Cooling device for air-conditioning switchgear cabinet and corresponding switchgear cabinet arrangement

Abstract

The invention relates to a cooling device (1) for air-conditioning switchgear cabinets, the cooling device (1) having a main circuit (2) which has a combustible refrigerant and a condenser (3) which is arranged in an outer air circuit (4) of the cooling device (1), and the cooling device (1) having an evaporator (5) in an inner air circuit (10), the invention relates to a cooling device (1) having an internal air circuit (4) which is fluidically isolated from the external air circuit (4), characterized in that the cooling device (1) has a secondary circuit (6) which has a non-flammable refrigerant and has 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 through the liquid-liquid heat exchanger. The application also describes a corresponding switchgear arrangement.

Description

[0001] The invention is based on a cooling device for switch cabinet air conditioning and a corresponding switch cabinet arrangement, wherein the cooling device has a main circuit with a combustible coolant and a condenser arranged in the external air circuit of the cooling device. The cooling device also has an evaporator in an internal air circuit, which is fluidically isolated from the external air circuit. The internal air circuit can have an air inlet opening and an air outlet opening, which lead to the inner space of the switch cabinet housing. The external air circuit can lead to the surrounding environment of the cooling device or the switch cabinet arrangement with its air inlet and air outlet. Therefore, the external air circuit can make ambient air flow through the external air circuit and has a fan for this purpose. The air flowing through the external circuit can act on a condenser configured for this purpose, for example, as an air-liquid heat exchanger. In the internal air circuit, the air circulating through the internal air circuit can act on an evaporator arranged in the internal air circuit. The evaporator can be designed as an air-liquid heat exchanger. A cooling device of this type is known from DE102018109604A1.

[0002] Directive 2006 / 42 / EC (Machinery Directive) requires that gases used in machines are free from explosion and fire risks, where failure of individual components is assumed. Therefore, if, in the case of switchgear cooling units, there is a hypothetical leak in the refrigerant-carrying parts, it is assumed that flammable gases (refrigerants) enter the switchgear and could ignite at internal fittings, thus igniting arcs during operation. Without safety functions that reliably prevent this from happening, switchgear cooling units using flammable refrigerants do not meet the Machinery Directive or cannot be operated with the safety required by the end user.

[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 an ingress of flammable refrigerant into the switchgear interior, for example 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.

[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 safety measures required by the Machinery Directive and thus does not require any adaptations to the rest of the switch cabinet arrangement, in particular the switch cabinet 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 has a non-flammable refrigerant and has an evaporator and a liquid-liquid heat exchanger, which is arranged in the external air circuit and through which heat is transferred from the non-flammable refrigerant to the flammable refrigerant.

[0007] The division of the cooling circuit of the cooling device 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 can be a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by the ground height difference. The secondary circuit can be designed as a heat pipe or include a heat pipe, for example. The non-flammable refrigerant can be or include carbon dioxide, for example.

[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-liquid heat exchanger having two liquid conducting lines fluidly isolated from each other.

[0015] The evaporators of the secondary and tertiary loops 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 geodetic height differences, and the tertiary circuit may be or include, for example, a heat pipe.

[0018] In the cooling device, fans may be arranged in the external air circuit and the internal air circuit, respectively. The fan in the external circuit allows air conveyed through the external air circuit to act on the condenser. The fan in the internal circuit allows air conveyed 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 above-described type, ambient air of the switchgear arrangement is conveyed via an external air circuit, while air received in an interior space of the switchgear housing is conveyed via an internal air circuit. The internal air circuit and the external air circuit may be fluidically isolated from one another, so that no air exchange occurs between the external air circuit and the internal air circuit.

[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.

[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. Arranged in the switchgear housing 200 are components 300 which generate heat and can generate arcs, at which flammable refrigerant accumulated 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 switch cabinet 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 switch cabinet housing 200, it flows out of the internal circuit 10 and flows back into the interior 13 of the switch cabinet housing 200 in the lower region of the switch cabinet housing 200. During the passage through the internal air circuit 10, the air acts on the evaporator 5, which is configured in the present example as an exchanger of an air-liquid thermocompressor circuit, as a result of which the air is cooled.

