Waste heat recovery by Thermoelectricity RENOTER ...

Waste heat recovery by Thermoelectricity RENOTER Project

A project led by Renault Trucks

DIESEL POWERTRAIN Innovative Technologies for Future Emissions Targets June 5 & 6, 2012 / INSA de Rouen - FRANCE

Introduction RENOTER acronym for: “Récupération d’ENergie à l’échappement d’un mOteur par ThERmoélectricité” 8

partners (including 3 laboratories)

Q4-2008 4M€

to Q2-2012

project

Partially

funded by French Government Renault – Valeo – Renault Trucks

2

RENOTER project presentation

Robert Yu, Cédric de Vaulx (June 6th 2012)

Project goals

• Focus on cheap, efficient, and sustainable TE materials • Work on material integration and scaling-up process • Target cost is 0.2 – 1.0 €/We (all included) Renault – Valeo – Renault Trucks 3



Energy balance

Renault – Valeo – Renault Trucks 4



Available energy Car application




Available energy Truck application 650

6 5 4 200

3 2

100

1 0 0

0.1 0.2 0.3 Exhaust gas mass flow rate (kg/s)

0

EGR gas temperature (°C)

400

300

10

600

7

550 8 500 450

6

400 4

350 300

% of time

8

% of time

Exhaust gas temperature (°C)

500

2

250 200

0

0.02 0.04 0.06 0.08 EGR gas mass flow rate (kg/s)

Exhaust Avg. T° ~230°C – Avg. Q ~100g/s

~18kW

EGR Avg. T° ~400°C – Avg. Q ~45g/s

~17kW

0.1

0

Note: Enthalpy (kW) down to 100°C




Thermoelectricity Seebeck effect Hot source P type

N type

I(A)

cold sink

PMAX

E02 N 2 S 2 ∆T 2 A = = 4R 4ρ L

S = Seebeck coefficient [V.K -1 ] N = number of TE legs ρ = electrical resistivity [Ω.m] ∆T = temperature gradient [K] A Section = [m] L Length Renault – Valeo – Renault Trucks 7



Typical values : S = 150 µV.K-1, ρ = 1.10-5 Ω.m

1 TE pair : PMAX ~ few tens of mW

hundreds of TE pairs are needed!

Materials

TE Material

ZT

ZT

OK for 600°C

200°C

400°C

Max Temperature

1

-

NO (250°C)

0.75

1.0

0.8

1.4

N-type

P-Type

Bi2Te3

PbTe LAST (Ag-Pb-Sb-Te)

State-of-art

Est. € per dm3 800-900 700

YES (600°C)* 500-800

TAGS (Te-Ag-Ge-Sb)

-

0.7

1.2

Zn4Sb3

-

0.7

1.2

NO (400°C)

25

Mg2Si

~

0.3

0.8

YES (600°C)

80-450

HMS

-

0.4

0.6

YES (800°C)

150

Skutterudites (CoSb)

0.5

0.7

YES (700°C)

300-450

SiGe-nanostructured

0.2

0.4

YES (1200°C)

2900

Clathrates (GaGe)

0.2

0.7

YES (>1000°C)

3000

(*encapsulated) Renault – Valeo – Renault Trucks 8



Materials Project development Successful lab. production of the legs for the project prototype (>1500)




Thermoelectric generator cooling fluid

hot gas

Compact + light weight Easy packaging (flexible geometry) Sub-components technologies validated Able to support any type Electrical power of previous TE material + resists Cold Hot Conductive Repetition Elastic tubes tubes layer with oflayer the TE legs stages high T°C




Thermoelectric generator Hot tubes technology stainless steal EGR tubes insulating layer Nickel coating

1 triple hot tube Hot tube with TE legs Renault – Valeo – Renault Trucks 11



228 TE legs

Simulation and testing

Fluids conditions

Size, architecture of P-N legs

Materials Between Legs & HEX

Global TEG Size

Results

Thermal & electrical balance Renault – Valeo – Renault Trucks 12



Simulation and testing

LT Radiator Pump

Tank

Renault – Valeo – Renault Trucks RENOTER project presentation


DPF

Bypass valve

TEG

Simulation and testing System simulation Thermo-Electric Generator Sizing & Model Tgas=? °C ; Qgas=? kg/h; DP=? mBars - Material to be used

Resizing

- Dimensions and number of legs - Optimizaion of electrical power/cost

Climatic conditions & Driving Cycle

TEG System Simulation Vehicle Model Engine Power =? KW Engine consumption =? Kg/h Tgas=?° °C ; Qgas=? kg/h;

14

Renault – Valeo – Renault Trucks RENOTER project presentation


- TEG Gas flow rate & By-pass flow rate? - Electric power generated =? W - Pressure drop of the TEG =? mbars - Consumption of the pump, fan…? W - Net electric power? W - Engine real consumption? Kg/h - Engine coolant temperature control

Simulation and testing TEG testing

RENOTER TE Generator at the CRITTM2A test bench Renault – Valeo – Renault Trucks 15



Simulation and testing Results




Results & balance




Conclusion

Materials:

Alternatives to Pb/Te

“Reasonable” cost

Higher ZT needed ~200°C

Good Mg2Si type P required

Performance: source: Renault Trucks

18

Benefits of direct integration

Issue with low voltage / high current

Power below pay-off level

Material improvement & research should continue if we want a mass market application Renault – Valeo – Renault Trucks RENOTER project presentation


Acknowledgments

• RENOTER project team

• DGCIS (Direction Générale de la Compétitivité, de l'Industrie et des Services)

• Région Basse-Normandie


