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Magnetic field enhancement of water vaporization
Jun NakagawaDepartment of Applied Chemistry, University of
Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan,and TDK
Corporation, Materials Research Center, 570-2 Matsugashita,
Minamihatori, Narita,Chiba 286-8588, Japan
Noriyuki Hirota and Koichi Kitazawaa)
Department of Applied Chemistry, University of Tokyo, 7-3-1
Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
Makoto ShodaResearch Laboratory of Resources Utilization, Tokyo
Institute of Technology, 4259 Nagatsuta, Midori-ku,Yokohama
226-8503, Japan
Received 29 April 1999; accepted for publication 19 May 1999
The water vaporization rate, an essential process for all the
biological processes, was found to be
significantly influenced under static magnetic fields up to 8 T
in air and oxygen. The magnitude of
the effect depended on the fieldfield gradient product BdB/dx
rather than on B itself. Under
forced flow conditions of the atmosphere, both enhancement and
suppression of the vaporization
rate were observed depending upon the direction of the gas flow
relative to the field gradient. A
mechanism is proposed to explain the results in a systematic
manner based on the assumption of the
creation of magnetic wind driven by the gradient susceptibility
distribution caused by water content
distribution in the atmosphere. It is discussed that this
magneto enhancement of vaporization may
be the indirect cause of frequently reported field effects on
living organisms. 1999 American Institute of Physics.
S0021-89799900117-6
It has been of great concern and still remains controver-
sial whether the magnetic field exerts any effect on the
pro-
cesses of living bodies.1 There are, however, two
essentially
different types of conceivable field effects. One is a
direct
field effect on biochemical reactions, while the other is
indi-
rect via changes in the surroundings. In the case of the
former effect, the concern might be its possible conse-
quences that the genetic influence of the magnetic field
could
have on living organisms. In the case of the latter,
however,
the magnetic field effects can be considered as any other
external parameters such as temperature, pressure, or me-
chanical stirring which are no cause for worry.
In the experiments so far performed on living bodies,
however, little efforts have been made to discriminate the
indirect effects from the direct ones. If water vaporization
is
enhanced under magnetic fields, it then changes the content
in the surrounding aqueous and gaseous media and lowers
the temperature of the water, which in turn will change the
experimental conditions and hence changes the results. This
study reports that water vaporization is indeed
significantly
enhanced by the application of magnetic fields.
In the course of studies on microbial processes, we no-ticed a
faster drying of incubation solutions under magnetic
fields. In order to confirm the observation quantitatively,
we
designed a simplified experiment to observe the rate of va-
porization of water precisely in the presence of magnetic
fields.
As shown in Fig. 1, an increase was observed in the
magnetic field of the water vaporization rate from vessels
placed in different positions in a horizontal
superconducting
solenoid magnet of the field distribution given in Fig. 2. A
similar enhancement was observed at 293 and 303 K as well.
Because the vaporization rate enhancement was greater
when the vessel was placed off the field center (x
60 mm), we assumed that it was due to the field gradient
rather than the field itself. A volume magnetic force of
(/0)BdB/dx would be exerted on a substance with the
volume susceptibility in the field gradient dB/dx , where
0 is the permeability of vacuum. If both the air and thewater
are uniform in values, there will not be any flow
created by the magnetic force. In the design of the experi-
ment, the water phase should be uniform, but there could be
some nonuniform distribution of in the atmosphere be-
cause of the occurrence of vaporization.
The possibility of magnetic convection in the atmo-
spheric gas was hence examined. The paramagnetic volume
susceptibility of air, air0.3736106, in System Inter-
national SI units is mainly contributed by oxygen gas,
O21.8028106, while nitrogen and water vapors are
both diamagnetic with much smaller contributions, N2
0.0063
10
6
and H2O
0.0068
10
6
at 293 K, 1atm. During the vaporization process, a
susceptibility gradi-
ent could be created along the vertical z axis in the atmo-
sphere above the water surface. This is because the water
vapor content should be larger near the water surface than
at
a distance if the diffusion process of water vapor in the
at-
mosphere is the rate determining step of the vaporization,
as
shown in Fig. 3. The saturated vapor pressure of water, 2338
Pa 0.0231 atm., in the air at 293 K reduces the susceptibil-
ity of the air to sat , 2.35% less than the air of the dry
air.
