Boiler for a heating system and a corresponding heating system

Abstract

The invention relates to a boiler (1) for a heating system (100) carrying a working medium, in particular hot water or hot air, wherein the boiler (1) has a combustion chamber (2) and a boiler wall (3) enclosing the combustion chamber (2) with at least one thermoelectric element (4) for providing electrical energy, characterized in that the at least one thermoelectric element (4) has means (5) on its hot side facing the combustion chamber (2) for promoting thermal conductivity between the combustion chamber (2) and the at least one thermoelectric element (4) and / or means (5) on its cold side facing away from the combustion chamber (2) for promoting thermal conductivity between the thermoelectric element (4) and a working medium of a heating system (100). A corresponding heating system is further described.

Description

[0001] The invention is based on a boiler for a heating system that carries a working medium, in particular hot water or hot air. Such a boiler and such a heating system are known from DE 10 2015 005 786 A1. Similar devices are also described in DE 10 2007 037 391 A1 and EP 2 267 370 A1. A heating system can also be an engine whose thermal energy is dissipated, e.g., via a cooling circuit.

[0002] Such boilers and heating systems incorporate electrical consumers, such as control units and pumps for circulating the working fluid in a heating circuit or supplying fuel. To ensure the operational capability of electrical consumers independently of a power grid, for example, in the event of a power grid failure or in the absence of a power grid, for example, on ships, it is known to equip the boiler with thermoelectric elements, such as Peltier elements, to generate electrical energy from the heat emitted by the boiler.

[0003] The efficiency of such thermoelectric elements depends heavily on the temperature difference between the hot and cold sides of the thermoelectric element. While the boiler itself is made of a metal that conducts the heat generated in the combustion chamber well, such as aluminum, the thermoelectric element contains semiconductor components and other components that conduct heat less well than the boiler wall. This results in the thermoelectric element having an insulating effect compared to the rest of the boiler wall.This leads to the fact that in the boilers and heating systems known from the state of the art, the heat is transferred predominantly in those areas of the boiler wall from the combustion chamber to the working medium which do not have thermoelectric elements, whereby the temperature difference in the area of ​​the thermoelectric elements is comparatively lower and thus the efficiency of the thermoelectric elements decreases.

[0004] It is therefore the object of the invention to further develop a boiler and a corresponding heating system of the type described above in such a way that the thermoelectric elements have a high efficiency.

[0005] This object is achieved by a boiler according to claim 1. A corresponding heating system is the subject of the independent claim 12. Advantageous embodiments are described in the dependent claims.

[0006] While the hot side faces the combustion chamber of the boiler or faces the exhaust gas that is hot during the combustion process, the cold side faces away from the combustion chamber and can preferably be overflowed by the working medium, e.g. by the heating water or the hot air.

[0007] With the aid of the means for promoting thermal conductivity, the thermal conductivity of the thermoelectric elements can be increased on the cold side and / or on the warm side. For a given heating load on the hot side, this leads to an increase in the heat flow into the thermoelectric element and / or, for a given temperature and given volume flow of the working medium flowing over the thermoelectric element, an increase in the heat flow out of the thermoelectric element, thus increasing the thermal conductivity of the thermoelectric element and thus increasing the temperature difference between the cold and warm sides of the thermoelectric element, which ultimately increases the efficiency of the thermoelectric element compared to a thermoelectric element without the means for promoting thermal conductivity.

[0008] The means for promoting thermal conductivity can be configured to increase the surface area of ​​the thermoelectric element, in particular a cold side and / or a hot side of the thermoelectric element, and / or a portion of the vessel wall covering the thermoelectric element, in particular its cold and / or hot side, and in thermally conductive contact. For this purpose, the means can be designed as a structuring of the surface of the thermoelectric element or of the portion of the vessel wall covering the thermoelectric element and in thermally conductive contact. The structuring can be produced in any desired manner. The structuring can be produced by an abrasive process or by ablation. The structuring can be or have an etched surface. The structuring can also be produced by applying structural elements to the surface of the thermoelectric element.The structural elements or means can be, for example, pins, tubes, plates, walls, fins, or a combination thereof. The thermally insulating effect of the thermocouples can be offset by at least 50% in one embodiment with the means for promoting thermal conductivity.

[0009] The heating system can comprise at least one burner, a boiler with a combustion chamber, and an air-exhaust system. The heating system's task is to convert the liquid or gaseous fuel into thermal energy. This is then transferred into a liquid working medium (hot water heater) or a gaseous working medium (air heater) for heating rooms and / or fresh water, e.g., for showers, etc. Electrical energy is required to operate the individual modules of a heating system, such as a fuel-carrying pump, an air blower for combustion, a pump, or similar for conveying the heat-transferring heating fluid or the heating air.

