U.S. patent application number 14/159006 was filed with the patent office on 2015-07-23 for infrared gas heater.
The applicant listed for this patent is Martin BRICE, Tharwat SAAD, Eddie WILSON. Invention is credited to Martin BRICE, Tharwat SAAD, Eddie WILSON.
Application Number | 20150204538 14/159006 |
Document ID | / |
Family ID | 53544457 |
Filed Date | 2015-07-23 |
United States Patent
Application |
20150204538 |
Kind Code |
A1 |
BRICE; Martin ; et
al. |
July 23, 2015 |
Infrared Gas Heater
Abstract
The invention is directed to an infrared gas heater for a
building, comprising: a first straight energy emitter tube; a
U-shaped energy emitter tube connect to said first straight, energy
emitter tube; a second straight, energy emitter tube having and end
connected to said U-shaped energy emitter tube; a reflector system
for reflecting heat energy toward the floor of a building; a frame
having rollers mounted thereon, said rollers for supporting said
first and second straight, energy emitter tubes; a gas heating
source connected to the first straight, energy emitter tube at the
end opposite the U-shaped energy emitter tube; and whereby the
second straight, energy emitter tube at the end opposite the
U-shaped energy emitter tube is a gas exhaust.
Inventors: |
BRICE; Martin; (Charlotte,
NC) ; SAAD; Tharwat; (Huntersville, NC) ;
WILSON; Eddie; (Charlotte, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BRICE; Martin
SAAD; Tharwat
WILSON; Eddie |
Charlotte
Huntersville
Charlotte |
NC
NC
NC |
US
US
US |
|
|
Family ID: |
53544457 |
Appl. No.: |
14/159006 |
Filed: |
January 20, 2014 |
Current U.S.
Class: |
126/91A |
Current CPC
Class: |
F24H 3/087 20130101;
F24D 19/062 20130101; F24D 5/08 20130101; F24D 2200/04 20130101;
F23C 3/002 20130101 |
International
Class: |
F23C 3/00 20060101
F23C003/00; F24H 3/08 20060101 F24H003/08; F24D 19/06 20060101
F24D019/06; F24D 5/08 20060101 F24D005/08 |
Claims
1. An infrared gas heater for heating a building, comprising: two
straight, energy emitter tubes; a U-shaped energy emitter tube
connect to one end of each of the two straight, energy emitter
tubes; two lower reflectors, wherein one is positioned above each
of said straight, energy emitter tubes; an upper reflector
positioned above said two lower reflectors, thus creating an air
space; a support frame for supporting said two straight, energy
emitter tubes, said U-shaped energy emitter tube, said two lower
reflectors, and said upper reflector; one flow restrictor,
positioned within the energy emitter tube at the end adjacent the
U-shaped energy emitter tube; two fasteners to securely position
each of the straight, energy emitter tubes and each end of said
U-shaped energy emitter tube on said frame; at least two rollers
positioned on said frame, wherein at least one of said rollers
support a straight, energy emitter tube, thus permitting each
straight, energy emitter tube to expand and contract relative to
said frame, to allow for different expansion and contraction rates;
a gas heating source positioned adjacent one end of one of said
straight, energy emitter tube opposite said U-shaped energy emitter
tube; and an exhaust outlet at the other end of the other straight,
energy emitter tube, opposite said U-shaped tube.
2. The infrared gas heater of claim 1, wherein said lower
reflectors are asymmetrical and shaped to reflect energy away from
said straight, energy emitter tubes.
3. The infrared gas heater of claim 2, wherein said asymmetrical
lower reflectors are M-shaped in cross section, wherein a leg of
the M-shaped cross section further away from a longitudinal center
line of said frame is more horizontal than a leg of said
asymmetrical reflector nearest said longitudinal center line.
4. The infrared gas heater of claim 1, wherein said asymmetrical
reflectors and said symmetrical reflector are constructed from
aluminum having at least a 95% reflectance value.
5. The infrared gas heater of claim 1, wherein said rollers are
constructed of metal and can withstand the energy emitted from the
straight, energy emitter tubes.
