Effect of Magnetic Fields
on Fire
Katsuo Maxted
Aviation Fire Dynamics
March 15, 2013
Outline
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•
•
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Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Modeling Affects on a Diffusion Flame
Benefits Using Magnetism
Introduction
Magnetism
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•
Defined as the phenomena that
accounts to forces exerted by
magnets
Depends on other magnetic fields,
temperature, and pressure
Introduction
Types of Magnets
•
Ferromagnets are permanent and
have the strongest influence.
N
S
Introduction
•
Types of Magnets
Paramagnets are temporary magnets
that created from an applied
magnetic field
N
N
S
S
Introduction
•
Types of Magnets
Diamagnets are the weakest
magnets that exhibit an opposing
magnetic field to an applied one
S
N
N
S
Introduction
•
Types of Magnets
Electromagnets are magnets
composed of wires carrying an
electric current
N
S
Introduction
Magnetic Fields have been applied in:
•
•
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Bio-magnetics [1]
Magnetic Resonance Imaging
(MRI)
Enhance Combustion Processes
Introduction
•
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Units are in T (Tesla) for strength
and T/m (Tesla per meter) for
intensity
Refer to magnetic gradient for
multiple field lines
Paramagnetism, Ferromagnetism, &
Diamagnetism
Introduction
Magnetic field affects all gases:
•
•
Oxygen is known for its
paramagnetism
Nitrogen, Carbon Dioxide, and
most hydrocarbon fuels are repelled
because of their diamagnetic nature
[2, 3]
http://www.youtube.com/embed/ozhIQG8XBkY
Outline
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•
•
•
•
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Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Modeling Affects on a Diffusion Flame
Benefits Using Magnetism
Magnetic Properties
•
•
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Background [4, 5, 6]
In the presence of an external
magnetic field, a flame on wax
paper forms an equatorial disk and
is more luminous
Faraday attributed this to deflection
of charged particles from the flame
Von Engel & Cozens said deflection
is caused by diamagnetic gases
Magnetic Properties
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Effect on Fluid Flow
For highly conductive fluids like
plasma and salt water, Lenz’s law
indicates that a charged fluid will
follow the direction of a magnetically
induced electromotive force
Magnetic field lines perpendicular to
fluid flow direction increase it’s
speed while parallel magnetic fields
do the opposite [2]
Magnetic Properties
Effects in Chemical Reactions
•
•
•
Spin (S) indicates the angular momentum of a
charged particle
The multiplicity or overall spin of a molecule is
defined as 2S + 1 where S = ½*(number of
unpaired electrons)
Maxwell’s theory states that a moving charged
particle creates a magnetic moment, indicating
that a higher spin generates a stronger
magnetic moment
Magnetic Properties
Effects in Chemical Reactions [7]
•
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Oxygen gas (which is in a singlet state) must
be broken into triplets before becoming
paramagnetic
Radicals are paramagnetic with a spin S = ½
Diamagnetic effects cause radicals to form in
pairs, causing doublets to excite to triplets, and
after reaction, spins are conserved from
diamagnetic predecessors
Magnetic Properties
Effects in Chemical Reactions [7]
•
•
Magnetic control on spin
Four spin states: exchange
interaction, electron spin-dipolar
interaction, hyperfine interaction and
Zeeman interaction
Magnetic Properties
•
Effects in Chemical Reactions
Example: Photochemical Process [8]
Stationary temperature dependence of the reacting
system on external radiation value in the presence and
in the absence of magnetic field
Magnetic Properties
•
Effects in Chemical Reactions
Example: Photochemical Process [8]
Stationary concentration dependence of biradicals
on external radiation value in the presence and in
the absence of magnetic field
Magnetic Properties
•
•
Magnetic field Intensity of 1 T is said to
alter combustion characteristics [3, 9]
Production of 1 T rare-earth magnets
can replace the need for
electromagnets [10, 11]
Magnetic Properties
Dipole alignment
•
•
Oxygen has randomly oriented
dipole moments that align with the
applied field
Nitrogen, Carbon Dioxide and most
hydrocarbon fuels form a net
dipole moment in opposition to the
applied field
Magnetic Properties
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Three Regimes for blocking gas flow [12]:
First Regime - At low velocities, gas flow
is diffused through the magnetic curtain.
