Solar Assisted Essential Oil Distiller Solar Tracking Feasibility & Design

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1 Peter Coutts Phase 3 Lab Write Up P15484 Essential Oil Distiller 10/28/14 Project Background: Solar Assisted Essential Oil Distiller Solar Tracking Feasibility & Design 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

2 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:

3 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.

4 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)

5 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.

6 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 o Can revert to a plan B if prototyping fails Ultimate reasons other tracking devices were not selected because:

7 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.

8 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: 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)

9 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

10 3) The Wheel/ Gearing 4) Box Collector/ Trough Risks:

11 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 conversation (so far) between me and Daniel Connell, see Solar Flower Contact s 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:

12 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.

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16 Plan B Solar Cell Tracker: Conceptual Drawing: