Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SYSTEM, METHOD, AND CONVERSION KIT FOR
CONTROLLING SMOKE DURING AIR FRYING IN A RANGE OR OVEN
BACKGROUND
[0001] This disclosure is in the field of appliances used for cooking and, in
particular, catalytic
devices used in connection with a range or oven to control odors and smoke.
[0002] Residential appliance manufacturers have recently introduced oven
models that
incorporate cooking techniques that utilize rapid recirculation of hot air in
the oven cavity to "fry"
foods in a manner that is perceived to be healthier than conventional deep fat
frying.
[0003] These cooking techniques can generate large quantities of smoke that
are emitted from the
oven vent or can leak through various pathways in the oven cavity. These smoke
emissions are
viewed as a negative experience by the users and as a result the appliance
manufacturers have
received many complaints and disgruntled users have posted videos and comments
on social media
sites.
[0004] US 8,418,684 B2 to Robinson, Jr. ("the '684 patent") reviews prior art
for a catalytic
converter unit for use in combination with an oven for treating odiferous
emissions emanating
from an oven cavity of a residential range or oven during cooking. The '684
patent discloses a
system and method that include a housing that contains an electric heating
element and a catalyst
unit. The housing may connect to other components of the range or oven to
complete the venting
of the exhaust from the range or oven. The electric heating element is
arranged so that infrared
radiation from the hot surface of the element is visible by the inlet face of
the catalyst. The power
output of the heater is sized so that the catalyst reaches a minimum operating
temperature to initiate
the catalytic reaction in advance of the temperature increase in the air
coming from the cavity. The
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Date Regue/Date Received 2023-01-25
system and method destroy the odors that come from the cooking process so as
to improve the
cooking experience. The subject matter of the '684 patent is incorporated by
reference herein.
[0005] Different cooking cycles within the oven cavity create air flows and
air flow temperatures
and, therefore different emissions and different rates of emissions. The
catalytic conversion unit
of the '684 patent is intended for a cooking cycle like baking, where there is
a natural draft air
flow. For example, in a cooking cycle like baking a fan typically draws air
from the middle of the
cooking chamber and circulates it around the cooking chamber, the heated air
flowing around the
food item being cooked. However, in a cooking cycle like air frying, an active
air flow is used, in
which the fan reverses direction, blowing air into the middle of the cooking
chamber with the
heated air flowing directly to the food item. Because the air is nearer to the
heating elements when
blown, the air contacting the food item is at a higher temperature during air
frying than it would
be during baking. Air frying causes aerosolized grease droplets in certain
foods that can cause
smoking.
SUMMARY
[0006] Embodiments of this disclosure are adapted for use in an oven
including an air
frying mode, a cooking chamber containing a circulation fan on a wall of the
cooking chamber,
and a plurality of heating elements adjacent to and surrounding the fan to
form four corners
located about the fan. A catalyst is located on the inlet or suction side of
the circulation fan. The
catalyst can eliminate the smoke to a level that is nearly non-existent or at
least would not be
observable or objectionable to the user. The catalyst is composed of a
substrate, such as a woven
wire cloth, expanded metal, or permeable paper-like material that is
impregnated with a
catalytically active coating comprised of a high surface area aluminum oxide
based washcoat and
an active component or components. The shape of the substrate can be round,
square, rectangular
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Date Recue/Date Received 2023-01-25
or any other geometric shape that is selected to provide sufficient coverage
to achieve the
necessary performance.
[0007]
In one embodiment, a screen including a corrugated pattern is coated with
the
catalyst on at least half of the screen. The catalyst includes a precious
metal having a mass loading
in a range of 20 g to 50 g per cubic foot of catalyst volume. The screen is
sized for installation
on the inlet or suction side of the circulation fan and includes means for
connection to the inlet or
suction side of the circulation fan. Without the screen installed the oven
emits a first amount of
volatile organic compounds when cooking a predetermined food in air fry mode
under
predetermined conditions. With the screen installed the oven emits a second
amount of volatile
organic compounds at least 95% lower than the first amount of volatile organic
compounds when
cooking the predetermined food in the air fry mode under the predetermined
conditions.
[0008]
In another embodiment of this disclosure, one to four metal foil catalysts
are used.
Each metal foil catalyst is located between a corresponding one of the four
corners and the fan.
