Power Generation for the Better Water Maker: Subsystems Design Review October 29, 2013

Agenda ● Concept Selection o Treadle o Bike ● Subsystems ● Engineering Requirements ● Proof of Concept ● Budget/Cost Analysis ● Project Plan to DDR

Problem Statement The Better Water Maker was developed to disinfect water in nations with high mortality rates due to poor water and sanitation systems. The goal of our team is to provide a low cost, efficient power generation system for the Better Water Maker that does not tire the user, while it is fun and easy to use.

Concept Selection The original selection was too much like re-inventing the wheel From there, we toyed with a mechanical treadle design Finally, we worked back towards a more reasonable design

Treadle Pump Used in developing world for irrigation Piston-Cylinder System Difficult to translate into power

Mechanical Treadle Treadle Lathe Arc Trainer Treadle Sewing Machine

Our Design: Treadle After careful consideration, we decided to move back to the bike design.

Subsystems Seating Power Train Electronics User Interface Sanitation System Interface Structural Components Manuals Testing Risk Analysis

Engineering Requirements FunctionImportanceUnitsRangeGoal ValueCN Fulfilled ER1Cost9USD CN7, CN8 ER2Generated Power9W, V , 14.3CN1, CN14, CN17 ER3Shipping Size3weightCN4 ER4Training Time3minutes5-3010CN16 ER5Ease of Repair3minutes CN7, CN10, CN16 ER6Effort Required9n/aLow IntensityCN2, CN12, CN13 ER7Weight3lbCN3, CN16 ER8 Number of Installers3People1-31 CN3, CN7, CN10, CN16 ER9Number of Tools3ToolsCN7 ER10Unit Life3 Gallons Treated>180,000 CN5, CN6, CN9, CN10, CN15, CN16 ER11Support User9lb CN5, CN12 ER12 Can Hook Up to 12V Car adapter9BinaryYes CN14

Proof of Concept “Historically, two treadles were used for some tasks, but even then the maximum output would have been quite small, perhaps only 0-15 percent of what an individual using pedal operated cranks can produce under optimum conditions.” (Wilson, “Understanding Pedal Power”, 1986)

Proof of Concept “A person can generate four times more power (1/4 horsepower [hp]) by pedaling than by hand-cranking.” “Pedal power enables a person to drive devices at the same rate as that achieved by hand-cranking, but with far less effort and fatigue.” Test Plan - run motor with a second motor to determine required torque Our power requirement = 23 to 29 Watts (Wilson, 1986)

Schematic *P13417 Design potentially wooden gearbox versus plastic 1-4 motors ergonomic recumbent seat, potentially adjustable will re-evaluate effectiveness 4 gears and 1 sprocket inside of gearbox

Block Diagram

Mechanical Analysis RPM output of 7424 Max torque value of 3.7 lb f -ft o Low stress on shaft *Calculations made using Shigley’s Design of Machine Elements

Electrical Details of Pump and Bulb ● 12V nominal system ○ Operates closer to 14V ○ Voltage is limited to 14.3V in current design ● Pump turns on after ~10s, bulb draws power immediately ○ Controlled using a capacitor ● Resistance of system with pump off = ~9.3Ω ● Resistance of system with pump on = ~7.17Ω

Electrical Systems in the Generator ● DC Motors ○ Possibility of using from 1 to 4 DC motors ● Regulator Circuitry ○ Limits voltage to a max value ■ Current design limits voltage to 14.3V ■ We would like this raised to 15V ● LED user interface ○ Display information to the user

Regulator Circuit ● Would like to make use of Team 13417’s design ○ Limits voltage at 15V ● 1 inductor ● 5 capacitors ● 10uF to 100uF ● 3 diodes ● 4 ICs ● 2 switching regulators, 2 amplifiers

Selection of DC Motors ● Run tests at different RPM ● Develop a voltage to RPM ratio for each motor or set of motors ● Need to generate 15V under load at a reasonable RPM ● Once a motor configuration is selected, the gear ratios in the gearbox can be finalized ○ Gear ratio is based on RPM user input

Risk Assessment: Design

Risk Assessment: Ergonomics

Risk Assessment: Project Planning & Shipping

Risk Curve ●Add risks as they arise ●Review and adjust risks on Fridays ●Superimpose lines to stay on track ●Current value = 105

Feasibility Parts are readily available o Standardized sizes Design aspects are fundamental High RPM, high efficiency

Test Plan ER2: Generated Power ER4: Training Time ER5: Ease of Repair ER6: Effort Required ER8 and ER9: Number of Installers and Tools

Bill of Materials (BOM)

BOM for Power Generation System

BOM for User Interface

Budget

Cost Analysis This is not an actual cost estimate, preliminary cost estimate. Many of the component’s manufacturers have not responded or have not been contacted. Yellow=Variable Pricing Orange=Worst Case Pricing

Project Plan List of tasks that will be completed before the Detailed Design Review An action item log is also maintained to delegate more specific tasks

Project Plan

Manuals Template is prepared Pictures are the main ingredient User Manual will contain: o The Use Of the BWM o Setting Up the BWM o Properly Using the BWM o Maintainng the BWM o Troubleshooting and Repairing the BWM o Parts and Tools o Contact Information

Questions?