Heat pump unit for separating co 2 from the ambient air

Abstract

The present invention relates to a heat pump unit for separating CO2 from the ambient air, comprising a heat pump circuit, which has a first compressor, a condenser and an air-heated evaporator having a fan, and comprising a direct air capture (DAC) module having an adsorbent, wherein the heat pump circuit is configured to use CO2 as refrigerant, wherein the DAC module is arranged in an air flow of the fan, wherein the heat pump unit is configured to conduct a refrigerant from a region between the first compressor and the condenser into the DAC module in order to heat the adsorbent and to desorb the CO2, and wherein the DAC module is connected to the heat pump circuit in order to introduce desorbed CO2 into the heat pump circuit.

Description

[0001] R.415509

[0002] - 1 -

[0003] Description

[0004] title

[0005] Heat pump unit for CO2 removal from ambient air

[0006] State of the art

[0007] The present invention relates to a heat pump unit for CO2 separation from the ambient air and a method for operating the heat pump unit.

[0008] Heat pumps are a promising alternative to combustion-based heating systems within the framework of the energy transition, as they emit no pollutants and can be powered by electricity. The high COP values ​​of modern systems also significantly improve efficiency compared to purely electric heating. CO2 (R744) is commonly used as a refrigerant, offering several advantages due to its non-toxicity, good availability, and performance compared to other synthetic materials. Another important technology for combating climate change involves capturing CO2 from the atmosphere. This process, known as "Direct Air Capture" (DAC), currently uses amine-based adsorbents that are cyclically charged and discharged.It would be desirable to have a heat pump unit that can extract CO2 from the ambient air, thereby minimizing parasitic energy demand and generating economies of scale.

[0009] Disclosure of the invention

[0010] The heat pump unit according to the invention for CO2 separation from the ambient air with the features of claim 1 and the method according to the invention for operating the heat pump unit with the features of claim 11 have the advantage that the energy requirement for R.415509

[0011] -2 -

[0012] The separation of CO2 can be reduced. Furthermore, leaks in the heat pump circuit can be compensated for. According to the invention, this is achieved by the heat pump unit for CO2 separation from the ambient air comprising a heat pump circuit and a Direct Air Capture (DAC) module with an adsorbent. The heat pump circuit has a first compressor, a condenser, and an air-heated evaporator with a fan. The heat pump circuit is configured to use CO2 as a refrigerant. The DAC module is arranged in an airflow of the fan, and the heat pump unit is configured to direct a refrigerant from the area between the first compressor and the condenser into the DAC module to heat the adsorbent and desorb the CO2 adsorbed in the adsorbent.The DAC module is connected to the heat pump circuit to introduce the desorbed CO2, primarily as a refrigerant, into the heat pump circuit. The DAC module requires large air volumes for operation, necessitating large fans with correspondingly high drive power. By positioning the DAC module on the evaporator fan, the fan can be used efficiently to supply the air-heated evaporator and the DAC module with ambient air. To desorb the collected CO2, the adsorbent must be heated. The combination with the heat pump circuit can efficiently generate heat, which can then be used for CO2 desorption.

[0013] The DAC module can be efficiently heated by diverting hot refrigerant from the area between the first compressor and the condenser in order to desorb the adsorbed CO2.

[0014] In the heat pump cycle, the refrigerant is compressed in the first compressor, which is typically a piston compressor, and then releases usable heat to the condenser. The liquid refrigerant is then injected into the evaporator, where it absorbs heat from the surroundings. The condenser is typically a plate heat exchanger, and the condensation of the refrigerant allows, for example, domestic hot water to be heated on the usable side. The evaporator is typically a heat exchanger through which ambient air is drawn by a fan to extract heat and evaporate the refrigerant. R.415509

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[0016] The dependent claims describe preferred embodiments of the invention.

[0017] Preferably, the DAC module includes a shielding mechanism to isolate the adsorbent from the ambient air when refrigerant is introduced into the DAC module. This allows the DAC module to be isolated from the fan's airflow, enabling efficient heating of the adsorbent. Furthermore, the shielding mechanism can prevent desorbed CO2 from escaping into the environment.

[0018] Preferably, the shielding mechanism incorporates louvers and / or flaps. This allows the DAC module to be quickly and reliably shielded from the ambient air.

[0019] The DAC module includes at least one pipe to guide the refrigerant through the adsorption medium, with the pipe being connected to the heat pump circuit for refrigerant return. This allows the refrigerant to efficiently transfer heat to the adsorption medium and then be returned to the heat pump circuit. The refrigerant can preferably also be condensed within the pipe to transfer further heat of condensation to the adsorption medium.

