Cabinet cooling apparatus

Abstract

Disclosed herein is a heat transfer apparatus comprising a heat absorbing panel having first and second main faces containing plural passages for conveying a working fluid in both liquid and gaseous states around an interior portion of the panel, wherein the first main face is opposite the second main face and the first main face is configured to contact a body to be cooled; a condenser in fluid communication with the heat-absorbing panel, wherein the heat absorbing panel and the condenser form a hermetically sealed system configured to allow the working fluid to circulate between the heat-absorbing panel and the condenser without a compressor; and a chimney, comprising a lower opening, an upper opening, and an air channel extending from the lower opening to the upper opening; wherein the apparatus is configured such that the condenser is disposed within the air channel.

Description

[0001] Cabinet Cooling Apparatus

[0002] Field

[0003] The present invention relates to a heat transfer apparatus.

[0004] Background

[0005] Railway electronics such as switchgears, data communications, power supplies, and signalling systems must be protected in order to prevent damage to railway electronics from the environment which could lead to railway network delays or downtime. Accordingly, such electronics are often stored in cabinets. However, during hot summer periods, the high ambient air temperature, combined with radiant heat from the sun, and the heat generated by the railway electronics themselves, can lead to temperatures inside the cabinets rising to over 70°C, leading to failure of the railway electronics and correspondingly potential railway delays / downtime.

[0006] The present invention was devised in this context.

[0007] Summary

[0008] According to a first aspect of the present invention there is provided a heat transfer apparatus. The heat transfer apparatus comprises a heat absorbing panel having first and second main faces containing plural passages for conveying a working fluid in both liquid and gaseous states around an interior portion of the panel, wherein the first main face is opposite the second main face and the first main face is configured to contact a body to be cooled; a condenser in fluid communication with the heatabsorbing panel, wherein the heat absorbing panel and the condenser form a hermetically sealed system configured to allow the working fluid to circulate between the heat-absorbing panel and the condenser without a compressor; and a chimney, comprising a lower opening, an upper opening, and an air channel extending from the lower opening to the upper opening; wherein the apparatus is configured such that the condenser is disposed within the air channel.

[0009] In some embodiments, the apparatus further comprises a securement means for securing the apparatus to the body to be cooled.

[0010] In some embodiments, the apparatus further comprises a chimney hood coupled to the upper opening. In some embodiments, the apparatus is configured such that the condenser is positioned towards the upper opening of the chimney.

[0011] In some embodiments, the apparatus is configured such that the condenser is elevated relative to the heat-absorbing panel.

[0012] In some embodiments, the chimney of the apparatus is configured such that the second main face of the heat absorbing panel is exposed to the inside of the chimney, wherein the heat absorbing panel and the chimney together form at least part of the air channel.

[0013] In some embodiments, the condenser comprises a pipe at least partially surrounded by condenser fins.

[0014] In some embodiments, the condenser has plural elongate fins arranged around the exterior thereof.

[0015] According to a second aspect of the present invention there is provided a system. The system comprises a body to be cooled and an apparatus according to the first aspect of the present invention coupled to the body to be cooled such that the first main face of the heat absorbing panel contacts the body to be cooled.

[0016] In some embodiments, the body to be cooled is a cabinet containing electronic equipment and the heat absorbing panel is in thermal contact with at least a portion of an apex roof of the cabinet.

[0017] In some embodiments, the apparatus is coupled to the cabinet via lifting lugs of the cabinet.

[0018] In some embodiments, the apparatus is a first apparatus and the system further comprises a second apparatus according to the first aspect of the present invention, wherein the first main face of the heat absorbing panel of the first apparatus contacts a first side of an apex roof of the cabinet, and wherein the first main face of the heat absorbing panel of the second apparatus contacts a second side of the apex roof of the cabinet that is different to the first side. In some embodiments, the chimney of the first apparatus and the chimney of the second apparatus are connected to form a single chimney.

[0019] In some embodiments, the system further comprises a thermal paste covering the first main face of each heat absorbing panel.

