Transcript Document

Thermoelectric Analysis
for Optimized Waste Heat Power Generation
in Marine Applications
Tucker Doane
Angela Fouquette
Philep Levesque
Summary
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Potential benefits of thermoelectrics
Objectives for this year
How thermoelectric materials work
Background on previously done work
This year’s progress and development
Future work
Potential Benefits
Thermoelectric Generators Applied to Marine Diesel Exhausts
• Increase efficiency
and plant
performance
• Decrease in fuel
consumption
• Decrease in operating
costs
• Decrease
environmental impact
Objectives
• Understand the fundamental properties of thermoelectric
generators
• Provide the lab with devices to characterize these properties
and model various applications
• Model material properties of thermoelectric modules and
elements
• Compare heat transfer with flow rates and pressure drops for
the most efficient performance values
• Comparing results to industry standard tests and modules
Thermoelectric Introduction
Seebeck Effect: A voltage
is created in the presence of
a temperature difference
between two dissimilar
metals
Z = Figure of Merit
S = Seebeck Coefficient
σ = Electrical Conductivity
κ = Thermal Conductivity
Thermoelectric Introduction
Seebeck Coefficient: used to
characterize the sensitivity of
different materials
V = Voltage
T = Temperature
Background
•Previous work at Maine Maritime Academy focused on improvement and
implementation on existing systems
•R/V Friendship and Gas Micro-Turbine (2009)
•Hybrid lifeboat test platform development and implementation (2010)
•Improved heat exchanger development (2013)
Seebeck Coefficient Measurement Apparatus
(SCMA)
• Device to measure temperature and voltage output of manufactured
modules, elemental samples, wires, etc.
• Used to understand fundamental properties of existing and newly generated
materials
• Testing initially done with several types of Hi-Z modules
Design and Development
• Copper chosen due to its excellent heat transfer characteristics
• Each copper block measures 2 x 2 x 5/8 inches
• Capable of accepting existing modules, new samples, wires, etc.
Control Schematic
8
4
7
3.5
7
3.5
6
3
6
3
5
2.5
5
2.5
4
2
4
2
3
1.5
3
1.5
2
1
2
1
1
0.5
1
0.5
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Current (A)
1.6
1.8
0
0
0
2
0.2
0.6
0.8
1
1.2
1.4
1.6
Current (A)
Delta T = 300 deg F
Delta T = 200 deg F
4
8
4
7
3.5
7
3.5
6
3
6
3
5
2.5
5
2.5
4
2
4
2
3
1.5
3
1.5
2
1
2
1
1
0.5
1
0.5
0
0
0
0
0.2
0.4
0.6
0.8
Current (A)
1
1.2
1.4
1.6
Voltage (V)
8
Power (W)
Voltage (V)
0.4
0
0
0.2
0.4
0.6
0.8
Current (A)
1
1.2
1.4
1.6
Power (W)
0
Voltage (V)
4
Power (W)
Voltage (V)
8
Power (W)
Delta T = 400 deg F
Delta T = 500 deg F
Max Power vs Temperature Differential
3.5
3
Power (W)
2.5
2
1.5
1
0.5
0
0
100
200
300
Temperature Differential (deg F)
400
500
SCMA Uses and Future Work
• Can be used to test and characterize newly made
samples and materials, as well as other unknown
devices
•Stabilize temperature differential:
•Automate temperature control
•Establish a better way of cooling
Test Bed Development
• Provide the ability to test different modules,
materials, and scenarios in a controlled and
designated environment
• Designed to accept newly made thermoelectric
devices
• Will be designed to utilize gas as the heating medium
• Will have an associated cooling system to promote a
greater temperature differential
System Overview
Heat Sink
Heat Engine
(Heat Source)
Exhaust
Heat Recovery Device
TEG Modules
To Atmosphere
Heat Exchanger Design
Mass flow
Heat Exchanger
Slot Height
Pdrop
Boundary Layer
Convective
Coefficient
• Designed to replicate
existing marine
applications
Re, Pr, Nu
Temp in
Qtransfer
• Heat provided to
simulate pressure and
air flow through the
