Recessed profile

1. A system for ventilating a room comprising: first and second recessed hollow profiles for mounting to a wall system in a wall of a building,

wherein each of said first and second recessed hollow profiles comprises:

a casing forming a hollow profile interior which is in the form of a flow space and which has an inlet and an outlet;

a heat exchanging material through which air can flow and which is arranged in the flow space between the inlet and the outlet; and

a ventilation system for bidirectional flow conveyance through the heat exchanging material; wherein

the ventilation system has exactly one axial fan with a dead flow zone around the centre of the axial fan, the axial fan which can be operated bidirectionally, the fan arranged in the flow space and is spaced apart from the heat exchanging material such that a flow homogenizing distance therefrom is maintained, which defines a flow homogenizer space within the hollow profile interior, and wherein an air diffusor is arranged in the flow homogenizer space between the fan and the heat exchanging material so that a flow of air produced by the axial fan is distributed uniformly through the heat exchanging material by avoiding insufficient air flows over a cross section of the heat exchanging material due to the dead flow zone of the axial fan;

wherein the heat exchanging material of the first recessed hollow profile is not shared with the second recessed hollow profile and wherein the heat exchanging material of the second recessed hollow profile is not shared with the first recessed hollow profile, and

wherein the first and second recessed hollow profiles are switched alternatively to opposite directions of flow and wherein the first and second recessed hollow profiles are connected to each other as a hollow ventilation profile.

2. The system according to claim 1 , wherein each of said first and second recessed hollow profiles has a first flow guidance device between the fan and the outlet and/or a second flow guidance device between the fan and the inlet.

3. The system according to claim 1 , in which the flow homogenizing distance for each of said first and second recessed hollow profiles is less than 10 cm.

4. The system according to claim 1 , wherein each of said first and second recessed hollow profiles is smaller in cross-section than a rectangular boundary, with at least one side of the rectangular boundary having a length of less than 15 cm.

5. The system according to claim 1 , in which for each of said first and second recessed hollow profiles

the axial fan has a fan impeller, the outer circumference of which can be described in at least one plane perpendicular to the fan axis by a circle, and

the flow homogenizing distance is equal with a variation of at most 20% to the radius of the circle.

6. The system according to claim 1 , wherein for each of said first and second recessed hollow profiles

the heat exchanging material is a ceramic material.

7. The system according to claim 1 , which is formed in or as a hollow adapter profile of a window or as part of a window frame.

8. The system according to claim 1 , wherein for each of said first and second recessed hollow profiles the flow homogenizing distance is less than 1 cm.

9. The system according to claim 1 , wherein each of said first and second recessed hollow profiles is smaller in cross-section than a rectangular boundary, wherein each of two perpendicular sides of the rectangular boundary has a length of less than 15 cm.

10. The system according to claim 1 , wherein each of said first and second recessed hollow profiles is smaller in cross-section than a rectangular boundary, with at least one side of the rectangular boundary, having a length of less than 8 cm.

11. The system according to claim 1 , wherein each of said first and second recessed hollow profiles is smaller in cross-section than a rectangular boundary, wherein each of two perpendicular sides of the rectangular boundary has a length of less than 8 cm.

12. The system according to claim 1 , wherein for each of said first and second profiles

the axial fan has a fan impeller, the outer circumference of which can be described in at least one plane perpendicular to the fan axis by a circle, and

the flow homogenizing distance is equal with a variation of at most 10% to the radius of the circle.

13. The system according to claim 1 , wherein for each of said first and second hollow profiles

the axial fan has a fan impeller, the outer circumference of which can be described in at least one plane perpendicular to the fan axis by a circle, and

the flow homogenizing distance is exactly equal to the radius of the circle.

14. The system according to claim 6 , wherein the ceramic material contains a proportion of metal oxide.