Heating system with a heat generator in a heating circuit and electric heating for such a heating system

Abstract

Heating system (1) with a heat generator (5) and at least one heating surface (7), which are connected in a heating circuit (3) via a pipe system (2) and form a heating flow (10) to the at least one heating surface (7) and a heating return (11) for a heat transfer fluid (4), wherein a heat control device (13) is assigned to the heat generator (5), characterized in that an electric heater (15) acting on the heat transfer fluid (4) is arranged between the heating flow (10) and the heating return (11) and has a plastic body (25) made of an electrically conductive plastic, which is connected to the heat control device (13) and can be put into operation by the heat control device (13) alternatively or additionally to the heat generator (5) according to a heat demand (14).

Description

[0001] The invention relates to a heating system with a heat generator and at least one heating surface in a heating circuit according to the preamble of claim 1. The invention also relates to an electric heater for such a heating system according to claim 9.

[0002] A heating system is a heat transfer system in which water, as a heat transfer fluid, is heated in a conventional hot-water heating system and distributed via a piping system to a heat dissipation device. In building heating systems, the warm heating water releases heat energy into the environment via heating surfaces, such as radiators or wall or floor heating. In a heating circuit, the heat transfer fluid is transported to the heating surface via a heating flow and, after dissipating the heat, returns to the heat generator via a heating return. A heat control device is assigned to the heat generator. The heat control device regulates the amount of heat to be transported via the heat transfer fluid according to the current heat demand.

[0003] Heating systems play a particularly important role in implementing statutory energy and climate targets. Buildings, not only in Germany, account for a large share of energy consumption, and the largest share of this is heating. Depending on the efficiency of the heating system's hot water preparation, these devices can cause particularly high energy consumption, for example, an inefficient boiler. Against this backdrop, the highest possible efficiency of a heating system is desirable.

[0004] Furthermore, it must be taken into account that, in accordance with legal regulations, at least a proportion of the heat generated must be generated using non-fossil fuels.

[0005] The present invention is based on the object of improving the efficiency of the generic heating system and ensuring that at least a portion of the heat generated is not generated using fossil fuels.

[0006] This object is achieved according to the invention by a heating system having the features of claim 1. The object is also achieved by an electric heater having the features of claim 9.

[0007] According to the invention, an electric heater acting on the heat transfer fluid is arranged between the heating flow and the heating return. The heater is connected to the control device and can be operated by the control device as an alternative to or in addition to the heat generator. The electrically conductive plastic heats up rapidly under electrical current, so that the heater heats the returning heat transfer fluid. Heat is generated without consuming fossil fuels and is transferred to the heat transfer fluid in the heating circuit. The heat generated is determined by the electrical output, which is influenced by the heat control device.

[0008] The plastic body of the electric heater is made of plastic with a higher conductivity than the heat transfer fluid and can heat up faster under electric current than a conventional heat generator using fossil fuels, thus also increasing the speed of the heating system to meet the requested heat demand. In one advantageous embodiment, the plastic body is made of an intrinsically conductive polymer and provides efficient heat generation at a comparatively low cost compared to an electric heater. In another embodiment, extrinsically conductive polymers are used to heat the heat transfer fluid, where the conductivity is achieved through fillers, for example, metals or carbon particles, or possibly nanoparticles.

[0009] In one embodiment of the invention, the heat generator is a boiler. Boilers are very common in existing heating systems, so that by supplementing an electric heater according to the invention with a plastic body, heat generation can be at least partially replaced by the boiler.

[0010] To improve the efficiency of the heating system and reduce fossil fuel consumption, the heat control system determines the heat demand and determines a first heat quantity allocated to the electric heater and a second heat quantity allocated to the heat generator of the total heat to be transferred to the heat transfer fluid. In this way, the second heat quantity is generated quickly by the electric heater and without consuming fossil fuels.

[0011] The electric heater with an electrically conductive plastic body is advantageously installed upstream of the heat generator, so that when the heat generator and electric heater are operating simultaneously, the flow temperature can be adjusted for optimal efficiency of the heat generator—especially a boiler. The heat control device determines the appropriate heat quantities for the appropriate adjustment of the flow temperature of the heat generator.

[0012] In an advantageous embodiment, when determining the first partial heat quantity attributable to the electric heater and the second partial heat quantity attributable to the heat generator of the total heat quantity to be transferred to the heat transfer fluid, heat transfer via the electric heater is prioritized. This means that the electric heater is primarily used to heat the heat transfer fluid in order to utilize the advantage of rapid heat generation by the electric heater and, moreover, to avoid the consumption of fossil fuels by using a large partial heat quantity. In the preferred embodiment, this is optimized in that the heat generator is only activated for heat transfer when the capacity of the electric heater for heat generation has been exhausted and the heating system has to meet a higher heat demand than the electric heater can meet.

[0013] A further increase in the efficiency of the heating system according to the invention is achieved when the heat transfer fluid is a dispersion of carbon nanoparticles in demineralized water. Such a configuration of the heat transfer fluid improves the effectiveness of heat transfer and, in combination with the electric heater according to the invention with electrically conductive plastic, reduces the energy required to provide heat to the heating surfaces. The dispersion of carbon nanoparticles in demineralized water has a high heat transfer coefficient and is capable of very rapidly absorbing the heat provided by the electric heater with an electrically conductive plastic, in particular a polymer, and effectively transporting it to the heating surfaces.

[0014] A permanently stable dispersion is achieved when carbon nanoparticles are dispersed in demineralized water with a surface area ratio of 250 to 300 square meters per gram of weight. The heat transfer fluid containing the inventive dispersion of water and carbon nanoparticles does not settle even after extended periods and can transport heat faster and more effectively than conventional heating water or other aqueous heat transfer fluids, without the need for chemicals. Carbon nanoparticles exhibit good thermal conductivity, so the specific heat capacity of the heat transfer fluid is significantly higher than that of conventional heating water.

[0015] A particularly stable dispersion for a high-performance heat transfer fluid is formed when the carbon nanoparticles are dispersed in a ratio of 10 to 80 grams per 1000 kilograms of water. A ratio of 60 grams of carbon nanoparticles per 1000 kilograms of water has proven particularly advantageous.

[0016] An effective heat transfer fluid made of demineralized water and dispersed carbon nanoparticles is characterized by a dispersion configuration such that the heat transfer fluid has an electrical conductivity between 30 and 40 microsiemens per centimeter. The electrical conductivity of the heat transfer fluid is lower than the electrical conductivity of the plastic body of the electric heater.

[0017] In the preferred embodiment of the invention, the carbon nanoparticles are formed as carbon nanotubes, whose properties, particularly the high surface area-to-mass ratio, are highly advantageous for the formation of the heat transfer fluid. By dispersing carbon nanotubes with the inventive configuration, the specific heat capacity of conventional heating water can be regularly increased by 25 percent, thus increasing the effectiveness of heat transfer.

[0018] An embodiment of the invention is explained in more detail below with reference to the drawings. They show: Fig. 1 a schematic view of an embodiment of a heating system with a heat generator and an electric heater, Fig. 2 an embodiment of an electric heater with a plastic body for a heating system, Fig. 3 an embodiment of a heat transfer fluid as a dispersion of water and carbon nanoparticles, Fig. 4 a schematic representation of the operation of the heating system according to Fig. 1.

[0019] Fig. 1 shows a schematic view of a heating system 1, whose piping system 2 forms a heating circuit 3 in which a heat transfer fluid 4 circulates. The heating system 1 comprises a heat generator 5, namely a boiler 6 in the exemplary embodiment, and at least one heating surface 7, for example, radiators 8 or underfloor heating 9, which are supplied with warm heat transfer fluid 4 via a heating flow 10. After heat transfer, the heat transfer fluid 4 is discharged via a heating return 11 in the heating circuit 3 to absorb heat again. To move the heat transfer fluid 4, a circulation pump 12 is arranged in the heating circuit 3 in the exemplary embodiment shown.

[0020] A heat control device 13 is assigned to the heat generator 5, which controls the heat generator 5 for the purpose of heat transfer according to a predetermined heat requirement 14, i.e., the heat requested for the heating surfaces 7. In addition to the heat generator 5, the heating system 1 comprises an electric heater 15, which is connected to the heat control device 13 and can be operated by the heat control device 13 alternatively or in addition to the heat generator 5. The electric heater 15 is connected upstream of the heat generator 5 so that a higher temperature of the heat transfer fluid 4 can be provided in the flow of the heat generator 5.

[0021] How Fig. 4 illustrates that the heat requirement 14 is determined in a determination step 16 based on a specification 17, taking into account an actual value, for example the current room temperature 18. After determining the heat requirement 14, the control device 13 determines a first partial heat quantity 19 attributable to the electric heater 15 and a second partial heat quantity 20 attributable to the heat generator 5 of the total heat quantity to be transferred to the heat transfer fluid to cover the heat requirement 14. During the determination 21 of the partial heat quantities 19, 20, heat transfer via the electric heater 15 is prioritized, so that the heating of the heat transfer fluid 4 takes place primarily by means of the electric heater 15.During the prioritization 22 of the control of the electric heater 15, given information on the performance 23 of the electric heater 15 is taken into account and the heat generator 5 is only activated for heat transfer when the performance 23 of the electric heater 15 is exhausted, i.e. a greater heat requirement 24 has been determined than the electric heater 15 can serve.

[0022] The active part of the electric heater 15 is a Fig. 2, which generates electrical heat under the action of an electric current. The plastic body 25 consists of an intrinsically conductive polymer, which has high conductivity and, with this property, is very effective in the operation of the heating system according to the invention and heats up very quickly. It can therefore transfer heat very quickly to the heat transfer fluid of the heating system, and the provision of heat via the electric heater also significantly reduces the heating system's fuel consumption.

[0023] Enclosed within the plastic body 25 is a continuous pipe coil 26 with a fluid inlet 27 and a fluid outlet 28 for the heat transfer fluid circulating in the heating circuit. The pipe coil 26 is enclosed in dense windings within the material of the plastic body 25, so that a long flow path within the plastic body 25 provides a large transfer surface for heat transfer from the plastic body 25 to the heat transfer fluid. Electrical connections are formed on the side of the plastic body 26 as elongated contact rails 29. In the illustrated embodiment, the contact rails 29 are made of copper.

[0024] The plastic body 25, made of electrically conductive polymer, is formed as a solid block in which the coiled tube 26 is recessed. This improves the electrically conductive polymer's ability to generate electrical heat for effective heating of the plastic body.

[0025] In a further embodiment, the plastic body of the electric heater 15 is formed by parallel arranged plates made of electrically conductive plastic.

[0026] The heat transfer fluid 4 is a dispersion of demineralized water 30 and carbon nanoparticles 31, which are Fig. 3. The presence of carbon nanoparticles 31 significantly increases the specific heat capacity, allowing the circulating heat transfer fluid 4 to supply heat more effectively to the heating surfaces 7. With its high heat capacity, the dispersion with carbon nanoparticles particularly well utilizes and supports the advantages of electrical heating with an electrically conductive plastic body by effectively absorbing and transporting the rapidly generated electrical heat.

[0027] To prepare the dispersion, feed water is demineralized or distilled. Carbon nanoparticles 31 are dispersed in the demineralized water 30, with a surface area ratio of 250 to 300 square meters per gram of weight. A stable dispersion, which is not prone to sedimentation of the carbon nanoparticles 31 even after extended periods, is obtained with a ratio of 10 to 80 grams of carbon nanoparticles per 1000 kilograms of water.

[0028] In the illustrated embodiment, the carbon nanoparticles 31 are embodied as carbon nanotubes, i.e., carbon nanotubes (CNTs) with diameters in the nanometer range. They are constructed from honeycomb lattices of carbon atoms. Carbon nanotubes have a comparatively very large surface area, making them particularly well-suited for the function of the heat transfer fluid, namely heat absorption and dissipation. Another advantageous property of the carbon nanotubes, which improves the effectiveness of the heat transfer fluid 4 when dispersed with demineralized water 30, is their particularly good thermal conductivity.

[0029] For a stable dispersion of demineralized water 30 and carbon nanoparticles 31, in the illustrated embodiment of a heat transfer fluid 4 for the heating system 1 ( Fig. 1) Carbon nanotubes are dispersed in a preferred ratio of 60 grams per 1000 kilograms of water. The interaction of the heat transfer fluid 4 with carbon nanoparticles 31 with the electric heater 15 in the heating circuit 3 ( Fig. 1) significantly improves the efficiency of heat transfer. The electrical conductivity of the dispersion is lower than the conductivity of the plastic body 25, so that the latter can effectively provide electrical heat to the electric heater 15. List of reference symbols (part of the description) 1 heating system 2 Piping system 3 heating circuits 4 Heat transfer fluid 5 heat generators 6 boilers 7 Heating surface 8 radiators 9 Underfloor heating 10 Heating flow 11 Heating return 12 Circulation pump 13 Heat control device 14 Heat demand 15 Electric heating 16 Determination 17 Default size 18 Actual size 19 First partial heat quantity 20 Second partial heat quantity 21 Determination of partial heat quantities 22 Prioritization 23 Performance 24 Greater heat demand 25 plastic bodies 26 Pipe coil 27 Fluid inlet 28 Fluid outlet 29 Contact rail 30 Demineralized water 31 carbon nanoparticles

Claims

[1] Heating system (1) with a heat generator (5) and at least one heating surface (7), which are connected in a heating circuit (3) via a piping system (2) and form a heating flow (10) to the at least one heating surface (7) and a heating return (11) for a heat transfer fluid (4), wherein the heat generator (5) is assigned a heat control device (13), characterized by that an electric heater (15) acting on the heat transfer fluid (4) with a plastic body (25) made of an electrically conductive plastic is arranged between the heating flow (10) and the heating return (11), which is connected to the heat control device (13) and can be put into operation by the heat control device (13) alternatively or in addition to the heat generator (5) in accordance with a heat requirement (14). [2] Heating system according to claim 1, characterized bythat the plastic body (25) is made of plastic with a higher conductivity than the heat transfer fluid (4). [3] Heating system according to claim 1 or 2, characterized by that the electric heater (15) is connected upstream of the heat generator (5). [4] Heating system according to one of the preceding claims, characterized by that the heat generator (5) is a boiler (6). [5] Heating system according to one of the preceding claims, characterized by that the heat transfer fluid (4) is a dispersion of carbon nanoparticles (31) in demineralized water (30). [6] Heating system according to claim 5, characterized by that the carbon nanoparticles (31) have a surface area ratio of 250 to 300 square meters per gram of weight. [7] Heating system according to claim 5 or 6, characterized by that the carbon nanoparticles (31) are dispersed in a ratio of 10 to 80 grams per 1000 kilograms of water. [8] Heating system according to one of claims 5 to 7, characterized by that the carbon nanoparticles (31) are formed as carbon nanotubes. [9] Electric heating for a heating circuit according to one of claims 1 to 8, characterized by that the electric heater (15) has a plastic body (25) made of electrically conductive plastic, in which a continuous pipe coil (26) with a fluid inlet (27) and a fluid outlet (28) for the heat transfer fluid (4) circulating in the heating circuit (1) is enclosed. [10] Electric heater according to claim 9, characterized by that electrical connections on the side of the plastic body (25) are designed as elongated contact rails (29). [11] Electric heater according to claim 9 or 10, characterized by that the plastic body (25) consists of an electrically conductive polymer. [12] Electric heater according to one of claims 9 to 11, characterized bythat the plastic body (25) consists of solid material in which the pipe coil (26) is recessed.

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