Carbon dioxide climate system and method for operating a carbon dioxide climate system

Abstract

Carbon dioxide air conditioning system comprising a cooling device (2) with a refrigerant circuit (3), wherein carbon dioxide (K) is incorporated as a refrigerant in the refrigerant circuit (3) and wherein the refrigerant circuit (3) comprises means for evaporating and condensing the carbon dioxide (K).

Description

Technical field

[0001] The invention relates to a carbon dioxide climate system and a method for operating a carbon dioxide climate system, preferably with a carbon dioxide climate system according to the invention. State of the art

[0002] Air conditioning systems using carbon dioxide (CO2) as a refrigerant are known from the prior art. In these systems, the carbon dioxide is converted between states of matter through evaporation and condensation, thereby absorbing and releasing heat. Carbon dioxide air conditioning systems are therefore suitable for both cooling and heating. Such a carbon dioxide cooling system is described, for example, in Deng et al. 2006, "Particular characteristics of transcritical CO2 refrigeration cycle with an ejector". However, the evaporation and condensation of the carbon dioxide are associated with losses, which is why regular replenishment of the carbon dioxide storage is necessary.

[0003] To limit the warming of the Earth's atmosphere, it is already known that the CO2 content of the atmosphere, which has increased due to industrialization, must be actively reduced. So-called "Direct Air Capture" (DAC) systems can be used for this purpose; however, these are currently only available as large-scale industrial plants and are difficult to integrate into automated carbon dioxide recovery chains. Disclosure of the invention

[0004] The object of the present invention is to overcome the disadvantages of the prior art and in particular to propose a carbon dioxide climate system and a method for operating a carbon dioxide climate system which has reduced maintenance requirements and can save on material costs.

[0005] This problem is solved with regard to the carbon dioxide climate system by the features of claim 1. With regard to the method for operating a carbon dioxide climate system, the problem is solved by the features of claim 6.

[0006] Advantageous embodiments are the subject of the following description and figure description, as well as the dependent claims.

[0007] The features described and claimed in relation to the device shall also be deemed to be disclosed and claimable in accordance with the procedure, and vice versa.

[0008] The carbon dioxide air conditioning system comprises a cooling device with a refrigerant circuit, wherein carbon dioxide is absorbable or incorporated as a refrigerant in the refrigerant circuit and wherein the refrigerant circuit comprises means for evaporating and condensing the carbon dioxide.

[0009] According to the invention, it is provided that a gas scrubbing device is included, which is designed in such a way that carbon dioxide can be extracted from an air stream external to the refrigerant circuit and wherein a connecting section is formed which is fluidly connected to the refrigerant circuit in such a way that carbon dioxide can be transferred from the gas scrubbing device into the refrigerant circuit.

[0010] The means for evaporating and condensing the carbon dioxide can advantageously be, for example, a compression agent, in particular a gas compressor, which is designed to compress a gaseous carbon dioxide phase, and a condensing agent, in particular a gas cooler, which is designed to condense the gaseous carbon dioxide phase, and an expansion agent, in particular a throttle valve, which is designed to reduce the pressure of a liquid carbon dioxide phase, and an evaporation agent, in particular an evaporator, which is designed to evaporate the liquid carbon dioxide phase.

[0011] This achieves the particularly advantageous result that the carbon dioxide captured by the gas scrubber can be used directly to compensate for refrigerant losses in the carbon dioxide cooling system. This reduces the required maintenance frequency of the cooling system, saves on maintenance and carbon dioxide refrigerant costs, and improves indoor air quality by filtering carbon dioxide from the air in a building and / or room connected to the climate control system.

[0012] According to a first advantageous embodiment, the gas scrubbing device may include an electrolysis unit in which a redox reaction can be carried out using electrical energy, in particular converting an aqueous alkali salt solution, preferably sodium chloride solution or potassium bromide solution, to a halogen, hydrogen, and an alkali. Sodium chloride (NaCl) is particularly preferably converted to chlorine (Cl₂), hydrogen (H₂), and sodium hydroxide (NaOH) using electrical energy. Alternatively, the electrolysis and / or redox reaction can also take place, for example, with lithium chloride (LiCl), potassium bromide (KBr), or sodium bromide (NaBr). In a particularly preferred alternative embodiment, potassium bromide is converted to bromine (Br₂), hydrogen, and potassium hydroxide (KOH) using electrical energy. This advantageously provides chemical reactors for further reaction steps.

