Cooling arrangement and method for cooling at least one oil-air external heat exchanger

Abstract

A cooling arrangement (20) for cooling at least one OAEHE in a transformer. The cooling arrangement (20) comprises at least one impeller motor device (10), at least one fluid conduit (11) and a first fluid discharge device (12). The first fluid discharge device (12) comprises a fluid inlet arranged to receive fluid from the at least one fluid conduit (11) and at least one fluid outlet arranged to direct the fluid towards the OAEHE, the at least one impeller motor device (10) is adapted to supply fluid to an inlet of the first fluid discharge device (12) via the at least one fluid conduit (11) and to flow fluid through the at least one fluid outlet of the first fluid discharge device (12) in the direction of the at least one OAEHE. The cooling arrangement (20) further comprises a second fluid discharge device (22) adapted to perturb fluid flowing through the at least one fluid outlet of the first fluid discharge device (12).

Description

Technical Field

[0001] Embodiments herein relate to the field of transformers. Specifically, embodiments herein relate to a cooling arrangement for cooling at least one oil - air external heat exchanger (OAEHE) in a transformer. Background Art

[0002] Power transformers are devices used in the power grid of a power system. Power transformers convert voltage and current in order to transmit and distribute electrical energy. Power transformers involve high currents and thus, heat generation is inevitable. This heat is propagated in the oil inside the transformer tank. For the normal operation of the transformer, it is important to release this heat to the surrounding environment. An important part of oil cooling is carried out by placing external devices such as radiators, cooler banks, etc., through which the transformer oil circulates and gets cooled. Currently, air cooling of transformers is carried out using conventional fans (i.e., vane - type fans) or natural convection. Existing cooling using standard fans generates high noise, is structurally complex, heavy and difficult to maintain. For high - power - rated transformers, natural convection is not sufficient and thus, forced cooling is required for this operation.

[0003] External transformer cooling is typically obtained through a bank of radiators, allowing the oil to circulate externally from top to bottom. The cooling process is carried out by ambient air in natural or forced convection. The present invention relates to the case of forced convection, which is typically provided by a set of large fans that blow air over the radiators. The cooling efficiency depends on the air velocity and thus on the power consumption of the fans, which is a significant operating cost and worthy of substantial reduction.

[0004] The present disclosure proposes an improved and viable solution for the cooling arrangement. Summary of the Invention

[0005] As part of the embodiments developed herein, one or more problems have been identified. By replacing the conventional fan with a bladeless fan that blows air from a remote impeller and injects it through an air multiplier, the power consumption and noise level can be reduced since the impeller noise can be easily controlled. However, a bladeless fan consisting of linear (circular, rectangular or other shapes) thin slots cannot provide a uniform flow to cool all the hot surfaces. Assuming the bladeless fan is an annulus, the resulting jet has a roughly cylindrical shape, where the velocity in the core is lower and higher at the edges. The cooling pattern will be very non - uniform, where the surfaces of some panels have a high heat transfer coefficient while the surfaces of other panels have none at all. The panel areas with extremely low air velocity will not be adequately cooled and the hot oil will be re - injected into the transformer tank.

[0006] The aim of the embodiments herein is to enhance the cooling of the OAEHE of the transformer.

[0007] According to one aspect, this object is achieved by providing a cooling arrangement for cooling at least one OAEHE in a transformer. The cooling arrangement includes at least one impeller motor device, at least one fluid pipe, and a first fluid discharge device. The first fluid discharge device includes a fluid inlet and at least one fluid outlet. The fluid inlet is arranged to receive fluid from at least one fluid pipe, and the at least one fluid outlet is arranged to direct the fluid towards the OAEHE. The at least one impeller motor device is adapted to supply fluid to the inlet of the first fluid discharge device via at least one fluid pipe and cause the fluid to flow through at least one fluid outlet of the first fluid discharge device in the direction of the at least one OAEHE. The cooling arrangement further includes a second fluid discharge device adapted to disturb the fluid flowing through at least one fluid outlet of the first fluid discharge device.