A baffle cover plate then covers the fan, the plurality of heating elements,
and the one to four
metal foil catalysts.
[009] In methods of this disclosure for treating emissions of an oven when air
frying, the
emissions pass through the catalyst from the cooking chamber and into an
exhaust vent of the
oven.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an isometric view of an example embodiment of a catalytic
system of this
disclosure.
[0011] FIG. 2 is a top perspective schematic type depiction of a generic
residential range or oven
showing the catalytic conversion unit in assembled relation with the oven or
range.
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Date Recue/Date Received 2023-01-25
[00012] FIG. 3 is a cross-sectional side view of the range or oven of
FIG. 2 outfitted with
the catalytic conversion unit of the present invention.
[0013] FIG. 4 is an enlarged, upper right section of the range or oven of FIG.
3, showing the
structures defining an emission pathway.
[0014] FIG. 5 is a front elevation, exploded assembly view of the catalytic
system of FIG. 1.
[0015] FIG. 6 is a partial, front elevation view of the left hand side of the
catalytic system of FIG.
1.
[0016] FIG. 7 is a bottom view of the left hand side of the catalytic system
of FIG. 1.
[0017] FIG. 8 is a cross-section, front elevation view of the left hand side
of the catalytic system
of FIG. 1.
[0018] FIG. 9 is a top perspective, exploded assembly view of the catalytic
system of FIG. 1 with
the upper catalytic screens removed.
[0019] FIG. 10 is a graph comparing emissions during a test of the catalytic
system of this
disclosure ("CCC Catalyst") during a self-cleaning cycle of the residential
range or oven with those
of a prior art catalytic system ("OEM Catalyst").
[0020] FIG. 11 a graph comparing emissions during a test CCC Catalyst when
cooking bacon in
the residential range or oven with those of the OEM Catalyst.
[0021] FIG. 12 a graph comparing emissions during a test CCC Catalyst when
cooking a turkey
in the residential range or oven with those of the OEM Catalyst.
[0022] FIG. 13 a graph comparing emissions during a test CCC Catalyst when
cooking chicken
wings in the residential range or oven with those of the OEM Catalyst.
[0023] FIG. 14 is a graph comparing total emissions of the CCC Catalyst with
those of the OEM
Catalyst during a first and second cooking cycle of the chicken wings.
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Date Recue/Date Received 2023-01-25
[0024] FIG. 15A is an embodiment of a minimum diameter exhaust port used in an
embodiment
of a residential range or oven configured with an air frying mode. The exhaust
port may be the
same size diameter as the inlet port or may be a different size diameter. In
embodiments, the
exhaust port may be a 7 mm diameter exhaust port.
[0025] FIG. 15B is an embodiment of a maximum diameter exhaust port used in an
embodiment
of a residential range or oven configured with an air frying mode. Again, the
exhaust port may be
the same size diameter as the inlet port or may be a different size diameter.
In embodiments, the
exhaust port may be a 36-3/4 mm diameter exhaust port.
[0026] FIG. 16A illustrates the location of the inlet boundary condition for
the exhaust through
the ports of FIGS. 15A& 15B.
[0027] FIG. 16B illustrates the location of the outlet boundary condition for
the exhaust through
the ports of FIGS. 15A& 15B.
[0028] FIG. 17A is first layer mesh screen velocity profile for the minimum
diameter exhaust port
of FIG. 15A.
[0029] FIG. 17B is a second layer mesh screen velocity profile for the minimum
diameter exhaust
port of FIG. 15A.
[0030] FIG. 17C is a side elevation view of the velocity profile through the
first and second layers
for the minimum diameter exhaust port of FIG. 15A.
[0031] FIG. 18A is first layer mesh screen velocity profile for the maximum
diameter exhaust port
of FIG. 15B.
[0032] FIG. 18B is a second layer mesh screen velocity profile for the maximum
diameter exhaust
port of FIG. 15B.
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Date Recue/Date Received 2023-01-25
[0033] FIG. 18C is a side elevation view of the velocity profile through the
first and second layers
for the maximum diameter exhaust port of FIG. 15B.
[0034] FIG. 19A is an embodiment of a corrugated screen catalyst of this
disclosure encased in a
rim structure to capture the raw edges of the substrate material and arranged
for installation to a
circulation fan cover of an oven. The catalyst can eliminate the smoke to a
level that is nearly non-
existent or at least would not be objectionable to the user.
