P12441: Thermoelectric Power Pack for Next Generation Stove Andrew Phillips – Project Manager Colin McCune – Lead Engineer Lauren Cummings – Electrical Engineer Xiaolong Zhang – Cost Engineer

Background 3 billion people use open fires and inefficient stoves regularly Requires large amounts of fuel Damage to ecosystem

Haiti Deforestation Soil erosion Decrease in agricultural yields Landslides Running out of fuel Need for more fuel-efficient stoves Add oxygen to combustion process Haiti Dominican Republic

Need for Power Haiti has a history of destructive earthquakes No power grid and no landlines Cell phones and radios for communication Difficult to charge

NeedsImportanceDescriptionComments/Status 13*Fan runs the entire duration of cooking 23*Plan to couple to team 12442’s stove. 33Cheap cost of system Component cost including PCB if applicable 43User-friendly operationMinimal user interaction 53Safe to operate 62Fan runs at start-upMultiple start/restart cycles 72Rugged designSurvive crush and drop test 82Operational in Harsh Environments Exposure to Rain, Moisture, Heat and Salinity 92Ability to charge USB device 101System must be transportable 1115 year life span (3x use per day) Customer Needs *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 11Component Cost3$1510 Including any PCB, for quantities of 1-10K. 22, 6, 8Power supplied to fan3W , 6, 8 Voltage supplied to the fan 3V1112 Converter needs to be adjustable. 48 Amount of startups that can be performed on battery power. 3Start up13 A system startup is the 20 minute period in which the fan is powered by the battery only. 53 User interaction to maintain proper system operation 3Actions10 The user shouldn’t need to perform adjustments to properly operate electronics. 62 Electrical connections provided to the stove. 3Connections642 input wires, 2 output wires 74, 7, 11Survive drop test2Drops220Survive 20, 2 meter drops. 84, 7, 11Survive crush test2PSI25 Enclosure must survive being stepped on 94, 7, 11Survive a rain test2hours12Put it in the shower. Engineering Specifications *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 104, 7, 11Survive a humidity test2hours15 Place the unit in an above 90% enclosed area. 115, 10 Enclosure surface temperature 2°C1055 Surface of enclosure may not exceed 55 °C during operation. 123, 5 User interaction to protect system 2Actions10 The user should not need to perform an action to protect the system 139USB output power2W Margin derived from specs 15, and USB output voltage2V4.755From USB spec 159USB output current2A.475.5From USB spec 169 Number of charges from battery 2Charges Product Life Span2Hours150011,000 Assume 3 hours/use, 2 uses/day, for 5 years 1810System Weight1lbs63Include battery packs Engineering Specifications cont. *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 1910Enclosure Volume1In5x5x53x3x1.5 Include battery packs 203User actions during operation cycle 1#20 Engineering Specifications cont. *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

System Architecture Maximum Power Point Tracker (MPPT) Network Power Storage and Distribution

MPPT Maximum Power Point Tracker (MPPT) Network

Maximum Power Point Tracker (MPPT) o Allows efficient power transfer from TEG to system

Power Distribution Power Storage and Distribution

The battery must always have enough power to run the system during start- up To prevent overdraw First USB is disabled Then fan is disconnected To prevent overcharging System will stop charging battery Battery Management

Battery Protection System Battery disconnect from MPPT and TEG when terminal voltage reaches 6.4 V USB and Fan disconnect from battery when terminal voltage reaches 5.8 V The voltage at the terminal of the switch (yellow) and the voltage at the input to the switch (blue)

CAT Procedure Step 1: Connect battery and power on circuit. Step 2: Run system until USB is disabled. Step 3: Run system until fan is disconnected. Step 4: Attach power pack to TEG. Step 5: Run system until powered by TEG, Step 6: Run system until fan is reconnected. Step 7: Run system until USB is re-enabled. Step 8: Run system until battery is disconnected. Step 9: Disconnect power pack from TEG. Step 10: Connect cell phone to USB output. Step 11: Charge cell phones until USB is disconnected. Step 12: Power off power pack.

Customer Acceptance Test (CAT) Bench Setup A A A A

The output power of the various systems sinks and sources.

The voltages at the various voltage sources of the system

The currents of the various systems

NeedsImportanceDescriptionComments/Status 13*Fan runs the entire duration of cooking 23*Plan to couple to team 12442’s stove. 33Cheap cost of system Component cost including PCB if applicable 43User-friendly operationMinimal user interaction 53Safe to operate 62Fan runs at start-upMultiple start/restart cycles 72Rugged designSurvive crush and drop test 82Operational in Harsh Environments Exposure to Rain, Moisture, Heat and Salinity 92Ability to charge USB device 101System must be transportable 1115 year life span (3x use per day) Project Status *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 11Component Cost3$1510 Including any PCB, for quantities of 1-10K. 22, 6, 8Power supplied to fan3W , 6, 8 Voltage supplied to the fan 3V1112 Converter needs to be adjustable. 48 Amount of startups that can be performed on battery power. 3Start up13 A system startup is the 20 minute period in which the fan is powered by the battery only. 53 User interaction to maintain proper system operation 3Actions10 The user shouldn’t need to perform adjustments to properly operate electronics. 62 Electrical connections provided to the stove. 3Connections642 input wires, 2 output wires 74, 7, 11Survive drop test2Drops220Survive 20, 2 meter drops. 84, 7, 11Survive crush test2PSI25 Enclosure must survive being stepped on 104, 7, 11Survive a rain test2hours12Put it in the shower. Project Status cont. *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Spec Customer Need DescriptionImportanceUnitsMarginalTargetComments/Status 125, 10Enclosure surface temperature2°C1055 Surface of enclosure may not exceed 55 °C during operation. 133, 5 User interaction to protect system 2Actions10 The user should not need to perform an action to protect the system 149USB output power2W Margin derived from specs 15, and USB output voltage2V4.755From USB spec 169USB output current2A.475.5From USB spec 179 Number of charges from battery 2Charges Product Life Span2Hours150011,000 Assume 3 hours/use, 2 uses/day, for 5 years 1910System Weight1lbs63Include battery packs 2010Enclosure Volume1In5x5x53x3x1.5Include battery packs Project Status cont. *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

SpecCustomer NeedDescriptionImportanceUnitsMarginalTargetComments/Status 1910Enclosure Volume1In5x5x53x3x1.5 Include battery packs 203User actions during operation cycle 1#20 Project Status cont. *Most important needs Importance Scale: 1 - Low Importance, 2 - Moderate Importance, 3 - High Importance

Complete design and implementation of the MPPT. Decrease system cost. Increase the efficiency of the DC-DC converters. Complete system PCB layout, and have PCB layout. Manufacture and test enclosure. Send system to Haiti for field testing. Future Work

Questions?