[0008] According to some embodiments, the second fluid discharge device can disturb the fluid flowing through at least one fluid outlet of the first fluid discharge device by applying a cross-flow jet to destabilize and / or broaden the fluid.

[0009] According to some embodiments, the applied cross-flow jet can be continuous.

[0010] According to some embodiments, the applied cross-flow jet can be pulsating.

[0011] According to some embodiments, the at least one impeller motor device can be adapted to supply fluid to the second discharge device.

[0012] According to some embodiments, the second fluid discharge device can be located between the first fluid discharge device and the at least one OAEHE.

[0013] According to some embodiments, the diameter of the second fluid discharge device can be smaller than or the same size as the diameter of the first fluid discharge device, and wherein the cross-flow jet can be applied outwardly from the second fluid discharge device.

[0014] According to some embodiments, the diameter of the second fluid discharge device can be larger than the diameter of the first fluid discharge device, and wherein the cross-flow jet can be applied inwardly from the second fluid discharge device.

[0015] According to some embodiments, the cooling arrangement can include a funnel. According to some embodiments, at least one fluid discharge device and / or the second fluid discharge device can be arranged in the funnel.

[0016] According to another aspect, the above object is also achieved by providing a method carried out by a cooling arrangement for cooling at least one OAEHE in a transformer. The cooling arrangement includes at least one impeller motor device, at least one fluid pipe, and a first fluid discharge device. The first fluid discharge device includes a fluid inlet for receiving a fluid flow from at least one fluid pipe and at least one fluid outlet. The cooling arrangement uses at least one impeller motor device to supply fluid into at least one fluid pipe. The cooling arrangement further conveys the fluid along at least one fluid pipe to the inlet of at least one fluid discharge device. The cooling arrangement further passes the fluid through at least one fluid discharge device. The cooling arrangement then further discharges the fluid through at least one fluid outlet in the direction of at least one OAEHE. The cooling arrangement further includes a second fluid discharge device. The cooling arrangement uses the second fluid discharge device to disturb the fluid flowing through at least one fluid outlet of the first fluid discharge device.

[0017] Embodiments herein are based on the recognition that by providing a second fluid discharge device that disturbs the fluid flowing out of the first fluid discharge device, the fluid velocity difference of the fluid flowing out of the first discharge device is reduced, and an improved redistribution of the fluid flow is allowed. Thereby, the cooling arrangement effectively provides strong and enhanced cooling to at least one OAEHE of the transformer. Brief Description of the Drawings

[0018] The further technical features of the present invention will become apparent from the following description of one or several exemplary embodiments given with reference to the accompanying drawings, in which:

[0019] Figure 1 is a schematic overview depicting a cooling arrangement according to an embodiment herein;

[0020] Figure 2a is a schematic overview depicting the fluid flowing out of the first fluid discharge device without any fluid disturbance;

[0021] Figure 2b is a schematic overview depicting the fluid flowing out of the first fluid discharge device with fluid disturbance;

[0022] Figure 3 is a flowchart depicting the method carried out by the cooling arrangement according to an embodiment herein;

[0023] It should be noted that the drawings are not necessarily drawn to scale, and for clarity, the dimensions of some elements may have been enlarged. Detailed Description of the Embodiments

[0024] Embodiments of the present disclosure introduce a cross-flow jet (such as a main bladeless fan jet) from, for example, a duct or a trough, which is perpendicular to the fluid from the fluid discharge device to disrupt or destabilize the fluid to become wider and cover more of the radiator surface. When intermittent or transient cooling is desired, the lateral jet (which may also be referred to as a control jet) can be continuous or pulsating. Computational fluid dynamics simulations can be used to optimize, for example, the jet, intensity, mass, and position of the fluid.

