Cooling devices for switchgear air conditioning and corresponding switchgear arrangements

Abstract

The invention relates to a cooling device (1) for air conditioning a switchgear cabinet, wherein the cooling device (1) has a primary circuit (2) with a flammable refrigerant and a condenser (3) arranged in an external air circuit (4) of the cooling device (1), and wherein the cooling device (1) has an evaporator (5) in an internal air circuit (10) which is fluidically isolated from the external air circuit (4), characterized in that the cooling device (1) has a secondary circuit (6) with a non-flammable refrigerant and has an evaporator (5) and a liquid-liquid heat exchanger (7) arranged in the external air circuit (4) and via which heat is transferred from the non-flammable refrigerant to the flammable refrigerant. The application also describes a corresponding switchgear cabinet arrangement.

Description

Technical Field

[0001] The present invention is based on a cooling device for switchgear air conditioning and a corresponding switchgear arrangement. The cooling device comprises a main circuit containing a flammable coolant and a condenser arranged in the cooling device's external air circuit. The cooling device also comprises an evaporator in an internal air circuit, which is fluidically isolated from the external air circuit. The internal air circuit may have an air inlet and an air outlet opening, which lead to the interior of the switchgear housing. The external air circuit may have an air inlet and an air outlet opening leading to the surrounding environment of the cooling device or the switchgear arrangement. The external air circuit may allow ambient air to flow through it and may include a fan for this purpose. The air flowing through the external circuit may act on a condenser configured for this purpose, for example, as an air-to-liquid heat exchanger. In the internal air circuit, the air circulating through the internal air circuit may act on an evaporator arranged in the internal air circuit. The evaporator may be designed as an air-to-liquid heat exchanger. This type of cooling device is known from DE 10 2018 109 604 A1. Background Art

[0002] Directive 2006 / 42 / EC (Machinery Directive) requires that gases used in machinery be free from explosion and fire risks, even if a single component fails. Therefore, if, in the case of switchgear cooling systems, there were a hypothetical leak in a refrigerant-carrying part, it could be assumed that flammable gas (refrigerant) could enter the switchgear and potentially ignite at internal fittings, thereby igniting an arc during operation. Without a safety function that reliably prevents this from happening, switchgear cooling systems using flammable refrigerants cannot comply with the Machinery Directive or operate with the safety required by end users.

[0003] The switchgear arrangements known from the prior art have the disadvantage that they are relatively complex to implement, since, for example, different actively driven closing members are required and have to be activated in the event of a detected leak and / or ingress of flammable refrigerant into the switchgear interior, e.g. in order to close a partition between the internal circuit of the cooling device and the switchgear interior so that no (further) refrigerant can enter the switchgear interior. Summary of the Invention

[0004] The object of the present invention is therefore to further develop the cooling device described at the outset in such a way that it incorporates all the safety measures required by the Machinery Directive and thus does not require any adjustments to the rest of the switchgear arrangement, in particular the switchgear housing.

[0005] This object is achieved by a cooling device having the features of claim 1. A corresponding switch cabinet arrangement is the subject matter of independent claim 16. Advantageous embodiments are respectively the subject matter of the dependent claims.

[0006] Therefore, a secondary circuit is provided in the housing of the cooling device, which circuit contains a non-flammable refrigerant and has an evaporator and a liquid-liquid heat exchanger, which is arranged in the external air circuit and transfers heat from the non-flammable refrigerant to the flammable refrigerant via the liquid-liquid heat exchanger.

[0007] The division of the cooling circuit of the cooling unit into a primary circuit and a secondary circuit, wherein the secondary circuit has a non-flammable refrigerant, ensures that even in the event of a leak in one of the two refrigerant circuits, no flammable refrigerant can enter the internal air circuit and thus the interior space of the switchgear housing.

[0008] The liquid-liquid heat exchanger can be a condenser of the secondary circuit and an evaporator of the primary circuit. The liquid-liquid heat exchanger can be designed as a plate heat exchanger.

[0009] The primary circuit can be designed as an active compressor refrigeration circuit with a compressor and an expansion member.

[0010] The main circuit can be arranged in the cooling device in a fluidically isolated manner from the internal air circuit.

[0011] The primary circuit can be completely ventilated to the surroundings of the cooling device. In particular, the primary circuit can be arranged completely in the external air circuit.

[0012] The secondary circuit may be a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by ground height differences. The secondary circuit may be designed as or include a heat pipe, for example. The non-flammable refrigerant may be or include, for example, carbon dioxide.

[0013] The cooling device may further comprise a tertiary circuit, wherein the condenser of the primary circuit is the condenser of the tertiary circuit and the evaporator of the secondary circuit is the evaporator of the tertiary circuit.

