Pedal PurificationUniversity of Notre DameSenior Design Group A6November 28, 2006

Team Rallye (from left): Nicole Del Rey Eric Sabelhaus Mike McConnell Tim Rodts

Objective

• 2006 ASME Design Competition requirements:– Allow user to convert 200 mL of ‘polluted’ water into pure

drinking water within one hour. – Compact, collapsible, transportable design.

• Group Requirements:– Robustness - adaptable as power source for emergency

applications. – Collapsible – components housed underneath user’s seat when

not in operation.

The Concept

Pedals and

Gears

Generator Heating Condensing

Pedals and Gears

Pedals and

Gears

Generator Heating Condensing

Considerations: • User comfort (height adjustment with angle-iron)

• Sustainable user RPM• Optimum gear configuration

Generator

Pedals and

Gears

Generator Heating Condensing

Considerations:

• Sprocket mount to 5/16” generator shaft

-fitted sleeve and set-screw• Exposed wire

-wire caps• Connection to alternative power sources

-fitted to female plug•Firm mounting to base

-L-brackets mounted to wood base

Heating and Condensing

Pedals and

Gears

Generator Heating Condensing

Packaging

Pedals and

Gears

Generator Heating Condensing

Packaging

Compact

Expanded

Packaging

Pedals and

Gears

Generator Heating Condensing

Packaging

Features:

•Collapsible chair back•Fold-up angle-iron supports•All components housed underneath chair on stationary base

Concept

Realization

FEASIBILITY ISSUES

Feasibility Issue #1: Energy Requirements

Pavailable = 150 W

Eavailable= (150 W)(3600 s)

= 540 kJ

Erequired = ρcVΔT +mhfg

= 523 kJ

Question: Can a bicycle pedal system provide enough energy to boil 200 mL water in 1 hour?

Answer: YES – at 100% efficiency!

Feasibility Issue #2: Pressure Reduction

Erequired = Eheat +Evaporize + Evacuum

Emax = 523 kJ

Emin = 510 kJ

Question: Would a pressure reduction system be feasible for energy savings, since water boils at lower temperatures under lower pressures?

Answer: Energy savings are minimal, hence pressure reduction is infeasible.

Feasibility Issue #3: Maximizing Gear Ratio

• Question: How can generator power output be fully utilized?

• Generator: maximum 5,000 rpm at GR = 55.7

• Obtained: 460 rpm at GR = 5.13– Yields ≈ 3.0 W

• Result: Need 3 sets of sprockets (ratios shown below) to maximize generator power output.

• Deemed infeasible for prototype due to cost issues related to purchasing/mounting sprockets

• Answer: For final design,

increase gear ratio!

TECHNICAL ISSUES

Technical Issue #1: Generator Shaft/Sprocket Connection

• Generator can handle radial load, verified by supplier.• Sprocket with set-screw in hub necessary.• For ANSI Chain #35, minimum

½” bore diameter, generator

has 5/16” shaft.

• Solution: fashion sleeve

in sprocket/hub to

match shaft diameter.

Technical Issue #2: Compact Packaging

• Solution: CAD model to verify location/ orientation of components. – 21” x 25.5” between

chair legs– Condensing unit

– Removable Base

• In disassembled state, all components must be housed underneath chair to meet ASME requirements.– Maximum girth = 165”

– Prototype girth = 135”

Technical Issue #2: Compact Packaging

21”

11”

6”

11.8”25.4”

20”28

”

Technical Issue #3: Material Selection

• Material Requirements:

– Lightweight

– Strong

– Stiff

– Durable

• σapplied ≈ 3.8 MPa

• HDPE chosen

– Meets all requirements

– σHDPE – UTS ≈ 45 MPa

sectioncross

pedalhalf

applied A

F

Use of PrototypePedaling Demo

Voltage Output at 0.2 A

Sprockets in Motion

Condensing System

CONCLUSIONS

Conclusions• Prototype shows individual feasibility of:

– Mechanical energy transfer– Power Generation– Heating unit– Condensing unit

• Compact, collapsible and transportable design was achieved.

• Prototype proves feasibility while satisfying:– $400.00 budget– Design schedule

• Concept Design is feasible with modification to gear ratio.