[0035] FIG. 19B is a front elevation view of the catalyst in the installed
state.
[0036] FIG. 19C is an isometric view of the catalyst of FIG. 19A in an
installed state.
[0037] FIG. 20 is an embodiment of a corrugated screen catalyst of this
disclosure including a rim
structure with clips.
[0038] FIG. 21 is another embodiment of a corrugated screen catalyst of this
disclosure including
a rim structure with tabs.
[0039] FIG. 22 is a chart comparing hydrocarbon emissions using embodiments of
a corrugated
screen catalyst of this disclosure over time (from 1 second to 9,107 seconds
(about 152 minutes)).
[0040] FIG. 23 is a chart comparing hydrocarbon emissions of an oven with air
fryer as built and
as modified using a corrugated screen catalyst of this disclosure.
[0041] FIG. 24 is a chart comparing hydrocarbon percent conversion using a
corrugated screen
catalyst of this disclosure.
[0042] FIG. 25 is a chart comparing particulate matter.
[0043] FIG. 26 is a chart comparing particulate matter % conversion using a
corrugated screen
catalyst of this disclosure.
[0044] FIG. 27 is a photograph of a baffle cover plate found at the back of an
oven. The plate
covers the heating elements, fan, and catalyst of this disclosure. This plate
is but one of many
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Date Recue/Date Received 2023-01-25
different types of fan covers or baffle plates used in the art and is provided
here for illustrative and
non-limiting purposes.
[0045] FIG. 28 is photograph of a catalyst of this disclosure located in a
lower corner of the heating
elements, between the heating elements and the fan.
[0046] Elements and Numbering used in the Drawings
Heated screen catalyst assembly
11 Cooking chamber
12 Residential range or oven with air frying mode
13 Range or oven door
10 14 Housing
Inlet to heated screen catalyst assembly
16 Thermal radiation source
17 Circuitry for connection to power source
18 Screen catalyst
15 19 Outlet from heated screen catalyst assembly
Untreated emissions
21 Emission path
22 Treated emissions
23 Outlet
20 25 Looped members of thermal radiation source
Vent tube
31 Rim structure
Foil catalyst
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Date Recue/Date Received 2023-01-25
41 Frame
43 Heating element
45 Fan
47 Baffle cover plate
49 Heating element corner
G Grease path
[0048] Referring first to FIGS. 1 to 9, embodiments of a heated screen
catalyst assembly 10 of this
disclosure is configured for use with a residential range or oven 12 that
includes an air frying mode.
The assembly 10 may be housed within the oven 12, with its inlet 15 exposed to
the cooking
chamber 11 of the oven 12. A housing 14 contains the assembly 10 and connects
either directly
or through the use of ancillary components to the cooking chamber 11 and to an
outlet 23 of the
oven 12. This provides a path for emissions during cooking or air frying from
the chamber 11 to
the outlet 23. Contained in the housing are an electric heating element or
thermal radiation source
16 and a catalyst screen 18.
[0049] In embodiments, the catalyst screen 18 is in the form of a wire mesh
cloth located on
opposite sides of the radiation source 16. The one catalyst screen 18 is
located closer to the inlet
15. The radiation source 16 heats the air entering the inlet 15 as well as the
screen 18. This first
screen 18 may be slightly hotter, at least initially, than the second screen
18, but the radiation
source 16 tends to equilibrate the two screens 18. The screens 18 may also be
hotter than the oven
cavity depending on what is programmed for the cook cycle, which may be an air-
frying cook
cycle. By way of a non-limiting example, the catalyst screen 18 may be in a
range of 600 F to
650 F, the oven cavity being in a range of 400 F to 425 F.
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Date Recue/Date Received 2023-01-25
[0050] The first screen 18 may be more surface heat reactive than the second
screen 18, which
receives air that has passed through the first screen 18 as well as the
radiation source 16. The air
may be at its maximum temperature at the second screen 18. See e.g. FIGS. 16A
ff. Unlike the
'684 patent, the degree of control needed in the heated screen catalyst
assembly 10 is not as
stringent a requirement. The catalyst screen 18 in close proximity to the
radiation source 16
superheats the screen 18 at a much higher temperature than air temperature
flowing throughout.