[0025] Figure 1 An integrated description and operation of a cooling arrangement 20 according to an embodiment of the present disclosure is illustrated. The cooling arrangement 20 includes at least one impeller motor device 10, at least one fluid duct 11, and a first fluid discharge device 12. The first fluid discharge device 12 can be hollow and includes a fluid inlet and at least one fluid outlet, the fluid inlet being arranged to receive fluid from the at least one fluid duct 11, and the at least one fluid outlet being arranged to direct the fluid towards at least one OAEHE (such as a radiator). The at least one impeller motor device 10 is adapted to supply fluid to the inlet of the first fluid discharge device 12 via the at least one fluid duct 11 and cause the fluid to flow through the at least one fluid outlet of the first fluid discharge device 12 in the direction of the at least one OAEHE. The cooling arrangement 20 further includes a second fluid discharge device 22, which is adapted to perturb the fluid flowing through the at least one fluid outlet of the first fluid discharge device 12. The cooling arrangement 20 can further include a funnel 15, such as a funnel duct having a Coanda boundary, to enhance the fluid flow. The operation of the cooling arrangement 20 is as described below:

[0026] The generated fluid (such as an air flow) can be brought (such as provided to) the impeller motor device 10. The fluid can be filtered through a filter before being brought to the impeller motor device 10.

[0027] The impeller motor device 10 then supplies (e.g., accelerates) fluid to the fluid conduit 11. The fluid conduit 11 may include thermal insulation material. The impeller motor device 10 may be located in the housing 16 at a distance from at least one fluid discharge device 12. The distance between the impeller motor device 10 and the at least one fluid discharge device 12 may be at least 1 meter, 3 meters, 5 meters or greater. According to some embodiments, at least one impeller motor device may be located in the housing at a distance of at least 3 meters from at least one fluid discharge device. The distance between the impeller motor device 10 and the at least one fluid discharge device 12 is advantageous, for example because the sound from the impeller motor device will be generated at a distance from the transformer, thus enabling a noise mitigation process (e.g., the soundproof housing 16 and the fluid conduit 11). By shifting the sound source to the soundproof housing, the operation of the fluid discharge device 12 can reduce the noise by 20 dB to 40 dB compared to, for example, a conventional vane fan. The housing 16 may be soundproof, thermally insulated, may include thermal insulation material, may be humidity controlled, may be dustproof and / or sound-absorbing. The housing 16 and the at least one fluid conduit 11 may be located underground or covered by a solid structure, which can reduce the risk of damage and intentional attack on the transformer substation. According to some embodiments, the cooling arrangement 20 may include a plurality of fluid conduits 11, which may be adapted to supply fluid to a plurality of first fluid discharge devices 12.

[0028] The fluid can be conveyed along the conduit 11 towards the inlet of the first fluid discharge device 12 with a minimum pressure drop. The first fluid discharge device 12 may be arranged (e.g., fixed) in the funnel 15. The funnel 15 may include a rounded smooth boundary 18 at the inlet of the funnel 15 to promote the Coanda effect, which alleviates edge turbulence and reduces the pressure drop at the inlet of the funnel 15. The inlet of the funnel 15 may include a filter grid 17. The filter grid 17 is used to prevent foreign objects from entering the OAEHE.

[0029] A fluid (such as a fluid flow like an air flow) can be forced to be distributed inside the first fluid discharge device 12 at high pressure.

[0030] Then, the fluid is discharged (e.g., ejected) at high speed through the outlet of the first fluid discharge device 12. According to some embodiments, the first fluid discharge device 12 includes at least one slit, and the fluid can be discharged through the slit, which may be narrow (e.g., designed to cause flow towards the OAEHE).

[0031] Due to the high velocity of the fluid, the fluid in the rear part of the first fluid discharge device 12 can be directed into the central region of the first fluid discharge device 12. And near the outlet of the first fluid discharge device 12, entrained fluid and / or moist fluid. Depending on the geometry and size of the first fluid discharge device 12, induction and entrainment (i.e., the Bernoulli effect) can multiply the initial fluid flow M by 10 to 50 times.

[0032] The aerodynamic shape of the annular surface of the first fluid discharge device 12 and the Coanda effect cause the fluid flow to be directed towards the OAEHE.