6. The infrared gas heater of claim 1, wherein said lower
reflectors are positioned to divert the energy emitted from the
straight, energy emitter tubes from one another.
7. The infrared gas heater of claim 3, wherein said frame includes
a longitudinal metal holder to support a leg of each asymmetrical
reflectors nearest said longitudinal center line, and said
asymmetrical reflectors are notched to allow free expansion and
contraction.
8. The infrared gas heater of claim 1, wherein said asymmetrical
reflectors enclose the top and sides of the straight, energy
emitter tubes thus reflecting heat energy toward a floor of a
building.
9. The infrared gas heater of claim 8, wherein said symmetrical
reflector encloses the top, and sides of said asymmetrical
reflectors thus reflecting heat energy toward a floor of a
building.
10. The infrared heater of claim 1, wherein said air space is an
insulating barrier to reduce convention loss.
11. The infrared heater of claim 10, wherein said air space is
filled with a physical insulation material.
12. An infrared gas heater for a building, comprising: a first
straight energy emitter tube; a U-shaped energy emitter tube
connect to said first straight, energy emitter tube; a second
straight, energy emitter tube having and end connected to said
U-shaped energy emitter tube; a reflector system for reflecting
heat energy toward the floor of a building; a frame having rollers
mounted thereon, said rollers for supporting said first and second
straight, energy emitter tubes; a gas heating source connected to
the first straight, energy emitter tube at the end opposite the
U-shaped energy emitter tube; and whereby the second straight,
energy emitter tube at the end opposite the U-shaped energy emitter
tube is a gas exhaust.
13. The infrared gas heater of claim 12, wherein said reflector
system includes one or more end plates extending downwardly
perpendicularly across each end of the first and second straight,
energy emitter tubes.
14. The infrared gas heater of claim 13, wherein said reflector
system also includes a pair of asymmetric downwardly directing
reflectors, one covering the top and sides of each straight, energy
emitter tube.
15. The infrared gas heater of claim 14, wherein said reflector
system also includes a symmetrical reflector covering the top and
outsides of the asymmetrical reflectors, wherein said one or more
end plates, said pair of asymmetrical reflectors, and said
symmetrical reflector have bottom edges which are level with the
bottom of said first and second straight, energy emitter tubes.
16. The infrared gas heater of claim 12, wherein said rollers
include at least 2 each of each straight, energy emitter tubes.
17. The infrared gas heater of claim 12, wherein said frame
reflector system is mounted on said frame.
18. An infrared gas heater for a building, comprising: a first
straight energy emitter tube; a U-shaped energy emitter tube
connect to said first straight, energy emitter tube; a second
straight, energy emitter tube having and end connected to said
U-shaped energy emitter tube; a reflector system for reflecting
heat energy toward the floor of a building; a frame for mounting
said first and second straight, energy emitter tubes and said
reflector system; said reflector system includes one or more end
plates extending downwardly perpendicularly across each end of the
first and second straight, energy emitter tubes, said reflector
system also includes a pair of asymmetric downwardly directing
reflectors, one covering the top and sides of each straight, energy
emitter tube; said reflector system also includes a symmetrical
reflector covering the top and outsides of the asymmetrical
reflectors, thus creating an air space; wherein said one or more
end plates, said pair of asymmetrical reflectors, and said
symmetrical reflector have bottom edges which are level with the
bottom of said first and second straight, energy emitter tubes; a
gas heating source connected to the first straight, energy emitter
tube at the end opposite the U-shaped energy emitter tube; and
whereby the second straight, energy emitter tube at the end
opposite the U-shaped energy emitter tube is a gas exhaust.
19. The infrared gas heater of claim 18, whereby said bottom edges
of said pair of asymmetric downwardly directing reflectors have a
pair of bottom edges positioned adjacent one another.
