P10462: Thermoelectric Power System for Cookstove

 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

 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

 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)

 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

 Current stove has fan that runs off AA batteries  Objective is to provide similar airflow using TEG as power source

 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 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

 System was designed for Taihuaxing TEP ◦ 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)

 Taihuaxing TEP ◦ Higher potential power output (5.9W) ◦ Similar pricing and lead time to TEP  Marlow TG L & L ◦ 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

 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 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

 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

 The TEG will be secured to the flat plate and heat sink through the use of four 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 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

 Estimated cost of prototype build is $  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