[0033] The cooling arrangement 20 may further include a hose (not shown). The hose may be arranged to enhance and / or homogenize the supplied fluid. Additional fluid can be added to the axial regions of the first fluid discharge device 12 and / or the second fluid discharge device 22 through the hose.

[0034] The obtained fluid flow can be increased to match the requirements of cooling at least one OAEHE in the transformer. A set of parameters can provide such a dedicated design. These parameters are:

[0035] a. The power of the impeller motor device;

[0036] b. The diameter and / or size of the fluid discharge device;

[0037] c. The slit thickness;

[0038] d. The annular shape of the first fluid discharge device 12 and the cross-sectional dimensions of the first fluid discharge device 12. The first fluid discharge device 12 can be circular, elliptical, rectangular or any other polygonal shape.

[0039] According to some embodiments, a cooler fluid can be injected through the first fluid discharge device 12, thus significantly enhancing external cooling.

[0040] The high-speed fluid can pass through the OAEHE, and its geometry will generate a pressure drop. The remaining fluid flow can be used to cool the second or multiple OAEHEs.

[0041] As a result of the operation of the cooling arrangement 20, the fluid flow is multiplied, typically increased by 10 to 50 times. The technology of the cooling arrangement 20 can utilize the surrounding fluid and / or moist fluid to amplify the fluid flow delivered to the first fluid discharge device 12. It is concluded that the cooling arrangement 20 effectively provides a powerful and efficient overall fluid flow to at least one OAEHE of the transformer. In addition, since the fluid humidity (e.g., moist / wet cooling air flow) can be used for external cooling of the transformer, the heat transfer between the cooling fluid and the OAEHE of the transformer can be significantly enhanced. By using the Bernoulli multiplication technique, the external cooling of the power transformer can thus be enhanced.

[0042] However, the first fluid discharge device 12 including the fluid outlet may not provide a uniform flow to cool all the hot surfaces of the OAEHE. Assuming that the first fluid discharge device 12 is an annulus, the resulting fluid may have a generally cylindrical shape, with a lower velocity in the core and a higher velocity at the edges. The cooling pattern will be very non-uniform, where some regions of the OAEHE have a high heat transfer coefficient while other regions have none at all. The regions of the OAEHE at very low air velocities may not be adequately cooled, and the hot oil may be reinjected into the transformer tank. Therefore, the cooling arrangement 20 further includes a second fluid discharge device 22 that is adapted to perturb the fluid flowing through at least one fluid outlet of the first fluid discharge device 12. The second fluid discharge device 22 can perturb the fluid flowing through at least one fluid outlet of the first fluid discharge device 12 by applying a cross-flow jet (e.g., a lateral jet or a control jet) to destabilize and / or broaden the fluid. This is advantageous because it reduces the fluid velocity difference of the fluid flowing out of the first discharge device 12 and allows for an improved redistribution of the fluid flow. According to some embodiments, the applied cross-flow jet can be continuous, and according to some embodiments, the applied cross-flow jet can be pulsating. A continuous jet is preferred in cases where stable operating conditions are required to ensure a certain level of cooling process stability. Pulsating jets are used in dynamic situations to ensure a high oscillation level of the jets and a significant reduction in energy consumption.

[0043] At least one impeller motor device 10 can be adapted to supply fluid to the second discharge device 22. At least one impeller motor device 10 can be adapted to supply fluid to the inlet of the first fluid discharge device 12 and / or the second fluid discharge device 22 via at least one fluid pipe 11 and / or via a second fluid pipe. At least one fluid pipe 11 and / or the second fluid pipe can include thermal insulation material. The second fluid discharge device 22 can be located between the first fluid discharge device 12 and at least one OAEHE. The second fluid discharge device 22 can be arranged in a funnel 15.

[0044] According to some embodiments, the diameter of the second fluid discharge device 22 can be smaller than or the same size as the diameter of the first fluid discharge device 12, and wherein the cross-flow jet is applied outwardly from the second fluid discharge device 22.