exhaust of a diesel
engine, boiler, or gas
turbine
Preliminary Design
• The test bed needs to have the largest possible
range of fluid flow characteristics to better
simulate a number of known exhaust systems
• Initial calculations and visualization done in
Microsoft Excel
• The basic parameters of flow and temperature
were sized based on Hatz Single Cylinder Diesel
to Caterpillar 2.2 L
Basic Flow and Heat Modeling
CAT 2.2 Calculated specs (Normal Operating Range/ Naturally Aspirated)
RPM Liters(Disp)
m^3
Density (STP) (kg/m^3)
m^3/min
2200
2.2
0.0022
1.169
2.42
2300
2.2
0.0022
1.169
2.53
2400
2.2
0.0022
1.169
2.64
2500
2.2
0.0022
1.169
2.75
2600
2.2
0.0022
1.169
2.86
2700
2.2
0.0022
1.169
2.97
2800
2.2
0.0022
1.169
3.08
2900
2.2
0.0022
1.169
3.19
3000
2.2
0.0022
1.169
3.30
Hatz Diesel (Single Cylinder 1B50 , 3.5-8 kW, 10HP)
RPM Liters(Disp)
m^3
Density (STP) (kg/m^3)
m^3/min
1000
0.517
0.000517
1.169
0.259
1200
0.517
0.000517
1.169
0.310
1400
0.517
0.000517
1.169
0.362
1600
0.517
0.000517
1.169
0.414
1800
0.517
0.000517
1.169
0.465
2000
0.517
0.000517
1.169
0.517
2200
0.517
0.000517
1.169
0.569
2400
0.517
0.000517
1.169
0.620
2600
0.517
0.000517
1.169
0.672
2800
0.517
0.000517
1.169
0.724
3000
0.517
0.000517
1.169
0.776
CFM
85.46
89.34
93.23
97.11
101.00
104.88
108.77
112.65
116.54
m^3/s
0.040
0.042
0.044
0.046
0.048
0.050
0.051
0.053
0.055
kg/min
2.83
2.96
3.09
3.21
3.34
3.47
3.60
3.73
3.86
kg/sec
0.047
0.049
0.051
0.054
0.056
0.058
0.060
0.062
0.064
CFM
9.129
10.955
12.780
14.606
16.432
18.258
20.083
21.909
23.735
25.561
27.387
m^3/s
0.004
0.005
0.006
0.007
0.008
0.009
0.009
0.010
0.011
0.012
0.013
kg/min
0.302
0.363
0.423
0.483
0.544
0.604
0.665
0.725
0.786
0.846
0.907
kg/sec
0.005
0.006
0.007
0.008
0.009
0.010
0.011
0.012
0.013
0.014
0.015
RESULTS
Min Flow
Mass
Flow(kg/s)
0.010
Max Flow
0.030
Temp (Celsius)
250
500
250
500
Power (kW)
2.33
5.21
6.99
15.62
Heat Load Requirements
Enthalpy Rate Equation
𝑄 = 𝑚𝐶𝑝 (𝑇𝑖𝑛 − 𝑇𝑎𝑚𝑏)
Heat Exchanger Fluid Flow Analysis
• How varying flow area, temperature, and length
effect velocity and flow regime (turbulent vs
laminar) for simple rectangular slot
• Turbulent preferred for fluid mixing
Heat Exchanger Basic Arrangement
Restriction Plate
Air
Flow
Air
Flow
Heat Transfer Area
Cooling Water
Cooling Plate
Cooling Water
Advanced Modeling using MATLAB
• To understand the tradeoff of pressure to
convective heat transfer, in addition to other
effects
• An attempt to predict the conditions within the
designed heat exchanger during operation and
testing
Illustrating the Tradeoff
Important Dimensionless Groups
• Reynolds Number
▫ Ratio of flow momentum rate to viscous force
𝜌∗𝜗∗𝐷
𝑅𝑒 =
𝜂
• Nusselt Number (Pr,Re)
▫ Ratio of convective conductance to molecular conductance
over hydraulic diameter
𝑁𝑢 =
ℎ
𝑘
𝐷
Important Non-typical Equations &
Estimators
• Prandtl Number
▫ 𝑃𝑟 =
𝜂∗𝐶𝑝
𝑘
• Nusselt Number
▫ NuL = 0.664*Pr^(1/3)*Re^0.8
▫ NuT = 0.036*Pr^(1/3)*Re^0.8
• Fluid Boundary Layer
▫
▫
5∗𝑥
𝐵𝐿𝐿 =
𝑅𝑒𝐿 0.5
0.16∗𝑥
BLT = 𝑅𝑒𝐿1/7
MATLAB Model
INPUTS
Tin, Mdot,
Hs, Ws, L
𝑓 ,Pdrop
Ө ,Cp,SW,
η ρ
Each element generates an
array based upon the input
parameters.
𝑄
Pr
NuL (Pr,Re)
NuT (Pr,Re)
Area, P, HR, D
h
Vel
Rt, Qtransfer
Re, ReL
BLL (ReL)
BLT (ReL)
Heating System
Electric Heat
Watlow Finned
Strip Heaters
1kW
Centrifugal
Blower
Fossil Fuel Heater
Metro Services
Ratiomatic
147 kW
Metro Services
Thermair Burner
44 kW
Final Design
Sizing
Restriction & Cooling Plate
Instrumentation
Construction
•
Future Work
• Complete construction of heat exchanger
• Order or build Heating System
• Utilize the R/V Quickwater
Acknowledgments
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Travis Wallace
Richard Kimball
Paul Wlodkowski
Lynn Darnell
Joshua Henry
Timothy Allen
Alan Trundy
Stephen Collins
James Stefanski
Questions