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DE-102024210881-A1 - Heat pump unit for CO2 extraction from ambient air

DE102024210881A1DE 102024210881 A1DE102024210881 A1DE 102024210881A1DE-102024210881-A1

Abstract

The present invention relates to a heat pump unit for CO2 capture from ambient air, comprising a heat pump circuit having a first compressor, a condenser and an air-heated evaporator with a fan, and a Direct Air Capture (DAC) module with an adsorbent, wherein the heat pump circuit is configured to use CO2 as a refrigerant, wherein the DAC module is arranged in an airflow of the fan, wherein the heat pump unit is configured to direct a refrigerant from an area between the first compressor and the condenser into the DAC module to heat the adsorbent and desorb the CO2 adsorbed in the adsorbent, and wherein the DAC module is connected to the heat pump circuit to introduce the desorbed CO2 into the heat pump circuit.

Inventors

  • Ulrich Kappenstein
  • Matthias Rink

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (13)

  1. Heat pump unit (1) for CO2 capture from ambient air, comprising: - a heat pump circuit (10) having 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 fan (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 the CO2 contained therein. Adsorbent (21) to desorb adsorbed CO2, 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 Claim 1 , wherein the DAC module (20) includes 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 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.
  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 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 fan (14).
  9. Heat pump unit (1) according to one of the Claims 6 until 8 , comprising a pump (24) which is set up to introduce the liquefied and separated desorbed CO2 into the heat pump circuit (10).
  10. Heat pump unit (1) according to one of the Claims 6 until 8 , comprise 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. A method for operating a heat pump unit (1) according to any of the preceding claims, comprising the steps: - Adsorbing (S1) 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 desorb the CO2 adsorbed in the adsorbent (21), - Introducing (S6) the desorbed CO2 into the heat pump circuit (10), in particular as a refrigerant.
  12. Procedure according to Claim 11 , encompassing the step: shielding (S2) the adsorbent (21) from the ambient air before the refrigerant is introduced into the DAC module (20).
  13. Procedure according to one of the 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).

Description

State of the art 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. 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. Ideally, a heat pump unit would be capable of capturing CO2 from the ambient air, minimizing parasitic energy consumption and generating economies of scale. Disclosure of the invention The heat pump unit according to the invention for CO2 capture from ambient air, comprising the features of claim 1, and the method according to the invention for operating the heat pump unit, comprising the features of claim 11, have the advantage that the energy requirement for CO2 capture can be reduced. Furthermore, leaks in the heat pump circuit can be compensated for. This is achieved according to the invention by the heat pump unit for CO2 capture from 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 in order 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. 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. 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 also a heat exchanger through which ambient air is drawn by a fan to extract heat and evaporate the refrigerant. The dependent claims describe preferred embodiments of the invention. 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. Preferably, the shielding mechanism incorporates louvers and/or flaps. This allows the DAC module to be quickly and reliably shielded from the ambient air. The DAC module contains at least one pipe to guide the refrigerant through the adsorption medium, with the pipe connected to the heat pump circuit to return the refrigerant. This allows the refrigerant to efficiently transfer heat to the adsorption medium and then be returned to the heat pump circuit. The medium can preferably also be condensed within the pipeline in order to transfer further heat of condensation to the adsorption medium. 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. 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 cir