Note: Descriptions are shown in the official language in which they were submitted.
CA 02713971 2013-05-01
THERMOCOUPLE SHUTOFF FOR PORTABLE HEATER
TECHNICAL FIELD
Provided is a device for shut-off of a portable heater. More particularly,
provided
is device to shut down a portable heater in response to certain atmospheric
conditions.
BACKGROUND
Combustion-powered heaters combust reactants to yield heat and reaction
products. Combustion-powered heaters consume a fuel and an oxidant and react
the fuel
and oxidant to yield heat and one or more combustion products. Some combustion-
powered heaters modify the composition of the local atmosphere by uptake of
one or
more reactants from the local atmosphere or release of one or more combustion
products
into the local atmosphere or both.
In some combustion-powered heaters, the combustion process consumes oxygen
from the local atmosphere as a combustion reactant. The consumption of oxygen
by a
combustion-powered heater can modify the composition of the local atmosphere
by
reducing the local oxygen amounts. In some amounts, reduced local oxygen may
be
undesirable. It remains desirable to develop technology to detect and address
atmospheric conditions such as undesirable amounts of local oxygen.
Some combustion-powered heaters release of one or more combustion products
into the local atmosphere. The combustion products may comprise, but are not
limited
to, carbon dioxide, carbon monoxide, and nitrogen oxides. The release of
combustion
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products can modify the composition of the local atmosphere by increasing the
amounts
of combustion products therein. In some amounts, the presence of one or more
combustion products may be undesirable. It remains desirable to develop
technology to
detect and address atmospheric conditions such as undesirable amounts of
combustion
products in the local atmosphere.
SUMMARY
Provided is an assembly comprising a combustion-powered heater, a target
component, and a transducer operatively engaged with said target component. A
combustion-powered heater may comprise a combustion site adapted to power said
heater. A target component may be engaged with the combustion site. A
transducer may
be adapted to measure the temperature of the target component and adapted to
shut-down
said combustion-powered heater in response to a temperature measurement of
less than a
temperature limit.
Further provided is a method of selectively shutting off a combustion-powered
portable heater. The method may comprise providing a combustion-powered
heater. The
heater may comprise a combustion site adapted to power said heater when in
operation.
The method may further comprise engaging a target component with said
combustion site
in such a manner that said combustion site heats said target component when in
operation. The method may further comprise operatively engaging a transducer
with said
target component. The transducer may be adapted to measure the temperature of
the
target component, and adapted to shut-down said combustion-powered heater in
response
to a temperature measurement of less than a temperature limit.
Further provided is an assembly comprising a portable, combustion-powered
heater, a radiant surface, and at least one thermocouple. The heater may
comprise a
combustion site adapted to power said heater. The heater may be adapted to
consume
oxygen from air and propane fuel. The radiant surface may be engaged with the
combustion site. The thermocouple may be embedded within the radiant surface.
The
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thermocouple may be adapted to measure the temperature of the radiant surface.
The
thermocouple may be adapted to cease holding open a normally-closed valve to
shut-
down said combustion-powered heater in response to a temperature measurement
of less
than a temperature limit.
BRIEF DESCRIPTION OF THE DRAWINGS
The present subject matter may take physical form in certain parts and
arrangement of parts, embodiments of which will be described in detail in this
specification and illustrated in the accompanying drawings which form a part
hereof, and
wherein:
FIGURE 1 is a perspective cross-sectional view of one embodiment of a heater
assembly;
FIGURE 2 is a longitudinal cross-sectional view of one embodiment of a heater
assembly;
FIGURE 3 is sectional view of one embodiment of a heater assembly;
FIGURE 4 is detail view of one embodiment of a transducer in a heater
assembly.
DETAILED DESCRIPTION
Reference will be made to the drawings, FIGURES 1-4, wherein the showings are
only for purposes of illustrating certain embodiments of a thermocouple
shutoff for
portable heater, and not for purposes of limiting the same. Specific
characteristics
relating to the embodiments disclosed herein are not to be considered as
limiting, unless
the claims expressly state otherwise.
