Note: Descriptions are shown in the official language in which they were submitted.
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Title: Centrifugal Humidifier With Sawtooth Ridged Impingement Surface
FIELD OF THE INVENTION
This invention relates to humidification devices, particularly
centrifugal humidifiers.
BACKGROUND OF THE INVENTION
Various types of humidification devices have been developed
to add moisture to dry air. In certain industrial and commercial
environments, centrifugal humidifiers are often used. In such devices, water
is propelled outwardly by a rapidly rotating plate or other body to impinge on
a surface where it is broken up into small droplets that are entrained in a
stream of air and then discharged to the surroundings.
Although the discharged air has a higher moisture content, the
size of the droplets produced on the impingement surface of known
centrifugal humidifiers is generally not sufficiently fine to be readily
absorbed by the air. Instead, such humidifiers tend to produce a mist-like
discharge. Not only does this result in a less than optimum overall humidity
level, it also tends to create water build up on the surfaces of walls,
equipment, furniture and so forth in the vicinity of the humidifier. More than
merely an inconvenience, this promotes the growth of moulds and other
microorganisms that can pose health risks to workers in the area.
Known centrifugal humidifiers are also limited in their
throughput and efficiency. While increased humidification can be obtained
by using larger humidifiers, or by using more humidifiers, doing so
increases energy consumption and heat generation from the electric motors
that are generally used to drive such centrifugal humidifiers.
Known centrifugal humidifiers also have a tendency to become
clogged with dust and other particles when they are used in industrial
environments such as textile mills.
It is a general object of the present invention to obviate or
mitigate these and other disadvantages of known centrifugal humidifiers.
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SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a
centrifugal humidifier having a dish or other body rotatable on an axis for
propelling supplied water outwardly by centrifugal force onto an
impingement surface, generally concentric to the axis of the rotatable body,
which breaks up the outwardly propelled water into fine droplets. The
humidifier of the present invention also has means to intake a stream of air
for entraining the fine droplets of water and thereafter to discharge the
stream of air to the surroundings.
The impingement surface of the humidifier of the present
invention has a multiplicity of sawtooth ridges. The ridges are each defined
by a broader, more gradually inclined first side that faces toward the
direction of rotation of the rotatable body, and a narrower, steeper second
side that faces away from the direction of rotation of the rotatable body.
Because of the sawtooth profile, the water tends to hit and
bounce repeatedly on the first sides of successive ridges which promotes
breaking up the water into finer droplets that are readily absorbed by the
stream of air. The centrifugal humidifier of the present invention can
therefor
produce a fog-like discharge, rather than the mist-like discharge of known
centrifugal humidifiers. This greatly reduces the problem of wetting nearby
surfaces, and also greatly increases the throughput the efficiency. The
invention eliminates or reduces the need for filters or similar moisture
eliminators which are commonly used in known centrifugal humidifiers to
reduce wetting, but which also tend to reduce efficiency by screening out the
finer water droplets as well as the larger ones. The sawtooth ridge
impingement surface of the present invention also resists buildup of dust
and other particles that can clog other centrifugal humidifiers.
Preferably, the centrifugal humidifier of the present invention
includes a fan to take in and discharge the stream of air, and also includes
a motor for driving the fan and for driving the rotatable body.
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Advantageously, the centrifugal humidifier of the present invention includes
as well a water reservoir, and the rotatable body is generally bell shaped,
with a broader flared rim and a narrower, cup-like lower portion immersed in
the reservoir, such that rapid rotation of the body causes water in the
reservoir to rise up the outer surface of the body to its rim from which it is
propelled outwardly onto the impingement surface.
Most preferably, the centrifugal humidifier of the present
invention also has a pump and conduit for delivering additional water from
the reservoir to the inner surface of the rotating body.