20. The infrared gas heater of claim 18, further comprising a
longitudinal metal holder connect to said frame and positioned to
receive said pair of bottom edges positioned adjacent one another
and secure these pair of bottom edges with the frame.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of infrared gas
heaters employed to heat large enclosed space such as a warehouse,
gymnasium, aircraft hanger, commercial applications such as retail
stores, or agriculture buildings for raising chicken or turkey
indoors, etc. The infrared heater of the present invention
comprises a U-shaped tube and dual straight tubes with energy input
at one end and exhaust at the other end. The key features are
asymmetric double reflectors over the dual straight tubes, a
symmetric reflector over the asymmetric double reflectors,
placement of flow restrictors within the tubes at the U-shaped tube
end of the heater, and rollers supporting the dual straight tubes
before and after the U-shaped tube. Other features will also be
known from the following disclosure.
PRIOR ART
[0002] Infrared gas heaters are known. They are available in many
shapes such as a single tube, a U-shaped tube having dual straight
tubes, multiple U shapes, and an L configuration. The key goal for
all infrared heaters is to deliver more radiant heat energy to the
floor level of a building to maintain the themial mass on the floor
level and to obtain quicker recovery when doors at the floor level
are opened and closed frequently. A repeatable testing method
documented in Standard EN416-2 has been developed to test the
efficiency of the infrared heaters. Infrared heaters produce
radiant heat energy, convection heat energy, and heat energy that
stems from products of combustion that are exhausted outside the
building, sometimes referred to as flue gas. As stated above the
key goal is to maximize the radiant heat energy and maintain it at
floor level. Current emphasis of consumer demand of heating
products that use fossil fuels is to minimize the impacts on the
environment by reducing the overall energy consumption and
therefore reducing the CO.sub.2 (carbon dioxide) emissions. The
invention disclosed in this application are new methods of
construction specifically relevant to a radiant heater which is
high efficiency and reduces overall the CO.sub.2 (carbon dioxide)
emissions for the operation of a building heating system.
[0003] This invention is directed to U-shaped tube with dual
straight tubes, where 2 pieces of straight tube are connected to a
U-shaped tube. Typical construction are for an energy input at one
end and an exhaust at the other end or energy input and combustion
air at the same end. The known U-shaped tube with dual straight
tubes may include a flow restrictor which is installed in the
exhaust end to recover heat energy just before it is exhausted.
[0004] There are many problems with U-shaped tube with dual
straight tubes infrared heaters. First the dual tubes have
different expansion rates due to the heat energy differences in
both tubes. The tubes therefore have to be able to expand and
contract independently. If they are restricted from freedom to
expand and contract then the force of the expansion induced by the
higher operating temperatures of a high efficiency heater may cause
any or all of the following issues; bowing of the emitter tubes,
distortion of the suspension brackets, or distortion of the
reflectors. Second, the heat energy inlet tube also heats the
exhaust tube. This is acerbated by the flow restrictor at the
exhaust end where the back pressure slightly slows the gas flow
rate allowing the heat energy inlet tube more time to transfer heat
to the exhaust gas. Therefore energy efficiency is lost at this
point. Typical reflectors above the dual tubes reflect the heat
down and back onto the tubes. This causes the heat energy to be
concentrated on the dual tubes heater thereby blocking some heat
from getting to the floor level. The heat energy is not widely
distributed when the reflectors bounce the heat back on the tubes.
This is another loss in efficiency. Standard infrared gas heaters
having a U-shaped tube with dual straight tubes typically transfer
50% of the heat energy to the floor level by radiant energy and
another 27% by convection heat energy. This means about 23% is
exhaust flue gas. The exhaust is also another point of loss
efficiency.
[0005] Thus there is a need to reduce the consumption of fossil
fuels by improving the energy efficiency of infrared heaters having
a U-shaped tube with dual straight tubes. These and other problems
are overcome with the present invention.
[0006] The radiant heat output from a body can be calculated as
Q=F.epsilon. F.sub.G .sigma. A (T.sub.1.sup.4-T.sub.2.sup.4).
[0007] Radiant Output Q is expressed in Btu/hr/ft.sup.2.
[0008] F.epsilon. is the emissivity function where a black body is
equal to 1.0 and all other surfaces are less than 1.0. In the case
of radiant tube heaters this is the emissivity of the emitter tubes
used to radiate the heat to the receiver.