[0014] The condenser of the primary circuit and / or the tertiary circuit may be a dual-circuit air-to-liquid heat exchanger having two liquid conducting lines that are fluidically isolated from each other.

[0015] The evaporators of the secondary and tertiary circuits may be dual-circuit air-to-liquid heat exchangers having two liquid conducting lines fluidly isolated from each other.

[0016] The tertiary loop may include or be a non-flammable refrigerant, such as carbon dioxide.

[0017] The tertiary circuit may be a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by geothermal height differences, and the tertiary circuit may be or include, for example, a heat pipe.

[0018] In a cooling device, fans can be arranged in both the external air circuit and the internal air circuit. The fan in the external circuit allows air delivered through the external air circuit to act on the condenser, while the fan in the internal circuit allows air delivered through the internal air circuit to act on the evaporator.

[0019] In a switchgear arrangement comprising a switchgear housing and a cooling device of the type described above, ambient air of the switchgear arrangement is conveyed via an external air circuit, while air received in the interior of the switchgear housing is conveyed via an internal air circuit. The internal air circuit and the external air circuit can be fluidically isolated from one another, such that no air exchange occurs between the external air circuit and the internal air circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Exemplary embodiments of the present invention are described with reference to the following drawings. In the drawings:

[0021] Figure 1 a schematic cross-sectional view showing a switchgear arrangement; and

[0022] Figure 2 A block diagram of a cooling device according to the present invention is shown. DETAILED DESCRIPTION

[0023] Figure 1 An exemplary embodiment of a switchgear arrangement 100 is shown, which has a switchgear housing 200 and a cooling device 1 mounted on a side portion thereof. Heat-generating and arc-potential components 300 are arranged in the switchgear housing 200, where flammable refrigerant accumulating in the interior 13 of the switchgear housing 200 can ignite, for example, at arcs generated during switching operations of the switchgear device 300.

[0024] The cooling device 1 has an internal air circuit 10, through which the air received in the interior 13 of the switchgear housing 200 is conveyed by means of a fan 12. When the heated air is introduced into the internal air circuit 10 in the upper region of the switchgear housing 200, it flows out of the internal circuit 10 and flows back into the interior 13 of the switchgear housing 200 in the lower region of the switchgear housing 200. While passing through the internal air circuit 10, the air acts on the evaporator 5, which in this example is configured as an air-to-liquid heat exchanger circuit, resulting in the air being cooled.

[0025] In the external air circuit 4 , the cooling device 1 has a condenser 3 , which is exposed to the ambient air of the switch cabinet arrangement 100 flowing through the external air circuit 4 and is likewise configured as an air-liquid heat exchanger.

[0026] Unlike cooling devices known from the prior art, in the cooling device 1 according to the invention, the evaporator 5 in the inside air circuit 1 is not fluidically connected to the condenser 3 in the outside air circuit 4 via a common refrigerant circuit. Instead, a primary circuit 2 with the condenser 3 and a secondary circuit 6 with the evaporator 5 are provided, which in turn are thermally coupled to each other in a fluidically isolated manner via a liquid-liquid heat exchanger 7.

[0027] To better understand the fluid interconnection of an exemplary cooling device according to the present invention, refer to Figure 2 Block diagram. The dashed horizontal line represents the airtight separation between the external air circuit 4, or the surroundings of the switchgear arrangement, and the internal air circuit 10, or the interior space 13 of the switchgear housing. Thus, the primary circuit 2, designed as a compressor circuit with a compressor 8 and an expansion element 9, is completely arranged within the external air circuit 4. Consequently, the primary circuit 2 can contain flammable refrigerant, since even if a leak occurs due to the separation between the internal air circuit 10 and the external air circuit 4, no flammable refrigerant can enter the internal air circuit 10 or the interior space 13 of the switchgear housing 200 (which houses the assembly 300). In a manner known from the prior art, the primary circuit 2 comprises an air-to-liquid heat exchanger, which is acted upon by a fan 12 and functions as a condenser. Unlike known cooling devices 1, the evaporator of the primary circuit 2 is a liquid-to-liquid heat exchanger 7, for example a plate heat exchanger, via which the primary circuit 2 is thermally coupled to the secondary circuit 6. The secondary circuit 6 comprises another air-to-liquid heat exchanger 5, which is also acted upon by a fan 12, acting on air conducted through the internal air circuit 10. The secondary circuit 6 is filled with a non-flammable refrigerant, so that the refrigerant entering the internal space 13 and escaping in the event of a leak cannot ignite at the arc of the component 300. The liquid-to-liquid heat exchanger 7 forms a condenser relative to the secondary circuit 6.