[0020] Brief Description of the Drawings

[0021] Example embodiments will now be described by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0022] Figure 1 is a view of the internal structure of a heat absorbing panel in accordance with aspects of the disclosure;

[0023] Figure 2 shows a heat absorbing panel and a condenser that are connected to form a hermetically sealed system in accordance with aspects of the disclosure;

[0024] Figure 3 shows an apparatus in accordance with an embodiment of the disclosure;

[0025] Figure 4 is a cross-sectional view of the apparatus of figure 3;

[0026] Figure 5 depicts a system in accordance with an embodiment of the disclosure; Figure 6 depicts another system in accordance with an embodiment of the disclosure.

[0027] Detailed Description

[0028] Figure 1 shows an internal view of a heat absorbing panel 10 in accordance with embodiments of the present disclosure.

[0029] A body of the heat absorbing panel 10 is formed from a first panel Ila and a second panel 11b. The first panel Ila and the second panel 11b can be welded together to form the main body of the heat absorbing panel 10. The first panel Ila and the second panel 11b may be formed from, for example, aluminium. Alternatively, an aluminium alloy or another metal such as steel may be used.

[0030] Extending within the body of the heat absorbing panel 10 are plural passages 12. The passages 12 may have a generally circular cross section, and may comprise a plurality of ribs to provide an increased surface area between the cavities of the passages 12 and the material of the main body of the heat absorbing panel 10. It will be appreciated that the ribs may be of any suitable profile, for instance, rectangular, square, triangular, or convex rounded profiles. They may alternatively have a more complex profile, such as a part-trefoil or part-clover-leaf profile. Furthermore, other internal features of the passages 12 that increase the surface area of the walls of the passages 12 may be used instead of ribs. The cross section of each passage 12 can be divided conceptually into two parts: a phase-change portion (upper portion of the cross section) and a drain channel (lower portion of the cross section). The surface area of the phase-change portion should be greater per unit volume than the surface area of the drain channel.

[0031] The passages 12 may be equally spaced across the length of the main body of the heat absorbing panel 10. The passages 12 are commonly terminated at each end of the heat absorbing panel 10 by manifolds 14a and 14b (not shown) sealing the passages 12 which, in turn, form a liquid- and gas-tight chamber. Each of the manifolds 14a and 14b includes a manifold channel. The manifold channel serves to connect the passages 12. The heat absorbing panel 10 includes connections 13 that allow access to the manifold channels.

[0032] The interior cavities of the heat absorbing panel 10, comprising the passages 12 and the manifold channels, are provided with a volume of working fluid. In particular, some of the fluid is in liquid phase and some of the fluid is in gas phase. The manifold channels allow the working fluid to flow between the passages 12 and pressure to be equalised.

[0033] There are a multitude of working fluids that can be used including water, ammonia, acetone, alcohols and blends thereof. The efficacy of the working fluid is driven by the conditions in which the heat absorbing panel 10 is used. We have found that an effective working fluid for the cooling of a railway electronics cabinet as discussed herein is the refrigerant R1234a.

[0034] Figure 2 shows a heat absorbing panel 10 and a condenser 20 in accordance with aspects of the disclosure. The heat absorbing panel 10 has a first main face 15a and a second main face 15b which is on an opposite side of the heat absorbing panel 10. The Main faces 23a, 23b of the heat absorbing panel 10 may be the faces of the heat absorbing panel 10 with the largest surface area.

[0035] The condenser 20 is connected via connecting tubes 21 to connections 13 of the heat absorbing panel 10 such that the heat absorbing panel 10 and the condenser 20 form a hermetically sealed system configured to allow the working fluid to circulate between the heat-absorbing panel 10 and the condenser 20 without a compressor, as will be discussed further below. The condenser 20 takes the form of a pipe extending substantially alongside the length dimension of the heat absorbing panel 10. The pipe is provided with fins 22. The fins 22 facilitate the condensation of working fluid located within the condenser 20 by virtue of increasing the condenser's surface area. The fins 22 shown in figure 2 are formed from a helical length of metal or other thermally conductive material wrapped around the condenser pipe. Alternatively, the fins 22 may be formed from separate annular pieces of thermally conductive material wrapped around the condenser pipe. Other condenser 20 forms are possible. For instance, in some embodiments the condenser 20 may comprise a panel upstanding from the heat absorbing panel 10, with the plural passages 12 of the heat absorbing panel 10 extending upwardly into the condenser 20. The condenser panel may have plural elongate fins arranged around the exterior thereof that, in some embodiments, have a length similar to the condenser panel itself.