[0045] According to some embodiments, the diameter of the second fluid discharge device 22 can be larger than the diameter of the first fluid discharge device 12, and wherein the cross-flow jet is applied inwardly from the second fluid discharge device 22.

[0046] Figure 2a A schematic overview is illustrated of the fluid flowing out of the first fluid discharge device 12 without any fluid perturbation according to an example.Figure 2b Illustrated is a schematic overview of an example according to an embodiment herein of fluid flowing out of a first fluid discharge device 12 in the presence of fluid perturbations from a second fluid discharge device 22. By applying an optimized cross-flow jet, the fluid from the first fluid discharge device 12 will be altered, broken into multiple transient vortices, or merely widened. This reduces the fluid velocity difference (e.g., gradient) and allows for better fluid redistribution and more accurate cooling of the surface of the OAEHE. The cross-flow characteristics can be identified through computational fluid dynamics simulations and other optimization methods. To avoid the fluid released from the outlet of the first fluid discharge device from remaining sharp when impacting the OAEHE, a continuous or pulsating lateral jet passing through the second fluid discharge device 22 or a separate duct impacts the first fluid discharge device 12 vertically or obliquely. This impact is to widen and / or destabilize the fluid from the first fluid discharge device 12, such that it moves or pulsates, for example, in a manner that covers all or most of the OAEHE surface at a sufficient speed to produce the desired cooling performance.

[0047] Reference will now be made to Figure 3 the flowchart depicted in

[0048] Action 301:

[0049] Filtered fluid can be generated and supplied to at least one impeller motor device 10. The filter is used to prevent dust and / or particles from entering at least one impeller motor device 10 and passing through at least one fluid duct 11 and the first fluid discharge device 12. At least one impeller motor device 10 can be located in a housing 16. The housing 16 can have one or more of the following: soundproof, heat-insulated, including heat-insulating material, humidity-controlled, dust-proof, and / or sound-absorbing.

[0050] Action 302:

[0051] The cooling arrangement 20 uses at least one impeller motor device 10 to supply fluid into at least one fluid duct 11.

[0052] At least one fluid conduit 11 may include thermal insulation material. The cooling arrangement 20 may include a plurality of fluid conduits 11 that may be adapted to supply fluid to a plurality of first fluid discharge devices 12.

[0053] Measure 303:

[0054] The cooling arrangement 20 conveys fluid along at least one fluid conduit 11 to the inlet of the first fluid discharge device 12. The first fluid discharge device 12 may be circular, oval, rectangular or any other polygonal shape. The fluid outlet of the first fluid discharge device 12 may follow the outer or inner perimeter of the first fluid discharge device 12. The cooling arrangement 20 may include a funnel 15, and the first fluid discharge device 12 may be disposed within the funnel 15. The funnel 15 may include a rounded smooth boundary 18 at the inlet of the funnel 15 to promote the Coanda effect, which reduces edge turbulence and decreases the pressure drop at the inlet of the funnel 15.

[0055] Measure 304:

[0056] The cooling arrangement 20 causes fluid to flow through the first fluid discharge device 12.

[0057] Measure 305:

[0058] The cooling arrangement 20 discharges (e.g., expels) fluid through at least one fluid outlet in the direction of at least one OAEHE. The first fluid discharge device 12 may include at least one slit that is designed to be narrow enough to change the physical properties of the fluid flow by the amount due to the Bernoulli effect, and the cooling arrangement 20 may discharge fluid through the slit in the direction of at least one OAEHE to cool at least one OAEHE. The cooling arrangement 20 further includes a second fluid discharge device 22. The second fluid discharge device 22 may be located between the first fluid discharge device 12 and at least one OAEHE. According to some embodiments, at least one impeller motor device 10 may be adapted to supply fluid to the second discharge device 22. According to some embodiments, the diameter of the second fluid discharge device 22 may be smaller than the diameter of the first fluid discharge device 12, and wherein a cross-flow jet may be applied outwardly from the second fluid discharge device 22. According to some embodiments, the diameter of the second fluid discharge device 22 may be larger than the diameter of the first fluid discharge device 12, and wherein a cross-flow jet may be applied inwardly from the second fluid discharge device 22. At least one impeller motor device 10 may be adapted to supply fluid to the inlet of the first fluid discharge device 12 and / or the second discharge device 22 via at least one fluid conduit 11 or via a second fluid conduit. At least one fluid conduit 11 and / or the second fluid conduit may include thermal insulation material. By providing the second fluid discharge device 22 that disturbs the fluid flowing out of the first fluid discharge device 12, the fluid velocity difference of the fluid flowing out of the first discharge device is reduced, and an improved redistribution of the fluid flow is allowed.

