trade-off in thermoelectric generator design for vehicle application - ko_ ecm2015.pdf · 2015. 10....
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> K. Oetringer • 2015-08-11> K. Oetringer • 2015-08-11
Trade-off in Thermoelectric Generator design for vehicle applicationECM 2015Aberdeen, 2015-08-11
Institute of Vehicle Concepts
K. Oetringer M. Eng.M. Kober Dipl. Ing. (FH)
www.DLR.de • Chart 1
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> K. Oetringer • 2015-08-11
Outline
• Introduction
• Motivation
• Basics
• TEG Evolution at DLR
• Optimization
• Design-Point
• Simulative Results
• Validation by Measurement
• Outlook
www.DLR.de • Chart 2
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 3
1) Treffinger P., Häfele Ch., Weiler T. DLR e.V. Stuttgart; Eder A., Richter R., Mazar B. BMW Group München: Energierückgewinnung durch Wandlung von Abwärme in Nutzenergie. 2008 VDI Tagung „Innovative Fahrzeugantriebe“, Dresden
About 2/3 of the chemical energy is transferred to heat
Motivation for waste heat recoveryBasic combustion engine
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 4
• thermal diffusion of electrons respectively holes to cold side
• Electric potential is proportional to ΔT:
• Dimensionless figure of merit ZT:
• Efficiency TE:
S Seebeck-coefficient
heiß
kalt
n p
+-- +
Kühlmittel
Abgas
heiß
kalt
n p
++-- ++
Kühlmittel
Abgas
TS
ZT2
h
kh
kh
in
el
TT
ZT
ZTTTT
Q
P
1
11
TU
S
σ electrical conductivityΚ thermal conductivityT temperature
Basics of thermoelectricity
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 5
• Electric potential is proportional to ΔT:
• Dimensionless figure of merit ZT:
• Efficiency TE:
S Seebeck-coefficient
heiß
kalt
n p
+-- +
Kühlmittel
Abgas
heiß
kalt
n p
++-- ++
Kühlmittel
Abgas
TS
ZT2
h
kh
h
h
kh
in
el
TTT
ZTT
TTQP
224
1
TU
S
σ electrical conductivityΚ thermal conductivityT temperature
Basics of thermoelectricity in application
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 6
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> K. Oetringer • 2015-08-11
Outline
• Introduction
• Motivation
• Basics
• TEG Evolution at DLR
• Optimization
• Design-Point
• Simulative Results
• Validation by Measurement
• Outlook
www.DLR.de • Chart 7
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 8
electrical TEG input power ( )
back pressure / cooling of exhaust( )
cooling load ( )(el. power for cooling water pump and cooling fan, quick heat-up phase)
rolling resistance ( )(weight increase)
roPprP
coPinP
Optimize the benefit for the application
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 9
Choosing a Design-PointBasic for Vehicle testing => WLTC
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 10
Choosing a Design-PointWhich Design-Point contains most energy?
15 g/s
400°C
possibleDesign-Point
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 11
Choosing a Design-PointWhich Design-Point contains most energy?
15 g/s
400°C
possibleDesign-Point
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 12
Choosing a Design-PointWhich Design-Point contains most energy?
15 g/s
400°C⋅ ⋅
:EnergycontainedbyDesignPoint: usableMassflow: heatcapacityofexhaust: usableTemperature: coldsideTemperatureofTEG
possibleDesign-Point
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 13
Choosing a Design-PointWhich Design-Point contains most energy?
Design-Point: 17g/s 855 K
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> K. Oetringer • 2015-08-11
• weight < 8 kg (without bypass)
• volume < 3 dm³ (without bypass and diffusers)
• el. peak power > 400 W
• el. power at Design-Point > 160 W
• gravimetric power density > 50 W/kg
• volumetric power density > 133 W/dm³
www.DLR.de • Chart 14
Simulative resultsCharacteristics of the optimized TEG
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 15
Measured resultsValidation of simulation
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 16
Measured resultsValidation of simulation
0,00
5,00
10,00
15,00
20,00
25,00
300,0
350,0
400,0
450,0
500,0
550,0
600,0
650,0
700,0
750,0
800,0
0 1 2 3
electricpo
wer
TEM2 [W
]
tempe
rature
[K]
Design‐Point maximum Point
Th_TEM2 [K] Tc_TEM2 [K] Th_sim [K] Tc_sim [K] P.el_TEM2 [W] P.el_sim [W]
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> K. Oetringer • 2015-08-11
Outline
• Introduction
• Motivation
• Basics
• TEG Evolution at DLR
• Optimization
• Design-Point
• Simulative Results
• Validation by Measurement
• Outlook
www.DLR.de • Chart 17
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> K. Oetringer • 2015-08-11
Philosophy to success:• Maximizing the benefit for OEM and Driver
=> taking into account negative effects• Not maximizing the el. power output
Reached goals:• Successful integration of high temperature modules• Validation of thermal simulation
Outlook:• Dynamic simulation to simulate a whole driving cycle• Improve / research at high temperature modules
www.DLR.de • Chart 18
Outlook / Summary
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> K. Oetringer • 2015-08-11www.DLR.de • Chart 19
• Potentials• Measuring vehicle• Materials• Concept development• Simulation• Functioning mock up• Validation
Project aim:Developing a new kind of Thermoelectric Generator increasing the efficiency of Range Extender and Hybrid Vehicles
Ministry of Finances and EconomicsBaden-Württemberg
The Project RExTEG
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> K. Oetringer • 2015-08-11
Thank you for your attention!
Institute of Vehicle ConceptsPfaffenwaldring 38‐4070569 Stuttgart
Kerstin Oetringer M. Eng.Phone: 0049 ‐ 711 6862 ‐[email protected]/fk
www.DLR.de • Chart 20