underwater thermoelectric generator p14254
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Underwater Thermoelectric Generator P14254. Agenda. Background Problem Statement Customer Requirements Engineering Requirements House of Quality System Analysis Functional Decomposition Concept & Architecture Development Engineering Analysis Risk Assessment Test Plan Project Plan. - PowerPoint PPT PresentationTRANSCRIPT
Underwater Thermoelectric GeneratorP14254
10/8/2013 Rochester Institute of Technology
Rochester Institute of Technology
Agenda
◼ Background◼ Problem Statement◼ Customer Requirements◼ Engineering Requirements◼ House of Quality
◼ System Analysis◼ Functional Decomposition◼ Concept & Architecture Development
◼ Engineering Analysis◼ Risk Assessment◼ Test Plan◼ Project Plan
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Rochester Institute of Technology
Discussion Points
● Heat Sinking● Materials● External vs. System Electronics Power Source
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Background
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Background Information
BOEING’S UUV, ECHO RANGER
▪ Developed in 2001 for seafloor mapping for oil/gas industry
▪ Currently testing the idea for potential military applications▪ ISR▪ Harbor security
▪ Current run time ▪ ~28 hours
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Rochester Institute of Technology
Background Information
• Boeing wants to extend the mission time of their submarine
• They are interested in thermoelectrics
• Our Task: Prepare a proof-of-concept underwater thermoelectric generator that charges a battery.
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Rochester Institute of Technology
Project Updates
Since last time...
◼ Battery voltage: 12V◼ Battery capacity: 750mAhr◼ Battery type: Li-ion◼ Emphasis on thermoelectric
and total system efficiency
❏ Was undecided❏ Was undecided❏ Was Li-Poly❏ We will not put much
emphasis on specific heat source
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Customer Requirements
◼ Continuously generate power◼ Operate efficiently◼ Charge a battery◼ Operate underwater◼ Heat source provides a constant source of
heat◼ System can withstand interior enclosure
temperature◼ Utilize passive safety features
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Engineering Requirements
◼ Power Output: 20W◼ Heat Source Power Input: 500W◼ Upper Ambient Operating Temperature: 30°C◼Thermal Overload Protection: 10% of max T◼Operates Without User Input: 0 interactions◼ Heat Source Temperature: Ideally 300°C
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House of Quality
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System Analysis
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Functional Decomposition
Generate Electrical
Power
Protect System
Resist Operating
Temperature
Operate Under Water
Resist Corrosion
Resist Pressure
Resist H20 Ingress
Generate Heat
Use Electric Heater
Transfer Heat
Spread Heat Reject Heat
Generate Electricity
Utilize Temperature Difference
Store Energy
Charge Battery
Transfer Electricity
Monitor Systems
Measure Power
(Power input and output)
Measure Ambient Conditions
(Temperature, humidity,
moisture content, pressure)
Resist Operating
Temperature
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Mechanical System Level View
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Thermal System Level View
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Red arrows are lost heat.
Main heat path: Source TEG Sink Water
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Electrical System Level 0
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Electrical System Level 1
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vv
Instrumentation System Level View
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Morphological Chart
*Ideas in red have proven to be not feasible
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Functions
Means Generate Heat
Spread Heat
Monitor Systems
Reject Heat
Enclosure Material
Enclosure Shape
Thermo-electrics Seal
1Cartridge Electric Heater
Air Embedded Microcontrollers Pump
Non-corrosive metal
enclusure
Rectangular Prism stacked Vacuum
2 Film Electric Heater Oil External
Computer Fan Ceramic Sphere single duct tape
3Resistor Electric Heater
Water Tactile Metallic Fins Plastic Cylinder top/bottom electrical
tape
4 Burning Copper Insulator Rubber Dumbbell all sides gasket
5 Friction Wheel Aluminum Rigid metals Hexagonal
Prism o-rings
6 Steel Polycarbonate Octagon weld
7 Polycarbonate/Metal Hybrid epoxy
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Criteria Solution 1 Solution 3 Solution 7 Solution 8 Solution 9Allowable Enclosure Temp 0 + 0 - 0Electronics temp 0 + 0 + +Autonomous 0 - 0 0 0Compact 0 - - 0 -Cost 0 - - - -
Easy of Assembly/Disassembly 0 + 0 - -Ease of Waterproofing 0 - 0 - -Easy to Troubleshoot 0 - - - +Efficiency of Thermoelectrics 0 0 + 0 0Cold Side Temperature 0 + + 0 0Manufacturability 0 - 0 - -Number of Gerbils 0 0 0 0 0Safe 0 + 0 0 0Weight 0 0 0 + 0
DATUM+ 5 2 2 2- 6 3 6 5
Function Solution 1 Solution 3 Solution 7 Solution 8 Solution 9Generate Heat Cartridge Cartridge Cartridge Cartridge CartridgeSpread Heat Copper Copper Copper Copper CopperMonitor Microcontrollers Ext Comp Microcontroller Microcontrollers MicrocontrollerReject Heat Fins Fins Fins Fins Fins
Enclosure Material Non Corrosive Metal Ceramic Non Corrosive Metal
Polycarbonate/Metal Hybrid Non Corrosive Metal
Enclosure Shape Rectangular Prism Dumbbell Rectangular Prism Rectangular Prism Dumbbell
Thermoelectrics Electrical Configuration Series Series Series Series Series
Thermoelectrics Mechanical Configuration All Sides All Sides All Sides - Double
Stacked TE's All Sides All Sides
Seal/Protect Gasket Gasket Gasket Gasket Gasket
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Pugh Conclusions
• Shapes: The simple rectangular prism won.• No External Control: We are going to have a
microcontroller anyway• Enclosure Material: Thermoelectric side will
need non-corrosive metal, electronics side can be plastic.