Second Regime - At slightly higher flow
velocities, gas flow is blocked at the
highest magnetic field gradient
Third Regime - At higher flow rates, the
gas flow is allowed to pass though
curtain in a pinched fashion
Magnetic fields do not separate nitrogen and oxygen!
Magnetic Properties
•
•
•
For combustion of alchohol [1, 2]
Application of magnetic field gradients of
20-200T/m under 0.5 - 1.4 T decreased
combustion temperature from 200 to 100
˚C
Combustion rate decreased for location of
highest magnetic field strength
Candle flame, hydrogen flame and
methane flame are also deflected toward
lesser magnetic field strengths
Magnetic Properties
•
•
Flame Quenching [3]
Candle flame can be quenched
between two cylindrical
electromagnets when interacting
with a field strength of 1.5 T and
intensity gradient of 50-300 T/m in a
5-10 mm space
Flame is not quenched below 0.9 T
Magnetic Properties
Radiative Emissions from Diffusion Flames [13]
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•
Magnetic field near reaction zone
greatly increases emission intensity
Cleaner burning - soot levels are
decreased
Magnetic Properties
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Studies in Microgravity [14, 15, 16]
Larger influence on diffusion flames
due to buoyancy induced
convective air flow
Longer burning periods on diffusion
flames
Affects flame shape without
pressurized containments
Magnetic Properties
Studies in Microgravity [14, 15, 16]
•
•
In microgravity, the magnetic field
causes the flame to behave like it’s
subjected to buoyant forces (which
can be isolated in normal gravity)
Large soot particles can be
decreased
Magnetic Properties
Summary
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Uniform Magnetic field produces no
observable change
Combustion is enhanced in the presence
of a decreasing magnetic field
Ferromagnets are ideal for
experimentation due to the absence of
Ampere and Lorenz forces
Outline
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Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Modeling Affects on a Diffusion Flame
Benefits Using Magnetism
Magnetic Confinement Fusion
Plasma in Relation to Fire
• Plasma is defined as a
quasineutral gas composed of
charged and neutral particles
•
The ‘reaction zone’ of a
diffusion flame at high pressure
may be characterized as a
plasma
http://www.youtube.com/embed/uPU9cEK5YsM
Magnetic Confinement Fusion
•
•
•
Stellarator
Toroidal Tokamak
Spherical Tokamak
Magnetic Confinement Fusion
• Stellarator [17]
QPS Coil-sets and plasma.
Modular coils are shown in
light blue, toroidal field coils
are pink, vertical field coils are
in tan. Color contours (blue =
low field, red = high field) show
the magnetic field strength on
the outer plasma magnetic flux
surface
Magnetic Confinement Fusion
• Toroidal Tokamak [18]
Magnetic Confinement Fusion
• Spherical Tokamak [19]
33
Outline
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Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Modeling Affects on a Diffusion Flame
Benefits Using Magnetism
Plasma Torch[20]
•
Hybrid (RF + DC) plasma torch
Plasma Torch[20]
•
Direct Current Induction
Includes anodes,
cathode and gas inlets
Plasma Torch[20]
•
Radio-frequency Induction
Advantages: large volume
plasma generation; cleanness;
simplicity; easy in-feeding into
plasma; long lifecycle
Includes metal watercooling sections; quarts
tube; body corpus and
gas former
Plasma Torch[20]
Plasma Torch[20]
Outline
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•
•
•
•
•
Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Modeling Affects on a Diffusion Flame
Benefits Using Magnetism
Affects on Diffusion
Flame [21]
Affects on Diffusion
Flame [21]
Evolution of the temperature along the flame axis, lift-off height and flame
length with the injection velocity of air in the presence of a magnetic field(MF)
and without magnetic field(WMF) for two injection velocities of CH4: 0.54(a)
and 0.79(d) for a position of the burner Z = +85mm.
