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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to improvements in a radiant-type
heating system, and more particularly to a tubular insert which may be
inserted into a heat-radiating tube to insulate the tube marginal portion
from the immediate heat of a flame, directed into the tube from an open
end thereof, to preheat air delivered to oxidize the flame tip, and to
reduce the heat gradient along the operative tube length.
2. Description of the Prior Art
In radiant heating systems of the general type disclosed in U.S. Pat. No.
3,310,047, a flame is directed into an open end of an elongated tube. When
so heated, the operative length of the tube emits usable infrared
radiation which is appropriately directed toward the desired space or
object to be heated.
However, several problems accompany the use of such heating systems. First,
it is difficult to heat the tube to a uniform temperature along its entire
operating length because the heat source is arranged at one end. In other
words, by providing the flame at one end of the tube, an undesirable heat
gradiant tends to develop along the tube. Otherwise stated, the tube is
normally hotter proximate the flame than it is at a remote location. Of
course, it is generally desired to heat the tube uniformly along its
length.
Another problem is the difficulty in completely oxidizing the flame so as
to reduce hydrocarbons in the fuel to carbon dioxide and water.
SUMMARY OF THE INVENTION
The present invention provides an improvement particularly adapted for use
in such heating systems, and which is designed to overcome the
aforementioned deficiencies.
The improvement may be used in a heating system having a burner head spaced
from an open end of an elongated heat-radiating tube, and wherein the
burner head is adapted to deliver a fuel to direct and support a flame
within a marginal portion of the tube proximate or adjacent its open end.
The improvement comprises a tubular insert adapted to be positioned within
the tube marginal portion, and further adapted to insulate the tube
marginal portion from the direct heat of the flame and to insure efficient
combustion of the fuel. The insert has a corrugated outer surface
comprising an alternating series of circumferentially-spaced
longitudinally-extending peaks and valleys. The peaks are adapted to
contact the inner surface of the tube to maintain the axis of the insert
substantially coincident with the axis of the tube.
The insert serves to insulate the tube marginal portion from the direct
heat of the flame, and serves to preheat air drawn into the tube and
passing through spaces between the valleys and the tube inner surface to
insure efficient combustion of the fuel.
When viewed in transverse cross-section, the insert may appear as a hollow,
multi-pointed star.
Preferably the insert has at least ten peaks, and has a length sufficient
to substantially embrace the flame, this length being normally at least
three times the nominal diameter of the tube.
Accordingly, one object of the present invention is to provide an insert
for a radiant-type heating system.
Another object is to improve the heat gradiant of a radiant-type heating
system.
Another object is to provide an insert for use in a radiant-type heating
system, and to insure efficient combustion of a flame-supporting fuel.
Still another object is to provide an improved insert capable of preheating
air drawn into a heat-radiating tube.
These and other objects and advantages will become apparent from the
foregoing and ongoing specification, the drawings, and the appended claims
.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary view, partly in central longitudinal vertical
cross-section and partly in side elevation, of a radiant-type heating
system, this view showing the tube, the burner assembly and the baffle
assembly, and particularly showing the insert arranged in the marginal
left end portion of the tube.
FIG. 2 is an enlarged fragmentary transverse vertical sectional view
thereof, taken generally on line 2--2 of FIG. 1, showing the tube marginal
portion and the insert arranged therein, and further showing the
surrounding hood structure in transverse cross-section.
FIG. 3 is an enlarged fragmentary transverse vertical sectional view
thereof, taken generally on line 3--3 of FIG. 1, this view being generally
similar to FIG. 2 but schematically illustrating heat radiating from the
tube being reflected by the hood structure.
FIG. 4 is a further enlarged fragmentary perspective view of the tube
marginal portion, with a portion thereof being cut away to expose the
outer surface of the insert.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
At the outset, it should be clearly understood that like reference numerals
are intended to identify the same elements and/or structure consistently
throughout the several drawing figures, as such elements and/or structure
may be further described or explained by the entire written specification
of which this detailed description is an integral part.
Referring initially to FIGS. 1 and 4, the present invention provides a
tubular insert, generally indicated at 10, which is particularly adapted
for use in a radiant-type heating system, generally indicated at 11, of
the general type disclosed in U.S. Pat. No. 3,310,047, the disclosure of
which is hereby incorporated by reference.
To further describe one possible environment of intended use, the heating
system 11 is shown as including a horizontally-elongated thin-walled tube
12 having a circular cross-section (FIG. 2) with a nominal four-inch
outside diameter and an open left end 13 (FIG. 1). An enclosing wall 14
proximate this tube left end 13 defines an internal compartment 15
communicating with the atmosphere through an opening 16 provided through
its vertical left end, and communicating with the interior of tube 12
through open end 13.
A blower assembly, generally indicated at 18, includes an electric motor
suitably arranged within compartment 15 and having its output shaft
arranged to rotate a blower wheel 19 by which air may be drawn into
compartment 15 through enclosing wall opening 16.
A burner assembly 20 is shown penetrating the enclosing wall 14 to have its
burner head 21 operatively arranged within the compartment 15 to sustain a
flame within tube 12. As shown, this burner head 21 is spaced
longitudinally from the tube open end 13 to permit air to be drawn into
the tube. This burner assembly 20 may be of any suitable type, and
includes the necessary piping and control devices to deliver a supply of
fuel and air, in the relative proportions desired, to burner head 21.
