Cooling device for control cabinet temperature control and a corresponding control cabinet assembly

Abstract

The invention relates to a cooling device (1) for control cabinet temperature control, wherein the cooling device (1) has a primary circuit (2) with a flammable coolant and with a condenser (3), which is arranged in an air outer circuit (4) of the cooling device (1), and wherein the cooling device (1) has an evaporator (5) in an air inner circuit (10) that is fluidically separated from the air outer circuit (4), characterised in that the cooling device (1) has a secondary circuit (6) with a non-flammable coolant, which has the evaporator (5) and a fluid-fluid heat exchanger (7) which is arranged in the air outer circuit (4) and with which heat from the non-flammable coolant is transmitted to the flammable coolant. The invention also relates to a corresponding control cabinet assembly.

Description

[0001] Cooling unit for control cabinet air conditioning and a corresponding control cabinet arrangement

[0002] 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 primary circuit containing a flammable refrigerant and a condenser arranged in an external air circuit of the cooling device. The cooling device further has an evaporator in an internal air circuit that is merely separated from the external air circuit. The internal air circuit can have an air inlet and an air outlet opening that are open into the interior of a switch cabinet housing. The external air circuit can be open with its air inlet and its air outlet to the environment of the cooling device or the switch cabinet arrangement. The external air circuit can thus be traversed by ambient air and can have a fan for this purpose. The air flowing through the external circuit can act on the condenser, which for this purpose is designed, for example, as an air-liquid heat exchanger.In the internal air circuit, the air circulated through the internal air circuit can be applied to an evaporator arranged within the internal air circuit. The evaporator can be designed as an air-liquid heat exchanger. Such a cooling device is known from DE 10 2018 109 604 Ai.

[0003] Directive 2006 / 42 / EC (Machinery Directive) requires that gases used in machinery do not pose a risk of explosion or fire, although it is assumed that individual components will fail. Therefore, if a refrigerant-carrying component in an enclosure cooling unit has a suspected leak, it can be assumed that flammable gas (refrigerant) will enter the enclosure and ignite on components that ignite arcs during operation. Without a safety function that reliably prevents this, enclosure cooling units that use flammable refrigerants cannot comply with the Machinery Directive or operate with the necessary safety for the end user.

[0004] The control cabinet arrangements known from the prior art have the disadvantage that they are comparatively complex to implement, since, for example, various actively driven closing elements are required and must be activated in the event of a detected leak and / or the entry of a flammable refrigerant into the interior of the control cabinet, for example in order to close a partition between the internal circuit of the cooling device and the interior of the control cabinet so that no (further) refrigerant can enter the interior of the control cabinet.

[0005] It is therefore the object of the invention to further develop the cooling device described at the outset in such a way that it combines all the safety measures required by the Machinery Directive and thus no adjustments to the remaining switch cabinet arrangement, in particular to the switch cabinet housing, are necessary.

[0006] This object is achieved by a cooling device having the features of claim 1. A corresponding control cabinet arrangement is the subject of the independent claim 16. Advantageous embodiments are the subject of the dependent claims.

[0007] Accordingly, the cooling device is provided with a secondary circuit comprising a non-flammable refrigerant, which has the evaporator and a liquid-liquid heat exchanger which is arranged in the external air circuit and with which heat is transferred from the non-flammable refrigerant to the flammable refrigerant.

[0008] By separating the cooling circuit of the cooling device into a primary circuit and a secondary circuit, of which the secondary circuit contains a non-flammable refrigerant, it is ensured 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 of a control cabinet housing.

[0009] The liquid-to-liquid heat exchanger can be a condenser in the secondary circuit and an evaporator in the primary circuit. The liquid-to-liquid heat exchanger can be designed as a plate heat exchanger.

[0010] The primary circuit can be designed as an active compressor refrigeration circuit with a compressor and an explosion device.

[0011] The primary circuit can be arranged in the cooling device so that it is fluidically separated from the internal air circuit.

[0012] The primary circuit may be fully ventilated to the surroundings of the cooling device.

[0013] In particular, the primary circuit can be arranged entirely within the external air circuit. The secondary circuit can be a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by a geodetic elevation difference. The secondary circuit can, for example, be designed as a heat pipe or comprise a heat pipe. The non-flammable refrigerant can, for example, be or comprise carbon dioxide.