[0010] The proposed solution enables the realization of a heating system that is at least largely electrically self-sufficient (not dependent on a permanent electrical supply), e.g. for the maritime or vehicle sector or general mobile heating sector such as for emergency, hall, construction site heating or for sanitary facilities. The heating system can have a highly efficient, environmentally friendly and / or multivariable heating system for fossil and / or renewable liquid or gaseous fuels, preferably comprising a plurality of thermocouples that convert the thermal energy generated in the heating system into electrical energy during operation. Preferably, at least one battery is provided for storing and later using the electrical energy converted by the thermocouples, e.g. for starting the burner of the heating system.

[0011] Maritime heating systems or those in vehicles, such as mobile homes or motorhomes, or mobile heaters, e.g., for hall or construction site heating, are powered by fossil or renewable fuels (liquid or gaseous). Due to mobility, electrical energy on board or in the vehicle is only available to a limited extent via batteries or with high energy losses via electric generators (auxiliary engines). Electrical energy supply via shore power or charging stations is only possible when available.

[0012] The use of thermocouples in heating systems, several of which can be combined to form thermoelectric generators, requires a high temperature gradient of several hundred degrees Kelvin between the "hot" side, which can be the inside of the combustion chamber, where the conversion of the fuel to the hot gas takes place, and the "cold" side, which can be the outside of the combustion chamber, where the working medium, in particular a fluid or gaseous heat transfer medium, flows over the cold side and, as a heated working medium, distributes the heat energy to heat exchangers (e.g. heating convectors) for the heating task.

[0013] A disadvantage of the state of the art is that the thermocouples have a thermally insulating effect and thus the heat transfer between the combustion chamber and the working medium takes place bypassing the thermocouples and takes place more intensively where the chamber wall of the combustion chamber has no thermocouples.

[0014] The means can be arranged between the at least one thermoelectric element and the combustion chamber and / or between the thermoelectric element and the heat-conducting working medium (hot water) or gas (hot air) and promote the heat transfer from the combustion chamber to the thermoelectric element and from the thermoelectric element to the heat-conducting working medium (hot water) or gas (hot air).

[0015] The means can be arranged on the inside of the combustion chamber, in particular at the exact or approximate position of the thermoelectric element. The at least one thermoelectric element can have a coating or cover with flame- and / or chemical- and / or physical-protective properties on the hot side facing the combustion chamber or exposed thereto, and / or an electrically, chemically, or physically-protective property on the cold side facing the heat-conducting working medium.

[0016] In an advantageous embodiment, the area of ​​the combustion chamber equipped with the thermoelectric elements is thermally separated or insulated from the rest of the combustion chamber. This can be achieved, for example, by dividing the combustion chamber and thermally decoupling the parts using structural measures and / or by arranging thermally insulating intermediate parts or insulators. The thermally decoupling effect in the area with at least one attached thermocouple can be at least 25% higher than for the equivalent area without thermal decoupling.

[0017] It is known from the prior art from DE 10 2019 001 348 A1 to direct the exhaust gases from the heating systems to a plate or diffuser base, or a dished base with its curvature facing or away from the flame tip, or a combination thereof. An advantageous embodiment of the present invention may therefore be to form or design the thermocouples on such a base of the combustion chamber, preferably at the base of the plate or diffuser or dished base, with the described means for promoting thermal conductivity between the thermoelectric element and a working medium of the heating system.

[0018] In a further advantageous embodiment, the cover of the thermoelectric elements facing the combustion chamber is made of a material that is at least 25% more heat-resistant than the rest of the combustion chamber material, e.g., bronze or gunmetal. While the rest of the combustion chamber can be made of a material with good thermal conductivity, such as aluminum with a melting point of approximately 660°C, the cover is subject to greater thermal stress than the rest of the combustion chamber wall due to the thermally insulating effect of the thermoelectric elements. On the cold side of the thermoelectric elements, the cover can be made of a material with high thermal conductivity and less heat resistance, e.g., aluminum.

[0019] Thus, in a further advantageous embodiment, a sandwich layering of the materials of the boiler wall is provided, in particular with a first cover made of particularly heat-resistant material for the thermoelectric elements of the hot side facing the combustion chamber and a second cover made of, in contrast, less heat-resistant material for the thermoelectric elements of the cold side facing the working medium.

[0020] The inventive embodiment can also be provided in any engine and / or motor and / or exhaust element with working medium, e.g. coolant on the cold side.

[0021] Advantageous embodiments of the invention are explained with reference to the following figures. Fig. 1 shows a schematic representation of an exemplary embodiment of a heating system; and Fig. 2 exemplary embodiments of suitable means for promoting thermal conductivity between a thermoelectric element and a working medium of a heating system or the exhaust gas from combustion.

