U.S. patent application number 10/996346 was filed with the patent office on 2006-05-25 for space heater with pretreated heat exchanger.
Invention is credited to Glenda Sue Burkett, William W. Burkett.
Application Number | 20060110141 10/996346 |
Document ID | / |
Family ID | 36127477 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060110141 |
Kind Code |
A1 |
Burkett; William W. ; et
al. |
May 25, 2006 |
SPACE HEATER WITH PRETREATED HEAT EXCHANGER
Abstract
A space heater with a linear source of infrared radiant energy
in heat exchange relationship with a heat exchanger formed of
copper or aluminum material. The copper is pretreated to soften the
copper and partially blacken the surface thereof. The aluminum is
anodized and electrolytically colored dark. The space heater is
thermally more efficient than a comparable space heater wherein the
copper or aluminum has not been pretreated. The linear source of
infrared radiant energy and heat exchanger are mounted in a heater
core that is thermally insulated by an air jacket from an exterior
case.
Inventors: |
Burkett; William W.;
(Galena, MO) ; Burkett; Glenda Sue; (Galena,
MO) |
Correspondence
Address: |
GRACE J FISHEL
11970 BORMAN DRIVE
SUITE 220
ST. LOUIS
MO
63146
US
|
Family ID: |
36127477 |
Appl. No.: |
10/996346 |
Filed: |
November 23, 2004 |
Current U.S.
Class: |
392/375 ;
392/356; 392/360 |
Current CPC
Class: |
F24H 3/0405
20130101 |
Class at
Publication: |
392/375 ;
392/356; 392/360 |
International
Class: |
F24H 3/02 20060101
F24H003/02 |
Claims
1. A space heater comprising an exterior case and a heater core
mounted inside the exterior case, said exterior case having an air
inlet for ambient air and an air outlet for heated air, said heater
core having a fan communicating with the air inlet and the air
outlet for moving air through the heater core, at least one linear
source of infrared radiant energy and a heat exchanger mounted in
the heater core, said heat exchanger having first and second sides,
said first side facing and surrounding said at least one linear
source of infrared radiant energy, said heat exchanger being formed
of said copper material pretreated at a temperature and for a time
sufficient to soften the copper material and to partially blacken
the surface of the copper, said space heater further having an air
passageway defining a path of air movement from the air inlet,
along the length of at least one linear source of infrared radiant
energy and along the length of the first side of the heat exchanger
and out the air outlet.
2. The space heater of claim 1 wherein the air passageway further
includes passing the air over the second side of the heat exchanger
before passing out the air outlet.
3. A space heater comprising an exterior case, a heater core
support mounted inside the exterior case, and a heater core
supported by the heater core support, said exterior case having
top, bottom, front, rear and side walls and an air Inlet for
ambient air in the rear wall and an air outlet for heated air in
the front wall, said heater core support comprising a front
mounting panel secured to the top, bottom and side walls of the
exterior case and spaced a distance from the front wall forming an
exhaust chamber, said front mounting panel having an aperture
flowably connecting the heater core to the exhaust chamber, said
heater core support further comprising a rear mounting panel
secured to the top, bottom and side walls of the exterior case and
spaced a distance from the rear wall forming an intake chamber,
said rear mounting panel having an aperture flowably connecting the
heater core to the intake chamber and a fan mounted in the
aperture; said heater core having at least one linear source of
infrared radiant energy and a heat exchanger mounted in the heater
core, said heat exchanger formed of copper material and having
first and second sides, said first side facing said at least one
linear source of infrared radiant energy, said heat exchanger being
pretreated at a temperature and for a time sufficient to soften the
copper material and to partially blacken the surface of the copper,
said space heater further comprising an air passageway defining a
path of air movement from the air inlet through the intake chamber,
over the at least one linear source of infrared radiant energy and
along the first side of the heat exchanger and through the exhaust
chamber to the air outlet.
4. The space heater of claim 3 wherein the heat exchanger is formed
of copper sheet and is heated under ambient conditions at a
temperature between about 850.degree. F. to about 900.degree. F.
for about 2 to 3 hours and then brushed to remove loose
particles.
5. The space heater of claim 3 wherein the linear source of
infrared radiant energy is mounted horizontally in the heater
core.
