Download 1 - Research

Third World Electric Generator
Electricity from Excess Heat
Group 22
Sung Hoon Bae (BME)
Daniel Rim (ChBE)
Chris Zachara (ChBE)
Owen Graduate School of Management
Bae, Rim, Zachara
http://www.bme.vanderbilt.edu/srdesign/2009/group22/
BME 273: Oral Report #4
Problem Statement

Bangladesh
 Large
population/high poverty rate
Population: 162 Million – 7th
 GDP (PPP): $1,500 per capita – 153rd

http://en.wikipedia.org/wiki/File:Flag_of_Bangladesh.svg
http://upload.wikimedia.org/wikipedia/en/f/f2/Bangladesh_(orthographic_projection).svg
Problem Statement

Only 30% electricity distribution (2002)
 25%
in urban and 10% in rural (2000)
 79% of population in rural (1999)

Government efforts
 30%
to 38% distribution from 2002-2008
 Slow progression
Rural Bangladesh Families

Average family has 6 members
 Typically

4 children
Total literacy is only 48%
 Considerably
lower in rural areas
Poverty is major threat to primary
education
 Lighting is a Basic Need

 Status
Symbol
 Needed for reading (above all else)
Objective

Generate electricity
 Household
scale generator
 “Reasonable” retail price
 Sufficient output electricity
 Utilize thermoelectric generator (TEG)
http://www.ct.gov/opapd/lib/opapd/newsletter-pics/dollar2520squeezed.jpg
http://image09.webshots.com/9/2/10/75/112721075ZEGbyv_fs.jpg http://www.odec.ca/projects/2007/sidd7g2/Images/appelectricty.gif
Design Criteria
•
•
•
•
•
•
•
Cost – cheap product and source of energy
Durability – long lasting materials
User friendly – simple design and simple
operation
Efficiency – efficiency of converting source
energy into light energy
Quality – quality of energy source (higher score
for naturally occurring energy source)
Portability – device should be mobile
Flexibility – extent of dependency of the device
on external environment
Determining Weight Values
Cost
Durability
User Friendly
Efficiency
Quality
Portability
Flexibility
Total
Cost
-
1
1
1
1
1
1
6
Durability
0
-
1
1
1
1
1
5
User Friendly
0
0
-
0
0
1
0
1
Efficiency
0
0
1
-
0
1
0
2
Quality
0
0
1
1
-
1
0
3
Portability
0
0
0
0
0
-
0
0
Flexibility
0
0
1
1
1
1
-
4
Determining Source of Light
.
Source of Energy
Gas Lamp
Electricity
Manual (Shake)
Criteria
Weight
Value
Product
Value
Product
Value
Product
Cost
6
4
24
4
24
5
30
Durability
5
4
20
5
25
5
25
User Friendly
1
3
3
5
5
5
5
Efficiency
2
2
4
1
2
2
4
Quality
3
1
3
4
12
1
3
Portability
0
5
0
5
0
5
0
Flexibility
4
2
8
4
16
0
0
Total
62
84
67
Brainstorming
Weather
dependent
Unlimited
energy source
Sun as energy
source
Keeps improving
Well understood
Efficient only in
large scale
Low efficiency
Expensive
Turbine system
Solar panel
Expensive
Complicated
design
No moving parts
User friendly
Cheap
Electric
Generation
Emerging
Technology
Thermoelectric
generation
Great flexibility
Simple design
Manual
Simple design
Relatively
expensive
No moving parts
Stirling generator
Uses any kind
of heat
User friendly
But not user friendly
Complicated
Expensive
Thermoelectrics




Phenomenon: temperature difference
creates electric potential or vice versa
Materials: specially doped
semiconductors, most commonly
made from Bismuth Telluride
Current Uses: portable refrigeration,
electronics cooling
Equations:
Advantages of TEG
Less Expensive than Turbine Technology
 Utilize Low Grade Heat
 Small
 Silent
 Reliable

 No
moving parts
 No maintenance
Challenges of Using TEG

TEG Only 10% Energy Efficient


Other design aspects will be very important
Significant Heat Gradient Needed
 The
“cold side” must be cooled
 Cold side is just mm’s away from heat source
Possible Heat Sources

Biogas Lamps
 Efficiency
 Consume
only 1.2-2.0 lm/W
120 to 150 L Biogas daily
 Rely on incandescent metals heated to 1000-2000°C



Over 90% of energy emitted as heat
10% Efficient TEG could, theoretically, double performance
Biogas Stoves
 Can

be quite efficient, but still produce excess heat
Heat-to-electricity unit would have no additional
energy costs
LED light
Commercial white LED light  65 lm/W at
20mA
 4 times as efficient as standard
incandescent
 Commercially available white LED light
are very cheap (exp. $6/6LEDs)

NiMH Batteries

Advantages
 Relatively
constant discharged voltage
 More current compared to other batteries
 Various capacity available

Safety Issues
 Careful
charging method is required
Timer controlled
 dT/dt detection
 dV/dt detection

Process Flow Chart
Q
+
Heat Source
TEG
E
Voltage Regulator
E
+
NiMH Batteries
E
Charging Controller
E
Current Controller
E
LED
L
Light
dV/dt
Initial Design: Overall
Heat Source
Thermal Grease
Storage Unit
Rechargeable
LED
Heatsink
Portable
Generating Unit
Convection
Initial Design: Generating Unit
Coated with black Heat
color for maximum
heat absorption?
Source
Thermal Grease: maximizes contact
surface area between TEG and heatsink
Connecting joint
Pressurized attachment
Heatsink
Generating Unit
Components
• TEG
• Heatsink
• Thermal grease
Materials: TEG (TEC)

