Team P08404: Team Members: Ben Johns (ME) Adam Yeager (ME) Brian T Moses (ME) Seby Kottackal (ME) Greg Tauer (ISE) Faculty Guide: Dr. Stevens Review Date: 1/25/2008 Solar Pasteurizer Concept / System Design Review

P08404 System Review 2 Discussion Content Team Roles/Responsibilities Project definition – General overview – Customer Needs – Engineering specs Functional Diagram Subsystem Selection Concept Selection System Architecture Modeling High Risk Technologies/Feasability

P08404 System Review 3 Team Roles and Responsibilities Ben Johns (ME) Team Leader Adam Yeager (ME) Mechanical Design Collector Subsystem Heat Exchanger Subsystem Brian T Moses (ME) Fluid Modeling Convective Loop Subsystem Solar Energy Radiation Model Seby Kottackal (ME) System Modeling Valve Subsystem Materials and Coatings Greg Tauer (ISE) Economic Analysis Fabrication Specialist Interfacing and Design of Experiments

P08404 System Review 4 Project Background short-supply/ Daily 5000 children are dying from diahorreal diseases directly related to lack of poor drinking water quality (Who Water for Life). It is this team’s goal to design a working prototype that can safely pasteurized water in a developing country.

P08404 System Review 5 Project Background Continued

P08404 System Review 6 Customer Needs I.End User Oriented Needs: 1.Safely pasteurize enough H20 for one typical family in a tropical climate. 2.Cheap a.To maintain: Must be affordable to upkeep for typical family of interest. b.To produce: Unit must be cheap enough to get into hands of customer. c.To use: Should have no consumables – no direct cost to run. 3.Easy to a.Use: Customer will likely have limited educational background, may be illiterate, and probably won’t know English. b.Assemble: If possible, end customer should be able to set up unit themselves. c.Maintain: Again, should be serviceable by end customer. 4.Safe: Device must not pose direct health risk to end user (no sharp edges, hot surfaces, excessive glare, etc.) 5.Durability: Device should last a significant amount of time II.EPA Oriented Needs: 6.Environmentally Friendly: Should be made of materials and employ processes that will not be harmful to the environment. 7.Distributable: Should be easy to get into end user’s hands. 8.Tamper Resistant: Should resist undesired repurposing. 9.Solar: Must be powered by solar energy, per project guidelines. NeedImportance Safely Pasteurize Enough Water9 Cheap9 Easy to Use3 Easy to Assemble3 Easy to Maintain3 Safe3 Environmentally Friendly3 Distributable3 Resistant to Unintended Uses1 Solar Powered9

P08404 System Review 7 Engineering Specs

P08404 System Review 8 Functional Diagram

P08404 System Review 9 Subsystem Concept Pugh

P08404 System Review 10 Subsystem Concept Pugh Cont.

P08404 System Review 11 Concept Selection A B D E C

P08404 System Review 12 Full Concept Pugh D

P08404 System Review 13 System Architecture

Tube in Tube Heat Exchanger Modeling Inlet dirty water temp of 20 C Outlet pasteurized water temp of 70 C Flow rate 100L/Day (8 hours) Length of 0.25” ID tubing needed to heat incoming water to 50 C L = 5.64 m (23” Coil)* *Can be consolidated into a 23” coil (with 0.25” gap) and fit inside 3” ID pipe.

P08404 System Review 15 Collector Tubing Length Estimation Inlet dirty water temp of 20 C Outlet pasteurized water temp of 70 C Flow rate 100L/Day (8 hours) Assumed Incident Solar Energy: 750 W/m2 (Average in summer in Haiti) Length of 0.25” ID tubing needed to heat incoming water to 70 C 50% Collector Efficiency: 1.66m 20% Collector Efficiency: 4.16m Min bend radius for tubing: 0.03m

P08404 System Review 16 Assuming: 4m of 0.25”ID tubing 24” x 36” Aluminum Collector Plate (Chosen for cost and availability) Collector Size Estimation Yields Collector Geometry: 9 passes of tubing with 4” dia. Bends This yields total tube length of 172” Rough Cost Estimation: $ ” 36” 24”

Convective Recirculation: Feasibility The density-driven convective loop is a known phenomenon. Pressure differences are the result of integrating density over two different columns of water. Even with the small pressures created, the expected flow rates (on the order of 5 ml/s) cause negligible losses in comparison.

P08404 System Review 18 High Risk Technologies Temperature sensing and control Problem: Previous design had a number of issues involving batching. Solution: Sense temperature remote to valve water exit. Employ convective loop to prevent stagnant water. Venting of accumulated air Problem: Air accumulation is a common problem with any device that heats water. Solution: Use vent tube extended above head level to release excess air. Water tight seals Problem: First generation design had a number of leaks on its collector. Solution: Use tubes attached to a flat plate to minimize opportunities for leaks.