[0009] F.sub.G is the geometric view factor defined as how well the
receiver can "see" the energy being transmitted in the infrared
wavelength from the source.
[0010] .sigma. is the Stefan Boltzmann constant
0.1714.times.10.sup.-8 BTU/Hr.sup.-1 Ft.sup.31 2 R.sup.-4
[0011] A is the surface area of the heat source which is the
emitter tubes.
[0012] T.sub.1.sup.4-T.sub.2.sup.4 is the absolute temperature of
the heat source to the power of four minus the absolute temperature
of the receiver to the power of 4. In terms of radiant heat energy
transmission, increasing the surface area of the source by as much
temperature/heat energy as possible is the critical multiplier to
increase the overall radiant output.
SUMMARY OF THE INVENTION
[0013] In the broadest sense, the present invention is directed to
an infrared gas heater for a building, comprising: [0014] a first
straight energy emitter tube; [0015] a U-shaped energy emitter tube
connect to said first straight, energy emitter tube; [0016] a
second straight, energy emitter tube having an end connected to
said U-shaped energy emitter tube; [0017] a flow restrictor within
the energy tube in close proximity to the U-shaped emitter tube;
[0018] a reflector system for reflecting heat energy toward the
floor of a building; [0019] a frame having rollers mounted thereon,
said rollers for supporting said first and second straight, energy
emitter tubes; [0020] a gas heating source connected to the first
straight, energy emitter tube at the end opposite the U-shaped
energy emitter tube; and [0021] whereby the second straight, energy
emitter tube at the end opposite the U-shaped energy emitter tube
is a gas exhaust.
[0022] In another broad sense, the present invention is directed to
an infrared gas heater for a building, comprising: [0023] a first
straight energy emitter tube; [0024] a U-shaped energy emitter tube
connect to said first straight, energy emitter tube; [0025] a
second straight, energy emitter tube having and end connected to
said U-shaped energy emitter tube; [0026] a flow restrictor within
the energy tube in close proximity to the U-shaped emitter tube;
[0027] a reflector system for reflecting heat energy toward the
floor of a building; [0028] a frame for mounting said first and
second straight, energy emitter tubes and said reflector system;
[0029] said reflector system includes one or more end plates
extending downwardly perpendicularly across each end of the first
and second straight, energy emitter tubes, said reflector system
also includes a lower pair of asymmetric downwardly directing
reflectors, one covering the top and sides of each straight, energy
emitter tube; said reflector system also includes an upper
symmetrical reflector covering the top and outsides of the lower
asymmetrical reflectors; [0030] wherein said one or more end
plates, said pair of lower asymmetrical reflectors, and said upper
symmetrical reflector have bottom edges which are level with the
bottom of said first and second straight, energy emitter tubes,
wherein the air space between said upper and lower reflectors
insulate the reflector system to reduce convection losses from said
lower reflectors which increases the temperature around said energy
emitter tubes; [0031] a gas heating source connected to the first
straight, energy emitter tube at the end opposite the U-shaped
energy emitter tube; and [0032] whereby the second straight, energy
emitter tube at the end opposite the U-shaped energy emitter tube
is a gas exhaust.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The drawings are to aid in the understanding of the
invention, but are not meant to limit the scope of the invention
beyond the broad scope of the claims. While the drawing may show
relative sizes of the components, it is also within the scope of
the invention to realize that infrared gas heaters of the present
invention can easily be produced in different sizes with different
BTU outputs.
[0034] The present invention is illustrated and described herein
with reference to the various drawings of exemplary embodiments, in
which like reference numbers denote like system components,
respectively, and in which:
[0035] FIG. 1 is an exploded, perspective view of infrared gas
heater of the present invention.
[0036] FIG. 2 is a cross-sectional end view illustrating the shape
of the asymmetrical reflectors as well as the symmetrical
reflector.
[0037] FIG. 3 is an exploded partial view of just the U-shaped
tube, the dual straight tubes and the flow restrictors that are
within the dual straight tubes.
[0038] FIG. 4 is a cross sectional view illustrating the support of
the dual straight tubes on rollers.
