Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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GENERATIOiIf OF ELECTRICI~."S~' TN A. FIREPI~,ACE USING
THERMOELECTRIC MODUJLE
l3ack~round of the )rnvenfion
Technical Field
The present invention generally relates to the.Ynaoelectric power and
more specifically relates to generation of electric power for a frrepiace
using
thermoelectric power.
Related Art
10 The popularity of gas burning stoves and fireplaces has increased
s ~Qnificantly over the past several decades. Burning gas such as natural gas
or
propane is typically a much more efficient way of producing heat and far more
clean
and easy to control than burning wood, wood pellets, coal or oil: The
efficiency and
convenience of gas bumina stoves and fireplaces is further enhanced by using
such
15 peripheral devices as a blower to circulate heated air through the room in
which the.
stove ox fireplace is placed, an ignition system to self start the fire, back-
up storage
devices, and control systems that automatically or manually control various
features
of the stave or fireplace. Many of these devices require electrical power to
operate
and thus contribute to the cost of operating a gas stove or fireplace.
Furthermore, in
20 areas where electrical power is unavailable or expensive, many of these
devices may
not be an option for use with a gas stove or fireplace.
Many known stoves and fireplaces have reduced heat generating
efficiency because much of the heat produced escapes through the combustion
exhaust system or into the structure suzrounding the stove or fireplace rather
than
25 heating the intended air space around the stove or fireplace. . Tmprovvig
the heat
generatixtg efficiency of stoves and fireplaces is an objective for many
manufacturers
of These products.
The use of therrnoeleetzic modules to produce electricity using a heat
source has been known for many years. Fire 1 schematically illustrates a
typical
30 thermoelectric module 1 that includes a number of alternate negative (NJ
and
positive (l.') type semiconductor thermo elements connected in series by metal
interconnectozs 2, 4 that are sandwiched between two electrically insulated
but
thermally conducting plates H, C. A heat source connected to plate H and a
heat
sink conaiected to plate C provide a temperature differential across the
tYtermo
35 elements that in turn geizerat.e a current (1~ that can be delivered to an
external load
Typically, increasing the temperature difference {c~T) across a
thermoelectric module will increase the power generated by the module within
limits
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of the materials used and the con$o ration of the module. Those skilled in the
art
are aware that materials with a high figure-of merit are preferred for use as
thermo
elements in a thermoelectric module. Heavily doped .semi-conductors, such as
tellurides of antimony and bismuth, are examples ofrnaterials with a high
figure-of
merit value. Manufacturers of thermoelectric modules such as continue to make
advances in the efficiency of thermoelectric modules 'by altering their
designs or
discovering near materials or combinations ofmaterials that are most
efficient.
Summary of the Inveutxoz~
The present invention generally relates to the use of a thennoelectzic
10 ~ module in conjunction with a fireplace or stove to generate electzicity
to run certain
features or peripheral devices related to the stove or fireplace. A
thermoelectric
module may be positioned adjacent to an exterior wall of the stove or
fireplace or
between interior and exterior walls of the stove or fireplace so long as the
module is
protected from the fire in the combustion cha.rrzber. F~ower generated by the
15 thermoelectric module nay be used for various purposes such as powering a
blowez,
a control unit, lights, sensors, ignition systems, and flame igniting aztd
control
devices. Furthermore, the power generated by the thermoelectric module may be
saved in a power storage device such as a rechargeable battery or capacitor
for a
later use by devices listed above.
20 One aspect of the invention relates to a thermoelectric fireplace that
includes a combustion chamber enclosure having an outer surface and an inner
surface defining a combustion. chamber, an outer enclosure surrounding a
portion of
the combustion chamber enclosure, and a thex~a.oelectric module positioned
adjacent
to the outer surface of the combustian chamber enclosure. In one embodiment,
the
25 thermoelectric also may be positioned between the combustion chamber
enclosure
and the outer enclosure. Heat generated in the combustion chamber in the
combustion chamber enclosure is used by the thermoelectric module to generate
power.