[0036] As shown in figure 2, the connecting tubes 21 of the condenser 20 may extend upwardly with respect to the plane of the heat absorbing panel 10 so that the condenser 20 is elevated with respect to the heat absorbing panel 10. Providing the condenser 20 above the heat absorbing panel 10 is advantageous because it allows condensed working fluid in the liquid phase to move from the condenser 20 to the heat absorbing panel 10 under gravity. The apparatus may comprise condenser supports to provide further structural support to the condenser 20 in its elevated position.

[0037] Figure 3 show an apparatus in accordance with an embodiment of the disclosure. The apparatus comprises a heat absorbing panel 10 connected to a condenser 20 via connecting tubes 21 (occluded) and a chimney 30.

[0038] The chimney has an upper opening 31a and a lower opening 31b and forms an air channel 32 extending therebetween. The chimney may be formed of stainless steel for ease of construction and to make use of stainless steel's high resistance to corrosion and rust, which may be particularly beneficial when the chimney 30 is situated outdoors.

[0039] The apparatus may be configured such that a surface of the chimney 30 contacts the second main face 15b of the heat absorbing panel. The chimney 30 may be secured to the heat absorbing panel 10 via a double-sided adhesive. The adhesive may further act as insulation between the body of the chimney 30 and the heat absorbing panel 10. The chimney 30 may comprise an installation hole (not shown), such that the condenser 20 can be inserted into the air channel 32 of the chimney 30 on install of the chimney 30 onto the heat absorbing panel 10, before the installation hole is sealed. In some embodiments, the chimney 30 may be formed of two main parts that are sealed around the condenser with two holes, separate from the openings 31a, 31b for each of the connecting tubes 21 to pass into the heat absorbing panel 10. In some embodiments, the chimney 30 may be shaped such that a lower portion of the chimney 30 comprising the lower opening 31b follows a plane of the heat absorbing panel 10 before an upper portion of the chimney 30 comprising the upper opening 31a extends vertically. In some embodiments, the condenser 20 may be disposed in the upper portion of the chimney 30. In some embodiments, the lower portion of the chimney 30 may be configured such that the second main face 15b of the heat absorbing panel 10 is exposed to the inside of the chimney 30. In other words, a surface of the lower portion of the chimney 30 that would be in contact with the heat absorbing panel 10 may contain an opening such that when the apparatus is assembled the chimney 30 and the heat absorbing panel 10 together form at least part of the air channel 32 between the lower opening 31b and the upper opening 31a. In some embodiments, this opening may extend from the lower opening 31b to the end of the lower portion of the chimney 30.

[0040] The shape of the chimney 30 may take many forms as long as the lower opening 31b is disposed at a lower position than the upper opening 31a relative to the ground, and there is space for the condenser 20 to be disposed in the air channel 32 of the chimney 30 without blocking the air channel 32. For example, the chimney may be configured such that the air channel 32 is substantially straight. The skilled person will be able to identify further examples of suitable chimneys from the disclosure herein.

[0041] The condenser 20 of the apparatus is disposed inside the chimney 30 as exampled in figure 4.

[0042] Figure 4 shows a cross-sectional view of the apparatus of figure 3.