[0039] FIG. 5A is an end view of M-shaped asymmetric reflector
30.
[0040] FIG. 5B is an end view of M-shaped asymmetric reflector
28.
[0041] FIG. 5C is a perspective view illustrating the overlap of an
asymmetrical reflector.
[0042] FIG. 6 is a graph of the efficiency of the present invention
versus a standard infrared gas heater.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] While all the components of the infrared heater are commonly
made of metal, the reflectors are constructed from highly
reflective aluminum which has a reflectivity of about 96 to 99%.
Other reflector materials such as aluminized steel or stainless
steel have a reflectivity of about 80%, and stainless steel
reflectors drops in reflectivity after 3 days of operation reducing
the radiant efficiency by 3.1% due to discoloration from the heat.
Gold plated metal has a reflectivity of about 99% but costs make it
ridiculously expensive. Accordingly highly reflective aluminum is
the best material for constructing the reflectors at a reasonable
price. Aluminum reflectors are commonly used in the construction of
radiant tube heaters where the reflectors are un-insulated, where
the emitter tubes are substantially in close proximity to the
reflectors the typical maximum temperature of aluminum reflectors
arranged in single layer is 450.degree. F., at this temperature the
reflector material is still relatively strong and able to support
its own weight without deformation. In the case that dual upper and
lower aluminum reflectors are used the insulating effect of the
upper reflector increases the lower reflector temperature to
750.degree. F., this increase in temperature significantly reduces
the strength of the aluminum reflector and increases the expansion
which takes place. In order to maintain coverage of the emitter
tubes along the length of the heater the aluminum reflectors must
be overlapped and remain stable during expansion and
contraction.
[0044] As illustrated in FIG. 1, the infrared heater 10, has dual
straight emitter tubes 12 and 14 that are secured to the U-shaped
emitter tube 16. These emitter tubes are typically made from high
temperature material such as aluminized steel, stainless steel and
titanium aluminum alloy coated steel to withstand the high
temperatures of the heater. These emitter tubes are typically
coupled together to form the shape shown in FIG. 1. The emitter
tubes 12, 14, and 16 are supported on two or more cross supports
18. The number of cross supports employed depend on the length of
the dual straight emitter tubes 12 and 14. Thus the size of the
infrared heater can vary depending on the length and diameter of
the emitter tubes. The longer the overall length, the more heat
energy necessary to raise the temperature of the emitter tubes and
therefore the gas heating source 20 can be made correspondingly
bigger.
[0045] As shown in FIG. 1, three cross supports 18a, 18b and 18c
are present. The cross support 18c adjacent the U-shaped emitter
tube 16 has a U-shaped bolt and nut 22 which tightly secures one
end of each of the dual straight tubes 12 and 14, and the U-shaped
emitter tube 16 to one another, as shown in FIG. 2. The other cross
supports 18a and 18b loosely support the dual straight tubes 12 and
14 because the U-shaped bolts and nuts 24a and 24b are not tightly
securing the dual emitter tubes 12 and 14 to the corresponding
cross supports 18a and 18b, as shown in FIG. 4. Since the gas
heating source 20 is located at one end of straight emitter tube
12, it is plain to see that the emitter tube 12 will be hotter than
emitter tube 14. Since the U-Shaped tube is secured tightly, the
loose fit at all other points along the length of the emitter tubes
12 and 14 allows the dual tubes to expand (relative to the secured
end) in a direction away from the U-shaped emitter tube 16 as they
heat up during use. An 15 foot long straight emitter tube 12
expands almost 3/4 inched longer than straight emitter tube 14. To
aid in the different expansion rates, the cross supports 18a and
18b include rollers 26 as seen in FIG. 4 (shown only with respect
to cross support 18a, but 18b is identical). The rollers 26 on
cross supports 18a and 18b support the emitter tube 12 and another
set of rollers 26 support the emitter tube 14. The rollers 26 allow
the emitter tubes 12 and 14 to expand or contract relative to the
secured cross support 18c, where the dual straight emitter tubes 12
and 14 and the U-shaped emitter tube 16 are fixedly secure.