Affects on Diffusion
Flame [21]
Evolution of the visual lift-off height with the injection velocity of air in the
presence of a magnetic field (MF) and without magnetic field (WMF) for two
injection velocities of CH4: 0.54 and 0.79 m/s for a position of the burner Z = 185mm.
Affects on Diffusion
Flame [21]
•
•
•
Affects on Diffusion
Flame [21]
Analysis
Magnetic fields of decreasing strength
lengthen lift-off height and accelerate
normal convection
Thermo-magnetic convection slows
normal convection for fields of
increasing strength
Field Modeling
Solenoid (hollow)
Magnetic Field Lines
Diffusion Flame
Field Modeling
• Geometry
Coil
0
Field Modeling
• Biot-Savart Law
Field Modeling
• Biot-Savart Law
Field Modeling
• Biot-Savart Law
•
•
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Field Modeling
Biot-Savart Law
Magnetic field vector in 3D space is
determined by the addition of two
integrals for two coils.
Ends of solenoids are connected with a
sinusoidal function
The connectors distort magnetic fields
lines so data was taken away from the
connectors
Field Modeling
Observations
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•
Magnetic fields lines running through
the outer regions of the electromagnets
are unpredictable and highly sensitive
to initial conditions
Field lines not affected by chaos slightly
deviate from their initial linear paths
when between magnets
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Conclusions
More coil windings (and hence a stronger
magnetic field) give straighter magnetic field
lines between the two solenoids, giving the
flame an increased linear stability
A longer flame length is due to the stronger
influence from the central area of an
electromagnet
Flame behavior in outer regions of
electromagnets is unpredictable
Outline
•
•
•
•
•
•
Introduction
Magnetic Properties in Combustion
Magnetic Confinement Fusion
Magnetic Induction in a Plasma Torch
Magnetic Field Line Modeling
Benefits Using Magnetism
Fire Suppression
•
•
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Fire scan be suppressed through
electromagnetic pulses, which is an
environmentally friendly alternative for
water and chemicals
Pulses are meant to scatter gases
necessary for reactions to take place.
Not applicable to large scale fires!
Applications
•
•
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Useful for entraining oxygen in
microgravity environments
Flame stabilization in combustion
engines
Experimental research in plasma
assisted combustion
References
[1] S. Ueno and K. Harada, “Experimental Difficulties in Observing the Effects of Magnetic Fields on Biological and
Chemical Processes”, IEEE Transactions on Magnetics, Vol. MAG-22, No.5, September 1986, pp. 868-873.
[2] S. Ueno and K. Harada, “Effects of Magnetic Fields on Flames and Gas Flow”, IEEE Transactions on
Magnetics, Vol. MAG-23, No.5, September 1987, pp.2752-2754.
[3] S. Ueno, “Quenching of Flames by Magnetic Fields”, Journal of Applied Physics, Vol. 65, No. 3, February 1989,
pp. 1243-1245.
[4] Prof. Zantedeschi, “ On the Motions Presented by Flame when under the Electro-Magnetic Influence”, The
London, Edinburgh and Dublin Philosophical Magazine and Journal of Science, Series 3, Vol. 31, No. 210,
December 1847, pp.401-424.
[5] M. Faraday, “ On the Diamagnetic Conditions of Flame and Gases”, The London, Edinburgh and Dublin
Philosophical Magazine and Journal of Science, Series 3, Vol. 31, No. 210, December 1847, pp.401-421.
[6] A. V. Engle and J. R. Cozens, “Flame Plasmas,” Advances in Electronics and Electron Physics, Vol. 20, 1964,
pp. 99-146.
[7] U. E. Steiner, “Spin Chemistry: how magnetic fields affect chemical reactions”, Summer School on Magnetic
Fields in Science, University of Konstanz, Cargese, Corsica, 2007. Received from http://mfscargese.grenoble.cnrs.fr/Steiner_Abstract.pdf.