[0022] The Fig. 1, the fluid-conducting heating system 100 shown in this case by way of example and merely schematically, and therefore not necessarily completely, comprises in particular a boiler 1 filled with fluid 10 as the working medium, having a combustion chamber 2, and a combustion chamber wall 3 surrounding the combustion chamber 2 and having a plurality of thermoelectric elements 4 for providing electrical energy. The combustion chamber 2 is fired by a burner 108. A pump, which represents an electrical consumer 102, supplies fuel from a fuel tank 107 to the burner 108. A further pump 103 is provided for circulating a working medium in a heating circuit with consumers (radiators, convectors, etc.) 106. The pumps and all other electrical consumers 102, 103 of the heating system 100 shown are supplied with electrical energy via an energy supply 101.

[0023] The electrical power supply 101 is of hybrid design and includes multiple power sources 4, 103. The additional power source 103 is configured as an island grid, symbolically represented here as a wind turbine. The heating system 100 shown, in particular, does not have a direct grid connection (shore power) for the electrical power supply and can, for example, be the heating system 100 of a ship, motorhome, or mobile home.

[0024] A control and regulation unit 104 is configured to supply the electrical loads 102 with power, depending on the operating state of the available power sources 4, 103, either via the electrical energy provided by the thermoelectric elements 4 and / or the electrical energy provided by the stand-alone grid 103, or via a combination of both. An electrochemical energy storage device 105, for example a battery, is provided as an electrical buffer storage device. The arrangement shown allows for various operating modes. Thus, the control and regulation unit 104 can be configured to prioritize the power supply via the additional power source 103, thus the stand-alone grid, and, for example, to ensure the power supply via the thermoelectric elements 4 in the event of a failure of the stand-alone grid. It can also be provided that, in the event of a failure of the additional power source 103, the power supply is provided via the energy storage device 105.It can also be provided that the thermoelectric elements 4 are exclusively intended to provide a charging current for the energy storage device 105, while the power supply of the electrical consumers 102 provides that the control and regulation unit supplies the additional power source 103 and / or the energy storage device 105 according to a selection criterion, for example, depending on an available amount of power from the additional power source 103 and / or the energy storage device 105. The control and regulation unit 104 can also be configured to provide a hybrid operation between the additional power source 103, the thermoelectric elements 4 and / or the energy storage device 105. The control and regulation unit 103 can also carry out a preset combination of all electrical power sources / energy carriers, for exampleFirst, the energy is fed from the thermoelectric elements, then from the additional power source 103, and finally from the energy storage device 105. The combination can be preset automatically according to a hierarchical process, e.g., based on the value of the energy type, or can be individually set by the system user.

[0025] The combustion chamber 2 has a multi-part boiler wall 3. In particular, the boiler wall 3 has a dished end 9, which in the region of its base has a wall section 6 which, via a thermal insulation 8, transitions into a further wall section 7 or borders the further wall section 7 via the insulation 8. The thermal insulation 8 has the task of interrupting or at least containing the heat flow from the wall section 6 at the base of the dished end 9, which has the thermoelectric elements 4, to the remaining parts of the boiler wall 3, in particular to the further wall section 7. With this measure, the temperature of the wall section 6 having the thermoelectric elements 4 can be kept high on the inside of the wall section 6 facing the combustion chamber 2, thus preventing an unwanted reduction in the temperature difference between the hot side and the cold side of the thermoelectric elements 4.The thermoelectric elements 4 are covered by a side of the dished end 9 facing the combustion chamber 2, which is provided with pins. The cover of the thermoelectric elements 11 facing the working medium 10 is provided with tubular rods. These form the means 5 for promoting thermal conductivity between the thermoelectric element 4 and the combustion chamber or a working medium of a heating system. Examples of this are shown in . Fig. 2 shown.

[0026] The Fig. Figure 2 shows four possible embodiments of means 5 for promoting thermal conductivity between the thermoelectric element 4 and the combustion chamber or a working medium of a heating system. The means are designed as structural elements protruding from the hot or cold side of the thermoelectric element. The means can be designed as parallel rods, tubes, walls, or fins. The structural elements can have a variable height. If the structural elements have a variable height, the heights of adjacent structural elements can be wave-shaped, as shown in the embodiment at the bottom right of the Fig.2. In the embodiment shown below left, the structural elements, for example, tubes, rods, or fins, are designed to cross in pairs. The means 5 are designed to increase the effective surface area of ​​the hot side or the cold side of the thermoelectric element 4 and thus increase the heat transfer between the cold side or the warm side and the working medium or the combustion chamber.