Portable heaters may be combustion-powered. Combustion-powered portable
heaters 100 are adapted to react fuel, and an oxidant at a combustion site. A
combustion
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site may be any region adapted for conducting a combustion reaction. Without
limitation, a combustion site may comprise a burner, or a catalytic surface.
A burner is a device adapted to generate a flame by combustion. In operation,
a
burner accepts a fuel and an oxidant, combusts the fuel and the oxidant, and
outputs heat
and a combustion product.
In some embodiments, a burner may be operatively associated with components
adapted to modify the output from the burner. Without limitation, a burner
output
modifier may be adapted to affect the efficiency of the heater, may be adapted
to affect
the rate of heat output, may be adapted to separate a flow of heat from a flow
of
combustion products, or may be adapted to focus or disperse a flow of heat.
Without
limitation, a burner output modifier may include a heat reflector, a heat
concentrator, a
heat diffuser, a chimney, a heat exchanger, a regenerator, or a radiant
surface.
In some embodiments, a burner may produce a naked flame exposed to the
environment. Without limitation, a heater comprising a burner adapted to
produce a
naked flame exposed to the environment will be referred to herein as a blue
flame heater
unless otherwise noted. In some embodiments a burner may be operatively
engaged with
a radiant surface adapted to shield the flame from the environment. Without
limitation, a
radiant heater is one embodiment of heater comprising a burner operatively
engaged with
a radiant surface adapted to shield the flame from the environment.
A catalytic surface is a combustion site adapted so that a fuel and an oxidant
may
react thereupon in catalyzed reaction to yield heat and a combustion product.
Without
limitation, the material of the catalytic surface may act as a catalyst in a
catalyzed
combustion reaction at the combustion site. Without limitation, a catalyst in
a
combustion reaction may catalyze the combustion reaction by speeding up the
reaction,
slowing down the reaction, lowering the ignition energy needed to initiate the
combustion
reaction, promoting more complete combustion, promoting cleaner combustion,
reducing
or eliminating certain combustion products, or increasing operating
efficiency.
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Without limitation, some catalytic surfaces comprise a catalyst supported by a
substrate. In certain embodiments a catalyst may comprise ruthenium, rhodium,
palladium, osmium, iridium, platinum, and mixtures thereof. Substrates may
comprise a
glass fiber, a porous metal, a ceramic, or a mixture thereof.
Without limitation, some fuels that a combustion site may react comprise,
methane, ethane, propane, butane, pentane, other alkanes, alkenes, alkynes,
kerosene, LP
gas, wood gas, other gas mixtures, oil, hydrogen, or mixtures thereof Without
limitation,
some oxidants that a combustion site may react comprise oxygen, gas mixtures
comprising oxygen, nitrous oxide, or mixtures thereof. Without limitation, air
is a gas
mixture comprising oxygen that may be used as an oxidant.
FIGURE 1 shows a combustion-powered portable heater 100. Without limitation,
the cross-sectional view also shows a device 80 adapted to shut off a
combustion-
powered portable heater 100.
FIGURE 2 shows a combustion-powered portable heater 100. Without
limitations, the cross-sectional view also shows a device 80 adapted to shut
off a
combustion-powered portable heater 100.
FIGURE 3 shows a combustion-powered heater 10. Without limitation, the
sectional view shows a fuel control valve 20 adapted to selectively permit
fuel flow to a
combustion site 40. During operation of heater 10, air flows into heater 10
from the
atmosphere 90. In the non-limiting embodiment showing in FIGURE 3, the heater
10
comprises intake apertures 70 to admit air into the heater 10. During
operation, air and
fuel undergo a combustion reaction at combustion site 40 to produce heat and
combustion
products. The non-limiting embodiment of a combustion site 40 shown in FIGURE
3 is a
burner 41. By contrast, in other non-limiting embodiments, combustion site 40
may
comprise a catalytic surface. Burner 41 comprises an inlet (not shown) for
accepting air.