[0020] Preferably, the heat pump unit includes a second compressor configured to compress the desorbed CO2. In particular, the second compressor is configured to liquefy the desorbed CO2. This allows the desorbed CO2 to be reliably introduced into the heat pump circuit or separated. The second compressor can be mechanically coupled to the first compressor or driven independently.

[0021] Preferably, a separator is arranged downstream of the second compressor to separate the desorbed CO2 from other air components. This ensures that no other air components mix with the refrigerant in the heat pump circuit. R.415509

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[0023] The desorbed CO2 can preferably be diverted to an external storage container. For example, the desorbed CO2 can be filled into reusable cartridges and thus fed into a collection system.

[0024] The DAC module is preferably located on the side of the evaporator facing away from the fan. This prevents the heat pump circuit from being affected by the cyclic heating of the DAC module.

[0025] The heat pump unit preferably comprises a pump configured to introduce the liquefied and separated desorbed CO2 into the heat pump circuit. The desorbed CO2 is preferably introduced into a refrigerant storage tank located between the evaporator and the first compressor.

[0026] Preferably, the heat pump unit includes an adjustable pressure valve between the first compressor and the separator, which is configured to increase the pressure at the separator by introducing compressed refrigerant in order to introduce the liquefied and separated desorbed CO2 into the heat pump circuit upstream of the first compressor. This allows the pump, as a complex component, to be replaced by a less complex pressure valve for introducing desorbed CO2 into the heat pump circuit.

[0027] Furthermore, the invention relates to a method for operating a previously described heat pump unit. In the method, CO2 from the airflow of a blower is adsorbed in an adsorbent of a DAC module in a first step. Once the adsorbent is largely saturated with CO2, a refrigerant from a heat pump circuit is introduced into the DAC module in a further step to heat the adsorbent and desorb the CO2 adsorbed in the adsorbent. The desorbed CO2 is then introduced into the heat pump circuit in a subsequent step. Thus, the energy required for CO2 separation can be minimized and any leakage in the heat pump circuit can be compensated for over its service life.

[0028] The method preferably further includes the step of shielding the adsorbent from the ambient air before the refrigerant is introduced into the DAC- R.415509

[0029] - 5 -

[0030] The module is initiated. This ensures, firstly, that the released CO2 does not escape back into the environment. Secondly, the adsorbent can be decoupled from the air flowing past it, which can draw heat and thus prolong the desorption process.

[0031] Preferably, the desorbed CO2 is compressed, in particular liquefied, and then separated from other air components before being introduced into the heat pump circuit. Separating these air components improves the purity of the CO2, thus enabling consistently efficient operation of the heat pump circuit with the introduced desorbed CO2.

[0032] Brief description of the drawings

[0033] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0034] Figure 1 shows a schematic process flow diagram of a heat pump unit according to a first embodiment of the invention.

[0035] Figure 2 shows a schematic process flow diagram of a heat pump unit according to a second embodiment of the invention and

[0036] Figure 3 shows a schematic flowchart of a method for operating a heat pump unit according to one of the embodiments.

[0037] Embodiments of the invention

[0038] Preferably, all identical components, elements, and / or units in all figures are designated with the same reference numerals. R.415509

[0039] - 6 -

[0040] Below, with reference to Figures 1 to 3, a heat pump unit 1 and a method for operating the heat pump unit 1 are described in detail.

[0041] Fig. 1 shows the heat pump unit according to a first embodiment of the invention with a heat pump circuit 10 and a Direct Air Capture (DAC) module 20. The heat pump circuit 10 has a first compressor 11, which can compress a refrigerant and direct it to a condenser 12. CO2 is used as the refrigerant in the heat pump circuit 10.

[0042] The hot gaseous refrigerant is condensed at the condenser 12, releasing usable heat. The condenser 12 is preferably a heat exchanger that can, for example, heat domestic hot water.

[0043] The condensed refrigerant then flows towards an air-heated vaporizer 13, passing through a suction gas superheater 33 and a pressure valve 25.

[0044] The suction gas superheater 33 is a heat exchanger between the refrigerant in the area between the condenser 12 and the evaporator 13, and the refrigerant between the evaporator 13 and the first compressor 11. The refrigerant between the condenser 12 and evaporator 13 transfers heat to the refrigerant between the evaporator 13 and the first compressor 11. The power gain from the subcooling of the refrigerant between the condenser and evaporator is greater than the power loss from the superheating of the refrigerant between the evaporator 13 and the first compressor 11, thus increasing the efficiency of the heat pump circuit 10.

[0045] The pressure valve 25 is arranged between the suction gas superheater 33 and the evaporator 13, which expands the refrigerant, largely evaporates it and supplies it to the evaporator 13 after cooling.

[0046] The evaporator 13 is another heat exchanger, to which heat from the ambient air is transferred when the refrigerant temperature is low.

