U.S. patent application number 10/022962 was filed with the patent office on 2002-07-18 for air purifier.
Invention is credited to Monagan, Gerald C..
Application Number | 20020094298 10/022962 |
Document ID | / |
Family ID | 23316235 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020094298 |
Kind Code |
A1 |
Monagan, Gerald C. |
July 18, 2002 |
Air purifier
Abstract
A system and method for purifying air by employing an air
purifier which includes an irradiation chamber having a titanium
element therein, an air circulator, and at least one ultraviolet
radiation source. Impure air is exposed to UV in the presence of
naturally occurring and reforming titanium oxide, a recognized
photocatalytic agent. The agent is resident on the surface of a
titanium element that is provided adjacent the at least one
radiation source. The system may produce a plurality of separate UV
energy spectra in distinct regions of the system. In this case,
each radiating region of the system can be optically isolated from
some or all of the other radiating regions by an optical isolator,
and the isolator can incorporate a catalytic titanium element.
Inventors: |
Monagan, Gerald C.; (Albion,
NY) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
ONE INTERNATIONAL PLACE
BOSTON
MA
02110
US
|
Family ID: |
23316235 |
Appl. No.: |
10/022962 |
Filed: |
December 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10022962 |
Dec 13, 2001 |
|
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09336470 |
Jun 18, 1999 |
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Current U.S.
Class: |
422/5 ;
250/455.11; 422/120; 422/24 |
Current CPC
Class: |
A61L 9/20 20130101 |
Class at
Publication: |
422/5 ; 422/24;
422/120; 250/455.11 |
International
Class: |
A61L 009/00; A61L
002/00; B32B 005/02; A62B 007/08; B32B 027/04; B32B 027/12; G01N
023/00; H01J 037/20 |
Claims
What is claimed is:
1. An air purification system comprising: a housing having a
catalytic titanium element and an irradiation chamber; an air
circulator for exposing air to the titanium element and for passing
air through the irradiation chamber, and an ultraviolet radiation
generator comprising at least one radiation source, the generator
mounted in the irradiation chamber for irradiating the air passing
through the irradiation chamber.
2. The air purification system of claim 1 further comprising: a
power controller capable of communication with an AC power source,
comprising: a pollution detector; and a system activator for
selectively powering the at least one radiation source in response
to a pollutant indicator signal received from the detector.
3. The air purification system of claim 2, wherein the pollutant
detector is capable of detecting the presence of a pollutant
selected from the group consisting of carbon monoxide, carbon
dioxide, benzene, methane, formaldehyde, sulfur dioxide, oxygen,
hydrogen, hydrogen sulfide, NO.sub.x,, ozone and aerosols.
4. The air purification system of claim 2, further comprising: a
timer associated with the power controller for determining a
selected time during which power is supplied to the at least one
radiation source.
5. The air purification system of claim 1, further comprising: a
heater mounted within the housing for providing heat to an external
environment.
6. The air purification system of claim 1, further comprising: a
cooling unit mounted within the housing for cooling an external
environment.
7. The air purification system of claim 1, further comprising: a
filter mounted within the housing for filtering the air passing
therethrough.
8. The air purification system of claim 1, wherein the housing is
adapted for insertion in a duct of an HVAC unit.
9. The air purification system of claim 1, wherein the generator
comprises a plurality of radiation sources, each source configured
to provide a different spectrum of radiation from that provided by
another source, the housing further comprising: at least one
titanium isolator configured to optically isolate distinct regions
of the irradiating chamber, so that air can be exposed to a
particular spectrum while passing through a particular region.
10. The air purification system of claim 9, wherein the at least
one isolator has a surface, upon which air may pass, that contains
titanium.
11. The air purification system of claim 10, wherein a first
radiation source is capable of generating radiation within a first
wavelength band of ozone-producing radiation and a second radiation
source is capable of generating radiation within a second
wavelength band of germicidal radiation.
12. The air purification system of claim 1, wherein the catalytic
titanium element is located adjacent to the ultraviolet radiation
generator.
13. A method for purifying air comprising: circulating impure air
through a chamber having a titanium element therein; and exposing
the air to ultraviolet radiation while the air circulates through
the chamber, thereby inducing a photocatalytic reaction causing a
reduction in pollutant level in the air.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of
co-pending U.S. application Ser. No. 09/336,470, filed Jun. 18,
1999, that is hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to air purifying devices that
employ ultraviolet radiation to destroy microorganisms and remove
odors and other impurities from the air.
BACKGROUND OF THE INVENTION
[0003] Today, a large number of pollutants can be found in the air
and water. Among the various harmful air pollutants that exist in
the air that people breath are pollen, lung damaging dust, smoke
and bacteria. Other pollutants include various organic vapors and
toxic gases. The environment is often contaminated with a variety
of noxious and toxic gases including carbon monoxide, methane,
sulphur dioxide, hydrogen sulfide and a broad variety of organic
vapors. Some of these are widely prevalent in the environment,
particularly in urban areas, and others tend to be pronounced in
homes, offices, or other confined spaces due to activities within
those spaces. Noxious or toxic materials may be produced from
tobacco smoking, cooking, open fireplaces, faulty appliances, or a
variety of other normal activities. Some of these are merely
unpleasant because of odors while others such as carbon monoxide
can be dangerous. Because these pollutants are so prevalent in the
air and are found in most locations, contact with them is
inevitable.
[0004] Typically, air pollutants cause general discomfort to many
people, and can be particularly troublesome to individuals that
suffer from emphysema, asthma, and hay fever and like allergies. It
has also been found, for example, that a high proportion of homes
have unsuspected carbon monoxide concentrations which contribute to
vague disorders such as lassitude and headaches at concentrations
far below levels that produce overt symptoms of toxicity. Hence,
apparatus and methods for removing air pollutants from the air
and/or sensing the presence of pollutants have wide spread economic
and therapeutic appeal.
[0005] Air purifiers are generally known and exist. A typical air
purifier includes a housing having a chamber mounting an
ultra-violet (UV) lamp. Air is drawn into the bottom of the housing
and passes through the chamber where it is exposed to UV radiation
emitted from the lamp, which denatures organic proteinous
particles, e.g., exterminates microorganisms, that are carried in
the air. The air is then discharged from the housing top to the
external environment. One prior art air purifier is shown and
described in U.S. Pat. No. 4,210,429 of Golstein. The Golstein air
purifier employs a UV lamp, which is mounted in a germicidal
chamber to exterminate microorganisms that are carried in the
incoming flow of air. A charcoal filter is seated above the
germicidal chamber and removes odors from the UV radiation exposed
air.
[0006] Another prior art air purifier is disclosed in U.S. Pat. No.
4,621,195 of Larsson. Larsson also describes an apparatus for
destroying microorganisms by irradiation with UV light emitted by a
UV lamp supported in an irradiation chamber. The irradiation
chamber is segregated into a set of minor chambers by a number of
partition walls. The partition walls have formed therein air-flow
openings that are oppositely located relative to the openings
formed in the adjacent partitions. This alternating arrangement of
air-flow openings maximizes the amount of time the air remains in
the irradiation chamber in order to maximize the amount of
microorganisms destroyed.
[0007] Photocatalytic systems such as the one disclosed in U.S.
Pat. No. 5,835,840 to Goswami also seek to improve indoor air
quality. In the Goswami system, a reactor is provided in which UV
lamps are installed such that surfaces coated with a semiconductor
catalyst (e.g., TiO.sub.2) are exposed to UV radiation as air
passes over the surfaces. The combination of the absorption of the
UV light photons by the catalyst in the presence of water molecules
in the air leads to the creation of hydroxyl radicals, which, in
turn, cause the destruction of chemical and microbiological
contaminants in the air.
[0008] There still exists a need in the art for improved air
purifiers that can exterminate microorganisms in the air as well as
reduce or eliminate odors. In particular, a compact, inexpensive
air purifier that is relatively easy to manufacture would represent
a major improvement in the art.
SUMMARY OF THE INVENTION
[0009] The present invention concerns air purifiers and methods of
purifying air by incorporating a titanium element within an
ultra-violet irradiation chamber. Titanium and its alloys develop a
thin, tenacious and highly protective surface oxide film. The
surface oxide of titanium will, if scratched or damaged,
immediately reheal and restore itself in the presence of air or
even very small amounts of water. This oxide layer, in the presence
of ultraviolet radiation and air, will promote photocatalysis.
[0010] The present invention also pertains to an air purifier and
methods for purifying air by employing ultraviolet radiation with
differing energy spectra. The air purifier may include an
ultraviolet (UV) generator comprised of one or more radiation
sources, that define distinct radiating regions that may be
optically isolated from each other. In this system, one or more
surfaces within the radiating regions comprise titanium or a
titanium-rich alloy, which have a naturally oxidized surface. The
air purifier photocatalytically treats air with various
combinations of ozone-producing radiation, cell wall-destroying
germicidal radiation and antimicrobial radiation, which may be
emitted from any of the radiating regions of the radiation system.