The non-limiting embodiment shown in FIGURES 3 and 4 also comprises a burner
CA 02713971 2010-08-20
output modifier 60. Without limitation, burner output modifier 60 comprises a
radiant
surface 61. Without limitation, the combustion-powered heater 10 shown in
FIGURES 3
and 4 also comprises a transducer 50 in engagement with a component of heater
10. The
transducer 50 is adapted to detect the temperature of components with which it
is
engaged. In the non-limiting embodiment shown in FIGURE 3, the transducer 50
comprises at least one thermocouple 51, engaged with, and adapted to detect
the
temperature of, radiant surface 61.
In certain embodiments, the composition of the atmosphere can substantially
affect the combustion reaction during operation. "Good air" is a description
of air
quality. Good air is air from an atmosphere that has not been modified to
contain an
defined reduced oxygen content or to contain a defined amount of combustion
products.
The defined reduced oxygen content and the defined amount of combustion
products are
quantities that may be determined based on engineering judgment. In certain
embodiments, during operations in good air, the combustion reaction may be
substantially complete. In
certain embodiments, during operations in good air, the
combustion reaction will produce heat at some rate for a given fuel
consumption rate.
"Bad air" is another description of air quality. Bad air is air from an
atmosphere that has
been modified to contain a defined reduced oxygen content or to contain a
defined
amount of combustion products. In certain embodiments, during operations in
bad air,
the combustion reaction may be substantially incomplete.. In certain
embodiments,
during operations in bad air the combustion reaction will produce heat at some
rate for a
given fuel consumption rate; wherein said rate of heat production in bad air
is
substantially less than the rate of heat production in good air for the same
fuel
consumption rate.
In some embodiments, because of predictable differences between the rate of
heat
produced by combustion in good air and the amount of heat produced by
combustion in
bad air, a transducer 50 sensitive to temperature may be used to detect
changes in
combustion related to changes local air quality and, thereby, used as a
detector of
atmospheric quality in terms of good air versus bad air. Such temperature
detection may
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be performed by sensing of the temperature at the combustion site, or by
sensing
temperature of materials or components engaged with the combustion site 40.
That is, a
transducer 50 may be used to discriminate between heater operations within
good air and
burner or heater operations within bad air by measuring the temperature of
heater
components heated by heat produced at a combustion site 40.
Without limitation a transducer 50 may be electrical or mechanical. A
transducer
50 may comprise at least one thermocouple 51, a thermoelectric material, a
thermostat, a
bi-metallic strip, or a pyrometer.
In some embodiments, and without limitation, operating temperature data of
components or materials of the heater 10, can be used to determine air
quality. In certain
embodiments, operating temperature data of components other than those
components in
a combustion site 40 can be used to determine air quality. In some
embodiments, a
transducer 50 is used to take operating temperature data of components of the
heater 10
or to acquire a signal representative of operating temperature data of
components of the
heater 10. Components of the heater 10 from which a transducer 50 is used to
take
operating temperature data or to acquire a signal representative of operating
temperature
data are target components 62. Target components 62 may include a burner
output
modifier 60, a radiant surface 61, or any other component of the heater 10 or
material
within the heater 10 other than a combustion site 40, a burner 41, a catalytic
surface (not
shown), or a flame (not shown).
In certain embodiments, operation of a combustion-powered heater 10 in good
air
may result in an operating temperature of target components or materials 62 at
or above
some predetermined temperature. Without limitation, in certain embodiments,
operation
of a combustion-powered heater in bad air may result in an operating
temperature of the
target components or materials 62 below some predetermined temperature.
In certain embodiments, a transducer 50 comprises at least one thermocouple
51.
