Jörg Schwieger1, Bernd Baumann1, Marcus Wolff1, Freddy Manders2, Jos Suijker2

1Heinrich-Blasius-Institute of Physical Technologies, HAW Hamburg, Berliner Tor 21, 20099 Hamburg, Germany 2Philips Lighting, Steenweg of Gierle 417, 2300 Turnhout, Belgium

Influence of electrical conductivity and plasma

pressure on temperature distribution and

acoustical eigenfrequencies of high-intensity

discharge (HID) lamps

Agenda

24.10.2013 2

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

• Introduction

• Physics & Model

• Results

HID lamp

24.10.2013 3

Applications

• Street lights

• Industrial lights

• Automobile headlights

Main advantages

• Solar like luminance density

• High efficacy

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de 3

Arc tube

• Discharge arc: Light emission by excited atoms

• Filling: Hg, Ar and metal halides

• Static pressure: Atmospheric or higher

Problem description

24.10.2013 4 Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

Straight Distorted

Increased energy effciency

High frequency AC operation

Oscillating heat source

Alternating temperature and pressure

Excitation of acoustic resonances (at EF)

Arc flickering possible

Lamp destruction possible

Simulation physics

24.10.2013 5 Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

Charge conservation

Electric field

Elenbaas-Heller equation

Temperature field with

conduction and convection

terms

Navier-Stokes equation

Fluid velocity field

under influence of gravity

and pressure

Wave equation

Eigenfrequencies and –modes

FuuIp

uu

T

rad

p

qE

TucT

2

Tfcpc

p

0

2

2

0 E

Stationary

Eigenfrequency

),,( zyxT

Simulation model

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• HID lamp: Philips® 35W/930 Elite

• 3D symmetric model

• Horizontally positioned symmetry axis

Boundary conditions

Electric insulation

Wall

Constant temperature

Heat radiation

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

12 mm

0u

0 En

0TT

44 TTTn amb

0TT 0JEn

g

2.2 MPa

46.2 kHz

3.4 MPa

44.3 kHz

2.8 MPa

45.1 kHz

Results

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Influence of plasma pressure

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

Temperature distribution: Higher pressure → larger arc deflection

Acoustical eigenfrequency: Slight decrease at increasing pressure

Results

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Influence of electrical conductivity

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

J.O. Hirschfelder, C.F. Curtiss, R.B. Bird, Molecular Theory

of Gases and Liquids (Wiley Press, London, 1964)

P. Flesch, M. Neiger, Understanding anode and

cathode behaviour in high-pressure discharge

lamps, J. Phys. D: Appl. Phys. 38, 3098 (2005)

Results

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Influence of electrical conductivity

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

0.23 S/m

(3,250 K)

44.4 kHz

4.7 S/m

(4,000 K)

44.1 kHz

0.90 S/m

(3,550 K)

45.1 kHz

Temperature distribution: Significant change at 1.0 S/m

Acoustical eigenfrequency: Small changes

• Influence of plasma pressure and electrical conductivity:

Minor changes in Eigenfrequencies

Major changes in temperature distribution

Experimental validation

Observation of light emitting arc with camera

Conclusions

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• Influence of plasma pressure and electrical conductivity:

Minor changes in Eigenfrequencies

Major changes in temperature distribution

Experimental validation

Observation of light emitting arc with camera

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

Thank you for your attention.

Backup

24.10.2013 11 Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

Experimental results

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Light intensity distribution

Eigenfrequency

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

42 kHz

Simulation

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Stationary analysis

• Steep electric potential profile at electrodes

• Joule heating source

• Buoyancy driven flow

Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,

joerg.schwieger@haw-hamburg.de

89 V

0 V

5700 K

800 K 0.2 m/s