The naturally oxidized surface containing titanium dioxide absorbs
the UV light photons and, in the presence of water molecules in the
air, creates hydroxyl radicals, which, in turn, causes the
destruction of chemical and microbiological contaminants in the
air.
[0011] The air purifier of the present invention includes a housing
having an irradiation chamber, an air inlet for introducing air
into the irradiation chamber, and at least one radiation source
disposed within the irradiation chamber. Also within the chamber
(or the inlet), a titanium element is disposed such that air
passing through the purifier device will flow over or along this
titanium element. The radiation source or sources are generally one
or more lamps, each of which is capable of producing one or more
predetermined bands of UV radiation in the range of about 160 nm to
about 360 nm. A particularly effective UV radiation for
photocatalytic treatment has a wavelength of approximately 254
nm.
[0012] In one embodiment of the present invention, a single
radiation source with distinct radiating or radiation regions is
provided in the air purifier. One of these radiating regions may
emit a wavelength between about 160 nm and about 200 nm that is
effective to ionize oxygen in the air being treated into ozone,
while another distinct radiation region may emit a wavelength
between about 230 nm and about 280 nm that is effective to destroy
the cell walls of active ingredients such as spores and fungi in
the air being treated. In one embodiment, the titanium catalyst is
disposed in the first (ozone generating) region. In others,
titanium catalytic elements can be disposed in a plurality of
regions. Treatment of air by both of these radiation regions of the
radiation source results in the production of free radical oxygen
atoms that, in turn, convert carbon monoxide in the air being
treated into carbon dioxide, and which also help reduce the
toxicity of volatile organic compounds contained in the air being
treated by oxidizing the volatile organic compounds.
[0013] It is to be understood that a plurality of radiation sources
may be provided in the air purifier. Each radiation source can be
divided into at least two radiating regions, one of which generates
a first energy maximum of ozone-producing radiation and a second,
separate energy maximum of germicidal radiation and, optionally, a
third separate energy maximum of radiation each as described above
with respect to the single radiation source embodiment of the
present invention. Again, the titanium catalysts can be disposed in
each of the regions or only in one region.
[0014] The radiation sources may have even more than two radiating
regions, wherein the additional radiating regions may produce
either an additional wavelength between about 160 nm and about 200
nm that is effective to ionize oxygen in the air being treated into
ozone, or an additional wavelength between about 230 nm and about
280 nm that is effective to destroy the cell walls of active
ingredients such as spores and fungi in the air being treated, or a
wavelength of between about 330 and about 360 nm that is effective
to reduce the toxicity of volatile organic compounds by oxidizing
the volatile organic compounds.
[0015] Alternatively, the radiation sources can each be a dedicated
source, primarily emitting radiation within a single radiation band
with a single energy maximum.
[0016] Generally, the radiation regions will have lengths with
respect to each other that approximately correspond to their
wavelength relationships, such that the radiation region which
produces the longest wavelength will have the largest region
length. Likewise, the radiation region which produces the shortest
wavelength will generally have the smallest region length. In a
preferred embodiment, the titanium catalyst is disposed within the
chamber at a location where it is directly exposed to UV radiation
in at least one region.
[0017] The air purifier may farther include an air inlet and an air
outlet also formed in the housing for collecting and discharging
air, respectively. Moreover, each radiation region of each
radiation source may be optically isolated from each of the other
radiation regions of all of the radiation sources such that each
radiation region is prevented from producing radiation that may
interact with or "see" radiation from any of the other radiation
regions of any of the radiation source(s). This optical isolation
may be effected by the placement of structural optical isolator(s)
such as baffles or barriers or a combination thereof in
predetermined locations with respect to the radiating regions of
the radiation sources. The optical isolator can be formed in part
or wholly from titanium (e.g. a thin sheet or foil of titanium).
This foil may preferably have a thickness of between about 0.030
inch to 0.050 inch. In other embodiments, radiation source(s) are
mounted either individually or in groups to brackets made from
titanium foil or sheet.
[0018] Also, a predetermined fraction of the inside surface of the
irradiation chamber of the air purifier and/or the surfaces of the
optical isolator can be made of one or more elements or compounds
and/or coated with one or more elements or compounds in order to
catalyze the reactions caused by the interactions between the
wavelengths produced from the radiating regions and air pollutants,
microorganisms and other airborne targets of the air purifier.
[0019] A first energy maximum may occur at a first relative maximum
of the total radiation source energy output that is in the range
between about 160 nm and about 200 nm and represents radiation that
is effective to ionize oxygen in the air being treated into ozone.
A second energy maximum may occur at a second relative maximum of
the total radiation source energy output that is in the range
between about 230 nm and about 280 nm and that is effective to
destroy the cell walls of active ingredients such as spores and
fungi in the air being treated. Further, a third energy maximum of
the total radiation source energy output may occur in the range
between about 330 nm and 360 nm that is effective to reduce the
toxicity of volatile organic compounds. These energy maxima, alone
and in concert, act to convert portions of air treated in the air
purifier to free radical oxygen ions that, in turn, help convert
carbon monoxide in the air being treated into carbon dioxide, as
well as help reduce the toxicity of volatile organic compounds in
the air being treated by oxidizing the volatile organic
compounds.
[0020] The air purifier may further include a heater mounted within
the housing that generates heat, a cooling element mounted within
the housing for generating and providing to the external
environment cool air, and a filter element, mounted within the
purifier, for filtering the air.
[0021] According to another embodiment of the invention, the air
purifier includes a housing element having an irradiation chamber,
an air inlet for allowing air to enter into the housing, an air
outlet for allowing air to exit the housing, an air passage element
for introducing air into the irradiation chamber and for moving air
out of the chamber, and at least one titanium catalyst.
[0022] The present invention further encompasses a system for
purifying air. The system includes a housing element having an air
inlet, an air outlet, and an irradiation chamber, an air
introduction element that introduces air into the irradiation
chamber, a titanium catalyst, and at least one radiation source,
mounted within the irradiation chamber, that generates UV radiation
having first and second energy maxima within a pair of wavelength
intervals. The system further includes a power supply element that
supplies power to the air introduction element and the lamp
element.
[0023] The system can further include a timer element, mounted on
the housing, for allowing a user to select a time period in which
power is supplied to the lamp. The system can further include a
heater, a cooling element, and a filter element, all mounted within
the housing.
[0024] According to other aspects of the air purifying system, the
air introduction means is a blower and the power supply element
includes a ballast.
[0025] The method of the present invention includes providing a
housing having an air inlet and an irradiation chamber, with a
titanium element disposed therein. Activation of at least one
radiation source within the chamber induces a photocatalytic
reaction causing a reduction in pollutant level in the air passing
through the chamber. Kinetics for this reaction are favored because
the naturally oxidized surface of the titanium element contains
titanium dioxide. When a solid semiconductor catalyst, such as
titanium dioxide, is illuminated with greater-than-bandgap
ultraviolet or near ultraviolet light, electron excitation occurs
within the solid. Electron-hole pairs generated by the
photoexcitation can then react with water or oxygen to lead to the
formation of hydroxyl and other oxygen-containing free radicals.
These radicals may attack and oxidize organics such as chemical and
microbiological contaminants in the air.
[0026] The radiation source or sources may be capable of generating
or producing a band or spectrum of UV radiation with the following
energy maxima in each of its radiation regions: a first energy
maximum within a first wavelength band or spectrum of
ozone-producing radiation between about 160 nm and about 200 nm, a
second energy maximum within a second wavelength band or spectrum
of cell wall destroying radiation between about 230 nm and about
280 nm, and an optional third energy maximum of volatile organic
compound detoxifying radiation between about 330 nm and about 360
nm. These two or three wavelength intervals may cooperate to
destroy microorganisms carried in the air and substantially
simultaneously deodorize the air. In an embodiment of the invention
that only includes a single radiation source that emits a single
band of radiation, a preferred wavelength for such UV radiation is
about 254 nm.
[0027] The method further provides for introducing air into the
irradiation chamber through the air inlet, irradiating the inlet
air within the chamber, and discharging the irradiated inlet air to
an external environment.
[0028] The invention further pertains to a gas detection and air
purification system that employs an air purifier to remove gas
detected by a gas sensor from the external environment. In this
embodiment, the purifier can operate in response to an output
signal generated by the detector when a selected gas is present in
the air.
[0029] The air purification and gas removal system of the invention
includes a housing having an irradiation chamber, a fan for passing
air through the irradiation chamber, and at least one radiation
source that is mounted in the irradiation chamber for irradiating
the air passing therethrough. The air preferably resides in the
irradiation chamber for a time sufficient to purify the air.
[0030] According to one aspect, the system further includes a gas
detection element, associated with the housing, for detecting the
presence of one or more gases in the air. According to one practice
of the invention, the gas detection element generates a gas output
signal indicative of the presence of the gas in the air. The gas
detection element employed in the present invention can detect the
presence of most harmful organic gases, such as carbon oxides,
benzene, methane, formaldehyde, sulfur dioxide, oxygen, hydrogen,
hydrogen sulfide, NOx, ozone and aerosols, and other harmful and/or
toxic vapors including organic vapors.
