P18422: Black Soldier Fly Composting Habitat Improvement

Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

From the Systems Phase, the group:

During the Preliminary Detailed Design Phase, the group plans to:

Feasibility: Prototyping, Analysis, Simulation

The focus on feasibility for the preliminary detailed design phase falls into four categories: Solar Panel Calculations, Electrical Component Selection, Bottom Layer Removal Experimentation, and Migration Ramp Experiments.

Solar Panel & Power Calculations


For a more detailed breakdown of these calculations see: Power Calculation Summary.

To see the calculations spreadsheet see: Solar Calculator.

To see the insolation data pulled for Rochester see: Rochester Solar Data.

Purpose: The team would like to install solar panels on the roof of the new passive house style shed on RIT campus.There may be some problem getting power off the RIT grid so we want to have an estimate of how much power we will draw in the winter and summer to use as power.

Solar Radiation

Solar Radiation

The image above shows the calculated and average solar radiation data for each month. Melissa from the team looked at one day for each month of the year when performing her calculations to get a variety of the best versus the worst days. When choosing days she ensured at least one of the winter days had little direct sunlight.

She found that the minimum insolation was 860.3 W/m2/day and the maximum insolation was 7853.6 W/m2/day.

The next step is to use these two insolation values to get an estimate of how much power is produced by the solar panel in a given day. Data was collected from a website in order to determine was the rated power for the panels were. It was also estimated the derate factor was 0.8 based on the life of a solar panel. Assuming there are four panels on the roof, the data below shows the minimum and maximum energy per day.

Power Calculations

Power Calculations

The conclusion is that in the winter it can be expected that 435 Wh/day of energy will be collected from the solar panels. This will be important moving forward in determining where the group chooses to use this energy during the winter if they do not find an alternative power source.

Electrical Subsystem

The Electrical Morph Chart consists of Functions that are crucial part of the project and for each Function there are multiple Solutions presented. These solutions were then combined to make a system and the most efficient system was then implemented towards the design.

The Electrical Pugh Chart contains the comparison of PLC and Manual control with the selected controller (RasPi). The RasPi was set as baseline with ‘+’ indicating if the component performs better for the given criteria, ‘-’ indicates if the component performs worst for the given criteria, and ‘0’ indicates if the component performs same for the given criteria. The final Net Score came out negative for both the PLC (-10) and Manual (-22) control supporting the selection of RasPi.

Link to the Control Systems Benchmarking Document that was used to select the controller that will be used moving forward.

PLC vs Raspberry Pi

The Micro810(PLC) and Raspberry pi 3. Both are good choices for the given system but the Raspberry pi 3 proves to be a better option as it fits comfortably within the allocated budget and is reliable for long term data collection. The available I/O connections for the Micro810 would require removing one Analog input signals which is one of the requirements for our customer. The Raspberry pi 3 has 26 available I/O connections which give enough room for connecting all the required signals. The table in the Controllers Comparison Document gives more detailed information on the selection choice.

Reasons for DC

During the primary design phase one of the biggest issues that came up was not having an AC supply to power the equipment in the passive shed. After group discussion, the few suitable alternatives that were proposed included:

  1. Continue requesting FMS to provide AC power and wait for a response.
  1. Using the Solar panels to generate DC power and using an inverter to convert to AC power and buying components that operate with AC power.
  1. Using the Solar panels to generate DC power and buying components that operate with DC power.

From the available options the most feasible solution is Option 3 as using directly DC powered components is that it allows a direct connection to the solar panel feed and would result in reduction of energy losses. Another advantage of using option 3 is that operation voltages are around 24V which is a lot safer to work with as will also reduce component damage in case of a power surge. A detailed discussion to our decision is in the DC Power Selection Document.

Here is a link to the Shed Electrical Plan document.

For more information on wire length calculations:Wiring Lengths

Volume Calculations

The volume and surface area of the composter were calculated for varying heights of food waste in the composter. The average volume and surface area of the larvae was also calculated. In order to estimate the number of larvae that could be housed in the composter at a time the available volume was calculated by assuming that the larvae would burrow up to 7 inches. The available volume was then calculated and divided by the area of the larvae and assuming that the larvae would only occupy 25% of the volume. Additionally the number of larvae was calculated by assuming that 1 square meter could support up to 1.5 million larvae. The surface area of composter was calculated and multiplied by this ratio. It was assumed that larvae can process up to 40 mg of food per larva per day. It was also assumed that larvae produced 2 microwatts of heat per larva, allow the heat output of the larvae to be calculated. It was determined that the composter will be able to process up to 70 kg of food waste a day and house about 1.9 million larvae.

Link to the Composter Sizing document.

Bottom Layer Removal

To see full report: PDD Bottom Layer Experiment.

Purpose: Make a sturdier iteration of the proposed bottom layer removal system. The team would like to more accurately test if this system functions the way it should. This includes not disturbing the top layer where the larvae are, easy to slide in and out of system, and to compare the solid sheet with the scissor system.

Set-Up: The team built a prototype constructed out of wood reinforced with screws. Supports were added to the sides and the back end of the prototype so that the metal sheets could better hold the weight of the dirt and more easily slide in and out at the correct angle. Melissa left the top and bottom of the system open so that you put dirt in the top and remove dirt from the bottom of the composter making it easier for one person to test. The slot in the front of the model is wider than the one cut into the plastic tub so it should be easier to run the scissor guard experiment. Melissa also made the prototype a little shallower so there is more of a handle to grip on the metal sheet.