Another aspect of the invention relates'to a thermoelectric system
30 configured to generate power in a ~lreplace. The thermoelectric system
includes a
combustion chamber enclosure and an outer enclosure. The thermoelectric system
includes a thermoelectzic module positioned adjacent to the combustion chamber
ene.losure and positioned between the combustion chamber enclosure and the
outer
enclosure. The thermoelectric module generates power using heal provided in
the
35 combustion chamber enclosure.
A fuzther aspect of the invention relates to a method of generating
power in a fireplace using a thermoelectric system that includes a
thezmoelectzic
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module. The fireplace includes a combustion cbamber enclosure having inner and
outer surfaces and an outer enclosure surrounding the combustion chamber
enclosure. The method includes positioning the thermoelectric module adjacent
to
the outer surface of the combustion chamber enclosure between the combustion
> chamber enclosure and the outer enclosure, heating the combustion chamber
enclosure, transferring heat from the combustion chamber enclosure to the
thermoelectric module, and generating power in the thermoelectric module from
the
transferred heat.
A yet further aspect of the invention relates to a thexznoelectric
fireplace that includes a compression molded combustion chamber enclosure
defining a corxlbustion chamber, and a thermoelectric module positioned
adjacent to
the combustion chamber enclosure. The thermoelectric module is positione3
relative co the combustion chamber enclosure so that heat generated in the
combustion chamber is transferred to the thermoelectric module for the
produetian
of power.
The above summary o f tha present invention is not intended to
describe each disclosed embodiment or every implementation of the present
invention. Figures in the detailed description that follow more particularly
exemplified embodiments of the invention. While certain embodiments will be
illustrated and described, the invention is not limited to use in such
embodiments.
Brief bescription of the Dratyinas
The invention may be more completely understood in consideration
of the following detailed description of various embodiments in the invention
and in
connection with accompanying drawings, in which;
Figure 1 is a schematic representation of a known power generating
thermoelectric module;
Figure 2 is a perspective view of an example fireplace in which
principles of the present invention may be applied;
Figure 3 is a perspective side view of the fireplace shown in Figure 2
with a porfion of the fireplace outer enclosure removed to illustrate an
exaruple
thermoelectric module and other aspects of the invention;
F ~aure 4 is a crass-sectional view of one example embodiment of the
invention taken along cross-sectional indicators 4-4 shown in Figure 3;
Figuxe 5 is a cross-sectional view of another example embodiment of
the invention taken along cross-sectional indicators 5-5 shown in Figure 3;
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Figure 6 is a top perspective view of an example therxnaelectric
module of the invention in use with a compression rnalded combustion chamber
enclosure; and
Figure 7 is a cross-sectional side view of another example
5 embodiment of the invention with a heat source positioned in the fireplace
plenuni.
While the invention is amenable to various modifications and
alternate forms, specifics thereof have been shown by uray of example in the
drawings and will he described in detail. It should be understood, however,
that the
invention is not limited to the pazticular embodiments described. On the
contrary,
10 the invention is to cover all modi$cations, equivalents, and alternatives
falling
within the spirit and scope of the invention.
Detailed Descnintion of the Prefierred Emhodirnent
The invention is applicable to stoves and fireplaces that provide a
heat source, and particularly to combustible gas fireplaces and stoves. The
invention
IS is directed to generating electrical power from heat provided by a stove or
fireplace
using a thermoelectric device. Power generated by the thermoelectric device
may be
used to power various features associated with the stove ar fireplace. While
the
present invention is not se limited, apprzciation of various aspects of the
invention
vriIl he gained through a discussion of the examples provided below.