[0028] To further optimize the efficiency of cooling device 1, both condenser 3 and evaporator 5 are dual-circuit designs, with either condenser 3 or evaporator 5 forming a tertiary circuit. Both tertiary circuit 11 and secondary circuit 6 are preferably designed as natural circulation refrigerant circuits driven by ground height differences. In one embodiment, secondary circuit 6 and / or tertiary circuit 11 may be designed as heat pipes.

[0029] The features of the invention disclosed in the above description, the drawings and the claims can be used to realize the invention both individually and in any combination.

[0030] Reference Number List

[0031] 1 cooling device;

[0032] 2 main circuit;

[0033] 3. Condenser;

[0034] 4 external air circuit;

[0035] 5 evaporator;

[0036] 6 secondary circuits;

[0037] 7. Heat exchanger;

[0038] 8 compressors;

[0039] 9 expansion member;

[0040] 10 internal air circuit;

[0041] 11Third level circuit;

[0042] 12 fans;

[0043] 13 interior spaces;

[0044] 100 switchgear layout;

[0045] 200 switch cabinet housing;

[0046] 300 parts.

Claims

1. A cooling device (1) for air conditioning of a switch cabinet, wherein: The cooling device (1) has a primary circuit (2) having a flammable refrigerant and a condenser (3) arranged in an external air circuit (4) of the cooling device (1), wherein the cooling device (1) has an evaporator (5) in an internal air circuit (10), the internal air circuit being fluidically isolated from the external air circuit (4), wherein the cooling device (1) has a secondary circuit (6) having a non-flammable refrigerant and having an evaporator (5) and a liquid-liquid heat exchanger (7) arranged in the external air circuit (4), and heat is transferred from the non-flammable refrigerant to the flammable refrigerant via the liquid-liquid heat exchanger (7), and is characterized in that the cooling device (1) includes a tertiary circuit (11), wherein the condenser (3) of the primary circuit (2) is the condenser of the tertiary circuit (11), and the evaporator (5) of the secondary circuit (6) is the evaporator of the tertiary circuit (11).

2. The cooling device (1) according to claim 1, wherein The liquid-liquid heat exchanger (7) is the condenser of the secondary circuit (6) and the evaporator of the primary circuit (2).

3. The cooling device (1) according to claim 1 or 2, wherein: The liquid-liquid heat exchanger (7) is designed as a plate heat exchanger.

4. The cooling device (1) according to claim 1 or 2, wherein: The main circuit (2) is designed as an active compressor refrigeration circuit having a compressor (8) and an expansion member (9).

5. The cooling device (1) according to claim 1 or 2, wherein: The main circuit (2) is arranged in the cooling device (1) in a fluidically isolated manner from the internal air circuit (10).

6. The cooling device (1) according to claim 1 or 2, wherein: The main circuit (2) is fully ventilated to the surroundings of the cooling device (1).

7. The cooling device (1) according to claim 6, wherein: The main circuit (2) is completely arranged in the external air circuit.

8. The cooling device (1) according to claim 1 or 2, wherein: The secondary circuit (6) is a passive refrigerant circuit.

9. The cooling device (1) according to claim 1 or 2, wherein: The non-flammable refrigerant includes carbon dioxide.

10. The cooling device (1) according to claim 1, wherein The condenser (3) of the primary circuit (2) and the condenser of the tertiary circuit (11) are dual-circuit air-liquid heat exchangers having two liquid conducting lines fluidically isolated from each other.

11. The cooling device (1) according to claim 1, wherein: The evaporator (5) of the secondary circuit (6) and the evaporator of the tertiary circuit (11) are double-circuit air-liquid heat exchangers having two liquid conducting lines fluidically isolated from each other.

12. The cooling device (1) according to claim 1, wherein The tertiary circuit (11) includes a non-flammable refrigerant.

13. The cooling device (1) according to claim 1, wherein The tertiary circuit (11) is a passive refrigerant circuit.

14. The cooling device (1) according to claim 1 or 2, wherein: A fan (12) is arranged in each of the external air circuit (4) and the internal air circuit (10), through which the evaporator (5) or the condenser (3) is acted upon by the air conveyed through the corresponding air circuit (4, 10).

15. A switch cabinet arrangement (100) comprising a switch cabinet housing (200) and a cooling device (1) according to any one of claims 1 to 14, wherein: Ambient air of the switchgear arrangement (100) is conveyed via the external air circuit (4), and air received in an interior space (13) of the switchgear housing (200) is conveyed via the internal air circuit (10).

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