[0059] Measure 306:

[0060] Use the second fluid discharge device 22 to disturb the fluid flowing through at least one fluid outlet of the first fluid discharge device 12. According to some embodiments, disturbing the fluid flowing through at least one fluid outlet of the first fluid discharge device 12 may include destabilizing and / or widening the fluid by applying a cross-flow jet. According to some embodiments, the applied cross-flow jet may be continuous. According to some embodiments, the applied cross-flow jet may be pulsating. The cooling arrangement 20 may add additional fluid to the axial regions of the first discharge device 12 and / or the second fluid discharge device 22 through a hose. The first fluid discharge device 12 and the second fluid discharge device 22 may be circular, elliptical, rectangular, or any other polygonal shape.

[0061] As a result, the embodiments herein thus provide a cooling arrangement 20 that includes at least one connected impeller motor device 10, a fluid conduit 11, a first fluid discharge device 12 that jets a powerful fluid stream, and a second fluid discharge device 22 that disturbs the fluid of the first fluid discharge device 12. The impeller motor device 10 can be located inside a housing 16, which can be protective and soundproof, and / or can be a heat-insulated, humidity-controlled, dust-proof, and sound-absorbing chamber. The fluid conduit 11 can be made of a strong and heat-insulating material. Examples of strong and heat-insulating materials are polymer composites, which can include reinforcements such as carbon fiber. For robustness, the fluid conduit 11 can also be made of metal and covered with concrete. The fluid outlet of the discharge device 12 can follow the outer perimeter of the discharge device 12. The fluid discharge device 12 outlet can include narrow slits through which the fluid moisture discharges and is directed towards the device to be cooled. The embodiments herein provide external cooling for large power transformers. The proposed cooling arrangement 20 is simple, lightweight, and easy to maintain. It is also silent because there are no moving parts at the cooling site. The silence is possible because the fluid discharge device 12 is separated from the impeller motor device 10, which can be confined in a housing that can be soundproof. The embodiments herein are based on Bernoulli's principle, which enables the inlet fluid flow rate provided by the impeller motor device 10 to be multiplied by more than an order of magnitude. The embodiments herein further are based on the use of the second fluid discharge device 22 to disturb the fluid flowing out of the first fluid discharge device 12.

[0062] It should be noted that, where appropriate, any feature of any aspect can be applied to any other aspect. Similarly, any advantage of any aspect can be applied to any other aspect.

[0063] In general, unless otherwise clearly defined herein, all terms used in the claims will be interpreted according to their ordinary meaning in the technical field. All references to "an / a / the element, apparatus, component, device, step, etc." will be construed openly as referring to at least one instance of the element, apparatus, component, step, etc., unless otherwise clearly stated. The steps of any method disclosed herein need not be performed exactly in the order disclosed, unless explicitly stated. The use of "first", "second", etc. for different features / components of the present disclosure is only intended to distinguish the features / components from other similar features / components, rather than to assign any order or hierarchy to the features / components.

[0064] It should be understood that the foregoing description and drawings represent non-limiting examples of the methods taught herein. Thus, the techniques taught herein are not limited by the foregoing description and drawings. Instead, the embodiments herein are limited only by the following claims and their legal equivalents.