[0014] The cooling device may further comprise a tertiary circuit in which 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.

[0015] The condenser of the primary circuit and / or the tertiary circuit can be a dual-circuit air-liquid heat exchanger with two fluidically separated liquid-carrying lines.

[0016] The evaporator of the secondary circuit and the tertiary circuit can be a dual-circuit air-liquid heat exchanger with two fluidically separated liquid-carrying lines.

[0017] The tertiary circuit may contain or be a non-flammable refrigerant, for example carbon dioxide.

[0018] The tertiary circuit may be a passive refrigerant circuit, preferably a natural circulation refrigerant circuit driven by a geodetic height difference, and the tertiary circuit may be or comprise, for example, a heat pipe.

[0019] In the cooling unit, a fan can be arranged in each of the outer air circuit and the inner air circuit. The fan in the outer circuit can supply the condenser with air drawn through the outer air circuit. The fan in the inner circuit can supply the evaporator with air drawn through the inner air circuit.

[0020] In a control cabinet assembly comprising a control cabinet housing and a cooling device of the type described above, ambient air of the control cabinet assembly is conveyed through the outer air circuit, and air collected in an interior of the control cabinet housing is conveyed through the inner air circuit. The inner and outer air circuits can be fluidically separated from one another, so that no air exchange can occur between the outer and inner air circuits. Exemplary embodiments of the invention are explained with reference to the following figures. In the following:

[0021] Figure 1 is a schematic cross-sectional view of a switch cabinet arrangement; and

[0022] Figure 2 is a block diagram of a cooling device according to the invention.

[0023] Figure i shows an exemplary embodiment of a switch cabinet arrangement 100 with a switch cabinet housing 200 and a cooling device 1 mounted thereon in a side part. Heat-emitting and possibly arc-generating components 300 are arranged in the switch cabinet housing 200, at which components a flammable coolant accumulating in the interior 13 of the switch cabinet housing 200 can ignite, for example at an arc generated during a switching operation of a switching device 300.

[0024] The cooling device 1 has an internal air circuit 10 through which the air taken in from the interior 13 of the switch cabinet housing 200 is transported by means of a fan 12. While the heated air is introduced into the internal air circuit 10 in an upper region of the switch cabinet housing 200, it flows out of the internal circuit 10 in a lower region of the switch cabinet housing 200 and back into the interior 13 of the switch cabinet housing 200. On its way through the internal air circuit 10, the air acts on an evaporator 5, which in this case is designed as an air-liquid heat exchanger of a compressor circuit, thereby cooling the air.

[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 is also designed as an air-liquid heat exchanger.

[0026] In contrast to the cooling devices known from the prior art, in the cooling device 1 according to the invention, the evaporator 5 in the inner air circuit 1 is not fluidically connected to the condenser 3 in the outer air circuit 4 via a common refrigerant circuit. Instead, a primary circuit 2, which has the condenser 3, and a secondary circuit 6, which has the evaporator 5, are provided, which in turn are fluidly separated from one another and thermally coupled to one another via a liquid-liquid heat exchanger 7. For a better understanding of the fluidic interconnection of an exemplary cooling device according to the invention, reference is made to the block diagram according to Figure 2. The horizontal dashed line represents the airtight separation between the outer air circuit 4, or the surroundings of the switch cabinet arrangement, and the inner air circuit 10, or the interior 13 of the switch cabinet housing.Accordingly, a primary circuit 2, which is designed as a compressor circuit with a compressor 8 and an expansion device 9, is completely arranged in the outer air circuit 4. The primary circuit 2 can therefore contain a flammable refrigerant, since even in the event of a leak, due to the separation between the inner air circuit 10 and the outer air circuit 4, no flammable refrigerant can enter the inner air circuit 10 or the interior 13 of the control cabinet housing 200 with the components 300 accommodated therein. The primary circuit 2 has, in the manner known from the prior art, an air-liquid heat exchanger, which is supplied with air by a fan 12 and functions as a condenser.In contrast to the 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 a secondary circuit 6. The secondary circuit 6 has a further air-to-liquid heat exchanger 5, which is also supplied with air by a fan 12, which is passed through the internal air circuit 10. The secondary circuit 6 is filled with a non-flammable refrigerant, so that in the event of a leak, any refrigerant escaping into the interior 13 cannot be ignited by an arc from the components 300. With respect to the secondary circuit 6, the liquid-to-liquid heat exchanger 7 forms a condenser.