[0043] The condenser 20 is disposed within the air channel 32 of the chimney 30 such that there is still a continuous path air can take between the lower opening 31b and the upper opening 31a. In other words, the condenser 20 does not fully block the air channel 32. In the embodiment depicted by figure 4, the condenser 20 is elevated relative to the heat absorbing panel 10. In use, the heat absorbing panel 10 absorbs heat from the region surrounding the heat absorbing panel 10, for instance, via conduction from a cabinet (body to be cooled) contacting the first main face 15a of the heat absorbing panel 10. As such, the region surrounding the heat absorbing panel 10 is cooled substantially. The heat energy evaporates the working fluid inside the heat absorbing panel 10, turning it from liquid to vapour through the absorption of the latent heat of evaporation. The evaporated portion of the working fluid expands and moves towards the condenser 20 via connecting tube 21. The relatively high surface area of the condenser 20 due to the fins 22 facilitates greater emission of heat into the air surrounding the condenser 20 inside the air channel 32 of the chimney 30 via radiation, cooling the vapour working fluid in the condenser 20. Cooling of the vapour working fluid causes the vapour working fluid to condense. Upon condensing, the vapour releases the stored latent heat to the air surrounding the condenser 20. The heated air rises inside the chimney 30 towards the upper opening 31a, in turn creating a pressure differential that draws air into the chimney via the lower opening 31b. The airflow created in the air channel 32 of the chimney 30 by air leaving via the upper opening 31a and the air drawn in through the lower opening 31b cools the condenser, creating a temperature differential between the heat absorbing panel 10 and the condenser 20 wherein the condenser is relatively cool. Condensation of the working fluid creates a low pressure region in the condenser 20 which helps attract more evaporated working fluid from the heat absorbing panel 10 into the condenser 20. Once condensed, the condensed liquid travels down the connecting tube 21 by the action of gravity and returns to the interior of the heat absorbing panel 10. The vaporization-condensation cycle can then repeat again, continuing to cool the region surrounding the heat absorbing panel. Elevating the condenser 20 with respect to the heat absorbing panel 10 allows for return of the working fluid in the liquid phase without the need to use any wicking structures. However, it will be appreciated that wicking structures may be used instead and / or in addition to having the condenser elevated.

[0044] Use of the chimney 30 enables the condenser 20 to be cooled via a corresponding air current, thereby accelerating the dissipation of heat absorbed by the heat absorbing panel 10 by completing the condensation of the working fluid back to its liquid phase more efficiently. The cooling of the condenser 20 allows for circulation of the working fluid between the heat absorbing panel 10 and condenser 20 without the use of a compressor. Furthermore, the chimney 30 enables the condenser 20 to be cooled passively. Thereby avoiding the added apparatus complexity, maintenance, and electricity use that would be associated with actively cooling the condenser. Figure 5 depicts a system in accordance with an embodiment of the disclosure. The system includes a body to be cooled 50. In the depicted example, the body to be cooled has an apex roof with two sides, a first side 51a and a second side 51b. The body to be cooled 50 may be a railway electronics cabinet. The system comprises two apparatus as discussed above, configured such that the first main face 15a of the heat absorbing panel of one of the apparatuses contacts the first side 51a, and a first main face 15a of the heat absorbing panel of the other apparatus contacts the second side 51b. The system may comprise a thermal paste between the body to be cooled and the heat absorbing panels 10 of the apparatuses. The thermal paste may be applied to the body to be cooled 50 and / or the heat absorbing panels 10 of the apparatuses before the assembly of the system. The use of thermal paste improves conduction of heat from the body to be cooled 50 to the heat absorbing panels 10 and thus allows the body to be cooled 50 to be cooled more effectively.

[0045] The apparatuses can be configured such that an upper portion of their chimneys 30 are connected to form a single air channel 32. In other words, the air channel 32 of the apparatus disposed over the first side 51a and the air channel 32 of the apparatus disposed over the second side 51b may converge to form a single air channel 32. Each apparatus may comprise a chimney hood 41 coupled to the upper opening 31a. As depicted in figure 5, the system may include a single chimney hood 41 for both apparatuses. The chimney hood 41 may make it more difficult for foreign objects to enter and block the air channels 32 but does not prevent airflow into the upper opening 31a.

[0046] In Figure 5, the system comprises securement means 40, that fixes the apparatuses to the body to be cooled 50. The securement means 40 may comprise a clamp securing the apparatuses to an existing part of the body to be cooled 50 such that no change needs to be made to the body to be cooled 50 itself to accommodate the apparatuses. In some embodiments wherein the body to be cooled 50 is a cabinet, the securement means may comprise bolts fastening each apparatus to lifting lugs of the cabinet.