[0046] As shown in FIGS. 1 and 2, the dual straight emitter tubes
12 and 14 are covered lengthwise respectively by M-shaped
asymmetric lower reflectors 28 and 30, as also shown in FIGS. 5A
and 5B. The M-shaped lower reflectors 28 and 30 are spaced above
the emitter tubes 12 and 14 and spaced above the U-shaped bolts 22.
This prevents the reflectors 28 and 30 from distorting due to
excessive temperature--especially lower reflector 28 which is
positioned over the hotter emitter tube 12. The outside walls 32 of
reflectors 28 and 30 are more horizontal than inside walls 34, thus
making these lower reflectors asymmetric in shape. The M-shaped
lower reflectors 28 and 30 reflect the radiant heat around the
emitter tubes 12 and 14 to more fully direct and spread the radiant
heat energy to the floor level. Further, each of the outside walls
32 and the inside walls 34 of lower reflectors 28 and 30 extend to
about the bottom of each emitter tube 12 and 14. This arrangement
insures that emitter tube 12 will not transfer heat energy to the
exhaust emitter tube 14, especially just before the exhaust gas in
emitter tube 14 exits the heater. Lastly the outside walls 32
spread the radiant heat energy toward the floor level in a larger
pattern since the outside walls 32 are more horizontal than inside
walls 34, as seen in FIGS. 5A and 5B. The vertical portion 36 of
the cross supports 18a,b,c as shown in FIG. 1 act to guide the
outside walls 32 when they expand and contract independently from
each other and the rest of the system. To guide the inside walls 34
during expansion and contraction, they are inserted into a T-shaped
extrusion bar 38. The T-shaped extrusion bar 38 is positioned
between, and extends the length of the emitter tubes 12 and 14. It
is supported by and secured to the cross supports 18a,b,c. To cover
the length of the emitter tubes 12 and 14 with a reflector profile,
M-shaped lower reflectors 28 and 30 overlap the next pair of
M-shaped lower reflectors. As the preferred material is aluminum
this overlap 58 as shown in FIG. 5C must allow the M-shaped lower
reflectors to freely move, where if they are the same profile shown
in FIG. 5A, they will become interlocked and the expansion during
heating will result in distortion. To enable the M-shaped lower
asymmetric reflectors to freely expand and contract without binding
to each other a notch 56 is made in one end of both outside walls
32 and inside walls 34 of the M-shaped asymmetric reflectors. Thus
the M-shaped lower asymmetric reflectors are supported but can
still expand and contract independently from each other and from
the emitter tubes 12 and 14 during heating and cooling.
[0047] As shown in FIG. 1, the U-shaped emitter tube 16 is covered
by an inner reflector 40 which directs radiant heat energy downward
to the floor level. Additionally a pair of end cap reflectors 42
and 44 prevents the radiant heat from escaping out the ends of the
infrared heater. End cap 42 has a pair of upside down U-shaped
holes 46 to allow for the emitter tubes 12 and 14 to slide
(expand/contract) through the end cap and connect to the gas
heating source 20 and the exhaust opening 48, which may include
sufficient piping to exit beyond the interior of the building.
Since the end cap reflectors 42 and 44 extend to the bottom of the
emitter tubes 12 and 14, all the heat energy is retained to
maintain a high temperature around the emitters and direct the heat
energy downwardly.
[0048] Lastly a symmetrical upper reflector 50 is positioned above
and around the M-shaped asymmetric lower reflectors 28 and 30 and
the lower reflector 40 over and around the U-shaped emitter tube,
as shown in FIGS. 1 and 2. This outer reflector is supported by
brackets 52, which are secured to the M-shaped asymmetric lower
reflectors 28 and 30, in a manner to create an insulation air gap
62 above and around the reflectors 28 and 30. Symmetrical upper
reflector 50 traps convection heat between it and the asymmetrical
reflectors 28 and 30 thereby preventing more convection heat
escaping from the back of the asymmetric lower reflectors 28 and 30
which in turn maintains a higher emitter temperature along the
length of the heater. This improves the overall efficiency of the
infrared gas heater 10, because maintaining high emitter
temperatures (source temperature T.sub.1) over as much surface area
of possible will give the most gain in radiant heat output. Typical
material thickness of the M-shaped asymmetric lower aluminum
reflectors 28 and 30 is 0.025'' to 0.032''. If thicker aluminum
material or Rigidized.RTM. aluminum is used then physical
insulation can be used in the air gap space 62 to reduce convection
losses from the back of M-shaped asymmetric lower aluminum
reflectors 28 and 30.