6. A space heater comprising an exterior case, a heater core
support mounted inside the exterior case, and a heater core
supported by the heater core support, said exterior case having
top, bottom, front, rear and side walls and an air inlet for
ambient air in the rear wall and an air outlet for heated air in
the front wall, said heater core support comprising a front
mounting panel secured to the top, bottom and side walls of the
exterior case and spaced a distance from the front wall forming an
exhaust chamber, said front mounting panel having an aperture
flowably connected to the exhaust chamber, said heater core support
further comprising a rear mounting panel secured to the top, bottom
and side walls of the exterior case and spaced a distance from the
rear wall forming an intake chamber, said rear mounting panel
having an aperture flowably connected to the intake chamber and a
fan mounted in the aperture; said heater core having a plurality of
heating chambers, a copper cylinder and at least one linear
infrared radiant heater mounted in each heating chamber, each
copper cylinder having first and second sides, said first side
facing the one or more of said linear infrared radiant heaters in
said heating chamber, said copper cylinders being pretreated at a
temperature and for a time sufficient to soften the copper material
and to partially blacken the surface of the copper; and said space
heater further comprising an air passageway defining a path of air
movement passing sequentially from the air inlet through the intake
chamber to the heater core, passing in the heater core over the
infrared radiant heaters and the first side of the copper cylinder
and over the second side of the copper cylinder in each heating
chamber to the exhaust chamber, passing from the exhaust chamber
out the air outlet.
7. The space heater of claim 6 wherein each copper cylinder is
formed of copper sheet and is heated under ambient conditions at a
temperature between about 850.degree. F. to about 900.degree. F.
for about 2 to 3 hours and then brushed to remove loose
particles.
8. The space heater of claim 7 wherein each linear infrared radiant
heater is mounted horizontally in the heater core.
9. The space heater of claim 7 wherein the copper sheet is about
0.02 inches thick and has an oxygen content of about 0.028% percent
by weight.
10. The space heater of claim 6 wherein the heater core has top and
bottom walls spaced respectively from the top and bottom walls of
the exterior case and side walls spaced respectively from the side
walls of the exterior case forming an air jacket that with inlet
chamber and outlet chamber insulates the exterior case from
overheating.
11. The space heater of claim 10 further comprising a high
temperature limit switch in the heater core that activates the fan
when the temperature In the heater core has risen to a selected
temperature.
12. The space heater of claim 11 wherein the high temperature limit
switch continues operation of the fan until the temperature in the
heater core has fallen below the selected temperature.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a space heater which
generates heat by passing an electrical current through a linear
source of infrared radiant energy in heat exchange relationship
with a pretreated copper or aluminum heat exchanger.
[0003] 2. Brief Description of the Prior Art
[0004] With the dwindling supply of fossil fuels and their
associated spiraling costs, more homes and businesses are using
space heaters as their primary or secondary heating source. After
safety, the most important feature to be looked for in a space
heater is thermal efficiency. Inefficient systems, such as found in
the prior art, require the use of excess amounts of energy, thus
increasing the cost of operation.
BRIEF SUMMARY OF THE INVENTION
[0005] In view of the above, it is an object of the present
invention to provide a more heat efficient space heater. Other
objects and features of the invention will be in part apparent and
in part pointed out hereinafter.
[0006] A space heater in accordance with the present invention has
a heater core with one or more linear sources of infrared energy,
preferably horizontally mounted. A heat exchanger formed of copper
or aluminum is mounted in the heater core. The heat exchanger is
preferably a cylinder mounted around one or more of the linear
sources of infrared energy.
[0007] When the cylinder is formed of copper, the copper is
pretreated at a temperature and for a time sufficient to soften the
copper and to partially blacken the surface thereof. The
absorptivity and emissivity of the cylinder as a heat exchanger is
improved thereby improving the thermal efficiency of the space
heater. When the cylinder is formed of aluminum, the aluminum is
anodized and electrolytically colored or dyed dark on the inside
surface.
[0008] In a preferred embodiment, the heater core is mounted on a
heater core support within an exterior case. An air jacket is
provided between the heater core and the exterior case such that
the exterior case is thermally insulated.
[0009] Cold air flows through an air inlet in the exterior case
through the heater core such that it passes between the one or more
linear sources of infrared energy and the inside of the cylinder.
Flow is reversed such that the air passes along the outside of the
cylinder. Heated air then exits through an air outlet in the
exterior case.
