1. PROJECT 11462 THERMOELECTRICS AND FAN SYSTEM FOR COOK STOVE PROJECT UPDATE – DEC. 16, 2010 Week 3

2. Updated Customer Needs NeedsImportanceDescriptionComments/Status 19Provide forced air flow to fire in current RIT stove design 23System easily removed from stove 39Cheap cost of system 435 year life span (3x use per day) 59No user interaction for system protectionChanged wording 63Variable flow rate controlChanged wording 73User-friendly operationChanged wording 81Environmentally friendlyNew Need 91Well packaged system 103Operational in harsh environmentsChanged wording 119Works with charcoal fire 123Ability to charge auxiliary device 133Plan to apply to team 11461's stoveChanged wording 141Fan runs at start-up 159Safe to operateNew Need 169System must be transportableNew Need 179Thermoelectric use

3. Updated Engineering Specs SpecDescriptionImportance Relates to CN UnitsMarginalTargetComments/Status 1Flow rate of air into stove91,6,14Kg/min0.8-10.5-1.2 2Flow Control Settings36,14#23 evenly distributed across the flow range 3Unit Price93$3015 4Coupling Time12,7,13min105 Further definition (tools required) pending system design 5Removal Time12,7,13,16min105New Spec 6Life Span34,10years35Assume 3 uses per day 7Aux Charging312,17Ah 8 Power for Fan Startup Until Battery Recharging 312,14,17V 9Thermoelectric ΔT911,17°C200 10Weight17,9,13,16Kg2.52 11Volume17,9,13,16m3m3 12Time to Reach Peak Performance114,17min3015Within 90% of SS 13User Actions During Operational Cycle36,7,14#64 14Single Use Operational Time34,10hrs912 Based on Brownell comments consider scaling back 15User Actions to Protect System35,7#10 16 System Temperature Under Worst Case Conditions 31,4,10,15°C 17 Maximum External Temperature of Housing 37,9,15°C

4. SYSTEM FUNCTIONS Provide air to stove fire Provide heat to power generating device (hot side) Control temperature at the power generating device (hot side) Convert heat into electricity Provide power to air flow device Provide cooling to power generating device (cold side) Control temperature at the power generating device (cold side) Means to connect/disconnect device from stove Provide auxiliary power hook-up Means to control air flow Means to store electrical energy Means to control electrical energy flow Means to enclose system/protect user Provide auxiliary power hook-up

5. SYSTEM FUNCTIONS BRAINSTOMRING FUNCTION – Provide forced air flow to combustion chamber – Fan – Compressed Air Source – Bellows FUNCTION – Provide heat to hot side of thermoelectric – Metal Rod – Contact Block (Contacts outside wall of combustion chamber) – Direct Contact (Thermoelectric to wall of stove) FUNCTION – Control temperature at hot side of thermoelectric – Temperature sensor/Reduced fan speed – Wax – Rod/Block Sizing

6. FUNCTION – Convert heat to electricity – Thermoelectric FUNCTION – Provide power to air flow device – Battery – Thermoelectric FUNCTION – Cooling cold side of thermoelectric – Heat Sink – Tube/Liquid cooling – Wax FUNCTION – Control cooling of thermoelectric – Fan speed FUNCTION – Means to connect and disconnect device from stove – Long Bolts – Dowels – Stand – Hook system – Latches – Track system FUNCTION – Control air flow – Throttling (car vent style) – Fan Speed – Adjustable scoop/bypass

7. FUNCTION – Means to store energy – Battery FUNCTION – Means to control energy flow – Well designed circuit (flip-flops, op-amps) FUNCTION - Means to enclose system/protect user – Metal Case – Fully enclosed components – Heat conduction barriers FUNCTION – Provide auxiliary power hook-up – USB port

8. P11462 System Block Diagram

9. P11462 Control System Block Diagram

10. CONCEPT SKETCHES

17. Risk Assessment IDRisk ItemEffectCause Likelihood Severity Importance Action to Minimize RiskOwner Describe the risk briefly What is the effect on any or all of the project deliverables if the cause actually happens? What are the possible cause(s) of this risk? L*S What action(s) will you take (and by when) to prevent, reduce the impact of, or transfer the risk of this occurring? Who is responsible for following through on mitigation? 1TEG overheatTotal System Failure Inadequate heat transfer control 236 In-depth heat transfer including FEM, testing Jeff 2Insufficient TEG coolingUnsustainable operation Heating up of TEG cold side 224 In-depth heat transfer including FEM, testing Brad 3TEG lead timeUnderpowered system Poor time management/ change in design 122Early analysis of power consumptionJared 4 Battery failure/destruction Total system failure Poor battery sizing, excessive heat 236 Proper battery sizing, means to bypass battery Fahad 5Product Cost Over acceptable/affordable value for Haitians Excessive component cost 224Design based on costJared 6Project BudgetOver budget Inaccurate pricing of materials, inefficient use of materials 122 Check pricing against other sources, approve plans before material fabrication Jared 7Component meltingSystem failure Excessive heating to components 224 Insulated design for sensitive components Tom/Jeff 8Lead timesOver budget/Late delivery Poor vendor selection, inadequate research 224 Secure correct shipping times/Plan for additional shipping time Jared 9Battery doesn’t charge Fan won't start immediately. Aux. device won't charge. Poor battery sizing, too little current to battery, battery malfunction 224 Size the battery more accurately through better testing. Allow TEG to charge aux device. Fahad

