Pedal Purification University of Notre Dame Senior Design Group A6 November 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 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 P available = 150 W E available = (150 W)(3600 s) = 540 kJ E required = 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 E required = E heat +E vaporize + E vacuum E max = 523 kJ E min = 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 σ applied ≈ 3.8 MPa HDPE chosen –Meets all requirements –σ HDPE – UTS ≈ 45 MPa

Use of Prototype Pedaling 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: –$ budget –Design schedule Concept Design is feasible with modification to gear ratio.