[0027] To further optimize the efficiency of the cooling device 1, the condenser 3 and the evaporator 5 are each designed as dual circuits, with one of the two circuits of the condenser 3 and the evaporator 5 forming a tertiary circuit. Both the tertiary circuit 11 and the secondary circuit 6 can preferably be designed as a refrigerant circuit in natural circulation, driven by a geodetic elevation difference. In one embodiment, the secondary circuit 6 and / or the tertiary circuit 11 can be designed as a heat pipe.

[0028] The features of the invention disclosed in the above description, in the drawings, and in the claims may be essential for the realization of the invention, both individually and in any combination. List of reference symbols

[0029] Cooling device

[0030] primary circuit

[0031] Condenser

[0032] outer air circuit

[0033] evaporator

[0034] Secondary circuit

[0035] heat exchanger

[0036] compressor

[0037] Expansion organ

[0038] inner air circuit

[0039] Tertiary cycle

[0040] fan

[0041] Interior

[0042] Control cabinet arrangement Control cabinet housing components

Claims

Claims Cooling device (i) for switch cabinet air conditioning, wherein the cooling device (i) has a primary circuit (2) containing a flammable refrigerant and having a condenser (3) which is 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) fluidically separated from the external air circuit (4), characterized in that the cooling device (1) has a secondary circuit (6) containing a non-flammable refrigerant, which has the evaporator (5) and a liquid-liquid heat exchanger (7) which is arranged in the external air circuit (4) and with which heat is transferred from the non-flammable refrigerant to the flammable refrigerant. Cooling device (1) according to claim 1, wherein the liquid-liquid heat exchanger (7) is a condenser of the secondary circuit (6) and an evaporator of the primary circuit (2).Cooling device (1) according to claim 1 or 2, wherein the liquid-liquid heat exchanger (7) is designed as a plate heat exchanger. Cooling device (1) according to one of the preceding claims, wherein the primary circuit (2) is designed as an active compressor refrigeration circuit with a compressor (8) and an expansion element (9). Cooling device (1) according to one of the preceding claims, wherein the primary circuit (2) is arranged in the cooling device (1) fluidically separated from the inner air circuit (10). Cooling device (1) according to one of the preceding claims, wherein the primary circuit (2) is completely ventilated to the environment of the cooling device (1). Cooling device (1) according to claim 6, wherein the primary circuit (2) is arranged completely in the outer air circuit. Cooling device (i) according to one of the preceding claims, in which the secondary circuit (6) is a passive refrigerant circuit, preferably a refrigerant circuit in natural circulation, driven by a geodetic height difference, for example a heat pipe. Cooling device (1) according to one of the preceding claims, in which the non-combustible refrigerant comprises carbon dioxide. Cooling device (1) according to one of the preceding claims, which has a tertiary circuit (11), in which 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). Cooling device (1) according to claim 10, in which the condenser (3) of the primary circuit (2) and of the tertiary circuit (11) is a dual-circuit air-liquid heat exchanger with two fluidically separated liquid-carrying lines. Cooling device (1) according to claim 10 or 11, in which the evaporator (5) of the secondary circuit (6) and of the tertiary circuit (11) is a dual-circuit air-liquid heat exchanger with two fluidically separated liquid-carrying lines. Cooling device (1) according to one of claims 10 to 12, wherein the tertiary circuit (11) comprises a non-flammable refrigerant, for example carbon dioxide.Cooling device (1) according to one of claims 10 to 13, wherein the tertiary circuit (11) is a passive refrigerant circuit, preferably a natural circulation refrigerant circuit, driven by a geodetic height difference, for example a heat pipe. Cooling device (1) according to one of the preceding claims, wherein each fan comprises a fan. (12) is arranged in the outer air circuit (4) and in the inner air circuit (10), with which the evaporator (5) or the condenser (3) is supplied with the air conveyed through the respective air circuit (4, 10). Switch cabinet arrangement (100) with a switch cabinet housing (200) and a cooling device (1) according to one of the preceding claims, wherein ambient air of the switch cabinet arrangement (100) is conveyed through the outer air circuit (4) and air taken up in an interior space (13) of the switch cabinet housing (200) is conveyed through the inner air circuit (10).

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