[0013] In an alternative embodiment, an electrodialysis unit can be provided instead of an electrolysis unit, wherein the alkali salt solution is separated into the alkali and an acid in an electrodialysis process, for example using a bipolar membrane.

[0014] According to a further advantageous embodiment, the gas scrubbing device may include an energy conversion unit, in particular a fuel cell or a flow battery, which is fluidly connected to the electrolysis unit such that at least a first product fraction of the redox reaction, in particular hydrogen, preferably hydrogen and the halogen, can be transferred into the energy conversion unit. The energy conversion unit is configured such that electrical energy can be generated by converting the at least first product fraction, in particular by producing an acid or the alkali salt solution, and the electrical energy can be transferred to the electrolysis unit. Preferably, chlorine or bromine and hydrogen are transferred from the electrolysis unit into the energy conversion unit and converted to hydrochloric acid (HCl) or hydrobromic acid (HBr), thereby generating electrical energy.Alternatively, only the hydrogen from the electrolysis unit is transferred to the energy conversion unit and reacted with a halide salt solution, in particular with potassium bromate (KBrO3), producing electrical energy and the original alkali salt solution. This can advantageously cover at least part of the energy demand of the electrolysis unit. It is also conceivable that the electrolysis unit could be operated with renewable energy, for example from photovoltaics, during periods of high energy production, and that the resulting chemical reactors could be stored in storage tanks. These reactors could then be used to generate electrical energy for the electrolysis unit and / or the cooling system during periods of low energy production, for example at night.

[0015] According to a further advantageous embodiment, the gas scrubbing device may include an absorption unit, wherein the absorption unit is fluidly connected to the electrolysis unit such that at least a second product component of the redox reaction, in particular the alkali, can be transferred into the absorption unit, and wherein the absorption unit is designed to draw in the air stream such that the air stream can be brought into contact with the second product component, the carbon dioxide from the air stream being bound in the gas scrubbing device by the conversion of the second product component to an intermediate product, in particular a carbonate solution. Advantageously, sodium hydroxide or potassium hydroxide is fed from the electrolysis unit into the absorption unit and reacts with carbon dioxide from the air stream to form sodium carbonate (Na₂CO₃) or potassium carbonate (K₂CO₃). This advantageously performs gas scrubbing.The absorbents advantageously also include filter media through which the airflow is passed, in particular to remove residual liquid carried in the airflow after contact with the alkali.

[0016] According to a further advantageous embodiment, the gas scrubbing device may include a carbon dioxide separator which is fluidly connected to the absorption unit, and preferably to the energy conversion unit and / or electrolysis unit, in such a way that the intermediate product can be transferred into the carbon dioxide separator and can be converted in the carbon dioxide separator, preferably with a halogen product, in particular with the acid or the halogen, to carbon dioxide and a residual product, preferably the aqueous alkali salt solution and / or an aqueous halide salt solution, wherein the carbon dioxide separator is fluidly connected to the refrigerant circuit via the connecting section, whereby the carbon dioxide can be supplied to the refrigerant circuit.Preferably, the sodium carbonate is reacted with hydrochloric acid to form carbon dioxide and sodium chloride, or the potassium carbonate is reacted with hydrobromic acid to form carbon dioxide and potassium bromide. Alternatively, the bromine from the electrolysis unit is reacted with potassium carbonate to form carbon dioxide, potassium bromate, and potassium bromide. Preferably, the potassium bromate is transferred to the energy conversion unit to react with hydrogen, releasing energy to form potassium bromide. Particularly preferably, the carbon dioxide is dried in the carbon dioxide separator, advantageously by gas drying, and / or its pressure is adjusted to that of the refrigerant circuit, thereby reducing the acid resistance requirements of the refrigerant circuit lines.The carbon dioxide is preferably introduced into the refrigerant circuit via a multi-ejector, whereby excess carbon dioxide can be separated from the refrigerant circuit and collected, for example, in gas cylinders. This advantageously closes the chemical cycle of the device.