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Rochester Institute of Technology
Engineering Analysis
• Battery Capacity• Leakage• Heat Sinking• TEM efficiency
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Batteries
Li-Ion instead of Li-Poly
● Li-Ion are more readily available and cost less than Li-Poly.Li-Poly’s higher energy density does not outweigh its cost, and it’s shape characteristics are not an added benefit to the project.
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Batteries
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Battery Voltage: 12 V
Battery Capacity:(20 W*95% efficiency )/12V = 1.58A
1.58A*0.5 hr charge time = 754mAhr
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Leakage
• At 2 feet test depth:• P = ρgh• P = 999 kg/m^3 * 9.81m/s^2 * 0.61m• P = 6 kPa or 0.87 psi• Test Spec IP68 met by a number of cheap
enclosures by Integra Enclosures
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Thermal Circuit Analysis
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Thermoelectrics
● 20% heat loss● 95% efficient charging
system● Constant Thermoelectric
Properties● Heat Sink is flat, isothermal
vertical plate.
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Heat Sink
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Length (cm) Resistance (K/W)9.7 0.199
5.6 0.500
3.8 1.00
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Budget
• Thermoelectrics – $40/ea• Enclosure – $200• Electronics (Including cabling, microcontroller, and
battery) – $250• Testing – $100
Rough Total - ~$550 + 40n
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Thermoelectrics
• Power strongly dependent on Heat Sink.
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Dumbbell Enclosure
• If heat sink has 0.5K/W or greater resistance, the “cold” side will be very hot
• We need to protect our electronics from damage
• Dumbbell shape best mitigates risk to electronics
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Rochester Institute of Technology
Risk Assessment
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Category Risk Item Effect Cause Likelihood Severity Importance Action to Minimize Risk
OverheatLocal system overheat of Thermoelectric device
Component degradation or loss. Replacing component delays testing.
Poor heat sinking, rapid removal from water
1 2 2
Heat sinking testing without component, follow test protocol for removing device from water
EnclosurePressure vessel breach due to failure of seals
Equipment degradation, possible partial or complete system loss. This is potentially a large time draw as multiple components would require replacing before resuming testing.
Deflection due to thermal or mechanical stress, improper assembly
2 3 6
Heat sinking and pressure testing without electronics, follow testing procedure for assembly
ElectricalElectrical failure of PCB / microcontroller
Possible component failure. Possible long lead time item requires replacing, delaying testing.
Short circuit 1 3 3Thorough subsystem testing and CAD simulation
ProjectLack of guidance / late guidance from Boeing
Design criteria left open-ended, design without Boeing input, last minute changes put project behind schedule
Boeing contact is busy, does not respond in a timely manner
3 1 3
Provide ultimatum proposal to Boeing, rely on benchmarking competitors where detailed technical information is needed.
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Test Plan
Test waterproofing without heat
Test thermoelectric, sensors, charging and max power point circuits
Test waterproofing with heat
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Test Plan◼ Test heat sink
◼ Integrate and test full system.
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1: Heat Sink2: Thermoelectric Array3: Heat Source4: Instrumentation5: Microcontroller & Charging circuit6: Battery
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Project Plan◼ We only have 2 weeks◼ This is how we do it
▪ 5 days --- integrate --- 5 days◼ Update EDGE & Risk Assesment
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Issues on the Horizon
● Thermoelectric clamping (300kPa min - recommend 1.2MPa)
● External vs system powered electronics (sensors, microcontrollers, etc)
● Heat sinking
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Clamping Configurations
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Questions
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Problem Statement◼ Current State
▪ Boeing’s current UUV, the Echo Ranger has a maximum mission time of 28 hours. Boeing would like to significantly extend this mission time.
◼ Desired State▪ Boeing would like to utilize a thermoelectric system to significantly extend
mission time of their UUVs.◼ Project Goals
▪ Demonstrate proof of concept of thermoelectric system▪ Use a temperature differential to charge a battery▪ Achieve maximum thermoelectric efficiency over a range of temperatures▪ Establish a UUV-based research partnership between Boeing and RIT
◼ Constraints▪ System must operate underwater▪ System must utilize a thermoelectric device▪ System must operate autonomously
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Rochester Institute of Technology
Customer Requirements
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Engineering Requirements
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