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.
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
Ease of Use (15%)
Ease of Repair (15%)
Local Materials (10%)
Ease of Construction (15%)
Five filtration concepts were considered (Terracotta
Pot with Sand, Reservoir/Filter, Fast Filtering Mesh,
Commercial Bag Filters, and Commercial In line Filters).
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.
The two tube cavity designs offer easier access to the
UV bulb and tube interior for cleaning and maintenance. The
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.
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
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.
Through this process, the following system concept was
developed. The team will move forward with detailed design
based on this concept.