[0051] Emissions during cooking or air frying follow an emissions path 21 in
which the emissions
enter the inlet 15 of assembly 10 as untreated emissions 20, pass through the
catalyst screen 10,
and exit the outlet 19 of the assembly 10 as treated emissions 22 which are
then exhausted or
vented through an outlet 23 of the oven 11.
[0052] In embodiments, catalyst element 18 is a screen catalyst. The screen
catalyst may include
a wire mesh cloth having a high surface area aluminum oxide coating that has
been impregnated
with catalytically active elements. Other substrate formats such as expanded
metal or metal foil
or ceramics could be used. The catalytically active elements may be a platinum
only element. In
other embodiments, it may be a platinum and palladium blend (although platinum
only performed
better during air frying). The coating may be a mixture of two aluminum oxide
phases, such as
the gamma and boehmite phases. Other elemental oxides may be present in lesser
amounts to act
as thermal stabilizers or to enhance the effectiveness of the catalytically
active elements. The
oxides are prepared and applied in a manner well known to those skilled in the
art.
[0053] The mesh size of the screen catalyst should be selected to provide
sufficient heat reactive
surface area without causing excessive pressure drop. In embodiments, the
screen catalyst may
in a range of a size 10 mesh wire cloth to a size 50 mesh wire cloth, there
being discrete values
and subranges within this broader range. In some embodiments, a size 30 mesh
wire cloth was
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Date Recue/Date Received 2023-01-25
used. The mesh size should also be selected so that the oven can pass fire and
explosion tests like
those performed by Underwriters Laboratories (restriction to flow in the vent
23 can blow door 13
open during a fire or other extreme temperature event). In tests, the 30 mesh
wire cloth provided
good balance between reactive surface pressure and pressure drop.
[0054] To maintain a consistent operating or catalytic temperature, a
catalytic conversion unit of
this disclosure includes a thermal radiation source 16. The heated screen
catalyst assembly 10
depends upon the source 16 for a consistent operative temperature of its
catalytic elements 18,
making the heated screen catalyst assembly 10 unaffected by temperature
variations caused by a
user opening the door 13 of the cooking chamber 11 during air frying or
cooking. In embodiments,
thermal radiation source 16 may include one or more looped members 25 being
arranged in a same
plane as one another. Adjacent to, spaced apart from, and overlapping the
looped members 25 is
at least two catalyst mesh or screen catalysts 18 arranged parallel to the
looped members 25, each
located on opposite sides of the looped members 25. In some embodiments, at
least two layers of
screen catalysts 18A, 18B are located on one side of the looped members 25 and
another at least
two layers of screen catalysts 18C, 18D are located on the other side of the
looped members 25.
[0055] Referring now to FIG. 10, tests of a heated catalyst assembly of this
disclosure were
performed using 1/2 cup of an OEM "monster mash" recipe in an Electrolux oven
with air frying
mode during the oven's self-clean setting over a period of three hours. The
catalyst temperature
within the heated screen catalyst assembly was 650 F. The prior art ("OEM
Catalyst" relied on
.. heat from the oven chamber to initiate the reaction. Due to heat transfer
effects, it lagged behind
the pyrolysis of the baked on food soil. Since the heater overcomes the heat
transfer issues, the
screen catalyst 18 activates faster, resulting in far less emissions. The
screen catalyst of this
disclosure, labeled as the "CCC Catalyst" in the figure, reduced the overall
emissions by 54%
Date Recue/Date Received 2023-01-25
compared to OEM Catalyst. The OEM Catalyst peaked at 204 PPMv of emissions.
The CCC
Catalyst peaked at 66 PPMv of emissions.
[0056] In other tests of embodiments of this disclosure, bacon was air fried
in the Electrolux oven
using the following parameters for each test:
Amount of Bacon: 1 lb per pan
Number of Cycles: 3
Oven Temperature: 350 F
Cook Time: 20 minutes
Dwell Time: 5 minutes
Oven Setting: Air Fry Mode
CCC Catalyst Temp.: 650 F
The OEM catalyst peaked at just under 6 PPMv for emissions at the largest
peak. See FIG. 11.
Because air frying bacon in the oven 12 does not lead to complaints of
smoking, this implies that
achieving fewer than 6 PPMv is "acceptable" for emissions. The CCC Catalyst
had 49.4%
reduction in emissions compared to the OEM Catalyst with an average of 0.34
PPMv. It was
observed that a fair amount of steam came out of the vent 23 during testing of
both catalysts.