[0031] According to another aspect, the system further includes a
power element for selectively supplying power to the housing, and
thus to the lamp, in response to the gas output signal. The power
element is preferably in electrical communication with the at least
one radiation source and the gas detection element.
[0032] The invention will next be described in connection with
certain preferred embodiments. However, it should be clear that
various changes and modifications can be made by those skilled in
the art without departing from the spirit and scope of the
invention. For example, various housings having differing shapes
can be employed to house the lamp.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The foregoing and other objects, features, aspects and
advantages of the invention will be apparent from the following
description and apparent from the accompanying drawings, in which
like reference characters refer to the same parts throughout the
embodiments and different views. The drawings illustrate principles
of the invention and, although not to scale, show relative
dimensions.
[0034] FIG. 1 is a plan view of a first embodiment of an air
purifier according to the invention;
[0035] FIG. 1A is an enlarged view of section 1A of the air
purifier of FIG. 1, in accordance with an embodiment;
[0036] In accordance with a further embodiment, FIG. 1B is an
enlarged view of section 1A of the air purifier of FIG. 1
illustrating use of a titanium catalytic element as a bracket to
which an ultraviolet lamp (radiation source) is mounted;
[0037] FIG. 2 graphically illustrates the relative maximum
wavelengths of radiation produced by the radiation source housed
within the air purifier of FIG. 1 according to a preferred
embodiment of the invention;
[0038] FIG. 3 is a plan view of an air purifier according to a
second embodiment of the invention;
[0039] FIG. 3A is a plan view of an embodiment similar to that of
FIG. 3 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0040] FIG. 4 is a plan view of the air purifier of FIG. 2 which
mounts a heat exchanger;
[0041] FIG. 4A is a plan view of an embodiment similar to that of
FIG. 4 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0042] FIG. 5 is a plan view of the air purifier of FIG. 3 which
mounts an air conditioning condenser;
[0043] FIG. 5A is a plan view of an embodiment similar to that of
FIG. 5 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0044] FIG. 6 is a plan view of a third embodiment of an air
purifier according to the invention;
[0045] FIG. 6A is a plan view of an embodiment similar to that of
FIG. 6 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0046] FIG. 7 is a plan view of an air purifying and gas detection
system in accordance with the present invention;
[0047] FIG. 8 is a plan view of a second embodiment of the air
purifying and gas detection system of FIG. 7;
[0048] FIG. 9 is a plan view of another embodiment of an air
purifying device according to the invention;
[0049] FIG. 9A is a plan view of an embodiment similar to that of
FIG. 9 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0050] FIG. 10 is a plan view of a third embodiment of the air
purifying device according to the invention;
[0051] FIG. 10A is a plan view of an embodiment similar to that of
FIG. 10 illustrating use of a titanium element 41 as a bracket for
the ultraviolet lamp 40;
[0052] FIG. 11 is a plan view of an alternate embodiment of the
radiation source of both the air purifier of FIGS. 1 and 3-6 and
the air purifying device of FIGS. 7;
[0053] FIG. 11A is a plan view of an embodiment similar to that of
FIG. 11 illustrating use of titanium elements 41 to separate four
ultraviolet lamps, but without optical isolator elements separating
radiating regions;
[0054] FIG. 12 is a graphical representation of the removal of
toluene from the air as a function of time with exposure to UV in
an air purification system in accordance with the present
invention;
[0055] FIG. 13 is a graphical representation of the removal of
toluene from the air as a function of time without exposure to UV
in an air purification system in accordance with the present
invention;
[0056] FIG. 14 is a graphical representation of the inactivation of
E. Coli in air as a function of time with exposure to UV in an air
purification system in accordance with the present invention;
[0057] FIG. 15 is a graphical representation of the inactivation of
yeast in air as a function of time with exposure to UV in an air
purification system in accordance with the present invention;
and
[0058] FIG. 16 is a graphical representation of the removal of
acetone from the air as a function of time with exposure to UV in
an air purification system in accordance with the present
invention.
DETAILED DESCRIPTION
[0059] The present invention includes an air purification system
that, in an embodiment, includes an irradiation chamber through
which air passes. A titanium element resides within this chamber;
the element may be a wall or other structure to which circulating
air is exposed. The combined effect of passing impure air over such
an element that has a naturally occurring titanium dioxide surface
and of exposing this air to UV radiation catalytically favors the
creation of hydroxyl radicals, which, in turn, cause the
destruction of chemical and microbiological contaminants in the
air. When a solid semiconductor catalyst, such as titanium dioxide,
is illuminated with greater-than-bandgap ultraviolet or near
ultraviolet light, electron excitation occurs within the solid.
Electron-hole pairs generated by the photoexcitation can then react
with water or oxygen to lead to the formation of hydroxyl and other
oxygen-containing free radicals. These radicals are then free to
attack and oxidize organics such as chemical and microbiological
contaminants in the air.
[0060] FIG. 1 shows an embodiment of an air purifier 10 according
to the present invention. For purposes of clarity, the internal
components of the air purifier throughout the figures are shown.
The air purifier 10 includes a housing 12 that has a front wall 14,
a pair of sidewalls 16, and a rear wall 18. The front and rear
walls 14, 18 have a baffle plate 20 formed thereon. A base 22
supports the front, side and rear walls 14, 16 and 18, and a top
cover 24 having an air outlet 26 defining an air outlet passageway
encloses the purifier 10.
[0061] The housing 12 mounts a substantially horizontal divider
plate 28 and a pair of vertically extending shield plates 29.
Preferably, the shield plates 29 are spaced from the baffle plates
20 and extend along the front and rear walls a selected distance
sufficient to cover the baffle plates 20. The divider plate 28 and
the shield plates 29 separate the interior of the housing into an
air intake chamber 30, an eradication chamber 31, and an air
discharge chamber 32. The shield plate 29 channels the intake air
from the intake chamber 30 into the eradication chamber 31, and
further provides a barrier between the external environment and the
glare of a UV lamp mounted within the purifier, as described
below.
[0062] The divider plate 28 includes an opening 34 formed at one
end of the plate that allows air to flow between the eradication
chamber 31 and the air discharge chamber 32. In the illustrated
purifier 10, the opening 34 has a substantially rectangular shape.
The baffle plates 20 are in fluid communication with the air intake
chamber 30, and, in combination, provide an air intake passageway
between the external environment and the interior of the
purifier.
[0063] The air purifier 10 mounts a fan 36 in the air discharge
chamber 32. The air purifier 10 includes a UV generating system of
one or more radiation sources. In the embodiment depicted in FIG.
1, the UV generating system includes one radiation source 40. The
radiation source 40 is supported within the eradication chamber 31,
beneath the divider plate 28 and is in electrical communication
with a power supply 38. The radiation source 40 is shown in FIG. 1
as a UV lamp, but may be provided as any radiation source that is
capable of producing UV radiation in the range of about 160 nm to
about 360 nm. The power supply 38, which preferably includes a
ballast and a transformer, is a conventional item and is
commercially available through Robertson Transformer Co., Ill.,
U.S.A.
[0064] The UV lamp 40 may have two contiguous and integrally formed
UV radiating or radiation region. According to one embodiment, in
the region of FIG. 1 denoted 1A (illustrated in FIG. 1A), UV lamp
40 has two radiating regions, 40A and 40B, which are physically
separated from one another by an optical isolator 41 which is
effective to optically isolate each radiation region.
[0065] For example, radiating region 40A may produce germicidal
radiation within a selected band sufficient to kill microorganisms,
such as airborne and surface bacteria, viruses, yeast and molds
that are carried in the incoming air. Radiating region 40B may
produce ozone generating radiation. In an embodiment of the air
purifier 10 of FIG. 1 where the UV lamp 40 has greater than two
radiating regions, each additional radiating region may produce
either germicidal radiation within a selected band sufficient to
kill microorganisms, such as airborne and surface bacteria,
viruses, yeast and molds that are carried in the incoming air, or
may produce ozone generating radiation, or may produce
antimicrobial radiation that is effective to reduce the toxicity of
volatile organic compounds.
[0066] Regardless of the number of radiating regions into which the
UV lamp 40 is divided, the radiating regions function individually
and in concert. For example, as is known, ozone serves as a
deodorizer by removing odors from the air, and further functions as
a redundant germicidal radiation generator by also producing
radiant energy sufficient to destroy microorganisms. The germicidal
radiation produced by radiating region 40A further limits the
amount of ozone that escapes from the air purifier 10 by reacting
with the ozone generated by the radiating region 40B to produce
atomic oxygen and oxygen free radicals.