[0010] The invention summarized above comprises the constructions
hereinafter described, the scope of the invention being indicated
by the subjoined claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0011] In the accompanying drawings, in which several of various
possible embodiments of the invention are illustrated,
corresponding reference characters refer to corresponding parts
throughout the several views of the drawings in which:
[0012] FIG. 1 is a perspective view of the exterior case of a space
heater in accordance with the present invention;
[0013] FIG. 2 is a perspective, exploded view of a heater core
support and a heater core for the space heater;
[0014] FIG. 3 is a perspective, exploded view of the exterior case
and an assembled view of the heater core support and heater core
for the space heater;
[0015] FIG. 4 is a cross-section of the space heater taken along
the plane of 4-4 in FIG. 5; and,
[0016] FIG. 5 is a cross-section of the space heater taken along
the plane of 5-5 in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Referring to the drawings more particularly by reference
character, reference numeral 10 refers to a space heater in
accordance with the present invention. Space heater 10 comprises an
exterior case 12, a heater core support 14 mounted inside exterior
case 12 and a heater core 16 supported by heater core support
14.
[0018] Exterior case 12 is a box-like structure including a front
wall 18, a rear wall 20, a top wall 22, a bottom wall 24 and side
walls 26, 28. An air inlet 30 is provided in rear wall 20 and an
air outlet 32 is provided in front wall 18. Air inlet 30 and air
outlet 32 are covered with protective grilles 34, 36, respectively.
As illustrated in the drawings, front wall 18 and top and bottom
walls 22, 24 may be integrally formed as a wrapper to which side
walls 26, 28 are joined with sheet metal screws 38 or by other
conventional methods of construction such as welding, brazing and
the use of fasteners, or combinations of methods as is known in the
art. Rear wall 20 has an outwardly projecting toe 40 upon which may
be mounted a filter 42 positioned over air inlet 30. Filter 42 may
be attached to rear wall 20 with male and female mating fasteners
44 such as sold under the trademark VELCRO. Filter 42 may be of
conventional construction, for example fiberglass or equivalent
material as is commonly used in furnace filters. It is preferred,
however, that filter 42 be a POLYTRON filter or equivalent.
[0019] A conventional power cord 46 extends from rear wall 20 for
connecting the electrical components within exterior case 12 to a
conventional 110 volt a.c. line. If desired, space heater 10 may
have a power cord strain relief 48 installed in the hole through
which power cord 46 passes. A variable thermostatic control 50 is
also mounted on rear wall 20. Thermostatic control 50 communicates
with the interior of space heater 10 through an opening provided in
rear wall 20. An on-off switch (not shown) may be provided on front
wall 18 or rear wall 20, if desired.
[0020] Exterior case 12 encloses heater core support 14. Heater
core support 14 comprises a front mounting panel 52 and a rear
mounting panel 54 such that heater core 16 is surrounded by an air
jacket 57. Front mounting panel 52 is secured to top wall 22,
bottom wall 24 and side walls 26, 28 and spaced a distance from
front wall 18. The space between front mounting panel 52 and front
wall 18 of exterior case 12 forms an exhaust chamber 56 which is
part of an air jacket 57. An aperture 58 is provided in front
mounting panel 52 above which is mounted a deflector shield 60 for
directing air towards air outlet 32. In similar fashion, rear
mounting panel 54 is secured to top wall 22, bottom wall 24 and
side walls 26, 28 and spaced a distance from rear wall 20. The
space between rear mounting panel 54 and rear wall 20 of exterior
case 12 forms an intake chamber 62, which like exhaust chamber 56
is part of air jacket 57. An aperture 64 is provided in rear
mounting panel 54 into which is mounted a fan 66 for inducting air
into space heater 10 though air inlet 30 in rear wall 20 and
forcing air out through air outlet 32.
[0021] Heater core 16 is supported by front mounting panel 52 and
rear mounting panel 54 a distance below top wall 22 and above
bottom wall 24 of exterior case 12 and a distance from side walls
26, 28. This spacing of heater core 16 from exterior case 12
completes air jacket 57. Air jacket 57 insulates exterior case 12
and prevents overheating. As such, it is possible for space heater
10 to be safely operated with exterior case 12 fitted into a wood
cabinet.
[0022] Heater core 16 comprises a top wall 70, a bottom wall 72 and
side walls 74, 76 and is mounted upon front mounting panel 52 and
rear mounting panel 54, those panels forming the end walls of the
heater core. At least one linear source of infrared radiant energy
78 is mounted between side walls 74, 76. In space heater 10 shown
in the drawings, mountings for three pairs of radiant heaters 78
are provided with the radiant heaters mounted horizontally.
Horizontal mounting of radiant heaters 78 is optimal as this
arrangement increases residence time of the air passing through
space heater 10 by obviating the chimney effect resulting from
vertical mounting.