[0052] In other tests of embodiments of this disclosure, a whole turkey test
was conducted with
the CCC Catalyst installed in the oven 12. A 231b whole turkey was used. The
cooking parameters
were:
Oven Temperature: 350 F
Cook Time: 4 hours
Oven Setting: Air Fry Mode
Catalyst Temperature: 650 F
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Date Recue/Date Received 2023-01-25
There were practically no emissions and very little steam. See FIG. 12.
[0053] In other tests of embodiments of this disclosure, chicken wings were
cooked on air fry
mode. The cooking parameters used in the tests were as follows:
Amount of Chicken: 31bs per pan
Number of Cycles: 3
Oven Temperature: 450 F
Cook Time: 35 minutes
Oven Setting: Air Fry Mode
CCC Catalyst Temperature: 650 F
Dwell Time: 10 minutes (Sequential runs only)
The CCC Catalyst reduced emissions by about 84% compared to the OEM catalyst.
See FIG. 13.
Cooking sequential trays of wings proved repeatability and showed that the
catalyst of this
disclosure has the capability to keep up with an high load usage condition.
Even under these
strenuous conditions, the CCC catalyst had a peak emissions point of 4.3 ppmv
vs 33.4 ppm for
the OEM catalyst.
[0054] Referring now to FIG. 14, as the tests consistently show, a heated
screen catalyst assembly
10 of this disclosure is capable of dramatically reducing both the odorous and
smoke emissions
from the air frying of chicken wings; that practically zero emissions come
from bacon and whole
turkey cooked on the air fryer setting; and the heated catalyst screen
assembly 10 significantly
improves the self cleaning performance of the oven when the heater is
energized during the initial
portion of the self-cleaning cycle.
[0055] Referring now to FIGS. 19A to 26, in other embodiments the catalyst is
not contained in a
self-contained heated catalyst assembly 10 but is instead a screen catalyst 18
or metal foil catalyst
12
Date Recue/Date Received 2023-01-25
40 connected to the fan 45 of the cooking chamber 11. The catalyst can
eliminate the smoke to a
level that is nearly non-existent or at least would not be observable or
objectionable to the user. In
embodiments, the catalyst is composed of a substrate, such as a woven wire
cloth, expanded metal,
or permeable paper-like material that is impregnated with a catalytically
active coating comprised
of a high surface area aluminum oxide based washcoat and an active component
or components.
The shape of the substrate can be round, square, rectangular or any other
geometric shape that is
selected to provide sufficient coverage to achieve the necessary performance.
[0056] Mass loading of the precious metal content may be in a range of 10 g to
75 g per cubic
foot, and more specifically in the range of 20 g to 50 g per cubic foot, of
catalyst volume, there
being subranges and discrete values within this broader range. A portion of
the substrate may
include the catalyst and another portion may not (e.g. 25% to 75% of the
screen is coated). For
example, a lower or upper half (or right or left half) of the substrate may be
coated with catalyst
and the corresponding half uncoated. In embodiments, 50% to 100% of the
substrate is coated,
there being subranges and discrete values within this broader range.
[0057] Before being coated the substrate may have a pattern impressed upon it
to increase the
active surface area contained within the physical dimensions of the selected
shape. The washcoat
layer may be co-impregnated with other chemical elements that promote the
overall reaction, or
protect the coating from temperature induced degradation, or protect the
active components from
deactivation caused by the accumulation of materials that are poisonous to the
active component's
functionality. The washcoated substrate is subsequently coated with an active
component that can
be solely comprised of various combinations of platinum group metals, such as
platinum and/or
palladium, or mixtures of platinum group metals and other base metals from
Groups 3 through 12
of the Periodic Table.
13
Date Recue/Date Received 2023-01-25
[0058] The ability to coat the substrate with a complete coating that is a
combination of the
washcoat materials, any promoter of types known in the art, and the active
components in a single
operation rather than a sequence of operations is also within the scope of
this disclosure.
[0059] The coated substrate may be encased in a rim structure 31 to capture
the raw edges of the
substrate material. The rim structure 31 can be made from various grades of
stainless steel, 304SS
being preferred, or grades of aluminum alloy capable of withstanding oven
temperatures up to
850 F, or aluminized steel. The rim structure 31 also provides locations for
the attachment of
mechanical fastening methods to hold the catalyst screen 18 in place inside
the oven. Among the
type of fastening systems are wire ties, springs, clips, tabs, or magnets.