[0017] The above-mentioned problem is also solved by a method for operating a carbon dioxide climate system, in particular according to one of the embodiments described above, comprising the following process steps: - Evaporation and condensation of carbon dioxide in a refrigerant circuit of a cooling device, absorbing and releasing heat.

[0018] The following process steps are provided according to the invention: - filtering carbon dioxide from an external air stream using a gas scrubber and - a transfer of the carbon dioxide into the refrigerant circuit through a connecting section that fluidly connects the gas scrubbing device and the cooling device.

[0019] To avoid unnecessary repetition, reference is made to the device described above regarding the advantageous effects and the advantageous embodiments of the method.

[0020] In summary, the present invention enables a method for operating a carbon dioxide climate system which reduces maintenance and saves costs.

[0021] According to an advantageous embodiment, a redox reaction can be carried out in an electrolysis unit of the gas scrubbing device using electrical energy, preferably by converting an aqueous alkali salt solution, in particular sodium chloride solution or potassium bromide solution, to a halogen, hydrogen, and an alkali. Sodium chloride is particularly preferably converted to chlorine, hydrogen, and sodium hydroxide using electrical energy. Alternatively, the electrolysis and / or redox reaction can also be carried out, for example, with lithium chloride, potassium bromide, or sodium bromide. In a particularly preferred alternative embodiment, potassium bromide is converted to bromine, hydrogen, and potassium hydroxide using electrical energy. This advantageously provides chemical reactors for further reaction steps.

[0022] In an alternative embodiment, electrodialysis can be provided instead of electrolysis, wherein the alkali salt solution is separated into the alkali and an acid in an electrodialysis process, for example using a bipolar membrane.

[0023] According to a further advantageous embodiment, at least a first product fraction of the redox reaction, in particular hydrogen, preferably hydrogen and the halogen, can be transferred from the electrolysis unit to an energy conversion unit, in particular a fuel cell or a flow battery, and the first product fraction is converted to, preferably acid or the aqueous alkali salt solution, and electrical energy, wherein the electrical energy is transferred to the electrolysis unit. Preferably, chlorine or bromine and hydrogen are transferred from the electrolysis unit to the energy conversion unit and converted to hydrochloric acid or hydrobromic acid, thereby generating electrical energy.Alternatively, only the hydrogen from the electrolysis unit is transferred to the energy conversion unit and reacted with a halide salt solution, particularly with potassium bromate, producing electrical energy and the original alkali salt solution. This can advantageously cover at least part of the energy demand of the electrolysis unit. It is also advantageously conceivable that the electrolysis unit is operated with renewable energy, for example from photovoltaics, during periods of high energy production, and that the chemical reactors are stored in storage tanks to be used during periods of low energy production to generate electrical energy for the electrolysis unit and / or the cooling device.

[0024] According to a further advantageous embodiment, at least a second product component of the redox reaction, in particular the alkali, can be transferred to an absorption unit, and the airflow can be drawn through the absorption unit such that the airflow is brought into contact with the second product component, whereby carbon dioxide from the airflow is absorbed into the second product component, thereby generating an intermediate product, in particular a carbonate solution. Advantageously, sodium hydroxide or potassium hydroxide is fed from the electrolysis unit into the absorption unit, which reacts with carbon dioxide from the airflow to form sodium carbonate or potassium carbonate. This advantageously performs gas scrubbing.The absorbents advantageously also include filter media through which the airflow is passed, in particular to remove liquid residues carried in the airflow after contact with the alkali.

[0025] According to a further advantageous embodiment, the intermediate product, and preferably a halogen product, in particular the acid or the halogen, can be transferred to a carbon dioxide separator and the intermediate product is converted at least to carbon dioxide and a residual product, preferably the aqueous alkali salt solution and / or an aqueous halide salt solution, and the carbon dioxide is fed through the connecting section into the refrigerant circuit. Preferably, the sodium carbonate is reacted with the hydrochloric acid to form carbon dioxide and sodium chloride, or the potassium carbonate is reacted with the hydrobromic acid to form carbon dioxide and potassium bromide. Alternatively, the bromine from the electrolysis unit is reacted with potassium carbonate to form carbon dioxide, potassium bromate, and potassium bromide. Preferably, the potassium bromate is transferred to the energy conversion unit to react with hydrogen to form potassium bromide, releasing energy.The carbon dioxide is preferably introduced into the refrigerant circuit via a multi-ejector, whereby excess carbon dioxide can be separated from the refrigerant circuit and collected, for example, in gas cylinders. This advantageously closes the chemical process cycle.