Product Model:CP2,31,06,L1,W4.5
 Laird






Technology
30mm x 30mm x 4.6mm
Qmax = 29.3W (TH=25°C)
Imax = 14.0 A (TH=25°C)
Vmax = 3.5V (TH=25°C)
ΔTmax = 67°C
Price = 23.42$ (http://www.mouser.com)
http://lairdtech.thomasnet.com/item/thermoelectric-modules-2/-series-peltier-solid-state-thermoelectric-coolers/pn-4059?&seo=110&bc=100|3001624|3001688|3001251
Materials: Thermal Grease

Product Name: Arctic Silver 5


Thermal Conductance: >350,000W/m2°C (0.001 in layer)




Peak: -50 to 180°C
Long term: –50°C to 130°C
Important Note


Thermal conductivity of air ~ 0.024W/m°C
Thermal conductivity of silver ~ 429W/m°C
Temperature Limits


Arctic Silver ®
Takes about 200hrs and several thermal cycles to achieve
maximum performance
Price = 9.99$ (newegg.com)/16in2


SATEG = 900mm2 = 1.4in2
Per Unit Price ≥ 9.99$/16in2 · 1.4in2 = 0.87$/prototype
http://arcticsilver.com/as5.htm
http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
Initial Design: Storage Unit

Storage Unit
Components

Batteries


NiMH Batteries
Controllers

Current controller

LED

Voltage regulator


For powering the LED
LED
Charging batteries
Materials: LED







Product Model:LED5 40-50DG WH
(TheLEDLight.com)
Emitted Color: White
Luminous Intensity = 6000mcd max at IA=20mA
Beam Angle = 40-50 degrees
Continuous forward current = 30mA
Forward voltage = 3.0-3.2V
Price = 6$/6LEDs
http://www.theledlight.com/5mmwhleds.html
Materials: NiMH Batteries

Product Name: Eneloop
 Sanyo



Voltage = 1.2V
Capacity = 2000mAh
Low self-discharging rate
 ~90%

after 360days
Long life cycle
 ~1000

Electric Co., Ltd.
charges
Price: 11.99$/4units (Amazon.com)
http://www.eneloop.info/home/performance-details/self-discharge.html
Experiment Set-up
LABVIEW
100kOhms
~5cm
Heat source: candle
Result: Short Term Drift
Voltage versus Time
0.7
0.6
Vmax~.61V
Amplitude (V)
0.9Vmax
0.5
0.4
Prototype I
Prototype II
Vmax~.32V
0.3
0.2
0.1
0.1Vmax
0
0~2sec 10
20
30
40
Time (sec)
Rise time ~47sec
~49sec
50
60
70
Result: Short Term Drift (power)
Power vs. time
0.004
0.0035
Wmax~.0035mW
Power (mW)
0.003
0.0025
prototype I
Prototype II
0.002
0.0015
0.001
0.0005
0
0
10
20
30
40
Time (sec)
50
60
70
Result: Long Term Drift
Peak Voltage ~ 0.625V
0.9Vmax
5minutes 40sec
Expected Cost and life span

TEG: ~$20/~200,000hrs = 22.8yrs*
 Depends







on individual TEG device
Heatsink: ~$20/indefinite
Batteries: $11/~4years
Voltage regulator ~ $0.5 (onsemi.com)
Charging controller ~ $0.7 (onsemi.com)
Current controller = $11.85 (theLEDlight.com)
Thermal grease: 0.87$/prototype
Total: ~ $(64.92+ X) /unit
Implementation Idea
Collect Stove Top Steam
 Advantages

 Consistent
Temperature
 Near TEG optimum (80o C)

Challenges
 Heat
Insulation
 Moisture
Future Work

Low voltage problem
 Increase insulation to improve TEG performance
 Find more efficient TEG (look into more expensive
TEG)




Extensive with more controlled setting
(controlled known temperature input)
Finish building charging unit that can safely
charge NiMH
Investigate Water Cooling
Work on Implementation
References







Department of Economic and Social Affairs Population Division (2009) (.PDF). World
Population Prospects, Table A.1. 2008 revision. United Nations.
<http://www.un.org/esa/population/publications/wpp2008/wpp2008_text_tables.pdf>.
Retrieved 2009-03-12.
"Bangladesh". <International Monetary Fund.
http://www.imf.org/external/pubs/ft/weo/2009/02/weodata/weorept.aspx?sy=2006&ey=200
9&scsm=1&ssd=1&sort=country&ds=.&br=1&c=513&s=NGDPD%2CNGDPDPC%2CPPPGDP
%2CPPPPC%2CLP&grp=0&a=&pr.x=35&pr.y=9. Retrieved 2009-10-01>.
<http://web.worldbank.org/WBSITE/EXTERNAL/EXTABOUTUS/IDA/0,,contentMDK:2138776
5~menuPK:3266877~pagePK:51236175~piPK:437394~theSitePK:73154,00.html>.
<http://www.geni.org/globalenergy/library/national_energy_grid/bangladesh/index.shtml>. .
http://www.malmberg.se/module.asp?XModuleId=14085
http://www.stefanv.com/electronics/using_nimh.html
http://www.tegpower.com/products.html