[0067] In another embodiment, illustrated in FIG. 1B, lamp 40 is
shown attached to mount 41; mount 41 is preferably formed from
titanium to enhance the desired photocatalytic effect to create
free radicals. Regions 40A and 40B may, in this embodiment,
constitute only a single radiating region; the radiation generated
by lamp 40 is preferably of wavelength approximating 254 nm. The
production of free radicals is increased due to the presence of
titanium mount element 41 (FIG. 1B).
[0068] Element 41 also is configurable (e.g. FIG. 1A) to optically
isolate each lamp (when multiple lamps are used) from one another.
FIG. 1A shows an enlarged view of such an optical isolator 41. The
optical isolator 41 should be made of a material through which the
UV radiation produced by the UV lamp 40 cannot travel, but around
which air may travel. Additionally, the optical isolator 41 may be
shaped and positioned (FIG. 1A) such that the radiation produced
from each radiating region 40A, 40B is optically isolated from all
other radiation regions of the radiation source. The optical
isolation of each radiating region is beneficial because it allow
each of the regions which prevents one wavelength from interfering
with a different wavelength, thus allowing each wavelength to
maximally affect the air being treated.
[0069] One of ordinary skill in the art will realize that the
optical isolator may be made of different materials, such as
aluminum, lead, steel or titanium, as long as the optical isolator
is effective to optically isolate each radiating region from all
other radiating regions while still being effective to allow air to
circulate through the air purifier and be properly exposed to, and
treated by, each radiating region of the radiation source 40.
[0070] The term "titanium" as used herein is intended to encompass
"pure" titanium and titanium-rich alloys that inherently form
natural, tenacious, self-replenishing titanium oxide surface
layers. The percent (by wt.) of titanium in such titanium-rich
alloys is preferably to be at least 50 percent.
[0071] For example, if element 41 is made, in whole or in part, of
titanium, then air that passes through the air purifier 10 and over
the titanium element 41 will, in the presence of the emitted UV
radiation(s) undergo a photocatalytic reaction. The titanium
catalyst 41 will assist in breaking down the constituents of the
air to create oxide ions and/or hydroxyl radicals that will convert
carbon monoxide in the air to carbon dioxide, and increase the
destruction and/or reduction of the levels of bacteria, virus,
mold, mildew, fungus and volatile organic compounds in the air by,
for example, oxidizing them and/or causing the formation of water
vapor. It should be appreciated that the titanium catalytic
elements of the present invention will naturally oxidize and
present a surface layer of mixed titanium oxides and related
compounds. It is this oxide-rich surface that provides, to a large
degree, the photocatalytic effect. Unlike the inherently
limited-life titanium dioxide coating suggested in the art, the
titanium catalysts of the present invention provide a self-renewing
surface as catalyst.
[0072] Element 41 may also be coated with other elements and/or
compounds in order to more effectively and/or more efficiently
reduce or destroy unwanted components of the air being treated by
the air purifier 10. Among these elements or compounds are silver
compounds or oxides and copper compounds or oxides, platinum or
gold. These compounds may be applied to the air purification system
via a coating either on, near or entirely separate from element 41.
The presence of these elements or compounds will assist any
photocatalytic reactions taking place in the air purifier 10 as
summarized in the teachings of U.S. Pat. Nos. 5,759,948 to Takaoka
et al. and 5,835,840 to Goswami, both of which are expressly
incorporated by reference herein.
[0073] Oxides of titanium provide particularly effective coatings
designed to promote photocatalysis. Significant enhancement of the
photocatalytic reactions that take place as air flows over such a
coating in the presence of ultraviolet radiation is thought to
occur irrespective of which of the various crystallographic forms
of titanium oxide is used. As a result, element 41 and/or other
surfaces exposed to the air within air purifier 10 on, near or
entirely separate from element 41, in an embodiment, are fabricated
from elemental titanium metal or a titanium-rich alloy.
[0074] Commercially pure titanium is an excellent oxygen getter
under most environmental conditions. As a result, titanium and
titanium-rich alloys naturally maintain an oxide-containing film
upon its metallic surface. Adherence of this surface film is
particularly tenacious. Further, this oxide-containing surface
layer will tend to reform as it is used up and fresh metallic
surfaces are exposed to the air as the chemical reactions with the
air and impurities therein proceed. Thus, these parts of air
purifier 10 may only require infrequent cleaning or
replacement.
[0075] The UV lamp 40 emits UV radiation having first and second
and, optionally, third energy maxima. The term "first and second
and, optionally third energy maxima" is intended to include the
maximum radiation lamp output values, as defined by the total
output radiation producing capabilities of the lamp, which occur
within selected intervals or band of wavelengths. Preferably, the
lamp 40 produces a maximum energy value within a wavelength
interval or band at about 254 nm.
[0076] Each radiating region 40A, 40B produces at least one energy
maximum lamp output value within a selected wavelength band at a
selected maximum wavelength. Each maximum energy lamp output value
can be either a relative or local maximum value or an absolute
maximum value of the total lamp output. Those of ordinary skill
will readily recognize that the maximum energy value of the lamp
output of each radiating region is a function of the relative size
of the radiating region in comparison to the total size of the
lamp. For example, the first maximum energy value of the radiating
region 40B depends upon the desired amount of ozone-producing
radiation to be produced by the lamp.
[0077] In exemplary embodiments of the invention, the radiating
regions 40A, 40B have lengths such that radiating region 40A is
longer than radiating region 40B. Generally, the combined length of
radiating regions 40A and 40B is between about 6 and 11 inches,
with approximately 9.0 inches being a preferred length. When the
overall length of the radiating regions 40A, 40B is approximately
9.0 inches, radiating region 40A will have a length of
approximately 7.0 inches, while radiating region 40B will have a
length of approximately 2.0 inches. In an embodiment of the air
purifier 10 of FIG. 1 where the UV lamp 40 has more than two
regions, each additional radiating region of the lamp 40 should
have a length of between 2.0 and 10.0 inches, depending on the
particular wavelength being emitted by the additional region. When,
in a preferred embodiment, a single wavelength is used, the overall
length can be from about 5 inches to 36 inches.
[0078] For example, the addition of a radiating region similar to
region 40A in FIG. 1 in terms of wavelength produced therefrom
should have a length of approximately 2.0 inches, while the
addition of a radiating region similar to region 40B in FIG. 1 in
terms of wavelength produced therefrom should have a length of
approximately 7.0 inches. The addition of a radiating region that
produces antimicrobial radiation that is effective to reduce the
toxicity of volatile organic compounds should, however, have a
length of approximately 9.0 inches.
[0079] One of ordinary skill in the art will realize that whichever
radiation region is the longest will have the maximum output value,
while the other regions will have relative maximum values within
their output value ranges.
[0080] Now referring to FIG. 2, the lamp outputs defined in
arbitrary units are plotted against a portion of the wavelength of
the total radiation produced by the lamp 40. The radiating regions
40A and 40B as well as an optional third radiating region, are
capable of producing three sets of wavelength maxima 44 and 46 and
48, respectively, within selected wavelength intervals. The first
relative maximum lamp output value 46 occurs at or near 185 mn,
where the radiating portion 40B preferably emits ozone-producing
radiation, within a wavelength band between about 160 nm and about
200 nm. The second maximum output value occurs at or near 254 nm,
where the radiating portion 40A preferably emits germicidal
radiation, within a wavelength band between about 230 nm and about
280 nm. This is a preferred wavelength region. The third maximum
output value occurs at or near 350 nm, where the radiating portion
40C preferably emits antimicrobial radiation that is particularly
effective in oxidizing volatile organic compounds (VOCs) to reduce
their toxicity, within a wavelength of between about 330 nm and
about 360 nm.
[0081] Those of ordinary skill will readily recognize that the lamp
40 can produce more than three maximum output values by providing a
additional radiating regions that also constitute a part of the
lamp 40. Additionally, other wavelength intervals can be selected
depending upon the desired use of the air purifier. The illustrated
lamp has a germicidal radiation producing regions 40A that is
approximately three times larger than the ozone-producing region
40B. This difference in lamp region size is shown by the maximum
energy value 44 which is substantially larger than the maximum
energy value 46. The preferred lamp 40 is manufactured by Light
Sources, Inc., Milford, Conn., U.S.A.
[0082] Referring again to FIG. 1, additional features of the air
purifier 10 are shown mounted on the sidewall 16. A power switch 50
controls the electrical power supplied to the ballast 38 and thus
to the lamp 40. A timer control unit 52 allows a user to select a
finite operational time for the air purifier 10, and is
commercially available from Pass & Seymour, Syracuse, N.Y.,
U.S.A.
[0083] The lamp 40 can be supported or mounted within the
eradication chamber 31 by any suitable means, such as by brackets,
and preferably includes a pair of lamp sockets (not shown) that are
mounted at either end of the lamp. The sockets are conventional
items sold by Light Sources, Inc. Titanium catalytic element and
mount 41 (see, e.g. FIG. 1B) is useful in supporting lamp 40.