[0026] The carbon dioxide climate system according to the invention and the method for operating a carbon dioxide climate system are explained below by way of example using purely schematic figures showing exemplary embodiments. Brief description of the drawings Fig. Figure 1 shows a schematic representation of the operation of a carbon dioxide climate system in a first embodiment. Fig. Figure 2 shows a schematic representation of the operation of a carbon dioxide climate system in a second embodiment. Embodiments of the invention

[0027] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0028] In the Fig. Figure 1 shows an air conditioning system 1 with a cooling device 2. The cooling device 2 comprises a refrigerant circuit 3, which includes means for evaporating and condensing carbon dioxide K. The means for evaporating and condensing the carbon dioxide K can advantageously be, for example, a compression agent, in particular a gas compressor, which is configured to compress a gaseous phase of the carbon dioxide K, and / or a condensing agent, in particular a gas cooler, which is configured to condense the gaseous phase of the carbon dioxide K, and / or an expansion agent, in particular a throttle valve, which is configured to reduce the pressure of a liquid phase of the carbon dioxide K, and / or an evaporating agent, in particular an evaporator, which is configured to evaporate the liquid phase of the carbon dioxide K.

[0029] The cooling device 2 is fluidly connected to a gas scrubbing device 11 via a connecting section 4. The gas scrubbing device 11 has an electrolysis unit 12, which is configured to carry out a redox reaction and / or electrolysis. For this purpose, the electrolysis unit 12 contains an alkali salt solution, in particular sodium chloride or potassium bromide, which, by expending electrical energy E, can be converted in a redox reaction to at least a first and second product component P1; P2, in particular hydrogen, a halogen, preferably chlorine or bromine, and an alkali, preferably sodium hydroxide or potassium hydroxide.

[0030] The first product component P1, in particular hydrogen and the halogen, more preferably hydrogen and chlorine or bromine, is transferred from the electrolysis unit 12 to an energy conversion unit 13. The energy conversion unit 13 can be, for example, a hydrogen chloride fuel cell or a flow battery. In the energy conversion unit 13, the first product component P1 is reactively converted to an acid, generating electrical energy E. In particular, the hydrogen and the chlorine or bromine are reacted to form hydrogen chloride or hydrogen bromide and dissolved, producing hydrochloric acid or hydrobromic acid. The electrical energy E is supplied to the electrolysis unit 12 and / or to the cooling device 2, in particular to the means for evaporating and condensing carbon dioxide K.

[0031] The second product component P2, preferably the lye, in particular sodium hydroxide or potassium hydroxide, is transferred to an absorption unit 14, which is arranged in the gas scrubbing device 11 such that it is at least partially in contact with ambient air. The absorption unit 14 is designed to draw in an air stream L, the air stream L being directed such that it comes into contact with the second product component P2, whereby carbon dioxide K, in particular with the lye, reacts to form an intermediate product PK, in particular sodium carbonate or potassium carbonate, and is thus bound in the gas scrubbing device 11. Advantageously, after contact with the second product component P2, in particular the lye, the air stream L is passed through a filter medium to remove residual liquid from the air stream L.

[0032] The intermediate product PK is transferred from the absorption unit 14 to a carbon dioxide separator 15, and a halogen product P3, in particular an acid, preferably hydrochloric acid or hydrobromic acid, is transferred from the energy conversion unit 13 to the carbon dioxide separator 15. The intermediate product PK and the halogen product P3 react in the carbon dioxide separator 15 to form carbon dioxide K and a residual product P4, in particular the original aqueous alkali salt solution. The carbon dioxide K is transferred via the transition section 4 to the refrigerant circuit 3, with the residual product P4, in particular the alkali salt solution, being transferred to the electrolysis unit 12, thus closing the chemical cycle.