[0047] We performed some testing of the system depicted in figure 5, where the body to be cooled 50 was a railway electronics cabinet. The internal temperature of the cabinet was monitored over a 14 day period in the summer, a time when conditions could lead to instants of failure of electronics due to high temperatures. Peak temperatures inside the cabinet were found to be reduced by an average of 11.5% when compared with similar cabinets in the vicinity without the apparatuses installed - a significant difference, especially given this temperature reduction was provided passively.

[0048] Figure 6 depicts another system in accordance with embodiments of the present disclosure. The system comprises an apparatus and a body to be cooled 60. In this example, the body to be cooled 60 does not have an apex roof.

[0049] The heat absorbing panel 10 of the apparatus is affixed to the top surface of the body to be cooled and the chimney 30 of the apparatus is affixed to the side of the body to be cooled 60 via securement means 40. The air channel 32 of the chimney 30 is substantially straight. The apparatus comprises a chimney hood / chimney cover 41. As in this embodiment the heat absorbing panel 10 is not covered by the chimney 30, in some embodiments the system / apparatus may further comprise a cover to protect the heat absorbing panel 10 from the environment.

[0050] Although the embodiments described above were conceived in the context of cooling cabinets for railway electronics, it will be appreciated that the described embodiments may be applied to other applications. For example, for cooling cabinets that contain electronics for providing internet access such as fibre optic signalling cabinets, to avoid outages in network connectivity.

Claims

Claims1. A heat transfer apparatus comprising: a heat absorbing panel having first and second main faces containing plural passages for conveying a working fluid in both liquid and gaseous states around an interior portion of the panel, wherein the first main face is opposite the second main face and the first main face is configured to contact a body to be cooled; a condenser in fluid communication with the heat-absorbing panel, wherein the heat absorbing panel and the condenser form a hermetically sealed system configured to allow the working fluid to circulate between the heat-absorbing panel and the condenser without a compressor; and a chimney, comprising a lower opening, an upper opening, and an air channel extending from the lower opening to the upper opening; wherein the apparatus is configured such that the condenser is disposed within the air channel.

2. The apparatus of any preceding claim, further comprising a securement means for securing the apparatus to the body to be cooled.

3. The apparatus of any preceding claim, further comprising a chimney hood coupled to the upper opening.

4. The apparatus of any preceding claim, wherein the condenser is positioned towards the upper opening of the chimney.

5. The apparatus of any preceding claim, wherein the condenser is elevated relative to the heat-absorbing panel.

6. The apparatus of any preceding claim, wherein the chimney is configured such that the second main face of the heat absorbing panel is exposed to the inside of the chimney, wherein the heat absorbing panel and the chimney together form at least part of the air channel.

7. The apparatus of any preceding claim, wherein the condenser comprises a pipe at least partially surrounded by condenser fins.

8. The apparatus of any of claims 1-6, wherein the condenser has plural elongate fins arranged around the exterior thereof.

9. A system comprising: a body to be cooled; and an apparatus according to any of claims 1-8; coupled to the body to be cooled such that the first main face of the heat absorbing panel contacts the body to be cooled.

10. The system of claim 9, wherein the body to be cooled is a cabinet containing electronic equipment and wherein the heat absorbing panel is in thermal contact with at least a portion of an apex roof of the cabinet.

11. The system of claim 10, wherein the apparatus is coupled to the cabinet via lifting lugs of the cabinet.

12. The system of either claim 10 or claim 11, wherein the apparatus is a first apparatus and wherein the system further comprises a second apparatus according to any of claims 1-8, wherein the first main face of the heat absorbing panel of the first apparatus contacts a first side of an apex roof of the cabinet, and wherein the first main face of the heat absorbing panel of the second apparatus contacts a second side of the apex roof of the cabinet that is different to the first side.

13. The system of claim 12, wherein the chimney of the first apparatus and the chimney of the second apparatus are connected to form a single chimney.

14. The system of any of claims 9-13, further comprising a thermal paste covering the first main face of each heat absorbing panel.

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