References
[8] A. A. Kipriyanov (Jr.), P. A. Purtov, “Magnetic field effects on chemical reactions near the disturbance of
stationary states conditions”, Chaotic Modeling and Simulation (CMSIM) 1: 53-65, 2012
[9] T. Aoki, “Radicals’ Emissions and Butane Diffusion Flames Exposed to Upward Decreasing Magnetic Fields,”
Japanese Journal of Applied Physics, Vol. 28, 1989, pp. 776-785.
[10] J. Baker, M. E. Calvert, K. Saito and R. Vander Wal, “Holographic Interferometry and Laminar Jet Diffusion
Flames in the Presence of Non-Uniform Magnetic Fields”, Sixth International Microgravity Conference, 2001, pp.
361-364.
[11] J. Baker, M.E. Calvert, K. Saito and R. Vander Wal, “An Analytical Model for Non-Uniform Magnetic Field
Effects on Two-Dimensional Laminar Jet Diffusion Flames”, Sixth International Microgravity Conference, 2001, pp.
361-364.
[12] S. Ueno and M. Iwasaka, “Properties of Magnetic Curtain Produced by Magnetic fields”, Journal of Applied
Physics, Vol. 67, No. 9, May 1990, pp. 5901-5903.
[13] N. I. Wakayama, “Effect of a Gradient Magnetic Field on the Combustion of Methane in Air”, Chemical
Physics Letters, Vol. 188, No. 3, Jan. 1992, pp. 279-281.
[14] N. I. Wakayama, “Magnetic Support of Combustion in Diffusion Flames under Microgravity”, Combustion and
Flame, Vol. 107, 1996, pp. 187-192.
References
[15] N. I. Wakayama, “Utilization of Magnetic Force in Space Experiments”, Advances in Space Research, Vol.
24, No. 10, 1999, pp. 1337-1340.
[16] F. Khaldi, K. Messadek, A. M. Benselama, “Isolation of Gravity Effects on Diffusion Flames by Magnetic
Field”, Microgravity Sci. Technology (2010) 22:1-5.
[17] D. A. Spong, D. J. Strickler, S. P. Hirshman, J. F. Lyon, L. A. Berry, D. Mikkelsen, D. Monticello, A. S. Ware,
“confinement physics and flow damping in quasi-poloidal stellarators”, The 14th International Stellarator
Workshop, Griefswald, Germany, 2003.
[18] Picture received from http://www.plasma.inpe.br/LAP_Portal/LAP_Site/Text/Tokamaks.htm.
[19] World Nuclear Association, Ian Hore-Lacy (Lead Author);PPPL (Content Source);Cutler J. Cleveland (Topic
Editor) "Nuclear fusion power". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.:
Environmental Information Coalition, National Council for Science and the Environment). [First published in the
Encyclopedia of Earth December 6, 2009; Last revised Date December 6, 2009; Retrieved March 14, 2013
<http://www.eoearth.org/article/Nuclear_fusion_power>
[20] V. Frolov, I. Matveev, D. Ivanov, S. Zverev, B. Ushin, G. Petrov, “experimental investigations of the hybrid
plasma torch with reverse vortex stabilization “, Applied Plasma Technologies, 1729 Court Petit, McLean, VA
22101, USA. Received from http://www.nipne.ro/rjp/2011_56_Suppl/0036_0040.pdf.
[21] M. Chahine, P. Gillon, B. Sarh, J. N. Blanchard, V. Gilard, “Magnetic Field Effect on Methane/Air Diffusion
Flame Characteristics”, Universite d’Orleans, 16 Rue d’Issoudun – BP 16729 45067 Orleans cedex 2, France.
Received from
http://data.cas.manchester.ac.uk/database3/SAMPLE%20III/Dropbox%20stuff/ECM/ECM%202011%20Papers/32
0.pdf.
Fin