During operation in good air, the combustion site 40 produces heat sufficient
to heat a
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target component or material 62 to a temperature high enough to produce an
output signal
consistent with good air from at least one thermocouple 51. During operation
in bad air,
the combustion site 40 does not produce heat sufficient to heat a target
component or
material 62 to a temperature high enough to produce an output signal
consistent with
good air from at least one thermocouple 51.
In certain embodiments, failure of at least one transducer 50 or thermocouple
51
to produce an output signal consistent with good air will trigger an alarm or
will trigger
actions to stop operations at combustion site 40 or heater 10. In certain
embodiments,
actions to stop operations at combustion site 40 includes shut off of the
valve 20 to
interrupt fuel flow necessary to continuing operations at combustion site 40.
In certain embodiments, the heat from combustion site 40 may affect objects
and
materials in contact engaged with combustion site 40. In certain embodiments,
heat from
combustion site 40 will propagate through components and materials from areas
proximate to or in contact with combustion site 40 to areas more distal from
combustion
site 40.
EXPERIMENT:
As shown in TABLE 1, nine experiments were performed on heater embodiments
similar to those shown in FIGURES 3-4. In each experiment at least one
thermocouple
51 was engaged with, and provided a potential substantially proportionate to
the
temperature of, a radiant surface 61. In each experiment, the cut-off
potential in the
thermocouple in millivolts was established as "TC mV @ Cut-Off' . A potential
in the
thermocouple of the cut-off potential or less would fail to hold open a fuel
control valve
20 and would allow the fuel control valve 20 to close, thereby cutting off
fuel to the
combustion site 40 and shutting down the heater 10. In each experiment the
heater 10
was started and the initial potential in the thermocouple 51 in millivolts was
recorded as
"Starting Thermocouple (mV)". The heater 10 was then isolated from the greater
atmosphere by sealing it in a small, substantially air-tight, enclosure with a
small amount
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of air. In each experiment, the percentage of oxygen in the air in the
enclosure was
monitored. Over time, the percentage of oxygen in the air in the enclosure
diminished.
Over time, the potential in the thermocouple 51 in millivolts diminished. In
each
experiment, the heater 10 was allowed to operate until the potential in the
thermocouple
51 in millivolts diminished to the cut-off potential and the heater 10 shut
down. In each
experiment, the percentage of oxygen in the air in the enclosure when the
heater 10 shut
down was recorded as "%02 Cut-Off'.
Without wishing to be bound to any particular theory, the data in TABLE 1 is
consistent with the conclusion that heat produced at a combustion site 40 is a
function of
the air quality of the atmosphere 90. The operating temperature data of the
components
of the heater 10 with which thermocouple 51 was engaged produced an output
potential
consistent with the components dropping in temperature as the air quality in
the enclosure
decreased. The data is consistent with a finding that the potential in
thermocouple 51 is a
function of air quality. The results of the experiments are shown in TABLE 1
below.
TABLE 1:
Test Number Starting Thermocouple (mV) %02 Cut-Off TC mV @ Cut-
Off
1 20.0 17.88 7.50
2 20.0 17.89 8.00
3 21.0 17.85 8.00
4 20.0 18.00 7.00
20.0 17.82 7.50
6 20.0 17.89 7.50
7 20.5 17.99 7.00
8 20.5 17.89 7.00
9 20.0 18.00 8.00
While the thermocouple shutoff for a portable heater has been described above
in
connection with the certain embodiments, it is to be understood that other
embodiments
may be used or modifications and additions may be made to the described
embodiments
for performing the same function of the thermocouple shutoff for a portable
heater
without deviating therefrom. Further, the thermocouple shutoff for a portable
heater may
include embodiments disclosed but not described in exacting detail. Further,
all
embodiments disclosed are not necessarily in the alternative, as various
embodiments
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may be combined to provide the desired characteristics. Variations can be made
by one
having ordinary skill in the art without departing from the teachings of the
current
application. Therefore, the thermocouple shutoff for a portable heater should
not be
limited to any single embodiment, but rather construed in breadth and scope in
accordance with the recitation of the attached claims.
