P07402: UV-Tube Water Disinfection Project

Select Product Concept(s)

Table of Contents

Concept Selection

The developed concepts were combined and narrowed through a scoring process using a series of Pugh's Matrices. The concepts were scored based on certain selection criteria, which were weighted by considering previously determined customer needs. This process was performed for each subsystem, resulting in a final system design concept which was developed through refinement and of the original subsystem concepts generated.

Selection Criteria

Seven main selection criteria used in most of the Pugh's matrices, with some variation (leakage, safety, efficiency were also considered in some sub-systems). The baseline criteria are

Cost (20%)
Ease of Use (15%)
Ease of Repair (15%)
Durability (10%)
Reliability (15%)
Local Materials (10%)
Ease of Construction (15%)

Water Input/Filtration

Five filtration concepts were considered (Terracotta Pot with Sand, Reservoir/Filter, Fast Filtering Mesh, Commercial Bag Filters, and Commercial In line Filters). The Filter Concept Selection Matrix revealed that the team will proceed with a combination of the bag filter and large reservoir sand filter. The water will first be filtered through sand to catch the larger particles, thus extending the life of the purchased bag filter. The bag filter will be suspended over a reservoir or bucket which will store the water until it is to be disinfected.

Tube Cavity

The two tube cavity designs offer easier access to the UV bulb and tube interior for cleaning and maintenance. The Tube Cavity Selection Matrix has revealed that the "Frame Support With Cover" design is favored due to it being a more simple design which uses cheap, easy to locate materials.

Power Systems

There are two sources of power for the device. It may be connected to the grid or powered from an alternative source (both of these options are being pursued). The alternative sources considered are solar and human powered DC generator input. The Alternative Power Selection Matrix shows that the two concepts score very close to one another, and therefore both concepts will be researched further.
DC Generator Power Inputs
The DC Generator power concept necessitates a mechanical system to transmit mechanical power into the motor/generator. Those concepts considered are a Fan Turbine, Flywheel - Handcrank, and Bike Pedal concepts. The Generator Input Selection Matrix reveals that the hand-cranked flywheel is the favored concept because of its simplicity and usage of readily-avaialble parts. The seated bike pedal concept is also a concept which will be looked at further.

Selected Concept

Through this process, the following system concept was developed. The team will move forward with detailed design based on this concept.