P19464: Water Purification System
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Preliminary Detailed Design

Table of Contents

Detailed Design Documents

Team Vision for Preliminary Detailed Design Phase

During this phase of our system design, we wanted to start looking into some of the more concrete factors that would influence our eventual prototyping. Chief among these concerns being cost, and feasibility of the design. We created CAD models of our designs and used these to create costed BOM's that allowed us to generate a clear idea of prototyping costs required. We feel confident that moving forward, we will be able to create a functioning prototype and iterate on our designs and final product.

Feasibility: Prototyping, Analysis, Simulation

Spiral Pump

Design Model

"Spiral Pump Prototype"

"Spiral Pump Prototype"

Bill of Material (BOM)

"BOM for Spiral Pump Prototype"

Test Plans

Flow Rate based on revolutions per minute:

This mission of this test is to determine how increasing the angular velocity of the spiral pump will affect the output flow rate and what angular velocity is needed to meet our customer requirements.

• 5 controlled angular velocities (6,8,10,12,14) RMP’s

• Each trial lasts two minutes

• Two operators, one controlling angular speed and one watching timer.

• Flow rate will be measured by weighing amount of water displaced

This test will determine the feasibility of this design by showing the angular velocity needed to produce the minimum 30L of water per day.

Head produced based on revolutions per minute:

The mission of this test is to determine how increasing the angular velocity of the spiral pump will affect the head produced and what angular velocity is needed to meet our customer requirements.

• 5 controlled angular velocities (6,8,10,12,14) RMP’s

• Each trial lasts two minutes

• Three operators, one controlling angular speed, one watching timer and another watching end of hose

• Head will be determined by fixing the end of the hose 1.5 meters above the surface of the water

• The test will pass when water is able to make it out the end of the hose.

• Once passed, the hose will be risen until failure. This test will determine the feasibility of this design by showing the angular velocity needed to produce the minimum 1.5m of head.

Water Hammer Pump

Bill of Material (BOM)

Multiple water hammer pumps will be constructed to determine optimal size. Part numbers and prices will vary with vendor and device scale. Part quotes are based off of a 1 inch diameter body with parts purchased from local hardware stores.

Total cost: $84.47

Surplus PVC will dramatically reduce the cost of prototyping the water hammer pump.

Test Plans

We need to be sure that a water hammer pump can operate in the customer specified conditions, and rivers suddenly flowing due to heavy rain don’t necessarily flow downhill at all points. In order for a water hammer pump to operate in a stream on flat ground, the kinetic energy of the water must be equal to the operating head of the pump. In other words, the flowing river water must have as much energy as the falling water normally used to power a water hammer pump.

An expression of Bernouli’s equation shows the sum of pressure energy, kinetic energy, and height energy is equal between two points:

"Bernouli's Equation"

This equation can “convert” between velocity and height. Considering a stream with an open surface as one point, we can use a 90° pipe open to the air as the second point:

A pipe redirecting kinetic energy to potential energy

A pipe redirecting kinetic energy to potential energy

For an open stream and open access pipe, both pressure terms are equal to 0 and are dropped. H1 is set to be 0 and is dropped. Velocity at point 2 is 0, so the V2 term drops.

Solving for equivalent pump input head H2 in terms river velocity V1 yields:

Bernouli's equation solved for H2

Bernouli's equation solved for H2

For any river flow velocity this equation represents the input energy available to our water hammer pump design.

We can solve this equation for V2 to find out the river velocity equivalent to a known pump input head. This way we can use existing pump designs with known input requirements as measures for the minimum flow velocity required for our design:

Bernouli's equation solved for V1

Bernouli's equation solved for V1

Knowing these relationships we can plan to test several options and variables in the design, outlined below:

Risk Assessment

"Updated Risk Management Table"

Plans for next phase

Located below is our updated Gantt chart describing the team goals for the future of the project. By our next three week update, we hope to have completed an initial prototype of our spiral pump design and address any minor concerns that come up in construction. Ideally, by the next three-week review we are able to begin accurate testing with confidence that we will achieve usable data to help dictate our next decisions and iterations.

"Three Week Gantt"


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