[0023] Each linear source of infrared radiant energy 78 comprises a
high resistance wire wrapped in a helical configuration. The
helically configured element is suspended within a quartz tube. The
tube is capped with ceramic end pieces or caps 80 by means of which
radiant heater 78 may be mounted in a hole 82 provided in side wall
76 and a hole 84 provided in a support bracket 86 bridging
apertures 88 provided in side wall 74. Electrically conductive
wires pass through holes 82, 84 for energizing radiant heater 78.
The tube may be vacuum sealed and may contain an inert gas. The
quartz tube may be clear, semi-translucent or translucent. In a
preferred embodiment linear source of infrared radiant energy 78
has a clear quartz tube. In a commercial embodiment, each of five
radiant heaters 78 is 250 watt.
[0024] A heat exchanger 90 in the form of a sheet of pretreated
copper or aluminum fashioned into a cylinder is mounted around each
of linear source of infrared radiant energy 78. Mounting tabs 92
are provided on one end of cylinder 90 for attachment of cylinder
90 in aperture 88. Cylinder 90 is shorter than the spacing between
side walls 74, 76 of heater core 16 so that there is a gap between
a free end of cylinder 90 and side wall 76. Each cylinder 90 has a
first or inside surface 94 facing radiant heater 78 and a second or
outside surface 96.
[0025] Divider panels 98 are provided for partitioning the inside
of heater core 16 such that each cylinder 90 is in a separate
compartment. Divider panels 98 are mounted on side wall 76 and are
shorter than the spacing between side walls 74, 76 of heater core
16 so that there is gap between a free end of divider panels 98 and
side wall 74. In the embodiment illustrated in the drawings,
divider panels 98 with side wall 76 form three heating chambers
100.
[0026] When heat exchanger 90 is formed of copper material, the
copper is pretreated at temperature and for a time sufficient to
soften the copper material and to partially blacken the surface of
the copper material. In a commercial embodiment, cylinder 90 is
formed from sheet copper having a thickness of 0.0216 inch and an
oxygen content of 0.028% by weight. Cylinder 90 is heated in an
oven under ambient conditions for several hours at a temperature
from about 850.degree. F. to about 900.degree. F. Any loose
blackened material is removed by dry brushing inside surface 94 and
outside surface 96 of cylinder 90. Mounting tabs 92 are bent over
and cylinder 90 installed in apertures 88 and attached to side wall
74 as described above. Good results have been obtained when
cylinder 90 is heated for two hours at a temperature between about
850.degree. F. and 875.degree. F. After which, cylinder 90 is dry
brushed and then further heated for one hour at 425.degree.. It is
believed that equally good results are obtained when cylinder 90 is
heated for three hours at 875.degree. F. and then dry brushed to
remove any loose particles. Removal of loose particles prevents
them from being swept out air outlet 32 when space heater 10 is
first operated. Pretreatment of the copper improves the heat
efficiency of space heater 10 by increasing the absorptivity and
emissivity of cylinder 90 and roughening inside and outside
surfaces 94, 96 for more turbulent air flow.
[0027] When cylinder 90 is formed of aluminum material, the
aluminum is pretreated by anodizing. During the anodizing process,
a clear film of aluminum oxide is laid down on the aluminum's
surface. For use in space heater 10, inside surface 94 of cylinder
90 is electrolytically colored a dark color to improve the
material's radiant-heat properties, i.e., absorptivity and
emissivity. It will be understood that outside surface 96 may also
be electrolytically colored.
[0028] In a commercial embodiment of space heater 10, a pair of
high temperature limit switches 102, 104 are provided in heater
core 16. First switch 102 is located in heater core 16 close to
front mounting panel 52 where air exits heater core 16 and is a fan
control switch. When the temperature in heater core 16 rises above
110.degree. F., fan 66 is switched on. Delayed starting of fan 66
is preferred such that cold air is not forced through air outlet
32. First switch 102 acts in reverse at the end of a heating cycle
when space heater 10 is shut off. Fan 66 continues to operate until
the temperature drops below 110.degree. F., improving the
efficiency of space heater 10 by extracting residual heat. Second
switch 104 is located in heater core 16 close to fan 66 and is a
safety switch. When the temperature in heater core 16 rises above
225.degree. F., space heater 10 is shut down as a safety feature
while first switch 102 keeps fan 66 running until the temperature
in heater core 16 falls below 110.degree. F. It will be apparent
that the temperatures at which switches 102, 104 operate are
arbitrary and a manner of design choice. Other switches 102, 104
may be used that are triggered at different temperature levels.