Claims

1. A cooling arrangement (20) for cooling at least one oil - air external heat exchanger (OAEHE) in a transformer, wherein, The cooling arrangement (20) comprises: at least one impeller motor device (10); at least one fluid pipe (11); and a first fluid discharge device (12), wherein the first fluid discharge device (12) comprises a fluid inlet and at least one fluid outlet, the fluid inlet being arranged to receive fluid from the at least one fluid pipe (11), the at least one fluid outlet being arranged to direct the fluid towards the OAEHE, wherein the at least one impeller motor device (10) is adapted to supply the fluid via the at least one fluid pipe (11) to the inlet of the first fluid discharge device (12) and to cause the fluid to flow through at least one fluid outlet of the first fluid discharge device (12) in the direction of the at least one OAEHE, and wherein the cooling arrangement (20) further comprises a second fluid discharge device (22) adapted to perturb the fluid flowing through at least one fluid outlet of the first fluid discharge device (12).

2. The cooling arrangement (20) according to claim 1, wherein, The second fluid discharge device (22) perturbs the fluid flowing through at least one fluid outlet of the first fluid discharge device (12) by applying a cross-flow jet to destabilize and / or widen the fluid.

3. The cooling arrangement (20) according to claim 2, wherein, The applied cross-flow jet is continuous.

4. The cooling arrangement (20) according to claim 2, wherein, The applied cross-flow jet is pulsating.

5. The cooling arrangement (20) according to any one of claims 1 to 4, wherein, The at least one impeller motor device (10) is adapted to supply the fluid to the second discharge device (22).

6. The cooling arrangement (20) according to any one of claims 1 to 5, wherein, The second fluid discharge device (22) is located between the first fluid discharge device (12) and the at least one OAEHE.

7. The cooling arrangement (20) according to any one of claims 2 to 6, wherein The diameter of the second fluid discharge device (22) is smaller than the diameter of the first fluid discharge device (12), and wherein the cross-flow jet is applied outwardly from the second fluid discharge device (22).

8. The cooling arrangement (20) according to any one of claims 2 to 6, wherein, The diameter of the second fluid discharge device (22) is larger than the diameter of the first fluid discharge device (12), and wherein the cross-flow jet is applied inwardly from the second fluid discharge device (22).

9. The cooling arrangement (20) according to any one of claims 1 to 8, wherein, The first fluid discharge device (12) and the second fluid discharge device (22) are circular, oval, rectangular or any other polygonal shape.

10. The cooling arrangement (20) according to any one of claims 1 to 9, further comprising a hose arranged to enhance and / or homogenize the supplied fluid.

11. The cooling arrangement (20) according to any one of claims 1 to 10, wherein, The cooling arrangement (20) comprises a funnel (15).

12. The cooling arrangement (20) according to claim 11, wherein, The at least one fluid discharge device (12) and / or the second fluid discharge device (22) is arranged in the funnel (15).

13. A method carried out by a cooling arrangement (20) for cooling at least one oil - air external heat exchanger (OAEHE) in a transformer, wherein, The cooling arrangement (20) comprises at least one impeller motor device (10), at least one fluid pipe (11) and a first fluid discharge device (12), the first fluid discharge device comprising a fluid inlet and at least one fluid outlet, the fluid inlet for receiving fluid from the at least one fluid pipe (11), the method comprising: using the at least one impeller motor device (10) to supply (302) the fluid into the at least one fluid pipe (11); Convey (303) the fluid along the at least one fluid conduit (11) to the inlet of the first fluid discharge device (12); Cause (304) the fluid to flow through the first fluid discharge device (12); Discharge (305) the fluid through the at least one fluid outlet in the direction of the at least one OAEHE, wherein the cooling arrangement (20) further comprises a second fluid discharge device (22), and wherein the method further comprises: Use the second fluid discharge device (22) to perturb (306) the fluid flowing through at least one fluid outlet of the first fluid discharge device (12).

14. The method according to claim 13, wherein, Perturbing the fluid flowing through at least one fluid outlet of the first fluid discharge device (12) includes destabilizing and / or broadening the fluid by applying a cross-flow jet.

15. The method according to any one of claims 13 to 14, further comprising: Generate (301) a filtered fluid to the at least one impeller motor device (10).

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