[0049] FIG. 3 illustrates the placement of flow restrictors 54
within the dual straight emitter tubes 12 and 14, near the end
where these emitter tubes connect to the U-shaped emitter tube 16.
Although any shape flow restrictor will work in the present
invention, the bent, zigzag flow restrictors 54 work well. The flow
restrictors cause a back pressure and turbulence within the emitter
tubes 12 and 14, and create a bigger thermal mass in the area of
the U-shaped emitter tube 16. This aids in exchanging more heat
energy from the gas to the emitter tube and thus increasing the
temperature of the emitter tubes 12 and 14 which in turn increases
the measured radiant output in these sections.
[0050] In contrast thereto, the standard infrared gas heaters place
the flow restrictors only in emitter tube 14 adjacent the exhaust
48. This propagates heat exchange between gas and the emitter tube
14 where the gas is significantly cooled and therefore does not
have the same gain in emitter tube temperature. Additionally the
exhaust gas is heated due to its proximity to the gas source 20 and
more heat energy flows out the exhaust. This is clearly illustrated
by FIG. 6. The solid line is a measure of the energy below the
firing emitter tube 12, while the dashed line is a measure of the
heat energy under the exhaust emitter tube 14. In the standard
heater, the dashed line increases as it approaches the exhaust
indicating an increase in heat energy just before the flue gas
exits to the atmosphere. Contrarily for the present invention the
solid line is highest at the gas source and tapers as it approached
the U-shaped emitter tube 16. Then the two flow resistors 54 just
before and just after the U-shaped emitter tube increase the heat
energy due to the increased turbulence, back pressure and the
thermal mass of the flow restrictors 54. Also note the height of
the solid line at the gas source 20. The total area under this
curve (of the dark line) is much larger that the total area under
the curve of the standard heater. This means more energy is being
transferred to the floor level and much less energy is escaping out
the flue. In fact the temperature of the flue gas from the present
invention is about half that of the standard heater. These two
charts explain the key results obtained using the present
invention. Moreover, the present invention heater known as the
"NXU" was a 175,000 BTU heater and it was compared to a 200,000 BTU
standard heater. Those skilled in the art would have readily
anticipated that the NXU heater should have a much smaller area
under the curve of the solid and dashed lines, than the standard
heater solid and dashed areas under the curve for the higher BTU
heater. Also the standard heater has a radiant energy at floor
level of about 50%. On the other hand, the present invention as a
radiant energy at floor level between 65 and 69%.
[0051] Further, note that the heated gas can either be pushed
through the emitter tubes 12, 14, 16, or it can be pulled through
the emitter tubes 12, 14, 16 depending merely on the position of
the blower. As indicated via FIG. 1, the blower is associated with
the gas heating source 20 and thus the gas is blown or pushed
through the emitter tuber 12, 14, and 16. On the other hand, the
exhaust 48 could contain the blower such that the gas in the
emitter tubes 12, 14, 16 are pulled therethrough.
[0052] Thus it is apparent that there has been provided, in
accordance with the invention, an improved infrared gas heater that
fully satisfies the objects, aims and advantages set forth above.
While the invention has been described in conjunction with specific
embodiments thereof, it is evident that many alternatives,
modifications, and variations will be apparent to those skilled in
the art of radiant heaters with dual straight emitter tubes 12 and
14 and the U-shaped emitter tube 16 in light of the foregoing
description. Accordingly, it is intended to embrace all such
alternatives, modifications, and variations as fall within the
spirit and broad scope of the appended claims
* * * * *