P18461: Solar Powered UV Water Purification
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Feasibility Analysis

Filter Selection

Simplistic View of Physical Contaminant Removal from Water With Different Membranes (Pore Size Decreases From Top to Bottom)

Simplistic View of Physical Contaminant Removal from Water With Different Membranes (Pore Size Decreases From Top to Bottom)

The opportunity for this project comes in the nonexistence of a lower cost portable water purification system that not only produces water that is safe for human consumption, but a system that also produces water that is absent of odors and tastes commonly associated with organic contaminants (i.e. Hydrogen Sulfide). By the inclusion of UV purification to handle micro-organisms; we aim to lower system cost by being able to choose a filter with smaller pore size such as a micro-filter. A micro-filter will still be able to remove many dissolved solids, which contribute to turbidity, and if a carbon block micro-filter is used then absorptive filtering can also take place.

Sediment Filter That Will Be Used Upstream To Extend the Life of the Carbon Block Filter

Sediment Filter That Will Be Used Upstream To Extend the Life of the Carbon Block Filter

Carbon Block Filter Selected for Prototype

Carbon Block Filter Selected for Prototype

According to the World Water Assessment Programme’s national water development report for Kenya, some of the common contaminants in Kenya’s surface water are:

Based on our filter selections...

Pump Selection

UV Bulb and Quartz Sleeve Selection

UV Batch Treatment

High Level Designs Considered For UV Treatment. Design 1 Was Chosen)

High Level Designs Considered For UV Treatment. Design 1 Was Chosen)

Originally we were planning on treating the water with UV continuously as water flowed through the system. After discussing this concept with Sarah Brownell it was decided that it may be infeasible to go through the testing and validation to complete this process in the MSD timeline, therefore a more conservative approach will be executed using the design chosen above. We will implement batch treatment.

Schematic of UV Batch Treatment)

Schematic of UV Batch Treatment)

In UV Batch Treatment a floating switch will trigger the batch treatment process to begin once the UV compartment is full of water. The pumps will shut down; the inlet valve will close; UV bulb will be turned on and will treat the water to about 40mJ/cm^2 (NSF/ANSI 55); the outlet valve will open; head pressure will be applied by pumps or a third valve that allows access to atmosphere; outlet valve will close and inlet valve will open and the system will start to filter water again and fill the UV compartment. With this process we are better able to assert control over the UV exposure of the water.

UV Dosage Vs. Class A and B (40 and 60, respectively) Standards NSF/ANSI 55 at Different Tube Radii)

UV Dosage Vs. Class A and B (40 and 60, respectively) Standards NSF/ANSI 55 at Different Tube Radii)

Flow Rate Through Entire System With Batch Treatment)

Flow Rate Through Entire System With Batch Treatment)

From this model the flowrate coming from the filters was approximated to be 1gpm, as you can see batch treatment (according to this model) does not dramatically hinder the flowrate through the system. Also, according to this model, flowrate will not be hindered by or optimized by the diameter of the UV housing (calculated as the volume released divided by the time required to: fill the UV compartment with 1gpm from the filters; treat the water to the standard dosage; then allow the water to drain from the compartment), because both volume and time to completion of a cycle are equivalently proportional to the diameter of the compartment.

A document explaining these calculations will be posted (for now the MATLAB code can be found in the directory of our EDGE folder archive). The model will likely change, however, as it contains many assumptions that limit its accuracy. This model is based on the inverse square law, but a more appealing model is the LSI multiple point source summation model, which takes into consideration the geometries and photon propagation from a cylindrical tube.

CAD Models

Modular System Design

Modular System Design

Above is a depiction of the modular design that we intend to create for our water purification system. The modular design will incorporate standard filter sizes and connections so that the user can use the combination of filters that most optimally suites their needs. We have already selected a combination of filters that we think will solve our customer's specific needs, as previously discussed.
Filter Housing Module

Filter Housing Module

Pre-Filter

Pre-Filter

As you will see with many water purification systems, a pre-filter is added to prevent large debris from entering the affluent stream of the water purification system so as to prevent it from clogging your downstream filters.
Electrical Housing

Electrical Housing

Attached to the Electrical Housing The UV Module Can Be Seen

Attached to the Electrical Housing The UV Module Can Be Seen

Electrical Schematics

Solar Panel to Battery

Solar Panel to Battery

Battery to 5V

Battery to 5V

Bill of Material (BOM)

The following is the Bill of material thus far. The bill is a combination of the parts needed for the housing (seen in the cad drawing below) and the components that are purchased (link to the spreadsheet).

Drawing by Phil Sammon & Graham Ardner

Drawing by Phil Sammon & Graham Ardner

Bill of Material

Design Files

Test Plans

For Preliminary Test Plans Click: Here

Tests are in their early stages of development, since most of this preliminary design period was spent performing feasibility analyses. Test plans will be drastically extended upon further by next review.

NSF/ANSI 42

NSF/ANSI 53

NSF/ANSI 55

NSF Protocol P248

Design and Flowcharts

High Level System Schematic of Chosen Concept (Concepts 6 and 9)

High Level System Schematic of Chosen Concept (Concepts 6 and 9)

A Second High Level System Schematic of Chosen Concept (Concepts 6 and 9)

A Second High Level System Schematic of Chosen Concept (Concepts 6 and 9)

Risk Assessment

For Updated Risk Assessments Click: Here (Changes are Highlighted in Yellow)

Design Review Materials

Design Review Presentation

Plans for next phase

Future Work

Phil's Three Week Plan

Ryan's Three Week Plan

Alex's Three Week Plan

Erik's Three Week Plan

Aaron's Three Week Plan

Graham's Three Week Plan

Justin's Three Week Plan


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