[0033] The transfer of the chemical reactors between the components of the gas scrubbing device 11 is carried out in particular via fluid paths, whereby the fluid paths can be set up for passive or active transport of the chemical reactors, for example via mechanical circuits.

[0034] In the Fig. Figure 2 shows a second embodiment of the operation of an air conditioning system 1. The cooling device 2 corresponds to the cooling device 2 of the first embodiment according to Figure 2. Fig. 1 and is fluid-conductingly connected to a gas scrubbing device 11 via a connecting section 4.

[0035] The gas scrubbing device 11 has an electrolysis unit 12, which is configured to carry out a redox reaction and / or electrolysis. For this purpose, the electrolysis unit 12 contains an alkali salt solution, in particular potassium bromide, which can be converted in a redox reaction to at least a first and second product fraction P1; P2, in particular to hydrogen, a halogen, preferably bromine, and an alkali, preferably potassium hydroxide, by expending electrical energy E.

[0036] The first product component P1, in particular hydrogen, is transferred from the electrolysis unit 12 to an energy conversion unit 13. The energy conversion unit 13 can, for example, be a chloride-hydrogen fuel cell or a flow battery.

[0037] The second product component P2, preferably the lye, in particular potassium hydroxide, is transferred to an absorption unit 14, which is arranged in the gas scrubbing device 11 such that it is at least partially in contact with ambient air. The absorption unit 14 is configured to draw in an air stream L, the air stream L being directed such that it comes into contact with the second product component P2, whereby carbon dioxide K, in particular with the lye, reacts to form an intermediate product PK, in particular potassium carbonate, and is thus bound in the gas scrubbing device 11. Advantageously, after contact with the second product component P2, the air stream L is passed through a filter medium to remove any residual liquid from the air stream L.

[0038] The intermediate product PK is transferred from the absorption unit 14 to a carbon dioxide separator 15, and a halogen product P3, in particular the halogen, especially preferably bromine, is transferred from the electrolysis unit 12 to the carbon dioxide separator 15. The intermediate product PK and the halogen product P3 react in the carbon dioxide separator 15 to form carbon dioxide K and a residual product P4, in particular the original aqueous alkali salt solution and an aqueous halide salt solution. The carbon dioxide K is transferred via the connecting section 4 to the refrigerant circuit 3, whereby the carbon dioxide K, particularly in the carbon dioxide separator 15, is adjusted to the pressure of the refrigerant circuit 3 and / or dried, thereby reducing the requirements for the lines of the refrigerant circuit 3. The residual product P4 is transferred to the energy conversion unit 13.

[0039] In the energy conversion unit 13, the hydrogen reacts with at least some of the residual product P4, in particular with the halide salt solution, generating electrical energy E and producing a residual product P4', in particular the original aqueous alkali salt solution. The electrical energy E is transferred to the electrolysis unit 12 and / or to the cooling device 2, in particular to the means for evaporating and condensing carbon dioxide K. The residual product P4' is transferred to the electrolysis unit 12. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] Deng et al. 2006 „Particular characteristics of transcritical CO2 refrigeration cycle with an ejector

[0002]