[0047] A refrigerant storage tank 32 is arranged downstream of the evaporator 13. The refrigerant can be supplied from the refrigerant storage tank 32 via the R.415509

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[0049] Suction gas superheater 33 to the first compressor 11 and the refrigerant passes through the heat pump circuit 10 again.

[0050] The heat pump unit 11 includes the DAC module 20, in which an adsorbent 21 is arranged that can adsorb CO2. The DAC module is located in the airflow of the fan 14 from the evaporator 13. Thus, ambient air can be drawn through the DAC module and the evaporator 13 by means of the fan 14, which eliminates the need for the DAC module 20 to have its own fan 14 and improves the energy efficiency of the CO2 capture using the DAC module 20.

[0051] The DAC module 20 is schematically arranged between the blower 14 and the evaporator 13, but is preferably located on the side of the evaporator 13 facing away from the air.

[0052] The DAC module has a shielding mechanism 26 that can shield the adsorbent 21 from the ambient air and the airflow of the fan 14 when refrigerant is introduced into the DAC module 20 to desorb the adsorbed CO2. The shielding mechanism 26 has louvers that can be easily opened and closed to shield the adsorbent 21 from the ambient air or to direct the airflow of the fan 14 through the adsorbent 21.

[0053] When the adsorbent 21 has adsorbed enough CO2, the shielding mechanism 26 closes to isolate the adsorbent 21 from the ambient air, and refrigerant is introduced from the heat pump circuit 10 into the DAC module 20. For this purpose, the heat pump circuit 10 has a control valve 31 between the first compressor 11 and the condenser 12, which opens to direct the refrigerant towards the DAC module 20.

[0054] In the DAC module 20, at least one pipe 15 is arranged by means of which the refrigerant can be guided through the adsorption medium 21, whereby the hot refrigerant transfers heat to the adsorption medium 21 in order to heat it and desorb the adsorbed CO2. Subsequently, the refrigerant is returned from the pipe 15 to the heat pump circuit 10 R.415509

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[0056] led, in particular into an area between the condenser 12 and the evaporator 13.

[0057] The CO2 desorbed from the adsorbent 21 escapes from the DAC module 20 through a shut-off valve 30 and is subsequently liquefied by a second compressor 22. In this embodiment, the second compressor 22 is a separate compressor connected to the first compressor 11 via a drive shaft. Alternatively, it can also be a compression stage integrated into the first compressor 11. Furthermore, the second compressor 22 can also be completely decoupled from the first compressor 11 and have its own drive.

[0058] The desorbed CO2 liquefied by the second compressor may contain further air components from the DAC module 20, which are separated from the liquefied CO2 in a separator 23. The other air components can be removed from the heat pump unit 1 via a shut-off valve 30. The liquefied CO2 is preferably collected in the separator 23.

[0059] Once a defined fill level is reached in the separator 23, a shut-off valve 30 to a pump 24 is opened, and the liquid CO2 is introduced by the pump 24 via an injector 34 into the refrigerant storage tank 32 of the heat pump circuit 10. After the separator 23 has been emptied, all shut-off valves 30 are closed, and the second compressor 22 and the pump 24 are stopped. The remaining gas volume can then be discharged from the separator 23 to the environment via the shut-off valve 30.

[0060] If, after several cycles, the refrigerant level in the storage tank 32 rises above a threshold, CO2 can be discharged from the heat pump circuit 10 via a shut-off valve 30 located on the storage tank 32. The CO2 from the heat pump circuit 10 can then be discharged, for example, into a storage container that is replaced periodically. The storage containers can preferably be fed into a suitable deposit return system. R.415509

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[0062] Figure 2 shows a second embodiment of the heat pump unit 1. The heat pump circuit 10 in the second embodiment is identical to the heat pump circuit 10 in the first embodiment. The second embodiment differs essentially in that a pressure valve 25 is provided instead of the pump 24.

[0063] The adjustable pressure valve 25 is located between the first compressor 11 and the separator 23 and is designed to increase the pressure at the separator 23 by introducing compressed refrigerant from the heat pump circuit 10, in order to introduce the liquefied and separated desorbed CO2 into the refrigerant storage tank 32 of the heat pump circuit 10. A check valve 35 is located between the pressure valve 25 and the second compressor 22, which prevents the refrigerant diverted from the heat pump circuit 10 by the pressure valve 25 from flowing towards the DAC module 20. If the separator 23 is to be emptied, or liquid CO2 is to be introduced into the refrigerant storage tank 32, the pressure level is raised via the pressure valve 25, using the pressure downstream of the first compressor 11, sufficiently to allow the CO2 to be directed into the refrigerant storage tank 32.This allows the pump 24 from the first embodiment to be replaced by a less complex pressure valve 25 for transporting the liquid CO2.