The difference in the volume magnetic force Fm ex-aElectronic
mail: [email protected]
JOURNAL OF APPLIED PHYSICS VOLUME 86, NUMBER 5 1 SEPTEMBER
1999
29230021-8979/99/86(5)/2923/3/$15.00 1999 American Institute of
Physics
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8/7/2019 Magnetic field enhancement of water vaporization -
Nakagawa 1999
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hance the vaporization. On the other hand, if the two flows
are opposite in direction, the field should rather suppress
the
vaporization rate.
As shown in Fig. 5, the vaporization under the oxygen
flow was enhanced at x0 vessel positions and suppressed
at x0 positions as exactly anticipated. The degree of both
enhancement and suppression was the largest at x60 mm positions.
These are the positions where the mag-
netic force and, hence, the magnetic convection are expected
to be maximized. This provides definite qualitative support
for the magnetic convection mechanism.
To substantiate the magnetic convection mechanism
quantitatively, a rough estimation was made on the convec-
tion velocity in the scheme of the idealized viscous flow of
the atmosphere. A simplified convection circuit may be as-
sumed in the vaporization cell of a total circular length of
60
mm, a height of 6.7 mm, which is half of the height of gas
phase above water surface, and width of infinite length in a
steady state viscous flow mode. If a force (/0)B
dB/dx is applied on this convection circuit along one di-
rection in the upper half of the circuit and the opposite
di-
rection in the lower half, then the circuit will turn around
with a linear viscous velocity of 0.34 m/s for 0.0088
10
6 and the viscosity of the air 1.8210
5 Pas.The real convection velocity is thought to be smaller
than this rough estimation because the values adopted are
the
possible maximum in their distributions. Compared with the
linear velocities of the externally forced gas flow employed
in the experiments, 0.0060.031 cm/s, the expected convec-
tion velocity is large enough to justifying the magneto-
convection mechanism.
For a liquid of higher vapor pressure, the motive force
(/0)BdB/dx should be accordingly increased to in-
duce the magneto convection and hence a more significant
magneto vaporization. This was confirmed when ethanol was
used instead of water. The equilibrium vapor pressure of
ethanol was 5866 Pa at 293 K, 2.5 times larger than that
ofwater. Enhancement of up to two times was observed for the
rate of ethanol vaporization in the same experiment shown in
Fig. 1, further supporting the mechanism proposed.
We may generally state the necessary conditions for the
occurrence of magneto convection in the atmosphere as the
presence of a magnetic susceptibility gradient in it, which
is
perpendicular to the magnetic field gradient. The conditions
are satisfied when vaporization takes place from the liquid
surface extending along the field gradient.
Occurrence of magneto convection has been reported in
relation to temperature gradient in the atmosphere2,3 and
with
the motion of N2
H2
O gas emitted in the air.4 However, this
report concerns the magnetic field effect on the
vaporization
process of a liquid.
In conclusion, the vaporization or drying process in the
air can be significantly enhanced under a magnetic field
gra-
dient in the tesla range. As a consequence, when living or-
ganisms are placed under a magnetic field with gradient,
they
may feel colder due to the latent heat of vaporization, and
they may experience aqueous environments with different
concentration of ingredients from the intended values. These
changes in environmental conditions should necessarily
cause some change in the experimental results when living
organisms are subjected to the magnetic field for examina-
tion. Therefore a special consideration must be taken whento
judge whether the magnetic field really has an effect on
living organisms.
1Biological Effects of Static Magnetic Fields International
Cryogenic Ma-
terials Commission, 1992.2 J. R. Carruthers and R. Wolfe, J.
Appl. Phys. 39, 5718 1968.3 J. Ecochard and G. Maret,
Naturwissenschaften 74, 39 1987.4 N. I. Wakayama, Combust. Flame
93, 207 1993.
FIG. 5. Vaporization rate a and normalized vaporization rate b
of water
under oxygen gas flow at a speed of 100500 ml/min.
2925J. Appl. Phys., Vol. 86, No. 5, 1 September 1999 Nakagawa et
al.
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