[0084] The air flow through the air purifier 10 is generally
depicted by the arrows 54, 55 and 56. Specifically, the arrows 54
depict the direction of air flowing into the air purifier and
between the air intake chamber 30 and the eradication chamber 31,
arrows 55 depict the direction of air flow through the chambers 31
and 32, and arrows 56 depict the direction of air leaving the
purifier. During operation of the air purifier, the fan 36 draws
inlet air into the air intake chamber 30 through the baffle plates
20 and then into the eradication chamber 31. The air contained
within this chamber is then exposed to the UV radiation generated
by the lamp 40. This UV radiation preferably has three discrete
maximum wavelengths, which serve to destroy microorganisms and to
deodorize the air. Element 41 of the air purifier 10 is shaped and
placed with respect to the UV lamp 40 and other elements of the air
purifier such that the air being treated by the air purifier is
able to be fully and freely treated by each radiating region of the
UV lamp. As previously described, this treatment is further
enhanced by exposure of the air to titanium element 41 within the
irradiation chamber. The air then travels through the opening 34
formed in the divider plate 28 into the air exhaust chamber 32 and
is then expelled from the air exhaust chamber 32 by the fan 36
through the air outlet 26.
[0085] FIG. 3 shows an air purifier 100 according to a second
embodiment of the invention. The air purifier 100 includes a
housing 102 that includes a front wall 104, a pair of sidewalls
106, and a rear wall (not shown). The front wall 104 preferably has
a baffle plate 115 formed thereon. A base 118 supports the front
and sidewalls 104 and 106 and the rear wall, and a top plate 120
having a plurality of longitudinal slits 122 defining air intake
openings encloses the purifier 100.
[0086] The purifier 100 mounts a pair of blowers 124 that are
electrically connected to a motor 126 by electrical leads 127A and
127B. The UV lamp 40 is supported within an irradiation chamber 132
and is connected by way of electrical lead 134 to a lamp power
source 38. The UV lamp 40 of FIG. 3, as well as the lamps shown in
FIGS. 4-6, preferably has two UV radiating regions 40A and 40B and
that are contiguous and integrally formed, as described above and
is separated by an optical isolator 41 also as described above. The
radiating region 40A emits UV radiation having selected germicidal
maximum wavelengths and radiating region 40B emits UV radiation
having a selected ozone-producing maximum wavelength. Also as
described above, the UV lamps 40 of FIGS. 3-6, may have additional
radiating regions, each of which may emit radiation having selected
germicidal maximum wavelengths, or selected ozone-producing maximum
wavelengths, or selected antimicrobial maximum wavelengths.
Further, the optical isolator/element 41 and/or other components of
the air purifier of FIGS. 3-6 are preferably made of titanium and
titanium-rich alloys as outlined above with respect to FIG. 1. The
lamp 40 can be supported within the housing by a variety of
fastening means, including element 41 itself. Such a category of
exemplary embodiments is depicted in FIGS. 3A, 4A, 5A, and 6A.
Supports may be brackets, and may preferably include a pair of lamp
sockets (not shown) mounted at either end of the lamp. The lamp
sockets are conventional items and are commercially available from
Light Sources, Inc. The blowers 24 and the motor 26 are also
conventional and commercially available.
[0087] Referring again to FIG. 3, additional features of the air
purifier 100 are shown mounted on, the sidewall 106. A timer 140
mounted on the uppermost portion of the sidewall allows a user to
select a finite operational time of the air purifier 100. A power
switch 142 mounted beneath the timer controls the power supplied to
the purifier. The electrical cord 144, which is connected to the
bottom-most portion of the sidewall 106, and the associated plug
146 connect to a conventional 120 volt AC outlet. Alternatively,
the plug 146 and the cord 144 can be connected to a 12V/24V DC
power source, with slight modifications to the ballast, as is known
by those of ordinary skill.
[0088] The air flow through the air purifier 100 is generally
depicted by the arrows 137 and 139. Specifically, the arrows 137
depict the direction of air flow into the air purifier 100, and the
arrows 138 depict the direction of flow of the outlet air. In
operation, the blowers 24 draw inlet air into the irradiation
chamber 132 of the purifier 100 through longitudinal slits 122. The
air contained within the chamber is then exposed to selected levels
of UV radiation emitted by the lamp 40. This radiation preferably
has two discrete selected maximum wavelength bands, which serve to
destroy microorganisms and deodorize the air. The irradiated air is
then discharged from the chamber 132 by the blower 124 through the
baffle plate 115.
[0089] The air purifier 100 can further include a heat exchanger
150, as shown in FIG. 4. The heat exchanger 150 is preferably
disposed in the bottom-most portion of the purifier 100, beneath
the lamp 40. The heat exchanger 150 has a main body portion 152
that mounts a heating coil (not shown), and has an inlet pipe 153
and an outlet pipe 154. Both pipes 153, 154 are connected to an
external water source. The inlet pipe 153 transports hot water from
the water source to the heating coil, and the outlet pipe 154
functions as the water returns. Thus, in the illustrated
embodiment, the air purifier 100, in addition to purifying air, can
function as a heater by providing heat to the external
environment.
[0090] As shown in FIG. 5, an air conditioning condenser 160 can
also be mounted within the housing 102. The illustrated condenser
160 can be supported within the housing by any suitable fastening
means, such as by a bracket. The condenser 160 allows the air
purifier to cool the surrounding ambient environment. The
illustrated air purifier thus provides a versatile and relatively
compact multi-functional unit that heats or cools the surrounding
environment, as well as purify the surrounding air.
[0091] FIG. 6 shows an air purifier 200 according to another
embodiment of the invention. The illustrated air purifier
constitutes a series of stacked compartments or cells 202 through
208. The cells can be secured together to form a unitary housing
210, and each cell is preferably in fluid communication with each
other. The uppermost cell 202 preferably is apertured with a series
of longitudinal slits 212 forming air inlet passageways. The cell
204 mounts the lamp 40 and forms an irradiation chamber for
exposing the incoming air to the germicidal and ozone-producing
radiation of the lamp 40.
[0092] The third cell 206 preferably mounts one or more, and most
preferably two, filters 214 and 216, as shown. The filter 216 is a
conventional particulate filter element that may be purchased from
Hepa Corporation, Anaheim, Calif., U.S.A. A typical filter
comprises a plurality of corrugated foil sheets and a Cross
membrane. The filter 214 is preferably a conventional charcoal
filter, and is disposed above the filter 216. In combination, the
filters 214 and 216 remove dust particles and odors from the
air.
[0093] The bottom-most cell 208 preferably mounts a blower 220. The
blower draws air into the multi-stacked air purifier through the
air inlets 212 and discharges the air through air outlets formed in
the bottom cell 208.
[0094] In one particular application of this air purifier, among
others, the purifier can be connected to the cold air return of the
central heating or cooling system of a residential or commercial
air circulation system. Thus, the air purifier can continuously
filter and purify the air recirculating in the system.
[0095] A significant advantage of the present invention is that the
lamp 40 mounted within the air purifier produces a maximum
radiation output within at least one separate and discrete
wavelength interval. Specifically, this interval may be preferredly
at about 254 nm. Those of ordinary skill will recognize that other
embodiments of the inventive air purifier can be attained by
varying the geometric shape and arrangement of the housing.
Moreover, those of ordinary skill will recognize that a plurality
of lamps can be employed, as described below with respect to FIGS.
11 and 11A, where each lamp produces one absolute maximum lamp
output value within a selected wavelength interval.
[0096] According to another feature of the invention, the air
purifiers illustrated in FIGS. 1, and 3 through 6 (and FIGS. 3A
through 6A) can be integrated with, or connected to, a pollutant or
gas detector which detects the presence of one or more types of
gas. As illustrated in FIG. 7, the air purifier of FIG. 1 is
coupled to a gas detector 234 to form an air purification and gas
detection system 222. Elements of the illustrated air purifier that
are common and similar to the elements of the air purifier of FIG.
1 are designated with like reference numerals plus a superscript
prime. The illustrated air purifier 10' includes a housing 12' that
has a front wall 14' and a rear wall 18'. A set of baffle plates
20' having a plurality of vertical slots 21 are formed in the front
and rear walls. A top cover 24' mounts a handle 25 and has an air
outlet 26' fornied therein. A fan 36' is mounted in the air outlet
passageway 26' to simultaneously draw air into the air purifier and
discharge irradiated air therethrough to the external
environment.
[0097] As previously described, the housing 12' mounts a divider
plate 28' and a pair of vertically extending and axially elongated
shield plates 29'. The illustrated shield plates 29' are spaced
from the baffle plates 20' formed in wall 14' and extend axially
along the front and rear walls a selected distance sufficient to
cover the slots of the baffle plates 20'. The divider plate 28' and
the shield plates 291 separate the interior of the housing 12' into
an air intake chamber 30', an irradiation or eradication chamber
31', and an air discharge chamber 32'. As illustrated, the shield
plate 29' channels the intake air from the intake chamber 30' into
the eradication chamber 31 ' and further provides a barrier between
the external environment and the glare of a UV lamp 40' mounted
within the purifier, as described below.