[0029] An auxiliary linear source of infrared radiant energy 106
may be mounted between front wall 18 of exterior case 12 and front
mounting panel 52 below air outlet 32. If this additional source of
radiant energy is provided, a heat deflector panel 108 may be added
to front wall 18 to provide a dead air space insulating front wall
18 from overheating. In addition, deflector shield 60 may be
made-of untreated copper and serve as a heat exchanger, absorbing
energy from auxiliary linear source of infrared radiant energy 106.
The auxiliary linear source of infrared radiant energy 106 boosts
the temperature of the air passing out of space heater 10 through
air outlet 32. In addition, radiation from auxiliary radiant heater
106 is reflected by copper deflector shield 60 to provides a
comforting warm glow seen through grille 34 over air outlet 32. It
should be understood that deflector shield 60 may also be formed of
pretreated copper or aluminum but the glow through grille 34 may be
somewhat compromised. In a commercial embodiment of space heater
10, auxiliary linear source of infrared radiant energy 106 is a 250
watt quartz heating tube. Auxiliary radiant heater 106 with the
five radiant heaters 78 in heater core 17 have a combined total
wattage of 1500 and draw about 12.5 amps such that space heater 10
operates on 110 volt a.c. power.
[0030] In operation, thermostat control 50 switches on radiant
heaters 78 and auxiliary radiant heater 106, when present, whenever
the temperature within the environment monitored by the thermostat
drops below a predetermined minimum. Power is also supplied to fan
66 causing the fan to be activated. When high temperature limit
switch 102 is provided, activation of fan 66 may be delayed until
the temperature in heater core 16 has risen to a selected
temperature. This is done so that the air coming from space heater
10 is warm on startup.
[0031] Upon being energized, radiant heaters 78 emit heat rays
which are absorbed and reemitted by cylinders 90. Cylinders 90 are
thereby heated. Activation of fan 66 causes air to be circulated
through space heater 10. The circulating air is initially forced
into intake chamber 62 through air inlet 30. From intake chamber
62, it is pulled through aperture 64 in rear mounting panel 54 into
that portion of air jacket 57 between heater core 16 and exterior
case 12. Air jacket 57 forms a plenum from which air is forced
through cylinders 90 passing over radiant heaters 78 and inside
surface 94 of cylinders 90. Upon reaching side wall 76 of heater
core 16, the air is deflected back along outside surface 96 of
cylinder 90. As the air passes through heating chambers 100, the
air is heated by radiant energy from radiant heaters 78 and by
energy reemitted by cylinders 90 before it exits through the gap
between the ends of divider panels 98 and side wall 74.
[0032] Heated air coming through aperture 58 in front mounting
panel 52 passes into exhaust chamber 56 where it may be further
heated by auxiliary radiant heater 106 before exiting through air
outlet 32. Deflector shield 60 in addition to reflecting radiation
from auxiliary radiant heater 106 such that a glow is seen through
grille 34 and serving as a heat exchanger, also channels the flow
of air such that it exits horizontally through air outlet 32. Air
directed in this manner has a better chance of mingling with
ambient air such that there is a more uniform dispersion of heat
and less air temperature stratification between floor and ceiling
level.
[0033] Once the monitored temperature rises above the preselected
minimum, thermostatic control 50 switches radiant heaters 78 and
auxiliary heater 106, when present, off. High temperature limit
switch 102 continues to operate fan 66 until the air passing
through heater core 16 falls below a preselected level thus
completing a heating cycle.
[0034] A single space heater 10 in accordance with the present
invention that is commercially available can effectively heat up to
800 square feet and is capable of safely increasing the temperature
of the air drawn through the unit by approximately 120.degree. F.
Thermal efficiency of space heater 10 is effected by pretreatment
of copper cylinders 90. In the commercial embodiment described
above, space heater 10 is 9% more thermally efficient than a space
heater wherein the copper cylinders have not been pretreated. This
improvement results in 9% more heat from the same amount of power
used. Other efficiencies result from stripping residual heat from
heater core 16 on shut down with high temperature limit switch 102
and from the horizontal and serpentine passage of the air through
cylinders 90 and then back along cylinders 90 increases the dwell
time of the air in heater core 16. It will be apparent that other
design features discussed above also contribute to the space
heater's thermal efficiency.
[0035] In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous
results attained. As various changes could be made in the above
constructions without departing from the scope of the invention, it
is intended that all matter contained in the above description or
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
* * * * *