of this sub-system is not known at this time because it depends upon the

availability of parts without purchase. Many of the parts can be retrieved from recycling or from

unwanted scrap materials on campus. The list of materials needed for the solar tracking sub system is

shown below.

“Plan B” – Solar Cell Tracker:

Conceptual Drawing: