Heat transfer fluid for the pipeline system of a heat transfer device, and use of such a heat transfer fluid in a heating circuit

Abstract

The invention relates to a heat transfer fluid (3) for the pipeline system (2) of a heat transfer device (1) and to the use of such a heat transfer fluid (3) in a heating circuit (13). In order to improve the efficiency of the heat transfer, the heat transfer fluid (3) consists of demineralized water (9) in which carbon nanoparticles (10) are dispersed, the carbon nanoparticles (10) having a surface area ratio of 250 to 300 square meters per gram of weight.

Description

Heat transfer fluid for the piping system of a heat transport device and use of such a heat transfer fluid in a heating circuit

[0001] According to claim 1, the invention relates to a heat transfer fluid for the piping system of a heat transfer device. The invention further relates to the use of such a heat transfer fluid in a heating circuit.

[0002] A heating system is a heat transfer system in which water, as a heat transfer fluid, is heated in a hot water heating system and distributed via a pipe system to a heat emission point. In building heating systems, the warm heating water releases thermal energy to the surroundings via heating surfaces, such as radiators or wall or floor heating.

[0003] Heating systems play a crucial role in achieving legal energy and climate targets. In Germany, as elsewhere, buildings account for a large share of energy consumption, with heating being the primary source. Depending on the efficiency of the hot water supply for the heating system, these systems can be particularly energy-intensive, for example, an inefficient boiler. Therefore, the highest possible efficiency rating for a heating system is highly desirable.

[0004] It is known that, in addition to the hot water heating equipment, the quality of the water as a heat transfer fluid also has a long-term impact on the efficient and trouble-free operation of the heating system. Especially in a closed heating circuit, little water is lost, and the heating water is therefore treated to ensure its long-term functionality. For this purpose, substances are added to the heating water to counteract corrosion of the heating system or limescale buildup. However, such additives cannot improve heat transfer through the heat transfer fluid.

[0005] The present invention is based on the objective of improving the efficiency of heat transfer.

[0006] This problem is solved according to the invention by a heat transfer fluid having the features of claim 1. The problem is also solved according to claim 6 by using such a heat transfer fluid in a heating circuit.

[0007] The invention, with its aim of improving the efficiency of heat transfer, does not build upon previous proposals for enhancing the longevity of a system, but rather improves the heat transfer capacity of the heat transfer fluid. It is based on the understanding that carbon nanoparticles possess certain properties which, when dispersed in a heat transfer fluid, significantly improve the efficiency of heat transfer. The invention has demonstrated that a permanently stable dispersion can be provided, and the heat capacity of the heat transfer fluid increased, when carbon nanoparticles with a surface area ratio of 250 to 300 square meters per gram of weight are dispersed in demineralized water. A dispersion of water and carbon nanoparticles is understood to be a homogeneous mixture in which the carbon nanoparticles are finely dispersed in the water.The heat transfer fluid with the inventive dispersion of water and carbon nanoparticles does not sediment even after a long time. In the inventive configuration of the heat transfer fluid, the carbon nanoparticles are stably carried by the water.

[0008] The heat transfer fluid according to the invention can transport heat quantities faster and more effectively than conventional heating water or other aqueous heat transfer fluids, without the need for the addition of chemicals. Carbon nanoparticles exhibit good thermal conductivity, which is even higher than that of natural diamond. Both components of the The heat transfer fluids according to the invention complement each other in their respective advantageous properties, wherein in the configuration according to the invention the specific heat capacity of the heat transfer fluid is significantly increased above the quality of conventional heating water.

[0009] 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 to be particularly advantageous.

[0010] In an advantageous embodiment of the invention, the carbon nanoparticles are dispersed in demineralized water with an oxygen content of less than 0.1 milligrams per liter. The demineralized water stably carries the dispersed carbon nanoparticles if the feed water is distilled or demineralized, depending on its quality, and the oxygen content is subsequently reduced to below 0.1 milligrams per liter by degassing. Prior to degassing, the water is advantageously treated and desalinated in one or two reverse osmosis stages.

[0011] 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.

[0012] In the preferred embodiment of the invention, the carbon nanoparticles are configured as carbon nanotubes, whose properties, in particular the large surface area to mass ratio, are very advantageous for the formation of the heat transfer fluid according to the invention. By dispersing carbon nanotubes with the configuration according to the invention, the specific heat capacity of conventional heating water can be reduced. regularly increased by 25 percent, thus increasing the effectiveness of heat transport.

[0013] According to a key aspect of the invention, the heat transfer fluid is used in a heating circuit. The heat transfer fluid is stable and, when used in a closed heating circuit over a long period, can increase the efficiency of heat transfer from the heat source to the heating surfaces and significantly contribute to reducing the energy consumption of a heating system.

[0014] According to another aspect of the invention, the heat transfer fluid according to the invention is used as a coolant in a cooling circuit, for example in an air conditioning system.

[0015] An embodiment of the invention is explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 shows a schematic view of an embodiment of a heat transfer device with a heat transfer fluid according to the invention. Fig. 2 shows an embodiment of a dispersion of water and carbon nanoparticles, Fig. 3 shows a perspective view of an exemplary embodiment of a carbon nanoparticle.

[0016] Fig. 1 shows a schematic view of a heat transfer device 1 for transporting heat via a heat transfer fluid, which in the illustrated embodiment is the heating circuit 13 of a heating system. A pipe system 2 of the heating circuit 13 carries the heat transfer fluid 3. The heat transfer fluid 3 is heated in a hot water heating system 4, for example a boiler or a heat exchanger, and in a flow pipe 5 of a Heat is supplied to the heating surface 6. The heating surface 6 is a device that transfers the supplied heat to the surroundings and comprises radiators or elements of a wall or floor heating system. After heat transfer at the heating surface 6, the heat transfer fluid 3 is returned to the hot water heating system 5 via the return line 7 of the pipe system 2, in order to absorb heat again in the closed heating circuit 13. In the illustrated embodiment, a circulation pump 8 is arranged in the heating circuit 13 to move the heat transfer fluid 3.

[0017] The heat transfer fluid 3 is a dispersion of demineralized water 9 and carbon nanoparticles 10, illustrated in Fig. 2. The presence of carbon nanoparticles 10 significantly increases the specific heat capacity of the heat transfer fluid, enabling the circulating fluid to transfer larger quantities of heat to the heating surface 6 more rapidly. To prepare the dispersion, the incoming water is demineralized or distilled and then degassed to an oxygen content of less than 0.1 milligrams per liter. Carbon nanoparticles 10 are added to the demineralized water 9 with a surface area ratio of 250 to 300 square meters per gram of weight, as indicated by arrow 14, and dispersed, i.e., a homogeneous mixture is formed.A stable dispersion, which does not tend to sediment the carbon nanoparticles 10 even after a longer period of time, is achieved with a ratio of 10 to 80 grams of carbon nanoparticles per 1000 kilograms of water.

[0018] In the illustrated embodiment, the carbon nanoparticles 10 are designed as carbon nanotubes (ent), which are shown schematically in Fig. 3. Carbon nanotubes (ent) are carbon-based tubes (carbon nanotubes = cnt) with diameters in the nanometer range. They are composed of honeycomb-like lattices of carbon atoms. With their outer surface area 11 and their inner surface area 12, carbon nanotubes (ent) have a comparatively very large surface area, making them particularly well-suited for the function of the heat transfer fluid, namely heat absorption and – Delivery. Another advantageous property of the carbon nanotubes (ent), which improves the effectiveness of the heat transfer fluid 3 in the dispersion with demineralized water 9, is the particularly good thermal conductivity, which at room temperature at 6000 W / (m K) is more than 2.5 times higher than that of natural diamond at 2190 W / (m K).

[0019] For a stable dispersion of demineralized water 8 and carbon nanoparticles 10, in the illustrated embodiment of a heat transfer fluid 3 for heating circuits 1 carbon nanotubes (ent) are dispersed in a preferred ratio of 60 grams per 1000 kilograms of water.

[0020] An effective heat transfer fluid made of demineralized water and dispersed carbon nanoparticles exhibits an electrical conductivity between 30 and 40 microsiemens per centimeter. In the illustrated embodiment with carbon nanotubes (ent) in a ratio of 60 grams per 1000 kilograms of water 9, the heat transfer fluid 3 exhibits an electrical conductivity of approximately 36 microsiemens per centimeter.

[0021] In an advantageous embodiment, the heat transfer fluid 3 with a dispersion of demineralized water 9 and carbon nanotubes (ent) has the following further properties: pH value at 20 e C: 8.2 Total hardness: 0.29 e dH Magnesium content: 0.004 mol / m³ 3 Sodium content: 0.41 mol / m³ 3 Nitrite content: 0.001 mol / m³ 3 Chloride content: 0.027 mol / m³ 3 Sulfate content: 0.004 mol / m³ 3 Nitrate content: 0.014 mol / m³ 3 Reference numeral list (part of the description) 1 Heat transfer device 2 Piping system 3 Heat transfer fluid 4 Hot water heating 5 lead time 6 heating surface 7 Return 8 Circulation pump 9 Demineralized Water 10 carbon nanoparticles 11 Outer surface 12 Inner surface area 13 Heating circuit 14 Arrow CNT carbon nanotubes

Claims

Claims 1. Heat transfer fluid (3) for the piping system (2) of a heat transport device (1) consisting of demineralized water (9) in which carbon nanoparticles (10) are dispersed, wherein the carbon nanoparticles (10) have a surface area ratio of 250 to 300 square meters per gram of weight.

2. Heat transfer fluid according to claim 1, characterized in that the carbon nanoparticles (10) are dispersed in a ratio of 10 to 80 grams per 1000 kilograms of water (9).

3. Heat transfer fluid according to claim 1 or 2, characterized in that the demineralized water (9) has an oxygen content of less than 0.1 milligrams per liter.

4. Heat transfer fluid according to one of the preceding claims, characterized by a configuration of the dispersion of water (9) and carbon nanoparticles (10) such that the heat transfer fluid (3) has an electrical conductivity between 30 and 40 microsiemens per centimeter.

5. Heat transfer fluid according to one of the preceding claims, characterized in that the carbon nanoparticles (10) are formed as carbon nanotubes (ent).

6. Use of a heat transfer fluid according to one of claims 1 to 5 in a heating circuit (13).

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