Note: Descriptions are shown in the official language in which they were submitted.
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HEATING DEVICE
The invention relates to a heating device according to the
preamble of claim 1.
A heating device of the type mentioned at the outset is
known from the patent document EP 0 632 239 Al. This
heating device consists of a combustion chamber and a gas
flue configured for guiding hot exhaust gas generated in
the combustion chamber, wherein this has an inlet region
and an outlet region and is configured connected to the
combustion chamber via the inlet region and wherein heat
transfer ribs having a wall thickness are arranged in the
gas flue for transfer of heat from the hot exhaust gas to
the gas flue. These heat exchange ribs, which can be
formed, for example, as an aluminum extrusion press profile
or also from a folded sheet, thereby extend in the cross-
section unchanged from the inlet region to the outlet
region. The gas flue itself is surrounded externally in a
known manner by the heater circuit water flowing through
from the heating device.
The invention is based on the object of improving a heating
device of the type mentioned at the outset. In particular,
a heating device with a further improved heat transfer in
the region of the gas flue from the exhaust gas to the
heater circuit water is to be provided.
This object is achieved with a heating device of the type
mentioned at the outset by the features listed in the
characterizations of patent claim 1.
According to the invention, it is thus provided that, on
the side of the inlet region, the wall thickness of the
heat transfer ribs and/or the distances of the heat
transfer ribs to one another are optionally configured
greater than on the side of the outlet region.
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In other words, the solution according to the invention is
distinguished by the fact that structural measures are
taken on the gas flue which take account of an exhaust gas
flow cooling between the inlet region and outlet region. On
the side of the inlet region, i.e., where the temperature
of the exhaust gas is still comparatively high, a thicker-
walled heat transfer rib is optionally used as at the
outlet region and/or a larger distance between the heat
transfer rib than at the outlet area is selected with
regard to the larger gas volume at higher temperatures at
the inlet area. These measures lead, in particular in
combination with one another, which will be explained in
more detail below, to a gas flue optimally adapted to the
respective temperature of the exhaust gas cooling in the
gas flue course.
The alternative solution, which lies in the hand with
respect to the variation of the wall thickness, namely to
simply provide a temperature-resistant material on the side
of the inlet region as on the outlet region, is thereby not
intended to solve the problem in so far as the processing
of different materials in the course of the gas flue would
be complicated and predictably problematic due to different
thermal expansion of the different materials.
Other advantageous further developments result from the
dependent patent claims.
The heating device according to the invention, including
its advantageous further developments according to the
dependent patent claims, is explained in more detail in the
following with the aid of the illustrative representation
of various exemplary embodiments.
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It shows
Figure 1 schematically the heating device according to the
invention with a combustion chamber, having four
gas flues surrounded by heater circuit water, and
having an exhaust gas collecting chamber;
Figure 2 schematic sectional view of the four gas flues
according to Figure 1 at the level of the inlet
region (section A-A);
Figure 3 schematic sectional view of the four gas flues
according to Figure 1 at the level of the outlet
region (section B-B);
Figure 4 in perspective, a half-open gas flue having a
total of three zones;
Figure 5 a sectional enlargement for the embodiment
example according to Figure 4; and
Figure 6 also enlarged (and also half-opened) a further
embodiment having webs between the heat transfer
ribs on the inlet region side.
The heating device illustrated in the figures consists, in
a manner known per se, of a combustion chamber 1 and of a
gas flue 2 configured for guiding hot exhaust gases
generated in the combustion chamber 1 with an extra burner
not shown, wherein this has an inlet region 2.1 and an
outlet region 2.2 and is configured connected to the
combustion chamber 1 via the inlet region 2.1, and wherein
heat transfer ribs 3 made of a metallic material having a
wall thickness are arranged spaced from each other on the
gas flue 2 for the heat transfer from the hot exhaust gas
to the gas flue 2.
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As in the initially mentioned prior art, in the heating
device according to the invention, in order to be able to
discharge a sufficient amount of exhaust gas from the
combustion chamber 1, it is provided that the combustion
chamber 1 is configured connected to a plurality (here
four) of parallel gas flues 2 through which the exhaust gas
flows. The gas flue 2 itself has a (approximately)
rectangular cross-sectional area with a length and a width,
wherein the length corresponds to a multiple of the width.
Furthermore, it is provided, in a manner known per se, that
the gas flue 2 is configured connected to an exhaust gas
collecting chamber 4 via the outlet region 2.2.
Furthermore, the combustion chamber 1 is thereby arranged
above the gas flue 2 and this above the exhaust gas
collecting chamber 4. The exhaust gas collecting chamber 4
is in turn connected in a known manner (and therefore not
specifically shown) to a chimney of a building or the like.
It is essential for the heating device according to the
invention that, on sides of the inlet region 2.1, the wall
thickness of the heat transfer ribs 3 and/or the distances
of the heat transfer ribs 3 to one another are optionally
configured greater than on sides of the outlet region 2.2.
As explained at the outset, these specifications lead to a
heating device in which, on the one hand, the heat transfer
ribs 3 in the inlet region 2.1 can well withstand the still
high temperatures of the exhaust gas and on the other hand,
with the aid of thin-walled heat transfer ribs 3 in the
outlet area 2.2, ensures particularly good heat transfer.
