Heating device

A heating device has a combustion chamber and a gas flue configured to guide hot exhaust gas generated in the combustion chamber, the flue having an inlet region and an outlet region and is configured connected to the combustion chamber via the inlet region. Heat transfer ribs having a wall thickness are arranged spaced from each other in the gas flue for the heat transfer from hot exhaust gas to the gas flue. The wall thickness of the heat transfer ribs and/or the distances of the heat transfer ribs to one another are optionally configured to be larger on the sides of the inlet region than on the sides of the outlet region.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a heating device according to the preamble of claim1.

2. Description of the Related Art

A heating device of the type mentioned at the outset is known from the patent document EP 0 632 239 A1. 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.

SUMMARY OF THE INVENTION

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 comprising a combustion chamber and a gas flue configured to guide hot exhaust gas generated in the combustion chamber, wherein the gas flue has an inlet region and an outlet region and is configured connected to the combustion chamber via the inlet region. Heat transfer ribs having a wall thickness are arranged spaced from each other in the gas flue for the heat transfer from hot exhaust gas to the gas flue.

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.

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.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The heating device illustrated in the figures consists, in a manner known per se, of a combustion chamber1and of a gas flue2configured for guiding hot exhaust gases generated in the combustion chamber1with an extra burner not shown, wherein this has an inlet region2.1and an outlet region2.2and is configured connected to the combustion chamber1via the inlet region2.1, and wherein heat transfer ribs3made of a metallic material having a wall thickness are arranged spaced from each other on the gas flue2for the heat transfer from the hot exhaust gas to the gas flue2.

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 chamber1, it is provided that the combustion chamber1is configured connected to a plurality (here four) of parallel gas flues2through which the exhaust gas flows. The gas flue2itself 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 flue2is configured connected to an exhaust gas collecting chamber4via the outlet region2.2. Furthermore, the combustion chamber1is thereby arranged above the gas flue2and this above the exhaust gas collecting chamber4. The exhaust gas collecting chamber4is 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 region2.1, the wall thickness of the heat transfer ribs3and/or the distances of the heat transfer ribs3to one another are optionally configured greater than on sides of the outlet region2.2.

As explained at the outset, these specifications lead to a heating device in which, on the one hand, the heat transfer ribs3in the inlet region2.1can well withstand the still high temperatures of the exhaust gas and on the other hand, with the aid of thin-walled heat transfer ribs3in the outlet area2.2, ensures particularly good heat transfer.

The figures in this case show a gas flue2with two different zones.FIG. 2shows the heat transfer ribs3, which are still comparatively thick-walled and arranged with a comparatively large distance from each other, in the inlet region2.1(section A-A).FIG. 3, on the other hand, shows the comparatively thin-walled heat transfer ribs3arranged at a comparatively small distance in the outlet region2.2(section B-B).

As can be readily understood,FIGS. 1 to 3show a basic constellation. However, gas flues2having 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 chamber1, it is thus provided, again, in other words, according to the invention, that a) the wall thickness of the heat transfer rib3is configured decreasing with increasing distance from the combustion chamber1and/or b) that the distance between the heat transfer ribs3is configured decreasing with increasing distance from the combustion chamber1. The said change from zone to zone can be effected continuously or also, which is structurally simpler, stepwise.

As the comparison ofFIGS. 2 and 3shows, it is also particularly preferred to provide that a flow surface2.3oriented perpendicular to the main flow direction of the exhaust gas in the gas flue2is configured larger in the inlet region2.1than in the outlet region2.2.

With regard to the dimensioning of the components of the heating device according to the invention, in which as already mentioned above, the gas flue2, 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 flue2arranged between the exhaust gas and the water has a wall thickness which is configured smaller than the smallest wall thickness of the heat transfer rib3. For this purpose, it is also preferably provided that the wall of the gas flue2is formed from a metallic sheet material. This wall of the gas flue extends over the complete length of the heating device.

Considered in more detail, in the heating device according to the invention, in which a wall of the gas flue2and the heat transfer ribs3are also configured as separate components, it is particularly preferred to provide that the heat transfer ribs3are configured as a support for the wall of the gas flue2against the external pressure of the water.

In contrast to the above-mentioned prior art, a wall region2.4left free from the heat transfer ribs3, is further provided on the gas flue2to further improve the heat transfer in the gas flue2for direct contact of the exhaust gas with a wall of the gas flue2. Thus, in the gas flue2, on the one hand, there are the wall regions2.5which are in contact with the heat transfer ribs3and supporting them, and, on the other hand, corresponding wall regions2.4that are left free. As shown in the figures, the heat transfer ribs3are thereby preferably arranged in one (see in particularFIG. 2) or several rows (see in particularFIG. 3) and multiple S-shapes in the gas flue2, 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 flue2and/or the heat transfer ribs3is/are formed from a material which is resistant to condensate resulting from the exhaust gas.

FIGS. 4 and 5show a further exemplary embodiment of the gas flue according to the invention. This gas flue is distinguished by the fact that the heat transfer ribs3have a greater distance for the inlet region2.1of the gas flue2than at an edge region of the gas flue2in a central region of the gas flue2, 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 ribs3at 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 rib3. At the same time, however, a sufficient support of the wall of the gas flue2is still ensured by the somewhat lengthened formation of the heat transfer ribs3in the edge region that is less pressurized with hot exhaust gas.

InFIG. 4, it can also be clearly seen that this gas flue2has a total of three different zones. In the front image area, the heat transfer ribs3on 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 ribs3in 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 toFIG. 4that the heat transfer ribs3of a zone (i.e., in a region in which the wall thickness and the distance of the heat transfer ribs3do not change) are formed from two sections3.1,3.2arranged one behind the other as seen in the flow direction of the hot exhaust gas, wherein a gap is provided between the sections3.1,3.2and the sections3.1,3.2are 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.

Finally, it is preferably provided with reference toFIG. 6that webs3.3are provided between the heat transfer rib3and, in particular, in a central region of the gas flue2, with reference to a flow of the hot exhaust gas. This requirement also serves to improve the heat transfer.

LIST OF REFERENCE NUMBERS