20 Embodiments of the present invention may be used in conjunction
with gas, electric or other types of heat sources that generate heat to
provide a
temperature differential across a thermoelectric module thereby generating
electric
power. bVhile the example embodiments of the present invention provided below
are described in conjunction with example ~~replae.c.s, the present invention
is
25 equally applicable to other systems or apparatuses such as furnaces and
stoves that
generate heat for the purpose of heating an air space such as a home or
commercial
building. Some example fizeplaces that may be used in accordance with the
present
invention include a direct vent, a universal vent, a B-vent, a
horizontaJlvertical-vent,
a dual direct vent, and a multisided unit having twe~ or three glass panels as
30 combustion chamber side panels.
As used herein, the phrase "combustion chamber enclosure" may
include any structure that at least partially encloses a space in which a
flame is
generated from combusting a material, solid or gas, or simulating a flame. The
phrase "transferring heat" may include either convretion or conduction heat
transfez.
35 A "thermoelectric module" as used herein urill be more completely described
below
but generally relates to a device that generates electrical power in the
presence of a
4
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temperature differential. A "heat source" may include, for example, an
electric or
gas heater.
Referring to Figures 2-5, respective front, side and cross-sectional
views of an example eznbodime.nt of a fireplace 10 is shown. Fireplace 10
includes
5 an outer enclosure 11, a combustion chamber enclosure 30, and a
thermoelectric
system 50. Outer enclosure I 1 includes top, bottom, first and second side,
and rear
panels 12, I4, 16, 18, 20. Outer enclosure 11 may also ixiclude a front
suzface 22
into which first and second vents 23, 24 are formed. Vents 23, 24 are used to
draw
air into and exhausting air from the internal space of fireplace 10.
10 Combustion chamber enclosure 30 iucludes fizst and second side
panels 31, 47, top and bottom panels 35, 39, and rear panel 43. As shown in
Figures
3-5, first panel 31 includes outside and inside surfaces 32, 34, top panel 3~
includes
inside and outside surfaces 36, 38, bottom panel 39 includes inside an,d
outside
surfaces 40, 42, and rear panel 43 includes an outside surface 44.
IS Thermoelectric system 50 may include a thermoelectric module 52,
heat sink 58 and leads 60, 62. Thermoelectric module 52 may include the basic
con$guration shown in Figure 1, including a plurality of therma elements P, N
connected in series with connectors 2, 4 and positioned between heat
conductive
plates H, C. Other thermoelectric module configurations may be used sa long as
the
20 thermoelectzic module 52 is capable of using heat to generate electrical
power. feat
sink 58 may be configured as a plurality of ribs as shown in Figure 3, or
other
stntctures that enhances heat dissipation to increase the temperature
differential
between opposing sides of thermoelectric module 52.
Tn another thermoelectric system embodiment shoran in Figure 5, a
25 portion of the system, such as a hear sink 158, may extend beyond the f rst
side
panel 16 and possibly even beyond an additional wall structure 80 positioned
adj scent the fireplace 14. Heat sink 158 may then be exposed to a colder
environment than that area between the combustion chamber enclosure 30 and the
outer enclosure 11. For example, heat sink 158 may extend outside of a house
30 where the fireplace resides so as to be exposed to cool/cold outdoor air.
Such a
configuration would create a much greater temperature differential across the
thermoelectric module resulting in improved power output.
Figures 3-4 illustrate thermoelectric system 50 mounted to outside
surface 32 of first side panel 31 of the combustion chamber enclosure 30.
35 Thermoelectric system 50 is orientated ~,vith the thermoelectric module 52
secured to
the combustion chamber enclosure 30 with dze heat sink 158 positioned away
from
the combustion chamber enclosure, fi5ure 4 iIlustxates the entire
thermoelectric
system 50 positioned between combustion chamber enclosure 30 and the first
side
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panel 16 and a removable side panel 28 of outer enclosure 11. Similarly,
Figure 5
illustrates that at least aportion of the thermoelectric system I50 is
positioned
between combustion chamber enclosure 30 and outer enclosure 11. In other
embodiments, the thezznoelectric system may be mounted to the outside surfaces
of
5 the top, bottom, rear or second side panels 35, 39, 43, 47 of combustion
chamber
enclosure 30 for various reasons such as, for example, improving power
generation
efficiency or meeting the size and shape constraints of the fireplace.