The figures in this case show a gas flue 2 with two
different zones. Figure 2 shows the heat transfer ribs 3,
which are still comparatively thick-walled and arranged
with a comparatively large distance from each other, in the
inlet region 2.1 (section A-A). Figure 3, on the other
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hand, shows the comparatively thin-walled heat transfer
ribs 3 arranged at a comparatively small distance in the
outlet region 2.2 (section B-B).
As can be readily understood, Figures 1 to 3 show a basic
constellation. However, gas flues 2 having more than two
zones can also be provided for implementing the solution
according to the invention. In order, on the one hand, to
meet the temperature loads and, on the other hand, the
decrease in the volume of the exhaust gas with increasing
distance from the combustion chamber 1, it is thus
provided, again, in other words, according to the
invention, that a) the wall thickness of the heat transfer
rib 3 is configured decreasing with increasing distance
from the combustion chamber 1 and/or b) that the distance
between the heat transfer ribs 3 is configured decreasing
with increasing distance from the combustion chamber 1. The
said change from zone to zone can be effected continuously
or also, which is structurally simpler, stepwise.
As the comparison of Figures 2 and 3 shows, it is also
particularly preferred to provide that a flow surface 2.3
oriented perpendicular to the main flow direction of the
exhaust gas in the gas flue 2 is configured larger in the
inlet region 2.1 than in the outlet region 2.2.
With regard to the dimensioning of the components of the
heating device according to the invention, in which, as
already mentioned above, the gas flue 2, on the one hand,
is configured for exhaust gas to flow through it and, on
the other hand, to be surrounded by water (in particular
heater circuit water), a particularly good heat transfer is
preferably provided, that a wall of the gas flue 2 arranged
between the exhaust gas and the water has a wall thickness
which is configured smaller than the smallest wall
thickness of the heat transfer rib 3. For this purpose, it
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is also preferably provided that the wall of the gas flue 2
is formed from a metallic sheet material.
Considered in more detail, in the heating device according
to the invention, in which a wall of the gas flue 2 and the
heat transfer ribs 3 are also configured as separate
components, it is particularly preferred to provide that
the heat transfer ribs 3 are configured as a support for
the wall of the gas flue 2 against the external pressure of
the water.
In contrast to the above-mentioned prior art, a wall region
2.4 left free from the heat transfer ribs 3, is further
provided on the gas flue 2 to further improve the heat
transfer in the gas flue 2 for direct contact of the
exhaust gas with a wall of the gas flue 2. Thus, in the gas
flue 2, on the one hand, there are the wall regions 2.5
which are in contact with the heat transfer ribs 3 and
supporting them, and, on the other hand, corresponding wall
regions 2.4 that are left free. As shown in the figures,
the heat transfer ribs 3 are thereby preferably arranged in
one (see in particular Figure 2) or several rows (see in
particular Figure 3) and multiple S-shapes in the gas flue
2, wherein the stipulation "multiple" simply means that a
plurality of S-shapes are arranged in succession in the
longitudinal direction.
In addition, since the heating device according to the
invention is to be operated as a so-called condensing
boiler in order to achieve a high efficiency, it is
particularly preferred to provide that the gas flue 2
and/or the heat transfer ribs 3 is/are formed from a
material which is resistant to condensate resulting from
the exhaust gas.
Figures 4 and 5 show a further exemplary embodiment of the
gas flue according to the invention. This gas flue is
distinguished by the fact that the heat transfer ribs 3
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have a greater distance for the inlet region 2.1 of the gas
flue 2 than at an edge region of the gas flue 2 in a
central region of the gas flue 2, with reference to a flow
of the hot exhaust gas. Again, in other words, a notch is
provided in the middle region of the heat transfer ribs 3
at the inlet region.
This specification has the advantage that the hot exhaust
gas streaming in, especially in the central region, can
initially cool down somewhat before it comes into contact
with the heat transfer rib 3. At the same time, however, a
sufficient support of the wall of the gas flue 2 is still
ensured by the somewhat lengthened formation of the heat
transfer ribs 3 in the edge region that is less pressurized
with hot exhaust gas.
In Figure 4, it can also be clearly seen that this gas flue
2 has a total of three different zones. In the front image
area, the heat transfer ribs 3 on the inlet side are shown,
which, in order to be able to withstand the hot exhaust
gas, are appropriately configured thick-walled and arranged
at a comparatively large distance from each other. The heat
transfer ribs 3 in the middle and the outlet-side region
are clearly thin-walled and arranged at a smaller distance
from each other.
In addition, it is provided in the embodiment according to
Figure 4 that the heat transfer ribs 3 of a zone (i.e., in
a region in which the wall thickness and the distance of
the heat transfer ribs 3 do not change) are formed from two
sections 3.1, 3.2 arranged one behind the other as seen in
the flow direction of the hot exhaust gas, wherein a gap is
provided between the sections 3.1, 3.2 and the sections
3.1, 3.2 are preferably arranged offset with respect to one
another. This requirement serves to swirl the flow in this
zone in order to increase the heat transfer again.
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Finally, it is preferably provided with reference to Figure
6 that webs 3.3 are provided between the heat transfer rib
3 and, in particular, in a central region of the gas flue
2, with reference to a flow of the hot exhaust gas. This
requirement also serves to improve the heat transfer.
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List of reference numbers
1 Combustion chamber
2 Gas flue
2.1 Inlet region
2.2 Outlet region
2.3 Flow surface
2.4 Wall region
2.5 Wall region
3 Heat transfer rib
3.1 Section
3.2 Section
3.3 Web
4 Exhaust gas collecting
chamber
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