It has been found that the centrifugal humidifier of the present
invention provides an effective solution to obviate or mitigate problems
presented by known prior art centrifugal humidifiers, as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and to
show more clearly how it may be carried into effect, reference will now be
made to the accompanying drawings in which:
Figure 1 is an oblique perspective view, partly exploded, of one
embodiment of a centrifugal humidifier according to the present invention;
Figure 2 is a crass-sectional view of the humidifier of Fig. 1;
Figure 3 is a perspective view of a component of the humidifier
of Fig. 1 which includes the impingement surface;
Figure 4 is a close up view of the impingement surface on the
component of Fig. 3;
Figure 5 is a cross-sectional view of the sawtooth ridges on
the impingement surface of Fig. 4;
Figure 6 is a perspective view of the impingement surface
component of an alternate embodiment of a humidifier according to the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring first to Figures 1 and 2, the humidifier 10 has three
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main sections, namely a base 11, a head 12, and a core assembly 13
positioned between the base 11 and the head 12.
The base 11 is generally box-like, and has side panels 14, end
panels 15, tapered sides 16, shoulders 17, and flanges 20. The material
used to construct base 11 must be able to support the core assembly 13
and the head 12, and should be rustproof since the lower inside portion of
base 11 provides a water reservoir 21. A heavy gauge galvanized sheet
metal can be used, wherein seams of adjoining pieces are welded.
Alternatively, base 11 may be constructed of plastic using molding
techniques as are known in the art.
The head 12 has a mounting plate 22, a hood 23, and an outlet
duct 24. The mounting plate 22 has an opening 25 and mounting holes 26.
Mounting plate 22 is sized to fit over the flanges 20 of the base 11 with a
gasket 19 between them.
The hood 23 is sized fio cover the opening 25 and has intake
vents 27 around a portion of its periphery near its lower edge, and an outlet
duct 28 on one side.
The head 12 can be made of duct material commonly known in
the art, such as sheet metal, plastic or other rustproof material.
The core assembly 13 includes a cover 30, and a motor 31
having a shaft 32, on which are mounted both a composite dish and cup 33,
34, and a fan 35.
The cover 30 has a top 36, a frustoconical sidewall 37, a iip 40
along the lower perimeter, and mounting tabs 41 which extend outwardly
from tip 40. The cover 30 is sized so that it can be mounted to the shoulders
17 of the base 11 resting on the lip 40 and secured by threaded fasteners
through the mounting tabs 41.
Preferably risers 42 are provided between the cover 30 and the
shoulders 17. The risers 42 are comprised of threaded rods, one end of
which are fastened to the shoulders 17 of the base 11 and the other end of
which are fastened to the mounting tabs 41 of the cover 30. This adds
space between the cover 30 and the base 11, thereby facilitating the
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evacuation of air and water droplets from underneath the cover 30.
The cover 30 is provided with sharp edged ridges 43 along the
inner surface of the sidewall 37 which are described in greater detail below.
The motor 31 is mounted on top of the cover 30, with a vertical
shaft 32 positioned coaxially with the cover 30 and extending both above and
below the motor 31. Motor mounting holes 44 are provided in the top
surface 36 of the cover 30, as is a shaft opening 45.
On the portion of the shaft 32 extending above the motor 31,
the fan 35 is mounted. On the portion of the shaft 32 extending below the
motor 31, an optional spool 47 is mounted using a stop collar or set screw
or other means known in the art.
The spool 47 has three flat cylindrical elements with different
outer diameters stacked together but separated by spacers of a smaller
diameter. The largest cylindrical surface of the spool 47 has a diameter
less than the largest diameter of the cup 34, and is positioned to face the
lower end of the shaft 32.
Immediately adjacent to the spool 47 and coaxially on the shaft
32 is mounted the rotating dish 33. The axial position of the dish 33 is such
thafi its rim 38 is aligned toward the ridges 43 of the cover 30
The cup 34 is assembled coaxially on the shaft 32 immediately
below the dish 33 and has a tapered profile that merges with the lower
portion of the dish 33.
A nut 52 is provided on the shaft 32 to secure the cup 34, dish
33, and spool 47.
Connection to an external water supply is provided through a
fitting 53 mounted in an end panel 15. The fitting 53 leads to a float valve
54
which is controlled by a float 55 in the water reservoir 21. When the water
level in the reservoir 21 falls below a predetermined level, the float 55
causes the valve 54 to open, permitting water to flow into the reservoir 21.