Claims

[1] Carbon dioxide climate system, comprising a cooling device (2) with a refrigerant circuit (3), wherein carbon dioxide (K) is absorbable or incorporated as a refrigerant in the refrigerant circuit (3) and wherein the refrigerant circuit (3) comprises means for evaporating and condensing the carbon dioxide (K), characterized by a gas scrubbing device (11) which is designed in such a way that carbon dioxide (K) can be extracted from an air stream (L) external to the refrigerant circuit (3) and wherein a connecting section (4) is formed which is fluidly connected to the refrigerant circuit (3) in such a way that carbon dioxide (K) can be transferred from the gas scrubbing device (11) into the refrigerant circuit (3). [2] Climate system according to claim 1, characterized by, that the gas scrubbing device (11) comprises an electrolysis unit (12) in which a redox reaction (P1) can be carried out using electrical energy (E), in particular an aqueous alkali salt solution, preferably a sodium chloride solution or potassium bromide solution, can be converted to a halogen and hydrogen and an alkali. [3] Climate system according to claim 2, characterized by, that the gas scrubbing device (11) comprises an energy conversion unit (13), in particular a fuel cell or a flow battery, which is fluidly connected to the electrolysis unit (12) in such a way that at least a first product fraction of the redox reaction (P1), in particular hydrogen, preferably hydrogen and the halogen, can be transferred into the energy conversion unit (13), wherein the energy conversion unit (13) is designed in such a way that electrical energy (E) can be generated by reacting the at least first product fraction (P1), in particular by producing an acid or the alkali salt solution, wherein the electrical energy (E) can be transferred to the electrolysis unit (12). [4] Climate system according to one of claims 2 or 3, characterized by, that the gas scrubbing device (11) comprises an absorption unit (14), wherein the absorption unit (14) is fluidly connected to the electrolysis unit (12) in such a way that at least a second product fraction of the redox reaction (P2), in particular the alkali, can be transferred into the absorption unit (14) and wherein the absorption unit (14) is designed to draw in the air stream (L) in such a way that the air stream (L) can be brought into contact with the second product fraction (P2), wherein the carbon dioxide (K) from the air stream (L) can be bound in the gas scrubbing device (11) by converting the second product fraction (P2) to an intermediate product (PK), in particular to a carbonate solution. [5] Climate system according to claim 4, characterized bythat the gas scrubbing device (11) comprises a carbon dioxide separator (15) which is fluidly connected to the absorption unit (14), and preferably to the energy conversion unit (13) and / or electrolysis unit (12), such that the intermediate product (PK) can be transferred into the carbon dioxide separator (15) and can be converted in the carbon dioxide separator (15), preferably with a halogen product (P3), in particular with the acid or the halogen, to carbon dioxide (K) and a residual product (P4), preferably the aqueous alkali salt solution and / or an aqueous halide salt solution, wherein the carbon dioxide separator (15) is fluidly connected to the refrigerant circuit (3) via the connecting section (4), whereby the carbon dioxide (K) can be supplied to the refrigerant circuit (3). [6] Method for operating a carbon dioxide climate system, in particular according to one of the preceding claims, comprising the following process steps: - Evaporation and condensation of carbon dioxide (K) in a refrigerant circuit (3) of a cooling device (2) with absorption and release of heat, characterized by - filtering carbon dioxide (K) from an external air stream (L) using a gas scrubber (11) and - a transfer of the carbon dioxide (K) into the refrigerant circuit (3) through a connecting section (4) which fluidly connects the gas scrubbing device (11) and the cooling device (2). [7] Method according to claim 6, characterized bya redox reaction (P1) using electrical energy (E) in an electrolysis unit (12) of the gas scrubbing device (11), preferably by converting an aqueous alkali salt solution, in particular sodium chloride solution or potassium bromide solution, to a halogen and hydrogen and an alkali. [8] Method according to claim 7, characterized by a transfer of at least a first product fraction of the redox reaction (P1), in particular hydrogen, preferably hydrogen and the halogen, from the electrolysis unit (12) into an energy conversion unit (13), in particular a fuel cell or a flow battery, and a conversion of the first product fraction (P1) to, preferably acid or the aqueous alkali salt solution and, electrical energy (E), wherein the electrical energy (E) is transferred to the electrolysis unit (12). [9] Method according to one of claims 7 or 8, characterized by, transferring at least a second product fraction of the redox reaction (P2), in particular the alkali, into an absorption unit (14) and drawing in the air stream (L) through the absorption unit (14) such that the air stream (L) is brought into contact with the second product fraction (P2), wherein carbon dioxide (K) from the air stream (L) is absorbed into the second product fraction (P2), thereby generating an intermediate product (PK), in particular a carbonate solution. [10] Method according to claim 9, characterized by, a transfer of the intermediate product (PK), and preferably a halogen product (P3), in particular the acid or the halogen, into a carbon dioxide separator (15) and a conversion of the intermediate product (PK) at least to carbon dioxide (K) and a residual product (P4), preferably the aqueous alkali salt solution and / or an aqueous halide acid salt solution, and a supply of the carbon dioxide (K) through the connecting section (4) into the refrigerant circuit (3).

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