Fireplace 10 may include auxiliary features that typically operate
using electrical power. For example, fireplace 10 includes an energy storage
device.
10 70, a blower 72, a control unit 74, arid an ignition system 26 (see Figure
1). Energy
storage device 70 may be, for example, a capacitor or rechargeable battery.
Preferably, energy storage device 70 is capable of being charged wish power
from
thermoelectric system 50 so that some of the fireplace features can operate
when
there fireplace is not generating heat sufficient for the thermoelectric
system to
15 produce power.
Blower 72 provides air circulation around the outside surface of
combustion chamber 30 and within outer enclosure 11. Blower 72 typically draws
cool air in through the lower first vent 23 and exhausts heated air through
the higher
second vent 24 on the front surface 22 of fireplace 10. In some embodiments,
20 blower 72 may be configured solely for the purpose of cooling
thermoelectric
module 52 while a separate blower is used to circulate air into and out of the
fireplace.
Control unit 74 may individually control or may represent any of a
number of different coatrol features that may be used with a fireplace. For
example,
25 control unit 74 may be an ignition system control such as the ignition
system
disclosed in U.S. Patant No, 6,520,199, a main flame valve control, a heat
sensor
control, a blower control, or a power allocation control unit. Control unit 74
may
include a microprocessor that is programmable to, for example, automatically
charge
or discharge energy storage device 70, turn on or offblower 72 at specified
times
30 during heating and cooling within combustion enclosure 30, automatically
fuming
on or off the main flame of the fireplace, maintaining the ignition system 26,
or
manually igniting a pilot light of the fireplace (not shown}.
Figure 3 illusurates hard wires extending betareen control unit 74,
blower 72 and energy storage device 70. I-iovc°ever, in other
embodiments, other
35 communication technology such as infrared, remote control or other wireless
communication may be used to send and receive control signals from the control
unit 74 and various electronically controlled devices of fireplace 10_
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The thermoelectric systems 50, 150 shown in Figures 3-5 may more
efficiently generate power when blower 72 moves air across heat sink 58, 1S8
to
increase the temperature differential across thermoelectric module 52, 15~. In
these
examples, blower 72 draws cool air in the direction B across a bottom portion
of the
5 combustion chamber enclosure 30, moves the alt in the vertical direction S
across
the thermoelectric system 50, ISO, and exhausts the air out from the fireplace
the
intended air space in front of the fireplace. Typically, the exhausted air is
heated
relative to the intake air by the time the air is exhausted from the
fireplace, thus
providing heating of the intended air space while at the same time cooling the
I0 thermoelectric module. In other embodiments, different types of cooling
devices
may be used in place of or in addition to a blower to cool the thermoelectric
system.
One example alternative cooling device is a closed-loop liquid-state cooling
system.
Power generation using thermoelectric system 50 znay be started in
several different ways. Heat is generated in the combustion chamber enclosure
30
I S using, for example, a gas fed flame, or may be generated by anotb.er heat
source
positioned between the combustion chamber enclosure 30 and the outer enclosure
28. The flame may be staved with the ignition system. 26 that includes, for
example,
a standing pilot light or a pilot light that that is manually ox automatically
controlled
by control unit 74 using power powered stored in energy stora?e device 70. As
heat
20 builds in or around the combustion chamber, the thermoelectric module 52
begins to
draw heat from the heat source and converts that heat into electrical power.