18. 10 Insufficient power for aux. device Aux. device does not charge TEG produces insufficient power 224 Produce design with minimal power consumption Tom 11Transient modeling Forced induction to fire may fail at start-up or battery will be drained Insufficient transient heat transfer modeling. Insufficient energy storage capabilities 326 Rigorous transient heat transfer analysis. Careful selection of heat transfer method and materials. Testing of stove (transient temps) Brad/Tom 12Battery is drained Fan won't start immediately. Aux. device won't charge. Battery too small and doesn't hold charge well. Excessive user interaction 313 Test battery many times to ensure charge is held. Incorporate an LED warning system to tell user that battery is drained. Fahad 13 Insufficiently connects to stove Failure to meet CN 9,10. Possible damage to unit.Poor design planning 224 Decide on robust design early in design process and test design. Tests should include durability testing. Brad 14 Unable to maintain max TEG efficiency TEG capabilities not optimized Transient effect on components 224In depth analysis / TestingTom/Jeff 15 Fan produces low flow rate Inadequate system Inaccurate sizing or analysis 122 Check analysis of flow rate from stove team, "size" fan for slightly higher flow Jared 16 Heat conduction rod melting Possible loss of heat transfer to thermoelectric Inadequate analysis of stove operating temperatures and material properties 236 Analyze stove operating temperatures. Carefully select material to suit Brad 17 Heat conduction rod conducts too much/not enough heat Possible overheating of thermoelectric/ Insufficient power generation Inadequate heat transfer analysis 236 Complete analysis of heat transfer characteristics of rod/block. Average stove operating temperatures taken into consideration Brad 18 Rod takes too long to heat up Improper system function. Fan may not operate at start- up Inadequate transient heat transfer analysis. Inadequate understanding of transient temperatures in combustion chamber. 224 Test stove to get understanding of transient temperatures. Model transient temperature characteristics of rod. Brad 19 TEG power producing capacity too small Underpowered system Unable to meet required ∆T or TEG incapable of producing required power 133 Design with minimal power consumption Jeff/Tom

19. 20 Inability to accurately model TEG Optimal power not being used TEG model changes as heat is consistently applied 224In depth analysis / TestingJeff/Tom 21 Electrical components fail/overheat System Failure Excessive heating to components. Complicated design. 236 Keep components insulated and distant from heat. Simplify design to incorporate as little components as possible Fahad 22Aux device overheatsDamage to aux. device Inability to turn off power to unit being charged when fully charged 212Unplug device when fully chargedTom 23 Fan produces insufficient pressure drop Forced air unable to reach fire Poor modeling/testing of stove 224Increase flow rateJared 24 Fan requires too much power Fan will drain power from battery, overdraw TE Poor fan selection or design, fan failure 122 Apply margin on battery size or fan sizing Jared 25Fan melts Loss of airflow, main system failure Fan placed too close to stove, stove heat underestimated 133 Testing to correctly estimate temperatures at proposed location Jared 26Fan lifespan too short System lifespan shorter than desired length Bearing failure, material degradation 122 Select fan with known lifespan (documentation) Jared 27 Inadequate means to prototype (tooling) Failure to provide prototype for testing. Failure to deliver product. Complex components, exotic manufacturing methods (CNC), insufficient thought given to lead times. 236 Consider means of production when in design process. Plan ahead for lead times. Brad 28 Casing conducts too much heat Jeopardize user safetyinsufficient insulation236Testing of radiant heat near controlsJeff 29 Faulty design of control system System failure Components not sized properly or break due to overheating from fire 236 Design system in insulated location / In depth analysis of design Tom/Fahad

20. Week 4 Plans Update Customer Needs and Engineering Specs based on feedback Iterate and expand risk assessment Determine values for Engineering Specifications Test 1 st generation stove to determine transient and operating temperatures Test TE to determine transient behavior Start proof-of-concept calculations and simulations Lecture HW

21. Preferred System Level Design Time 9 am Unavailable at 11am – 1pm