[0025] In the external air circuit 4 , the cooling device 1 has a condenser 3 which is acted upon by the ambient air of the switch cabinet arrangement 100 flowing through the external air circuit 4 and which 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 fluidly 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 . In this case, the horizontal dashed line indicates the airtight separation between the external air circuit 4 or the surroundings of the switch cabinet arrangement and the internal air circuit 10 or the interior space 13 of the switch cabinet housing. Thus, the main circuit 2 designed as a compressor circuit with a compressor 8 and an expansion member 9 is arranged completely in the external air circuit 4. Therefore, the main circuit 2 can contain flammable refrigerants, because 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 switch cabinet housing 200, in which the component 300 is accommodated. In a manner known from the prior art, the main circuit 2 has an air-liquid heat exchanger, which is acted on by a fan 12 and has the function of a condenser. Unlike the known cooling device 1, the evaporator of the main circuit 2 is a liquid-liquid heat exchanger 7, for example a plate heat exchanger, by which the main circuit 2 is thermally coupled to the secondary circuit 6. The secondary circuit 6 has another air-liquid heat exchanger 5, which is likewise acted upon by a fan 12 on air which is conducted through the internal air circuit 10. The secondary circuit 6 is filled with a non-flammable refrigerant, so that the refrigerant which enters the internal space 13 and escapes in the event of a leak cannot ignite at the arc of the component 300. With respect to the secondary circuit 6, the liquid-liquid heat exchanger 7 forms a condenser.

[0028] In order to further optimize the efficiency of the cooling device 1, the condenser 3 and the evaporator 5 are both designed as a double circuit, wherein either of the two circuits of the condenser 3 and the evaporator 5 forms a tertiary circuit. The tertiary circuit 11 and the secondary circuit 6 are preferably designed as a natural circulation refrigerant circuit driven by the height difference of the earth. In one embodiment, the secondary circuit 6 and / or the tertiary circuit 11 can be designed as a heat pipe.

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

[0030] Reference Numbers List

[0031] 1Cooling device

[0032] 2 Main circuit

[0033] 3 Condenser

[0034] 4 External air circuit

[0035] 5. Evaporator

[0036] 6 Secondary circuit

[0037] 7Heat exchanger

[0038] 8. Compressor

[0039] 9Expansion member

[0040] 10Internal air circuit

[0041] 11Third level circuit

[0042] 12 Fan

[0043] 13. Interior Space

[0044] 100 switch cabinet 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 main circuit (2), the main circuit (2) has a flammable refrigerant, and has a condenser (3) arranged in the external air circuit (4) of the cooling device (1), and wherein the cooling device (1) has an evaporator (5) in the internal air circuit (10), the internal air circuit is fluidically isolated from the external air circuit (4), and is characterized in that the cooling device (1) has a secondary circuit (6), the secondary circuit (6) has a non-flammable refrigerant, and has 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 through the liquid-liquid heat exchanger (7).

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 any one of the preceding claims, 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 any one of the preceding claims, 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 any one of the preceding claims, 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 any one of the preceding claims, wherein: The secondary circuit (6) is a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by the ground height difference, such as a heat pipe.

9. The cooling device (1) according to any one of the preceding claims, wherein: The non-flammable refrigerant includes carbon dioxide.

10. The cooling device (1) according to any one of the preceding claims, comprising 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).

11. The cooling device (1) according to claim 10, 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 fluidly isolated from each other.

12. The cooling device (1) according to claim 10 or 11, wherein: The evaporator (5) of the secondary circuit (6) and the evaporator of the tertiary circuit (11) are dual-circuit air-liquid heat exchangers having two liquid conducting lines fluidically isolated from each other.

13. The cooling device (1) according to any one of claims 10 to 12, wherein: The tertiary circuit (11) comprises a non-flammable refrigerant, such as carbon dioxide.

14. The cooling device (1) according to any one of claims 10 to 13, wherein: The tertiary circuit (11) is a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by the ground height difference, such as a heat pipe.

15. The cooling device (1) according to any one of the preceding claims, wherein: A fan (12) is arranged in the external air circuit (4) and the internal air circuit (10), respectively, through which the evaporator (5) or the condenser (3) is acted upon by the air conveyed through the corresponding air circuit (4, 10).

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

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