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Project Management Review. P10462: Thermoelectric Power System for Cookstove. Team & Roles. Young Jo Fontaine – ME – Thermoelectric Design, Placement, and Thermal Analysis Dan Higgins – EE – Power Control System Shawn Hoskins – ME – Project Leader, Interface Liaison
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Project Management Review P10462: Thermoelectric Power System for Cookstove
Team & Roles • Young Jo Fontaine – ME – Thermoelectric Design, Placement, and Thermal Analysis • Dan Higgins – EE – Power Control System • Shawn Hoskins – ME – Project Leader, Interface Liaison • Luke Poandl – EE – Battery and Auxiliary Power • Dan Scannell – ME – Fan Design/Selection, Placement, and Flow Analysis
Project Background • Rural Haitians currently cook indoors using inefficient wood-burning stoves • Due to incomplete combustion, particulate emissions are released and fuel is not being used to its full potential • The people of Haiti face serious health problems due to smoke inhalation as well as complete deforestation of their country due to inefficient use of wood • Goal of project track is to develop a stove that uses a thermoelectrically powered fan to introduce proper airflow and promote complete combustion of fuel
Project Background – Cont. • Goal of project is to develop a thermoelectric power system for a COTS cookstove • Thermoelectrics create an electric potential when subjected to a temperature difference • Using the heat from the fire, a thermoelectric module could possibly produce power for the fan, recharging a battery, and auxiliary uses (i.e. cell phone charging)
Objective • Power a fan using TEG • Start fan on battery power • When a sufficient temperature difference across the TEG is realized, power fan with output of TEG • Recharge the batteries with TEG power output • Provide auxiliary power for charging a cellphone with TEG power output • System should be affordable for Haitians and simple to build
Cookstove • Current stove has fan that runs off AA batteries • Objective is to provide similar airflow using TEG as power source
System Overview • System is designed as a “backpack” unit • Can be affixed to multiple stoves • Requires only two openings to be cut in current stove’s wall • Heat is supplied to the TEG through an aluminum rod (exposed to fire) and flat plate • TEG is cooled by an aluminum heat sink and airflow from the fan • Airflow is directed through a duct similar to the heat sink geometry and into the stove
System Overview – Cont. • System starts on battery power (3 AA’s) • System switches to TEG as main power when TEG begins to provide sufficient power • TEG powers the fan, recharges the batteries, and provides power for charging a cell phone
TEG Selection • System was designed for Taihuaxing TEP1-12635-3.4 • Provides 2.8 Watts of power at peak operation • Single order: $50 • 1,000+ order: $8.60 • Lead time: 1 week • Allows higher overheating protection compared to similar TEG’s (380°C)
Other TEG’s • Taihuaxing TEP1-1264-1.5 • Higher potential power output (5.9W) • Similar pricing and lead time to TEP1-12635-3.4 • Marlow TG 12-4-01L & 12-6-01L • Lower maximum temperature (250°C) • Higher prices ($12.50 to $20.00) • No lead time • Will order these additional TEG’s and use for testing/possible implementation
Revised Electrical System • Prevents overcharging of batteries • Does not allow auxiliary power use when TEG is not actively providing power • Does not incorporate MPPT, but was deemed most realistic/practical design
Flow Analysis • Flow analysis was redone using the square geometry of the heat sink as a duct • Results were compared to that of the stove’s current system • Minimal difference was realized between the two designs • Duct will be constructed of sheet metal and will be 2.6” square
“Thermal Bridge” Analysis • Design was redone by varying the length of rod within the combustion chamber, as opposed to the length of rod outside the stove • Length of rod outside the stove was set to 1cm • Found that potential for overheating and destroying the TEG was much more likely • Therefore, decided to keep original design • Also, melting point of aluminum is not expected to be reached
TEG Interface • The TEG will be secured to the flat plate and heat sink through the use of four 10-32 socket cap screws • Screws will pass through holes in the flat plate and heat sink larger than their diameter to prevent conduction from the hot side to the heat sink • Each screw will be secured using a 10-32 hex nut and will be insulated on each side with a PTFE washer • Heat sink and flat plate are larger than the footprint of the TEG to allow for screw through holes
Final BOM • Estimated cost of prototype build is $101.67 • Estimated cost of production (1000+) is $46.26 • This is assuming all parts are purchased off-the-shelf; some components can be fabricated for a lesser cost