Control
unit 74 may be used to power "on" the blower 72 either before ar afrer the
thermoelectric system 50 begins to generate electrical power by using energy
stored
in. the storage device 70 or using energy produced by thermoelectric system
S0. As
25 noted above, blowing aiur across the heat sink 58 (for example, using
blower 72)
improves the power ~utput from the thermoelectric system, and thus it may be
advantageous to begin air movement across the heat sink at a very early stage.
In
some eznbod3ments, energy storage device 70 may include a capacitor that
provides
a surge of power to meet the start up energy requirements for blower 72.
30 Power generated by the themnoelectric system 50 may be used for
powering other features not shown in the Figures such as, for example, lights
in and
around the fireplace, moving devices in and around the fireplace such as an
simulated ~.arxte element (see U.S. Patent Application No. 09/941,400), a
simulated
fuel bed {see U.S. patent Application. No. 09/851,803), an ember out of a log
(see
35 U.S. Patent Application I~To. 1014&3,175), a touch switch (see U.S. patent
Application No. I0/199,983), a proximity sensor (see U.S. Patent Application
Nos.
10/120,890 and 101119,474), moving a lenticular screen (see U.S. Patent
Application
No. 09/859,X9), a thermostat, and other alarms arid sensors such as a carbon
7
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mono~:ide sensor and an associated alarm. Another sensor and alarm system may
monztor the thermoelectric system and provide notification when the
thermoelectric
system is overheating or is in need ofrepairs so that the user or possibly the
control
unit can shut down the fireplace to conduct diagnostics andlor repairs.
Another example fireplace 200 that includes a thezxnoelectric system
250 is shown in Figure 6. Fireplace 200 includes a combustion chamber
enclosure
230 having an outer surface 232 and an inner surface 234 that def nes a
combustion
chamber 229. Thermoelectric system 250 nrlay be mounted to or otherwise
positioned adjacent to outer surface 232 so that therrnoelectric system 250
can use
heat from combustion chamber 229 to generated power. Combustion chamber
enclosure 230 may include inorganic fibers, binders and fillers, and may be
made by
a compression molding method to provide a compression molded article as
disclosed
in U.S. Patent Application Publication No. 200310049575 Al.
Thermoelectric system 250 may include the same or similar features
as disclosed above, including a thermoelectric modu.Ie 252, a heat si~~ 258, a
control
system (not shown), a power storage device (not shown), and a blower (noi
shown).
In a yet further example fizeplace 300 shown in Figure 7, a heat
source S1 that generates a temperature differential isi the thermoelectric
system 50
may be positioned between the combustion chamber enclosure 30 and the outer
enclosure 28 of the fireplace 300. For example, an. electric heater and at
least a
portion of the thermoelectric module 52 of the thermoelectric system maybe
positioned between the combustion chamber enclosure and the outer enclosure.
One example thermoelectric system for a fireplace produces a DC
voltage of about 5 to 1S Y and is capable of grovidi:ng current of about 250
to 1.000
m.P~.. The amount of voltage produced has a roughly inverse relationship to
the
amount of current tlxat can be drawn from the system. In one particular
example, the
system provides a DC voltage of about 13 'V and a currant of about S00 mA.
Tlte
current and voltage specifications for a thermoelect~zc module may also vary
depending on whether the thertno elements are arranged in series or in
parallel.
The thermoelectric system preferably includes two or more thermo
elements or thermo plates connected in series or in parallel. One example
thermoelectric system that provides sufficient power to run a blower and ether
basic
electronic features for a standard residential gas firepIaee includes five
thermo plate
cox3nected in series, such as thermoelectric module Model No. T208119-02 made.
by
Tellurex Corporation of Traverse City, ?vLT, U.S.A.
The present invention should not be considered limited to the
particular exarngles or materials described above, but rather should be
understood to
cover all aspects of the invention as fairly set out in the attached claims.
Various
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modifications, equivalent processes, as well as numerous stntctures to which
the
present invention may be applicable will be readily apparent to those of skill
in the
art to which the present invention is directed upon review of the instant
specification.
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