[0060] In some embodiments, the catalyst screen 18 is installed into the oven
on the inlet or suction
side of the circulation fan which is typically located on the back wall of the
oven cavity.
Installation in this location ensures that all the air being circulated by the
fan encounters the active
surface of the catalyst. Furthermore, this location does not impose a static
pressure on the
discharge from the circulation fan that can impede the cooking performance of
the oven which is
dependent upon the volume and velocity of the circulating air to "fry" food
within the cooking
chamber of the oven. However, because some ovens do not reverse the flow of
the fan, in other
embodiments the catalyst screen 18 may be installed on the discharge side of
the circulation fan.
Because of the structure of the catalyst substrate, when installed on the
discharge side there is
minimal effect on static pressure and air volume or air velocity needed for
proper cooking.
[0061] One embodiment of this disclosure utilized a 30-mesh woven wire cloth
made from 304SS
that was corrugated with a herringbone or zig-zag pattern to increase its
surface area and rigidity.
The substrate was subsequently coated with an aluminum oxide washcoat that was
impregnated
with rare earth oxides before being impregnated with a platinum-only active
layer. Mass loadings
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Date Recue/Date Received 2023-01-25
of 25 g, 26 g, 35 g, and 46 g per cubic foot of catalyst volume of the
precious metal content were
prepared. A commercially available residential oven that features an "AirFry"
mode was obtained
for the trials.
[0062] Prior to the catalyst being installed, the oven was run through the
AirFry cycle several
times with no food in it to break in the oven. This eliminated any volatile
compounds that remained
from the manufacturing process or off gas from the insulation that wraps the
oven cavity. Then
cook cycles without the catalyst being installed were done with the following
parameters to
establish a baseline of uncontrolled emissions:
Amount of Chicken: 3 lbs per tray
Number of Cook Cycles/Trial: 3
Oven Temperature: 450 F
Cook Time: 35 minutes
Oven Setting: Air Fry Mode
Dwell Time: 10 minutes (Sequential runs
only)
AirFry tray in rack position 3 and drip tray in rack position 1
minute dwell after last tray to collect any residual emissions
"Generous" coating of PAM cooking spray applied to each tray prior to cooking
in
accordance with the oven manufacturer's instructions
[0063] The cooking process was repeated with the catalyst being wired in place
on the intake side
20 of the circulation fan cover. Two types of data were collected during
the baseline and catalyst
equipped cooking trials. One was a filter catch to measure solid smoke
particles and condensable
organic compounds which comprise the visible smoke emissions from the oven.
The other was a
Date Recue/Date Received 2023-01-25
total hydrocarbon concentration using a Flame Ionization Detector ("FID")
which measures the
concentration of volatile organic compounds that comprise the odor of the
emissions.
[0064] The catalyst achieved the following reductions:
Visible Smoke Constituents 97.8%
Volatile Organic Compounds 98.0%
[0065] The smoke emissions from the oven for the catalyst-equipped trial were
essentially
invisible to the eye in comparison to the noticeable smoke plume seen during
the baseline trial. A
thermal image of embodiments of the full screen catalyst during the cooking
cycle had shown a
temperature rise in one half of the catalyst. Therefore, the half-coated
screen was an experiment
.. to see if that phenomenon translated to acceptable conversion performance.
The half-coated screen
did perform better than a complete screen with an overall lower precious metal
content but did
perform as well as the fully-coated screen with higher precious metal content.
Therefore, the half-
screen can be used if lower cost is desired and if lessened performance is
acceptable to a user or
oven manufacture. In comparison it did perform better than a complete screen
with an overall
lower precious metal content. This suggests that the area density of the
precious metals is key to
the performance over the total mass loading.
[0066] A screen catalyst may be useful in ovens where the geometry of the
internal baffle cover
plate for the back of the cavity does not allow for a foil catalyst. (The
baffle cover plate, along
with a fat filter, protect the oven fan from grease and food splatter.) In
other ovens, the size of
baffle cover plate may permit use of a foil catalyst. Foil catalysts have
higher levels of surface
area on which the catalytic reaction can take place. Catalyst performance is
proportional to the
amount of geometric surface area of the catalyst substrate.