In the illustrated embodiment, the water handling system
includes an optional pump 56, which draws water from the reservoir 21
through an inlet 58, and supplies water through a hose 57. The hose 57
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passes through an opening in the base 11, to a coupling 60 mounted in the
upper surface of the cover 30o From the coupling 609 a rigid tube 61 directs
the water to against the spool 47.
In operation, the motor 31 causes the fan 35 to rotate thereby
creating a stream of air entering the intake vents 27 and discharged through
the outlet duct 28, and also causes the dish 33 and cup 34 to spin with the
shaft 32.
As the cup 34 spins, it draws water upwardly from the reservoir
21. The water moves upwardly in the form of a thin film along the outer
surface 51 of the cup 34 and dish 33, until it reaches the rim 38 of the dish
33. At this point the spinning action causes the water to be thrown free of
the dish 33 whereupon it strikes the ridges 43 provided on the inner surface
of the cover 30.
Upon striking the ridges 43, the water is broken into very fine
particles. The very fine droplets are readily entrained and absorbed into the
air to provide a humidified air discharge from the head 12 that is fog-like
rather than mist-like. In this sense, the discharge is "non-wetting" because
objects even very close to the discharge do not become wet. The fog-like
discharge becomes invisible within a relatively short distance of the outlet
duct 28 in typical operation.
As the water in the reservoir 21 is depleted, the float valve 54
opens allowing supply water to flow into the reservoir 21 through the valve
outlet 59. This ensures that the water level in the reservoir 21 is sufficient
to
keep the lower portion of the cup 34 immersed.
As shown more clearly in Figs. 3, 4 and 5, the ridges 43 of the
cover 30 provide an impingement surface that is significantly different from
those of known centrifugal humidifiers. The ridges 43 present a sawtooth
profile with each ridge having a broader, more gradually inclined first side
62 that faces toward the direction of rotation of the spinning dish 33, and a
narrower, steeper second side 63 that faces away from the direction of
rotation of the spinning dish 33.
This sawtooth profile of the ridges 43 increases the effective
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impact surface. Water droplets thus impinge repeatedly on successive
ridges to be broken into a finer size. Moreover, less water is trapped
between successive ridges so throughput and efFiciency are enhanced.
The sawtooth profile is also less prone to entrapment and
buildup of dust and other airborne particles.
Measurement of the droplet size in the discharge during
operation of a prototype of this humidifier showed: 95 percent of the droplets
between 5 to 21 microns; a minimum size of 2.2 microns; and 50 percent of
the droplets under 11 microns. It was also observed that the discharge was
non-wetting on human skin at a distance of 20 centimetres.
In the embodiment illustrated in Fig. 3, the sawtooth ridges are
oriented radially. In an alternative embodiment shown in Fig. 6 the sawtooth
ridges are spirally inclined.
The operation of the illustrated embodiment of the present
invention is further enhanced by the optional pump 56. As described earlier,
the pump 56 draws water from the reservoir 21 to direct a stream of water
toward the spool 47 which then distributes a film of water outwardly onto the
inner surface 64 of the dish 33. This water rises up the inner surface 64
until it reaches the rim 38 of the dish 33, where it is thrown free to strike
the
ridges 43 in the same fashion as the water drawn upwards along the outer
surface 51 of the dish 33.
By using both the inner surface 64 and outer surface 51 of the
dish 33 to distribute water against the ridges 43, the rate at which water is
transferred to the surrounding air is increased. Use of an internal
circulation pump in a prototype of this humidifier has been measured to
double the performance with little effect on discharge droplet size.
Although only one tube 61 is illustrated, a plurality of tubes may
also be provided to direct water at various points.
It is to be understood that the invention is not limited in its
application to the details of an arrangement of components illustrated in the
accompanying drawings, since the invention is capable of other
embodiments and of being practiced or carried out in various ways within
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the scope of the claims. It is also to be understood that the terminology
employed herein is intended for the purpose of description and not
limitation. In its broadest scope, the present invention encompasses many
modifications and alternative embodiments, appropriate for different
circumstances.
