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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
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Influence of electrical conductivity and plasma pressure on temperature distribution and acoustical eigenfrequencies of HID lamps,
• Introduction
• Physics & Model
• Results
HID lamp
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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,
Arc tube
• Discharge arc: Light emission by excited atoms
• Filling: Hg, Ar and metal halides
• Static pressure: Atmospheric or higher
Problem description
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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
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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,
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,
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,
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,
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,
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,
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,
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,
89 V
0 V
5700 K
800 K 0.2 m/s