16
Date Recue/Date Received 2023-01-25
[0067] Unlike embodiments of this disclosure that include a self contained
unit with heater and
catalyst or make use of the screen catalyst, embodiments that make use of a
metal foil catalyst 40
are located behind the baffle cover plate 47 over the circulation fan
45/heater 43 section in the
back of the oven. The foil catalyst 40 is sized to fit within space
constraints of the area between
the heating element corners 49 and fan 45 in the back of the oven (see e.g.
FIG. 27). The frame 41
in which the catalyst 40 is contained may be any material suitable. The frame
can change based
on the method by which it is secured to the oven (e.g., screws or rivets
through tabs, tabs that fit
into slots in the oven, clips that attach it to the heater element, etc.). The
source plane of the
radiation source, that is, heating elements 42, run parallel to the emission
receiving surface of the
catalyst element 40.
[0068] By way of a non-limiting example, a foil catalyst 40 of this disclosure
may be 5.80" length
(fold to fold), 0.75" height, and 1.00" width (foil thickness). These
dimensions may be adjusted
if, for example, an oven manufacturer specifies a minimal clearance zone
around the fan 45. In
embodiments, the cell density of the foil substrate may be in a range of 20 to
50 cells per square
.. inch and provide a desired flow path, there being subranges and discrete
values within this broader
range. The cell patterns may be skew or herringbone. For example, in one
embodiment the
substrate included 45 cells per square inch using a skew flow path design.
Mass loadings in a
range of 10 g to 75 g, more specifically 20 g to 50 g per cubic foot of
catalyst volume may be used
for the precious metal loading, there being subranges and discrete values
within this broader range.
.. The catalytically active elements may be a platinum only element. In other
embodiments, it may
be a platinum and palladium blend.
[0069] Because catalysts perform better at higher temperatures, and because
catalytic
effectiveness was found to be dependent on the amount of oven-chamber air that
is routed through
17
Date Recue/Date Received 2023-01-25
the catalyst, in embodiments foil catalyst 40 arranged as foil bundles were
placed in the four
corners 49 of the heating element 43, see FIG. 27, to process a large portion
of the air being
circulated by the fan as it exits the baffle cover plate 47. For purposes of
this disclosure, a foil
bundle is a length of coated foil that is folded back and forth to create a
stack of length and height
for a given foil flow thickness. It can be tied with stainless wire or
encapsulated with a stainless
steel frame prior to installation into the oven.
[0070] After a successful smoke test with the four foil bundles, the bundles
were removed to test
effectiveness of smoke reduction for three, two, and one foil bundle
arrangements. During the
removal of foil bundles, grease paths G on the baffle cover plate 47 indicated
a region of high flow
in the lower left-hand corner 49. See FIG. 27. Therefore, with one foil bundle
placed in the bottom
left-hand corner, see FIG. 28, a successful smoke test was achieved. Due to
the inherent design of
air fry along with the catalyst placement, the air is recycled through the
catalyst multiple times
rather than a single-pass design where the catalyst is placed in the oven
exhaust duct. The number
of foil catalyst bundles, and the size of the bundles, used in an application
to achieve a desired
level of smoke and order control can be determined based on the oven
manufacturer's marketing
goal, target foods to be cooked, and the parameters of the oven's cooking
cycle (e.g., temperature,
air circulation rate, chamber volume).
[0071] In embodiments, cell density and precious metal loadings were modified
and adjusted and
tested per the following table, where the precious metal loading standard is
about 35 g per cubic
foot of catalyst volume:
Precious Metal Loading Cell Density Volume Hydrocarbon Control
PM Control
lyst Cata
(% of Standard) (cpsi) (% of Standard) (%DRE)
(%DRE)
Formulation B 100% 45 100% 79.8%
89.66%
Formulation D 71% 45 100% 44.3%
79.31%
Formulation E 143% 100 66.4% 49.3% 6.90%
Formulation F 143% 150 66.4% 61.9% 0.31%
18
Date Regue/Date Received 2023-01-25
A reduction in precious metal loading resulted in a dimensioned hydrocarbon
control, which was
a good proxy for overall catalyst performance (Formulation D), and there was a
noticeable increase
in the visual levels of smoke from the oven as well. The modification in
volume and cell density
(Formulations E and F above) helped achieve a greater clearance between the
fan and the catalyst.