PDD Prototype 1

PDD Prototype 1

PDD Prototype 2

PDD Prototype 2

Results: From these trials it can be concluded that the scissor guard is easier to operate because there is less range of motion required to open the guard and let the soil pore to the bottom layer and less soil to cut through to put the guard back in place. However, the scissor guard experienced more prominent bunching of the top layer of soil and uneven removal of layers since it is only removing a portion of the bottom layer. Interestingly, the solid guard bunched more on inserting the guard while the scissors bunched more removing it.

It should still be focused on making a easy to use handle so the operator can get a grip on the guard to pull. That was one of the major flaws with this design. In addition to this, there should be some testing done in regards to how much weight can be put on the guard for it still to be operational. Melissa had to remove part of the soil in the prototype because I could not move the guard.

Migration Ramps

Based on feedback received the migration ramp was redesigned to allow for a single exit location for the pre-pupae. The new ramp design number 4 seen in the migration ramp design document will be tested in the next phase to determine feasibility. The other designs seen in the document were determined to be less feasible due to the need for multiple collection sites or the possibility that the larvae could get lost in certain situations.

Drawings, Schematics, Flow Charts, Simulations

The Mechanical Drawing Packet shows assembly instructions, part detail and a bill of materials. The assembly drawings include hardware and overall dimensions to ensure that the composter is within the size set by our customer requirements. The part drawings include hole sizes and locations as well as critical angles for the migration ramps. Much of the material is listed as ½” HDPE because of the availability of the material from the prototype from P17422. Stainless or zinc-plated hardware was selected because the composter will be in a high heat, high humidity environment where corrosion is a primary concern. After the drawings were created, Dan consulted the experts in the ME machine shop for feasibility. All parts and assemblies were deemed to be able to be manufactured with little difficulty. Plans have been made to improve the 3-D model and the drawings in phase 4 based on feedback received by industry experts.

The Electrical Block diagrams show the wiring connections with both the PLC and Raspberry Pi. Both diagrams adequately show the connections between the sensors, components, and the controller. The PLC diagram has one less Analog Input connection as there Micro810 (PLC) only allows four Analog signals. Relays were implemented to create the link between the components and the controller, as the relay would connect or disconnect the power to the component when the controller requests.

PLC Block Diagram

PLC Block Diagram

Raspberry Pi Block Diagram

Raspberry Pi Block Diagram

Bill of Material (BOM)

The team has started developing a bill of materials outlining what parts are expected to be needed for both the shed/electrical system as well as the composter system. As the group continues to refine the final design, they will add greater detail to this document.

Link to the Bill of Materials Document.

Link to the Wiring Lengths Document.

Link to the Wire and Fan Research Document.

Solar Panel Wire Length

Solar Panel Wire Length

12 Gauge Wire Length

12 Gauge Wire Length

Test Plans

Test Plan Chart

Test Plan Chart

Above is a chart outlining the basic tests that the team plans to perform and what engineering requirement it is related so as to ensure that a test is ran for each given requirement. It also lists any standards have been found that relate to that test.

To see the test plan procedures written out for each of the above tests, please use the following link: Detailed Preliminary Test Plan

The next step is to convert the above procedures into more formalized data sheets. The group has completed one sample data sheet available in the following link: Initial Detailed Test Plan Data Sheets

The team has started exploring standards that relate to the test plan as well as the rest of the project. To see this research into those standards, please use the following link: Standards Documents.

For the next phase, the group plans on writing the proposal for the IEEE Grant. The plan of what to include is highlighted in the document: IEEE Standards Education Grant Information

Projected Budget

The below visual depicts the culmination of estimated costs associated with components related to the project. Items in white fill for price have been located through extensive online research and are, thus, reflective of actual market prices. Suppliers have also been identified in this initial attempt to capture budget costs for MSD 2. The items with orange-filled cost cells represent estimations or approximations based upon the choice of DC over AC. The group has only briefly looked into these areas, as they are still awaiting insight and approval from Bill Labine who is responsible for the construction of the shed. These items, along with the battery charger, will be looked into more closely in the time to follow.
P18422 Projected Budget

P18422 Projected Budget

Risk Assessment

The team reviewed and updated the cumulative Risk Assessment that was first created in the Problem Definition phase of the project. It is important to note that Risk RTC5 was successfully mitigated and, thus, removed from the below table. Please review the Planning and Execution page of the project site in order to gain additional information on this.
Risks Impact over Time Plot

Risks Impact over Time Plot

As this phase progressed, it also became aware to the group that risks experienced changes to their impact values. Specifically, risks REN3, RRS6, and RTC4 increased in impact values. This suggests that more attention and effort should be placed upon these items moving forward. As such, the associated mitigation strategies will be implemented and reviewed more frequently.

Risks Impact over Time Plot

Risks Impact over Time Plot

Additionally, the impact value of some risks (REN1, RTC2, RTC5) were lowered. These may still require attention; however, this attention will be less significant.

Design Review Materials

Link to our Design Review Agenda.

Link to our Controllers Comparison Document.

Link to our DC Power Selection Document.

Link to our Mechanical Drawing Packet.

Plans for next phase

During the Preliminary Detailed Design Phase, the group plans to:

Our overall work breakdown plan for the Detailed Design Phase:

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