[0098] Referring again to FIG. 7, the illustrated divider plate 28'
includes an opening 34' formed at one end, e.g., at the end
opposite the fan, that allows air to flow between the eradication
chamber 31 ' and the air discharge chamber 32'.
[0099] A UV lamp 40' is supported within the eradication chamber
31', illustrated as beneath the divider plate 28', and is
electrically connected to a lamp power supply 39'. The power supply
38' preferably includes a ballast and a transformer. The
illustrated lamp 40' is identical to the lamp described above in
relation to FIGS. 1 and 2, and preferably has a pair of contiguous
and integrally formed UV radiating regions 40A' and 40B'. The UV
lamp 40', like the lamp 40 in described in FIGS. 1 and 3-6, may
have additional radiating regions, each of which is optically
isolated from the other radiating regions by a titanium optical
isolator 41' and each of which may emit radiation having selected
germicidal maximum wavelengths or selected ozone-producing maximum
wavelengths, or selected antimicrobial maximum wavelengths. Also as
described above, the optical isolator 41' and/or other components
of the air purification device of FIG. 7 is preferably made of
titanium as outlined above with respect to FIG. 1. The lamp 40' can
be supported or mounted within the eradication chamber 31 ' by any
suitable means, such as by titanium brackets or other like
fastening mechanisms (e.g. within the spirit of the embodiments of
FIGS. 1B and 3A-6A).
[0100] The illustrated lamp power supply 38' is electrically
coupled via one or more electrical conductors with a power switch
50' that is mounted on sidewall 16' of the illustrated air
purifier. The power switch 50' controls the power supplied to the
ballast 39' from an external power source, and thus to the lamp
40'. A timer control unit 61 is mounted to one of the baffle plates
20' and is also electrically coupled to the power supply 38' via
electrical conductors (not shown) and to a timer control switch 53
mounted adjacent the power switch 50' on the sidewall 16'. The
timer switch in conjunction with the timer control 61 allows a user
to select a finite operational time for the air purifier 10'.
[0101] An external power source 235 supplies power via a power cord
89 to the air purifier 10'. The illustrated power cord is
preferably coupled to the lamp power supply 38' via separate
electrical conductors (not shown).
[0102] Referring again to FIG. 7, the illustrated gas detector 234
is preferably mounted between the external power source 235 and the
air purifier 10' and is directly coupled to the power cord 89. The
gas detector 234 can be any conventional gas detector of the type
compatible for use with the present invention, and which can detect
a variety of gases, such as carbon oxides, e.g., carbon monoxide
and carbon dioxide, hydrogen, oxygen, ethanol, propane, butane,
methane, formaldehyde, sulphur dioxide, hydrogen sulfide, NO.sub.x,
ozone, benzene, radon, and aerosols and other toxic or health
threatening gases or vapors including a broad variety of organic
vapors. In the illustrated embodiment, the gas detector includes a
pair of electrical adaptors 91 that are arranged for insertion into
a pair of corresponding electrical apertures of the type typically
formed in a conventional wall outlet 235. Gas detectors of the type
shown and described are available from several manufacturers,
including Pama Electronics Co. Ltd., Oceanside, N.Y., U.S.A.
According to one practice of the invention, the gas detector senses
the presence of a selected gas in the surrounding air. If the
detected level of gas is above a selected level, which can be
predetermined or selected according to the exigencies of the
situation and/or the particular mode of operation of the detector,
the detector 234 generates an output signal indicative of the
presence of the excess quantities of the selected gas. The detector
234 can also actuate an audible alarm and/or a visual alarm to
alert an occupant of the presence of the gas.
[0103] In operation, and as illustrated by the block arrows
illustrated in FIG. 7, air flows into the air purifier 10' through
the baffle plate slots 21 and travels between the front panel 14'
and the shield plate 29 which define the air intake chamber 30'.
The air is drawn into the air purifier by the operation of the fan
36'. The air then flows from the air intake chamber 30' into the
eradication chamber 31' where it is exposed to UV radiation emitted
by the lamp 40'. The irradiated air then travels through the
opening 34' formed in the divider plate 28' and into the air
exhaust chamber 32', where it is expelled through the air exhaust
passageway 26' by the fan 36'.
[0104] Additionally, the integrated gas detector 234 selectively
actuates the air purifier 10' to remove or reduce the levels of
selected contaminants e.g., one or more gases, from the surrounding
air. For example, if the gas detector senses the presence of a
selected gas in concentrations (typically measured in parts per
million (ppm)) above a selected level, the detector generates an
output signal that is transferred to the air purifier power supply
38' along power cord 89 and other associated wiring. The output
signal generated by the gas detector actuates the air purifier,
which in turn purifies the surrounding air for a selected period of
time. According to one practice, the gas detector output signal
activates the air purifier for a selected time period, e.g., 40
minutes, to remove or reduce the levels of gas in the surrounding
air. Concomitantly, the gas detector 234 continues to monitor the
levels of gas in the air to ensure that the levels do not remain
above a selected level. If the gas levels remain above the selected
level, e.g., due to a malfunction in the operation of the air
purifier, an audible and/or visual alarm can be activated by the
detector, in addition to maintaining, if desired, the operation of
the air purifier.
[0105] The gas detector and the air purifier can cooperate in a
number of ways to effect the necessary removal of pollutants from
the air that are sensed by the detector. For example, the ballast
circuit can include switching circuitry that activates the lamp in
response to the output signal generated by the gas detector.
[0106] A significant feature of the present invention is that the
integration of the gas detector with the illustrated air purifier
forms an automatic and modular gas detection and removal system
that continuously or periodically samples the surrounding air for a
selected gas and removes the selected gas therefrom when the sensed
gas level is beyond a predetermined range.
[0107] FIG. 8 shows an alternate embodiment of the air purifier
system 222 of FIG. 7. Elements of that system that are common and
similar to the elements of the embodiment of FIGS. 1 and 7 are
designated with like reference numerals plus a superscript prime.
Titanium element 41 may be incorporated as a bracket (e.g. FIG. 1B,
etc.) or as an optical isolator (e.g. FIG. 1A, etc.) The
illustrated system 222 includes an integrated gas detector 234'
that is mounted to or on the air purifier housing 12'. Thus, the
gas detector need not be adapted for direct insertion into a
conventional wall outlet, but rather can be mounted directly to the
air purifier unit 10', thus allowing the use of more conventional
gas detectors.
[0108] The illustrated gas detector can also be coupled with the
air purifier via radio frequency electromagnetic waves. According
to one practice, the gas detector includes an integrated radio
frequency (RF) transmitter. The air purifier has mounted thereon a
radio frequency receiver for receiving radio frequency output
signals generated by the RF transmitter portion of the detector.
During operation, the gas detector generates and emits an RF output
signal when the detector senses gas concentrations outside of a
predetermined range. The output signal is transmitted as a radio
frequency signal and is received by the RF receiver mounted in or
on the air purifier. Thus, a gas detector can be remotely located
from the air purifier without the necessity of coupling the two
with hard wiring.
[0109] FIG. 9 illustrates an alternate embodiment of the air
purifier of the invention. The illustrated air purifier 300 is
typically employed in commercial environments which require greater
quantities of air to be processed and purified. The illustrated air
purifier 300 includes a substantially cylindrical housing 302, a
bottom portion 304, and a top portion 306. The top portion 306
mounts a handle 310 which assists the user in handling the
purifier. The cylindrical housing 302 has formed thereon a
plurality of axially spaced rows of apertures 312 defining air
inlets, similar to the baffle plates of FIGS. 1 and 7-8. The
interior of the purifier mounts a cylindrical divider element 322
that separates the interior of the housing into an air intake
chamber 314 and an eradication chamber 318. The illustrated divider
322 has an opening 326 formed in one end that allows air to flow
between the inlet passageway 314 and the eradication chamber 318. A
UV lamp 40' is supported within the eradication chamber by a pair
of support stanchions 320,320 that are coupled to the inner surface
324 of the divider.
[0110] A blower 330 is disposed in the bottom portion of the
housing 302. The illustrated blower 330 has a plurality of radially
extending blades 332 which rotate in a selected manner to draw air
into the interior of the air purifier while simultaneously
discharging air through an air outlet 336 formed in the bottom of
the housing 302. A lamp power supply 340 similar to the power
supply 38 of FIGS. 1 and 7-8 provides a selected level of operating
power, typically supplied by a conventional wall outlet, to the
lamp 40'. The purifier housing 302 has mounted thereon a power
switch 344 for controlling the electrical power supply to the
ballast 38, and thus to the lamp 40'.
[0111] In operation, air is introduced through the air inlets 312,
312 by the operation of the blower 330, which is denoted by the
block arrows. The air is then carried along the air inlet chamber
314 and into the eradication chamber 318, where the UV lamp
irradiates the air for a time sufficient to purify the air. The fan
330 then discharges the irradiated air through the air outlet 336
located in the bottom of the purifier.
