P17484: Solar Water Heater
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

Summary

Our team intended on finalizing designs for our test stand, system plumbing, and electrical system. We also intended to begin initial testing of our pump and valve systems to ensure we could meter our flow down to the 0.5GPM required for our collector.

What We Accomplished

During this phase we were able to complete all of the things above we set out to do.

Progress Report

The progress report live document can be accessed here.

Drawings, Schematics, Flow Charts, Simulations

Stand Updates

The stand we plan to build for our system has been updated slightly since the Preliminary Design Review. Most notably, the uprights have been changed from 2x4 beams to 4x4 beams. Also, the single sheet of plywood on the base pieces has been changed from one large sheet to 2 smaller sheets per base. These changes can be seen below

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The complete detailed design review drawing package for our stand can be seen here.

Pump Wiring Diagram

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Above is a wiring diagram used to run the pump. The system is powered using a 12V lawn mower battery. A 5A inline fuse is used to protect the pump and there is a toggle switch to turn the system on and off.

Plumbing Diagram

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Above is the plumbing diagram used to test our pump and flow meter. This diagram has all components minus the solar collector.

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Above is the full plumbing diagram for our system including the solar collector.

System Layout

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Prototyping/Beta Testing

During this phase our team made a mock up of our plumbing in order to ensure we could meter our flow down from the pump output of 3GPM down to the solar collector maximum flow rate of 5GPM. During our initial testing we found that meter the flow down below ~.6GPM caused too much back pressure on the pump. Therefore we added a Y-valve to our system in order to bleed off extra flow. By doing this we were able to achieve our required flow rates. The video below shows our flow meter being adjusted throughout our flow range.

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Flow Meter Video

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Bill of Material (BOM)

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The whole Bill of Materials with links to where they were/will be purchased can be accessed here.

Test Plans

It is essential for the team to test and verify all aspects of the physical system. The test plans below have been derived in order to ensure that all manufacturing specifications are being met by purchased products, as well as to ensure that components such as the pump and power source are both safe for use and effective.

The team will be testing to ensure that:

Car Battery as Effective Source of Power

This test will simply involve hooking the pump to the source and allowing it to run. Once we ensure that the pump can move water while hooked to the battery, we can conclude that the power source is sufficient. Subsequent tests will ensure the battery has a long enough life span and other necessary characteristics

Car battery can provide energy for sufficient time frames

This testing will require us to run the pump for a time frame around 3 hours. We will hook the pump to the battery and run it until the battery dies. Charge and repeat multiple times to arrive at some confidence level for pump run time. If necessary, additional batteries can be purchased in the event that the single battery does not provide ample pumping time.

Pump flow can be dampened to the specifications of the flat plate collector

This test will involve running the pump without the flat plate collector and use a flow valve to adjust it to the specification of the flat plate collector. The maximum flow rate the flat plate can reach according to specifications is .5 gallons per minute (gpm). Using the flow valve as well as a lower voltage battery the team should be able to meet the suggested specifications of .2-.5 gpm.

Test temperature regulation to avoid pump’s exposure to temperatures outside of safe operating range (130°F)

Using the mixing valve that is included on our BOM, we will ensure that we can sufficiently control the water temperature to avoid pump malfunction. This is not something that will be tested outright because we risk catastrophic failure at higher temperatures. This testing will be ongoing and will require constant attention for the user. We can test the mixing valve capabilities but running hot and cold water through it from sources that do not require our pump as the medium to move water (hook to faucet), but we plan to minimize the risk of getting the internal pump mechanisms too hot.

Test maximum achievable temperature by plate

Run system outside in ideal weather conditions (clear skies, above average ambient temperature). We plan to run this test via a circulating water model (the inlet and deposit water locations are the same tank). We will measure the temperature and graph the increase and look for the stagnation point where the water temperature begins to stay constant rather than rising.

Test time for plate to heat some constant qty X of water to varying temperatures A,B,C,...

Running the system outside during a sunny day will be an ideal situation for this test, because in order to heat the water there must be sufficient enough solar radiation to do so. Using a stopwatch and thermometer the team will time how long it will take for water of a specific quantity to heat from average temperature of water (50°F) to varying temperatures. This process will take time, because the water may have to run through the collector several times in order to reach the desired temperatures.

Test the Overall Efficiency of the Flat Plate

There will be some difference in the amount of usable energy that arrives at the solar plate and the amount of usable energy that the plate is able to transfer into heat energy and use to heat water. We will measure/tabulate the total usable energy that arrives at the flat plate via the use of solar sensors and tabulated online data. We will then measure (via thermometer) the temperature that the plate was able to hear the water to. Mathematically we can then derive the amount of energy required to create that temperature increase. We can then compare the energy needed to the theoretical value of energy available and then compute efficiency.

The test plans document can be accessed here.

Test Plans & Engineering Requirements

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The test plans and engineering requirements document can be accessed here.

Flat Plate Collector Information

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Risk Assessment

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The new risks are listed above, and the whole risk assessment can be accessed here.

Issues and Concerns

Design Review Materials

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The presentation live document can be accessed here.

Notes From Presentation

Plans for next phase

MSD II Team Goals

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Gantt Chart

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The Gantt chart for MSD II is listed above, and the whole gantt chart can be accessed here.

MSD II Overarching Plans

The MSD I Self-Critique can be accessed here.

Preliminary MSD II Plan

Mike

Evan

Alex

Deven

Sarah

Deliverables for Early in MSDII


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