présentation générale du projetnanosioe.ee.ntu.edu.tw/download/@@@conference/2003...

25 Sept 2003 MINATEC 2003 Grenoble 1

Thermo-mechanicalmicro-sources

Orphée Cugat, Jérôme DelamareLaboratoire d’Electrotechnique de Grenoble, LEG-ENSIEG

&Patrice Rey

LETI – CEA, Grenoble

Thermomechanical micro-sources P. Rey (CEA) - O. Cugat & J. Delamare (LEG) 2

The overall goal

Replacing batteries in portable equipmentwith electrical generators,

powered by thermal engines,fed with hydrocarbon fuel.


Why hydrocarbon sources?

« Expensive » energy : dirty, non-renewable… butHighest energy density, even with low efficiency

Ener

gy d

ensi

tyW

.hr/k

g

164329480

11500

Octane Zn-airbattery

Libattery

Alkalinebattery

20 % - 5 %efficiency

2300

575

(Berkeley)


The engine contenders

•Reciprocating free-piston engine

We will NOT talk about fuel cells,thermo-photo-voltaics nor piezo-electrics

•Wankel rotary-piston engine•Turbine, turbo-reactor


Free-piston engine

valve d'échappement

chambre de combustion

piston

barre mobile

valve d'admission

stator du générateur électrique

terminaux électriquesSingle variation

NS

SN

NS

SN

SN

SN

NS

NS

Exhaust valve Main shaft Stator of electric generator

Piston

Inlet valve Electrical leads

Combustion chambers


Georgia-Tech free-piston prototype

Ø 3 mm pyrex glass tube


Free piston projects:

BirminghamExpected:

5000 rpm, 8 mW

Honeywell / Ritsumeikan Univ.Model : 10 x 15 x 1 mm

Twin symmetrical pistons600 Hz, 40 mW

KAIST Korea

1 mm thick glassCombustion chamber 1 mm

Piston 2 x 2 mm


Pros & consof the free-piston engine

•ADVANTAGES

–DIRECT ENERGY CONVERSION

–ROBUST SYSTEM - ONLY ONE MOBILE ELEMENT

–NO FRICTION IN ADDITIONAL MOVING PARTS

–LOWER FRICTION AT PISTON - NO ANGULAR CHARGE

–VARIABLE COMPRESSION RATIO – VARIOUS FUELS

–DRAWBACKS

–THERMAL INSULATION BETWEEN CHAMBERS

–HIGH & REPETITIVE FORCES


Free-piston projects

Korea Advanced Institute of Science and Technology - Publication• Fabrication and test of a MEMS combustor and reciprocating device – 2002

Honeywell International Inc• Patent N° 6 397 793 - jun 2002

Georgia Tech Research Corporation• Patent N° 6 109 222 - aug 2000

Birmingham University – Publication• Design and analysis of a Micro Reciprocating Engine for the time multiplexed deep Etching Process – 2002• Design and fabrication of micromachined internal combustion engine as a power source for microsystems - 2002

Ritsumeikan University - NEDOPower MEMS 2002


Wankel Engine (Berkeley, who else?)

1 2intake

compression

explosion

3 4exhaust


Wankel at Berkeley

Prototype Mini-motor : 13 mm, EDM, air-H2 : 3 W at 10 000 rpmAim: 30 W at 40 000 rpm


Micro-Wankel engine

At present 2.4 mm Si modelAim : Si fabrication, 1 mm x 300 µm10 to 100 mWSiC-coated Si


TURBINES

Tohoku

MIT

KU LeuvainØ 10 mm

100.000 rpm1 bar

16 W (10 %)


Tohoku turbines

3D prototypes : diam. 4 - 10 mmSteel, SiN

4 mm

10.000 rpm IR light polariser

5 mm20 mm

MEMS models:pyrex/Si/pyrex/Si/pyrex


Turbine-on-a-dime MIT

HUGE project :5 x 10 researchers

Turbine, compressor, combustion, bearings, generator

21 mm

3.7 mm

Overall with packaging : < 1 cm3 (20 x 20 x 4 mm)Aim : 10 to 30 W electrical power @ 1 million rpmGoal = 5% then 20 % overall efficiency


MIT micro-turbine :combustion performances

Fuel = HydrogenExhaust temperature > 1600°KMax power density :

150 – 500 - 1100 MW/m3 (propane, etylene, H2)Combustion efficiency : 60 - 95% (ethylene, H2)Overall external temperature : 750°KContinuous running for 38 h without obvious damage

June-July 2003 = fire tests with rotating turbine?


Micro-turbine challenges

ThermicsExhaust temperature > 1600°KStructural strength of Si < 650 °CThermal homogeneisation of deviceOverall external temperature : 750°KCo-generation?

MechanicsSi structural strengthSiC fabrication ?High speed air bearings

MIT : 8 wafer stack-upGenerator

Electrostatic ?High temperature electro-magnetics ?


Electrostatic converters

MIT : high speed electostatic starter/converter Breakdown around 100 V

=> 2nd generation = magnetic induction, Georgia-Tech Tokyo UniversityVariable capacitance converter


Electro-magnetic conversion

RMB

MMCIMM

Macroscopic magnetic generator(approx 10 x 15 x 15 mm)

Berkeley


LEG-LETI magnetic micro-generator MUMO

8 mm (SmCo) 16 – 30 poles


Power output of MUMO

1 V

Three-phase electrical output at 80.000 rpm (no load)Max power 0.5 W @ 100.000 rpm (load = 2-5 Ohm)

2 V


Scale reduction

Thermo-mechanical convertersTheory is favourableThermal problemsStructural problems Bearing problemsVery high-tech

Electro-mechanical convertersElectrostatics : scale reduction favourable

High voltage (>100V)Breakdown problems

Electromagnetic : Excellent electrical performancesHigh frequencyThermal behaviour of magnetic materialsMechanical resistance of magnetic materials


What next ?

MEMS :Overall integrated design motors/turbines/generatorsActuators design: valves, injectors, pumps, coolersMaterials : extreme temperature & speeds: SiC sintering/moulding ?Sensors (pressure, temperature, speed…)

ConvertersCurrent-voltage-frequency matchingIntegrationEnergy storage?Electro-magnetic compatibility?

ControlEngine controlConverter controlEnergy management

présentation générale du projetnanosioe.ee.ntu.edu.tw/download/@@@conference/2003...

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