[0064] Figure 3 shows a flowchart illustrating the process for operating the heat pump unit 1, wherein in a first step S1 CO2 from the airflow of the blower 14 is adsorbed in the adsorbent 21 of the DAC module 20. After sufficient CO2 has been adsorbed by the DAC module 20, in a step S2 the adsorbent 21 is shielded from the ambient air by means of the shielding mechanism 26. Subsequently, in a step S3 the refrigerant from the heat pump circuit 10 can be introduced into the DAC module 20 to heat the adsorbent 21 and desorb the CO2 adsorbed in the adsorbent 21.

[0065] The desorbed CO2 is compressed or liquefied in a subsequent step S4, after which, in step S5, the desorbed CO2 is separated from other air components. The CO2 separated from the ambient air can be introduced into the heat pump circuit 10 in a final step S6. Specifically, the CO2 R.415509

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[0067] CO2 is introduced into the refrigerant storage tank 32 of the heat pump circuit 10. When the refrigerant storage tank 32 of the heat pump circuit 10 is full, CO2 can also be removed from the heat pump circuit 10 and, for example, filled into external storage containers.

[0068] Thus, by combining a heat pump circuit with a Direct Air Capture module 20, CO2 can be separated from the ambient air with minimized energy requirements and introduced into the heat pump circuit 10 to compensate for leaks or collected and stored in other ways.

Claims

R.415509 - 11 - Claims 1. Heat pump unit (1) for CO2 removal from ambient air, comprising a heat pump circuit (10) comprising a first compressor (11), a condenser (12) and an air-heatable evaporator (13) with a fan (14), wherein the heat pump circuit (10) is configured to use CO2 as a refrigerant, and a Direct Air Capture (DAC) module (20) with an adsorbent (21), wherein the DAC module (20) is arranged in an airflow of the blower (14) to adsorb CO2 from the ambient air, wherein the heat pump unit (1) is configured to direct a refrigerant from an area between the first compressor (11) and the condenser (12) into the DAC module (20) to heat the adsorbent (21) and desorb the CO2 adsorbed in the adsorbent (21), and wherein the DAC module (20) is connected to the heat pump circuit (10) to introduce the desorbed CO2, in particular as a refrigerant, into the heat pump circuit (10).

2. Heat pump unit (1) according to claim 1, wherein the DAC module (20) comprises a shielding mechanism (26) to shield the adsorbent (21) from the ambient air when the refrigerant is introduced into the DAC module (20).

3. Heat pump unit (1) according to claim 2, wherein the shielding mechanism (26) comprises louvers and / or flaps.

4. Heat pump unit (1) according to one of the preceding claims, wherein at least one pipe (15) is arranged in the DAC module (20) to guide the refrigerant through the adsorption medium (21), wherein the pipe (15) is connected to the heat pump circuit (10) to return the refrigerant. R.415509 - 12 - 5. Heat pump unit (1) according to one of the preceding claims, comprising a second compressor (22) which is configured to compress the desorbed CO2, in particular to liquefy it.

6. Heat pump unit (1) according to claim 5, wherein a separator (23) is arranged downstream of the second compressor (22) to separate the desorbed CO2 from other air components.

7. Heat pump unit (1) according to one of the preceding claims, wherein the desorbed CO2 can be drained into an external storage container.

8. Heat pump unit (1) according to one of the preceding claims, wherein the DAC module (20) is arranged on the side of the evaporator (13) facing away from the blower (14).

9. Heat pump unit (1) according to one of claims 6 to 8, comprising a pump (24) which is configured to introduce the liquefied and separated desorbed CO2 into the heat pump circuit (10).

10. Heat pump unit (1) according to one of claims 6 to 8, comprising a controllable pressure valve (25) between the first compressor (11) and the separator (23), which is configured to increase the pressure at the separator (23) by introducing compressed refrigerant in order to introduce the liquefied and separated desorbed CO2 into the heat pump circuit (10) upstream of the first compressor (11).

11. Method for operating a heat pump unit (1) according to any one of the preceding claims, comprising the steps: Adsorption (S1) of CO2 from the airflow of a blower (14) in an adsorbent (21) of a DAC module (20), Introducing (S3) a refrigerant from a heat pump circuit (10) into the DAC module (20) to heat the adsorbent (21) and to desorb the CO2 adsorbed in the adsorbent (21), introducing (S6) the desorbed CO2 into the heat pump circuit (10), in particular as a refrigerant. R.415509 - 13 - 12. Method according to claim 11, comprising the step: shielding (S2) the adsorbent (21) from the ambient air before the refrigerant is introduced into the DAC module (20).

13. Method according to one of claims 11 or 12, comprising the step: Compression (S4), in particular liquefaction, of the desorbed CO2 and subsequent separation (S5) of the desorbed CO2 from other air components before the desorbed CO2 is introduced into the heat pump circuit (10).

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