[0027] The features described above may be essential, individually or in any combination, for the realization of relevant embodiments of the invention, the scope of protection being determined by the patent claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 005 786 A1

[0001] DE 10 2007 037 391 A1

[0001] EP 2 267 370 A1

[0001] DE 10 2019 001 348 A1

[0017]

Claims

[1] Boiler (1) for a heating system (100) carrying a working medium, in particular hot water or hot air, wherein the boiler (1) has a combustion chamber (2) and a boiler wall (3) surrounding the combustion chamber (2) with at least one thermoelectric element (4) for providing electrical energy, characterized by that the at least one thermoelectric element (4) has, on its hot side facing the combustion chamber (2), means (5) for promoting the thermal conductivity between the combustion chamber (2) and the at least one thermoelectric element (4) and / or, on its cold side facing away from the combustion chamber (2), means (5) for promoting the thermal conductivity between the thermoelectric element (4) and a working medium of a heating system (100). [2] Boiler (1) according to claim 1, wherein the boiler wall (3) has a plurality of thermoelectric elements (4) arranged at a distance from one another such that the boiler wall is free of the thermoelectric elements (4) in spaces between adjacent thermoelectric elements (4). [3] Boiler (1) according to claim 1 or 2, wherein the means (5) for promoting thermal conductivity are arranged to increase a free surface of the thermoelectric element (4) with respect to the combustion chamber (2) and / or with respect to a working medium. [4] Boiler (1) according to claim 3, wherein the means (5) comprise a plurality of thermally conductive elements (4) which are in thermal contact with the thermoelectric element (4) and project from the thermoelectric element (4), preferably a plurality of pins, tubes, plates, walls or fins, or a combination thereof. [5] Boiler (1) according to one of the preceding claims, in which the thermally conductive elements (4) are designed, with regard to their number and nature, to compensate for a thermally insulating effect of the thermoelectric element (4) by at least 50% compared to a similar or the same thermoelectric element (4) which does not have the thermally conductive elements (4). [6] Boiler (1) according to one of the preceding claims, in which the boiler wall (3) has a first wall section (6) with the at least one thermoelectric element (4) and at least one second wall section (7) which is free of thermoelectric elements (4), wherein the two wall sections (6, 7) are thermally separated from one another and preferably merge into one another via a thermal insulation (8). [7] Boiler (1) according to claim 6, wherein the thermal insulation (8) is designed to reduce a heat flow between the first and the second wall section (6, 7) by at least 25% compared to the state when the wall sections (6, 7) merge into one another without insulation. [8] Boiler (1) according to one of the preceding claims, in which the boiler wall (3) has a dished bottom (9) and / or plate and / or diffuser bottom or combination thereof, which has the at least one thermoelectric element (4), wherein the thermoelectric element (4) is preferably arranged on a side of the dished bottom (9) facing the combustion chamber (2). [9] Boiler (1) according to claim 8, wherein the at least one thermoelectric element (4), preferably several of these, is arranged on a base of the dished end (9), preferably exclusively there, in particular exclusively in a region of the dished end (9) or plate or diffuser end or combination thereof that is furthest away from an edge of the dished end (9). [10] Boiler (1) according to one of claims 6 to 9, in which the boiler wall (3) has a sandwich layering of different materials, which preferably has a first cover of the hot side of the thermoelectric elements facing the combustion chamber (2) made of particularly heat-resistant material, and particularly preferably further has a second cover of the cold side of the thermoelectric elements facing the working medium made of less heat-resistant material. [11] Boiler (1) according to the preceding claim, in which the cover (9) facing the combustion chamber is made of a material which has a heat resistance which is at least 25% higher than that of the remaining boiler wall (3). [12] Heating system (100) with a boiler (1) according to one of the preceding claims, a heating circuit (106) in which a working medium, in particular warm air or warm water, is guided, and with an electrical energy supply (101) for at least one electrical consumer (102, 103) of the heating system (100), characterized by that the at least one thermoelectric element (4) is a power source of the electrical energy supply. [13] Heating system (100) according to claim 12, wherein the electrical energy supply (101) has a connection to a further power source (103), preferably an island network, wherein preferably a regulating and control unit (104) of the heating system (100) is designed to control an electrical switch depending on a respective operating state of the power sources (4, 103) in order to connect the at least one thermoelectric element (4) and / or the further power source to the electrical energy supply (101). [14] Heating system (100) according to claim 13, wherein, when the further power source (103) is active, the regulating and control unit (104) is configured to connect the further power source (103) to the electrical energy supply (101) and, in the event of failure of the further power source (103), to connect the at least one thermoelectric element (4) to the electrical energy supply (103). [15] Heating system (100) according to one of claims 12 to 14, wherein the electrical energy supply (101) comprises an electrochemical energy store (105) which is supplied with a charging current by the at least one thermoelectric element (4). [16] Heating system (100) according to one of claims 12 to 15, in which the control and regulation unit (103) carries out a combination of all electrical power sources / energy carriers according to a hierarchical method, preferably preset according to the value of the type of energy, and / or these are individually set by the user of the system. [17] Heating system (100) according to one of the preceding claims, in which the means are provided on the engine and / or engine and / or exhaust elements with working fluid / coolant on the cold side.

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