[0112] FIG. 10 illustrates another embodiment whereby the air
purifying apparatus of the invention is integrated with a
heating/ventilation/air conditioning (HVAC) unit. The illustrated
HVAC unit 400 can be a conventional heating system that employs a
return air duct 404, a furnace portion 406, and a discharge air
duct 408. The furnace portion 406 of the HVAC 400 can include a
blower unit 410 to heat or cool single or multiple zones in a
building structure. The blower unit 410 has an electrical output
lead 432 that terminates in a terminal block 434.
[0113] The illustrated air purifying device of the invention is
mounted in the return or supply air duct 404 of the HVAC unit 400.
The air purifying device 420 includes a hinged control panel 422
that has an exposed surface panel 424 and an inner surface 426 that
mounts a UV lamp 40' via a pair of support stanchions 430. The
illustrated lamp is identical to the lamp previously described. The
mounting of lamp 40' inside the return air duct 404 effectively
creates an eradication chamber that purifies air passing
therethrough.
[0114] An electrical power cord 436 is connected electrically in
series with the terminal block 434 and the control panel 420. The
power cord terminates at a coupling connector 438 formed in the
control panel. The lamp 40' and the power cord 436 are coupled via
appropriate electrical wiring with an electronic ballast circuit
assembly 440 mounted on the inner surface 426 of the panel 420. An
electrical power switch 442 functioning as an on/off switch
operates the lamp 40' by selectively applying power to the
lamp.
[0115] The illustrated control panel 420 further includes a sight
glass aperture 450 that extends between the exposed and inner
surfaces of the control panel 420. The sight glass allows an
individual to view the interior of the return duct 404 to check
whether the lamp 40' is functioning. A power fuse 452 can further
be employed to protect the electronic circuitry associated with the
panel 420 and the lamp 40' from overvoltage and/or overcurrent
conditions.
[0116] In operation, the blower 410 circulates air between the
return air duct 404 and the air duct 408, and thus between the HVAC
unit and one or more zones within the building. As air is drawn
through the return air duct 404, it is irradiated by UV radiation
generated and emitted by the lamp 40' mounted therein. The
irradiated air exits the return duct 404 and is discharged through
the air duct 408 by the blower 410. Thus, the illustrated air
purifying device purifies air located in a particular zone of a
building.
[0117] Those of ordinary skill recognize that a gas sensor can also
be integrated with the air purifying device for HVAC units as
illustrated in FIG. 10 in accordance with the description set forth
in relation to FIGS. 7 and 8. According to one practice, the gas
detector can continuously monitor the air flowing throughout the
HVAC system to determine if a particular gas is present therein. If
so, the gas detector can generate an output signal that actuates
the air purification device 420. The operation of the air purifier
420 serves to purify the air passing through the HVAC system by
removing or reducing the levels of a particular gas. Optionally,
the detector can sound an alarm when the detected gas concentration
is greater than a predetermined threshold value or range. In severe
situations, the air purification device 420 can turn off the
furnace and continuously operate the air purifier, e.g., the UV
lamp 40', while actuating the blower unit 410 to continuously
circulate air throughout the system. The furnace is then restarted
once the levels of the detected gas are within an allowable range
of values.
[0118] The illustrated lamp can also be mounted in other locations
besides the return air duct, such as the discharge duct 408.
[0119] Additionally, the commercial air purification embodiment of
FIG. 9 can further include a gas detector as described above in
relation to FIGS. 7 and 8. Further, FIGS. 9A and 10A depict
titanium elements 41 as brackets instead of optical isolators.
[0120] In another embodiment of the present invention depicted in
FIG. 11 the air purifiers of FIGS. 1 and 3-6 of the air
purification device of FIG. 7 can mount a plurality of radiation
sources, such as UV lamps, wherein each UV lamp has a plurality of
radiating or radiation regions, each of which produces a radiation
having a maximum energy value that falls within a different
wavelength band. Specifically, each radiating region is capable of
generating a first energy maximum of ozone-producing radiation and
a second separate energy maximum of germicidal radiation and a
third separate energy maximum of antimicrobial radiation.
[0121] The preferred number of radiating regions in each of the
plurality of radiation sources is two, wherein one of the two
regions generates ozone-producing radiation and the other region
produces a second separate energy maximum of germicidal radiation.
Each radiation region does not, however, necessarily have to have
the same number of radiating regions nor do the radiating regions
of each of the radiation sources have to produce the same types of
radiation. For example, in an embodiment with three radiation
sources, two of the sources could have two radiating regions which
generate, respectively, ozone-producing radiation and a separate
energy maximum of germicidal radiation, while the third radiation
source produces ozone-producing radiation in the range of about 160
nm to about 200 nm, a separate energy maximum of germicidal
radiation in the range of about 230 nm to about 280 nm, and a
separate energy maximum of antimicrobial radiation in the range of
about 330 nm to about 360 nm.
[0122] The plurality of radiation sources are arranged such that
they may fit within the air purifier. One of ordinary skill in the
art will realize that the dimensions and/or the positional
relationships between the elements of the air purifiers of FIGS. 1
and 3-6 and the air purification device of FIG. 7 may have to be
slightly changed in order to accommodate the increased space
required to accommodate a plurality of radiation sources; however,
the elements included in the air purifier remain the same.
[0123] FIG. 11 and FIG. 11A show exemplary embodiments of this
multiple radiation source embodiment wherein four radiation sources
W, X, Y and Z are present. As shown each of the radiation sources
W, X, Y, and Z is preferably a UV-producing lamp similar in shape
and type to those depicted in the FIGS. 1 and 3-7 embodiment of the
present invention. While, generally, the radiation sources are
lamps of this shape and type, one of ordinary skill in the art will
realize that other radiation sources and/or shapes and types of
UV-producing lamps may be utilized in place of or in conjunction
with the lamps depicted in FIG. 11. Also, the number of radiation
sources in these embodiments may be greater or less than four as
long as the number is greater than one.
[0124] In the FIG. 11 embodiment, each radiation source W, X, Y,
and Z is preferably prevented from producing radiation that may
interact with radiation emitted from any of the other radiation
sources through the usage of titanium optical isolator 41 such as
those depicted in and described with respect to FIGS. 1 and 3-7. In
the FIG. 11A embodiment, elements 41 are shown separating the
sources; however specific/distinct radiation regions denoted R, S,
T are not isolated by element 41.
[0125] In the arrangement depicted in FIG. 11, the titanium optical
isolator 41 allows air to circulate through the radiation sources
W, X, Y and Z, while preventing the UV radiation emitted from each
source from "seeing" the radiation produced from any of the other
radiation sources. One possible path for air to travel is indicated
by the arrows of FIG. 11. The above-summarized arrangement of
radiation sources in FIG. 11, just as in FIGS. 1 and 37, allows the
radiation sources to work in tandem, with each source producing
radiation without being hampered by "seeing" other radiation.
[0126] As noted above, one of ordinary skill in the art will
readily ascertain that such an arrangement scheme may be carried
out with any number of radiation sources greater than one (i.e.,
fewer or greater than four sources) wherein each source has at
least two radiating or radiation regions. Optimally, each radiating
region is optically isolated from the other radiating regions of
that particular radiation source as well as each of the radiating
regions of the other radiating sources to form individual radiation
chambers through which air may freely travel and be treated by the
particular wavelength emitted from the radiation region in that
radiation chamber. One of ordinary skill in the art, however, will
realize that it is possible for the any or all of the FIGS. 1, 3-7
and 11 embodiments of the present invention to effectively treat
air wherein one or more of the radiating regions of the one or more
radiation sources are not optically isolated from each other.
[0127] In an exemplary embodiment of FIG. 11, each of the four UV
lamps W, X, Y, Z has three radiation regions R, S and T. (In FIG.
11A, two radiation regions S and T are denoted.) For example,
radiation source W is depicted as having radiation regions R, S and
T, wherein region R emits ozone-producing radiation in the range
between about 160 nm to about 200 nm, while region S emits
germicidal radiation in the range between about 230 nm to about 280
nm, while region T emits antimicrobial radiation in the range
between about 330 nm to about 360 nm.
[0128] Like the embodiments shown and described with respect to
FIGS. 1 and 3-7, each of the titanium optical isolator 41 for each
of the radiation regions R, S and T of each of the radiation
sources W, X, Y, and Z of FIG. 11 is preferably a barrier or baffle
made, at least partially, of titanium, platinum or gold.
[0129] Constructing the optical isolator/element 41 out of titanium
is also desirable due to the presence of titanium acting to enhance
the effects of the wavelengths of each of the radiating regions
40A, 40B or the UV lamp 40 thus producing hydroxyl and other
oxygen-containing free radicals.