A plurality of nine longitudinally-spaced baffles 22 are positioned within
the tube 12 toward its right end to provide a series flow resistance, and
to induce turbulance in the flow of hot gases passing through this portion
of the tube. Continuing rightwardly in FIG. 1, tube 12 is shown further
provided with a ninety degree elbow 23, a draft hood 24, and an uppermost
vertical conduit 25 leading to exhaust.
A horizontally-elongated hood structure 26 is shown as spaced from but
surrounding the top and side portions of the tube 12 for the operative
portion of its length. This hood structure 26 is open at its bottom (FIG.
3), and acts as a heat reflector to direct heat radiated from the top and
side portions of the tube downwardly through the open bottom of the hood
structure toward a space or object to be heated, as schematically depicted
in FIG. 3.
In operation, blower wheel 19 is rotated in the appropriate angular
direction to draw air into the compartment 15 through opening 16. The
rightward flow of such air passes around burner assembly 20 and may enter
tube 12 through its open left end 13.
A gaseous fuel and air are delivered through the burner assembly 20 and
pass through burner head 21 as a combustible mixture, where it is ignited
and burned within the marginal portion 28 of the tube 12 proximate its
left end 13. The heat and other products of such combustion advance
rightwardly along the tube 12 in a laminar flow until forced into
turbulance by passage through the restricted tortuous conduit defined by
the plurality of longitudinally-spaced baffles 22. After leaving the last
baffle, such flow continues through elbow 23, draft hood 24, and thence to
exhaust.
During such operation, tube 12 becomes heated and emits infrared radiation
which is directed downwardly by the contour of hood structure 26 to heat
the intended space or object, this being schematically depicted in FIG. 3.
However, one problem attendant the use of heating system 11 has been the
heat gradiant along the operative length of tube 12, this operative length
extending from left end 13 to the last baffle 22. It may be readily
appreciated that during the operating heretofore described, the sustained
flame proximate the burner head 21 may cause the tube marginal portion 28
to reach an undesired high temperature. Moreover, in such heating systems,
it is generally desirable to heat the tube 12 as uniformly as possible
along its operative length, so as to radiate an even or uniform heat.
To this and other ends, the present invention provides a tubular insert,
generally indicated at 10, which is adapted to be arranged within the
marginal end portion 28 of the tube, and is further adapted to contain or
confine the flame to insulate the tube marginal portion 28 from the direct
heat of the flame and to insure efficient combustion of the fuel.
Referring particularly to FIG. 4, the presently preferred embodiment of
insert 10 is shown as having a corrugated outer surface 101 comprising an
alternating series of circumferentially-spaced longitudinally-extending
peaks 102 and valleys 103, this appearing as a hollow multi-pointed star
when viewed in transverse cross-section (FIG. 2). The peaks 102 are
adapted to contact the inner surface 29 of the tube to maintain the
longitudinal axis of the insert 10 substantially coincident with the
longitudinal axis of the tube.
The configuration of the outer surface 101 of the insert defines with inner
surface 29 of the tube, a plurality of circumferentially-spaced
longitudinally-extending ports or passageways 104 which severally appear
to have a substantially triangular cross-section when viewed in transverse
cross-section (FIG. 2).
When the insert 10 has been positioned within the tube marginal portion 28,
as shown in FIG. 1, the flame will be substantially confined within the
hollow insert. Thus, the insert 10 is effective to insulate the tube
marginal portion 28 from the direct or immediate heat of the flame. At the
same time, it will be appreciated that the flame will heat the insert,
such that air drawn into the tube 12 through the plurality of passageways
104 will be preheated. After passing through these passageways, this
preheated air will be available to oxidize the flame tip to insure
complete combustion of the fuel.
While the presently preferred embodiment of insert 10 herein illustrated
and described, has ten peaks 102, it will be appreciated that other
configurations might also be adopted to obtain similar results. Moreover,
it is felt that by further increasing the number of such peaks, a more
laminar flow of heat downstream of the insert may be obtained. While the
length of the insert 10 is not deemed as being particularly critical, it
is preferred that the insert be of sufficient length to confine the
substantial length of the flame, such that preheated air passing through
passageways 104 may be delivered to the flame tip.
Thus, it will be seen that the present invention broadly provides a tubular
hollow insert arranged within the marginal end portion of a heat-radiating
tube, and adapted to contain the flame to insulate the tube marginal
portion from the direct heat of the flame and to insure efficient
combustion of the fuel. The insert broadly includes a corrugated outer
surface having an alternating series of circumferentially-spaced peaks and
valleys which extend the full length of the insert. The peaks are adapted
to maintain the tube and insert axes substantially coincident with one
another. Functionally, the insert serves to insulate the tube marginal
portion, and the relatively large area of insert outer surface 101 is
available to preheat air drawn into the tube and passing through the
passageways 104 between the insert outer surface 101 and the tube inner
surface 29 to insure efficient combustion of the fuel.
While a preferred embodiment of the invention has been shown and described,
it will be appreciated by persons skilled in this art that various changes
and modifications may be readily made without departing from the spirit of
the invention which is defined by the following claims.
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