However, increasing the cell density resulted in a significant loss of
performance and visual smoke
levels similar to a "No Catalyst" condition. This was likely a result of
increased pressure drop and
providing a path of "most resistance" (through the catalyst), resulting in
limited air flow being
processed by the catalyst.
[0072] The following catalyst orientations with the catalyst from Formulation
B:
lo = 00 degree orientation
= No visible smoke at 425 F for 25 minutes
= No visible smoke at 425 F for 35 minutes
= 150 degree orientation
= No visible smoke at 425 F for 25 minutes
= No visible smoke at 425 F for 35 minutes
= 45 degree orientation
= Small amounts visible smoke at 425 F for 25 minutes
= Small amounts of visible smoke at 425 F for 35 minutes
In tests conducted it was learned that temperature is a driving force of smoke
rather than the time
spent at each temperature. For example, 425 F for 35 minutes produced no smoke
whereas
450 F for 25 minutes produced smoke.
[0073] Embodiments of this disclosure, when installed in an oven having an air
frying mode, the
amount of volatile organic compounds exhausted by the oven when cooking a
predetermined food
19
Date Recue/Date Received 2023-01-25
in the air fry mode under predetermined conditions are at least 95% lower than
would bethe amount
of volatile organic compounds when cooking the predetermined food in the air
fry mode under the
predetermined conditions without the embodiments installed in the the oven
[0074] Example embodiments include an oven comprising a cooking chamber
including an air fry
cook mode; a vent; a heated catalyst assembly located between the cooking
chamber and the vent,
the assembly including a housing having an inlet connected to the cooking
chamber and an outlet
connected to the vent; the housing containing a thermal radiation heat source
located within the
housing between the inlet and the outlet, the thermal radiation source
including at least one looped
element; a first catalyst located toward the inlet in proximity to one side of
the thermal radiation
source; and a second catalyst located in proximity to an opposite side of the
thermal radiation heat
source; the first and second catalysts arranged in planes parallel to that of
the thermal radiation
heat source. In embodiments, the first and second catalysts are selected from
the group consisting
of a screen catalyst, a wire mesh cloth, an expanded metal or metal foil, and
a ceramic. A method
for treating emissions of an oven when air frying include treating the air
frying emissions within
the heated catalyst assembly.
[0075] In other embodiments, a heated catalyst assembly is arranged for use
with an oven having
an air frying mode, the heated catalyst including a housing having an inlet
connected to the cooking
chamber and an outlet connected to the vent; the housing containing a thermal
radiation heat source
located within the housing between the inlet and the outlet, the thermal
radiation source including
at least one looped element, a first catalyst located toward the inlet in
proximity to one side of the
thermal radiation source, and a second catalyst located in proximity to an
opposite side of the
thermal radiation heat source; the first and second catalysts arranged in
planes parallel to that of
the thermal radiation heat source. The first and second catalysts are selected
from the group
Date Recue/Date Received 2023-01-25
consisting of a screen, a wire mesh cloth, an expanded metal or metal foil,
and a ceramic. A
method for treating emissions of an oven when air frying includes treating the
air frying emissions
within the heated catalyst assembly.
[0076] In yet other embodiments, no self-contained heated catalyst assembly is
used. Rather, the
embodiment may be in a form of a conversion kit for use in an oven including
an air frying mode
and a cooking chamber containing a circulation fan on a wall of the cooking
chamber. The
conversion kit includes a screen including a corrugated pattern and coated
with a catalyst on at
least half of the screen, the catalyst including a precious metal having a
mass loading in a range of
20 g to 50 g per cubic foot of catalyst volume, the screen sized for
installation on the inlet or
suction side of the circulation fan and including means for connection to the
inlet or suction side
of the circulation fan. In a method of use, air frying emissions are passed
from the circulation fan
through the screen.
[0077] In yet other embodiments, the conversion kit may include one to four
metal foil catalysts.
The oven includes a cooking chamber including an air fry cook mode; a fan
located at the back of
the oven; a plurality of heating elements adjacent to and surrounding the fan
to form four corners
located about the fan; and the one to four metal foil catalysts, each metal
foil catalyst located
between a corresponding one of the four corners and the fan; and a baffle
cover plate covering the
fan, the plurality of heating elements, and the one to four metal foil
catalysts. In a method of use,
the air frying emissions pass through the fan where the emissions are
contacted by the metal foil
catalysts.
21
Date Recue/Date Received 2023-01-25