[0130] For example, if the optical isolator 41 is made of titanium,
then air that passes through the air purifier 10 and the titanium
optical isolator will react in the presence of the emitted UV
radiations and undergo a photocatalytic reaction wherein molecular
oxygen that is present in the air will react with the titanium to
break down other constituents of the air and to create oxide ions
and/or hydroxyl radicals that will convert carbon monoxide in the
air to carbon dioxide, and to increase the destruction and/or
reduction of the levels of bacteria, virus, mold, mildew, fungus
and volatile organic compounds in the air by, for example,
oxidizing them and/or causing the formation of water vapor.
[0131] The optical isolator 41 may also be coated with other
elements and/or compounds (i.e. platinum or gold) in order to more
effectively and/or more efficiently reduce or destroy unwanted
components of the air being treated by the air purifier 10. Among
these elements or compounds are silver compounds or oxides, copper
compounds or oxides, microcrystalline titanium or titanium dioxide.
These compounds may be applied to the air purification system via a
coating either on, near or entirely separate from the optical
isolator 41. The presence of these elements or compounds will
assist any photocatalytic reactions taking place in the air
purifier 10 as summarized in the teachings of U.S. Pat. Nos.
5,759,948 to Takaoka et al. and 5,835,840 to Goswami, both of which
is expressly incorporated by reference herein.
[0132] Oxides of titanium provide particularly effective coatings
designed to promote photocatalysis. Significant enhancement of the
photocatalytic reactions that take place as air flows over such a
coating in the presence of ultraviolet radiation is thought to
occur irrespective of which of the various crystallographic forms
of titanium oxide is used. As a result, optical isolator/element 41
and/or other surfaces exposed to the air within air purifier 10 on,
near or entirely separate from optical isolator/element 41, in an
embodiment, are fabricated from elemental titanium metal or a
titanium-rich alloy.
[0133] Commercially pure titanium is an excellent oxygen getter
under most environmental conditions. As a result, titanium and
titanium-rich alloys naturally maintain an oxide-containing film
upon its metallic surface. Adherence of this surface film is
particularly tenacious. Further, this oxide-containing surface
layer will tend to reform as it is used up and fresh metallic
surfaces are exposed to the air as the chemical reactions with the
air and impurities therein proceed. Thus, these parts of air
purifier 10 may only require infrequent cleaning or
replacement.
[0134] One of ordinary skill in the art will readily ascertain that
the usage of titanium and/or titanium dioxide and/or any of the
above-indicated elements or compounds may be slightly modified
while still providing for improved performance of the system.
Furthermore, the usage of titanium and/or titanium dioxide and/or
any of the above-indicated elements or compounds may also be
possible in conjunction with the embodiment depicted in FIG. 1.
[0135] The invention is further illustrated by the following
Examples 1 and 2, which should not be construed as further
limiting. Example 1 illustrates the efficacy of the air
purification system of the present invention in removal of toluene
from the air, as well as the inactivation of E. coli and common
bakers yeast. FIGS. 12 and 13 are graphical representations of the
removal of toluene from the air as a function of time with and
without UV exposure, respectively. FIG. 14 is a plot of E. coli
inactivation with time; FIG. 15 is a plot of bakers yeast
inactivation with time. Removal of acetone has also been
successfully shown utilizing the same air purification system; this
result is described in Example 2. FIG. 16 is a graphical
representation of the removal of acetone from the air (with UV
exposure) as a function of time. The specifications for the air
purification system used in Examples 1 and 2 are:
[0136] 20 W power,
[0137] a 254 nm UV radiation lamp,
[0138] the lamp mounted on a scored titanium bar in flexible duct
tubing (33 cm diameter and 80 cm in length.
[0139] The ducting was fed with a 500 cpm fan. The output intensity
(fluence rate or irradiance) of the lamp at 16 cm distance from the
lamp was 16 W cm.sup.-2 (1.6 W m.sup.-2 or 4 mol cm.sup.-2
s.sup.-1). This is a high level of UVC radiation. This entire
system was placed inside a sealed laboratory fume hood (dimensions;
160 cm w.times.110 cm h.times.60 cm d). When the system was
operating, there was no scent of O.sub.3 present. This system was
analyzed for its ability to destroy both a model VOC and to
inactivate microbes.
EXAMPLE 1
[0140] Toluene analysis: Toluene (40 ml or 35 g) was placed in a 25
cm evaporating dish and the dish was placed in the hood near the
500 cfm fan and left there for 2 h with the fan on. This allowed
the hood (4 m.sup.3) to be saturated with 35 g of toluene giving an
initial concentration of 7 gm.sup.3 (i.e. .about.2000 ppm). This
toluene concentration was stable for at least 4 h (see results).
Toluene was then collected for HPLC analysis by bubbling air from
the hood through 5 ml of dichloromethane (DCM). Bubbling was
carried out for 3 min. The bubbling system had a glass funnel as
the inlet placed inside the duct tubing. The funnel was connected
to tygon tubing linked to a peristaltic pump. The tubing was
attached to a glass pippette immersed in the DCM. The UVC lamp was
then switched on and an air sample was collected after 1, 2, 3 and
4 h. For a dark control, the UVC lamp was left off. Toluene
analysis was performed with a Shimadzu dual pump HPLC with a diode
array detector. A water to DCM gradient was used to elute the
toluene, and toluene identification was confirmed by retention time
and absorbance spectrum. All experiments were performed in
duplicate.
[0141] Microbial analysis: E. coli and common bakers yeast were
cultured by standard methods in liquid medium. They were sprayed in
the hood and allowed to be circulated by the 500 cfm fan for 1 h.
Microbes were collected on agar growth medium in standard petri
dishes. They were collected at 0, 1, 2, 3, and 4 h with the UVC
lamp either on or off. The plates were then incubated overnight at
37 C. for the E. coli, room temperature for the yeast. Colonies
were counted on the plates to determine titers. All experiments
were performed in duplicate.
[0142] Toluene degradation: Toluene, when incubated with the fan on
in darkness was maintained nearly at the initial concentration
(.about.2000 ppm). The t.sub.1/2 (half-life) was more than 16 h
based on the "toluene in darkness" plot of FIG. 13. This shows that
the toluene was not lost rapidly from the test system merely
because the 500 cfm fan was on.
[0143] When toluene was incubated in the photocatalytic air
purifier with the fan and the UVC lamp on, the toluene was rapidly
lost (see FIG. 12). It is assumed that the toluene is lost due to
photochemical degradation (probably oxidation). The toluene was
consumed by apparent exponential decay kinetics (pseudo first-order
kinetics), with a t.sub.1/2 of 1.85 h. This is described by the
following equation:
[toluene].sub.1=[toluene].sub.0e.sup.-kt
[0144] where:
[toluene].sub.0 is toluene at time t,
[toluene].sub.0 is toluene at time 0,
[0145] k is the first order rate constant, and t is time in
hours.
[0146] Based on a t.sub.1/2 of 1.85 h, k=0.37 (h.sup.-1)
[0147] E. coli inactivation: E. coli, when incubated with the fan
on in darkness was maintained at constant level (data not shown).
When E. coli was incubated in the test system with the fan and the
UVC lamp on, the bacteria were rapidly inactivated (see FIG. 14).
It is assumed that the bacteria were killed by the UVC radiation
(probably due to DNA damage) because 254 nm is near the peak
absorbance of DNA. Like the toluene, the bacteria were inactivated
by apparent exponential decay kinetics with t.sub.1/2=1.4 h. Using
the above equation, k=0.49 (h.sup.-1). Thus, bacterial inactivation
is somewhat faster than consumption of toluene. This is not
surprising since microbes are known to be hypersensitive to
UVC.
[0148] Yeast inactivation: Yeast was used as a model eukaryotic
microbe representing fungi and molds. The results with yeast were
very similar to those with the bacteria. Yeast, when incubated in
the photocatalytic air purifier with the UVC lamp on, were rapidly
inactivated (See FIG. 15). As above, apparent exponential decay
kinetics was observed. The t.sub.1/2 was 1.05 h and k=0.66
(h.sup.-). Thus, yeast was inactivated faster than E. coli. This
may reflect the greater DNA content of eukaryotic organisms.
Because both E. coli and yeast were inactivated rapidly, it may
reasonably be extrapolated that all microbial organisms will be
neutralized by the photocatalytic system tested.
[0149] Thus, the experiment of Example 1 demonstrates that: (1) the
half-lives for loss of toluene, E. coli and yeast were 1.85 h, 1.4
h and 1.05 h, respectively; (2) the photocatalytic air purifier
should remove more than 90% of the toluene in about 8 h; (3)
microbes are inactivated by the photocatalytic air purifier more
rapidly than the toluene is degraded; and (4) 90% of the microbes
would be inactivated in 6 h or less with the system employed.
EXAMPLE 2
[0150] A similar study (to Example 1) was undertaken to test
performance of the air purification system in removing acetone
(dimethyl ketone). The acetone was rapidly removed (see FIG. 16).
The acetone half-life was 0.60 h; therefore, the decay constant,
k=1.15 (h.sup.-1). This is about twice the rate of removal of
toluene detailed in Example 1.
* * * * *