GB2485469A

GB2485469A - Cooling heat generating equipment housed within a cabin

Info

Publication number: GB2485469A
Application number: GB1119339.8A
Authority: GB
Inventors: John Kirk
Original assignee: P2ML ENERGY Ltd
Current assignee: P2ML ENERGY Ltd
Priority date: 2010-11-09
Filing date: 2011-11-09
Publication date: 2012-05-16
Also published as: GB201018918D0; GB201119339D0

Abstract

A method for cooling heat generating equipment 12 housed within a cabin (room) 10 comprises forcing external air into the cabin through an air inlet 16 located in a lower region of the cabin, and distributing the air across a floor 20 of the cabin and upwards through the cabin towards an air outlet 26 located in an upper region of the cabin. A plurality of inlets and a plurality of outlets may be provided. Each inlet may comprise a variable speed fan and cowling 18. Each outlet may comprise a cowling 27 for weather protection and variable dampers 26 assist in varying air flow rate through the cabin. A filter (32a, fig 4) may be provided within each cowling of the inlets. A diffuser (36, fig 3) having a curved surface with a plurality of ports (16a) may distribute air parallel and radially across the floor. The air inlet may deliver air under the floor (figs 6 & 7). Equipment to be cooled may be telecommunication electrical equipment and the temperature in the cabin may be controlled. Cooling of a thermally insulated enclosure housing an uninterruptable power supply may be provided.

Description

COOIJNG METHOD AND APPARATUS

HELD OF THE INVENTION

The present invention relates to a method and apparatus for cooling an enclosure, such as a cabin, for housing electrical and &ectronic equipment and, in particular, though not exdusiv&y, for a cabin for housing telecommunications equipment.

BACKGROUND TO THE INVENTION

Electrical and &ectronic equipment such as telecommunications equipment is often designed or warranted to work within a specified temperature range. A typical upper temperature limit is 50 °C. It is, therefore, often important to employ an environmental control system when operating such equipment. It is, for example, known to house such equipment within a cabin as part of a mobile telecommunications network base station installation to provide a secure controlled environment for the equipment. When operating such equipment in warmer climates, particularly in the summer time, it is known to use air conditioning to cool an environment within the cabinS However, such air condifioning systems can consume a relatively high proportion of the overall energy consumed by the installation comprising the equipment and the environmental control system. This is particulady true in hotter climates.

It is also known to use air extraction systems to cool such equipment when housed within a cabin, particularly in northern Europe where maximum summer temperatures are generally limited to 35 °C. Such systems may be more energy efficient than air conditioning systems. Such an air extraction system may comprise an inlet for cool air from the exterior of the cabin, an outlet, a duct extending from above equipment housed within the cabin to the outlet and an extractor fan mounted at the outlet to extract warm air through the duct and expel the warm air through the outlet to the exterior of the cabin. However such air extraction systems may require a duct to be fitted to each individual piece of equipment which may invahdate a manufacturer's warranty for the equipment. Such systems may also stiU consume a significant proportion of the total power consumed by the instaflation.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a method for cooling heat generating equipment housed within a cabin, comprising: forcing externS air into the cabin through an air inlet located in a lower region of the cabin; distributing the air from the air inlet across the floor of the cabin; and permitting the distributed air to move upwardly through the cabin towards an air outlet located in an upper region of the cabin.

The method may be configured for use in controlling the environment within a cabin that accommodates equipment that generates heat, for example heat generated during operation of electrical or electronic equipment.

In use, the air forced into the cabin from an external location and which has been distributed across the cabin floor will move upwardly through the cabin to effect cooling of any associated equipment contained within the cabin, Distributing the inlet air across the cabin floor and then permitting or facilitating upward movement of the distributed air may advantageously assist to establish a piston, layer or blanket of upward moving cooling air which may permit more sustained and uniform extraction of heat from the cabin equipment. Further, establishing a moving layer or blanket of air, which may be visuali.sed as an air piston, within the cabin by first distributing the air across the cabin fioor may assist to uniformly or substantially homogeneously displace air heated by the electrical equipment and minimise recirculation of the heated air throughout the cabin.

The present invention may avoid the need to fit ducts to the equipment.

However, in some embodiments individual eqthpment ducting may be utilised.

The method may comprise forcing air into the cabin to establish a positive pressure within the cabin r&ative to exterior conditions. This may assist to impede or prevent moisture ingress into the cabin when the cabin is located outdoors, for example, in an exposed position.

The air inlet may be located at a level below or adjacent a lower extremlty of the equipment. Single or multiple air inlets may be provided.

The air outlet may be located at a level above or adjacent an upper extremity of the equipment. Single or multiple air outlets may be provided.

Air may be forced into the cabin using a fan arrangement, A single fan arrangement may be provided. A single fan arrangement may be provided to force air through one or a plurality of air inlets. A single fan arrangement may be associated with a respective air inlet. In such an arrangement an air inlet and a fan arrangement may be provided as an integrated unit. in some arrangements a plurality of fan arrangements may be provided.

The method may comprise forcing air into the cabin at a speed in the range of 0.1 to 5 mis. The method may comprise forcing air into the cabin at a speed in the range of 0.35 to 2 mis, The method may comprise forcing air into the cabin at a speed in the range of 0.45 to I mis. Forcing air into the cabin at such slow rates may prevent the circulation of air within the cabin and may ensure that warm air heated by the equipment generally moves upwardly towards the outlet with substantially no downward recirculation of the warm air. Furthermore, such inlet flow rates may permit sufficient distribution of the inlet air across the floor of the cabin before being caused to move upwardly through the cabin.

The method may comprise varying the inlet flow rate of the inlet air. for example by use of a variable fan unit. The method may comprise varying the inlet flow rate of the inet air in accordance with a de&red coong reqthrement. The inlet flow rate may be varied in accordance with thermodynamic condiflons associated with the cabin and equipment, for example a temperature differential internally and externally of the cabin.

In this arrangement the inlet flow rate may be matched with a desired cooling requirement which may assist in minimising energy expenditure. For example, in conditions where a large temperature differential exists a lower flow rate may be sufficient to maintain the electrical equipment within desired operational temperature ranges. This may permit associated equipment, such as fan equipment to be operated under minimum load and duty conditions at substantially all times, permitting the useful life of such equipment to be maximised, The method may comprise forcing air into the cabin through the inlet at a level generally adjacent to the floor.

The method may comprise forcing air into the cabin through the inlet at a level above the floor.

The method may comprise forcing air into the cabin through the inlet at a level below the floor. In such an arrangement the floor may be configured to permit passage or the air therethrough, for example by grates, vents, apertures, slots or the like, to permit upward movement of the distributed air.

The method may comprise forcing air into the cabin through the inlet in a direction generally parallel to the floor. When air is forced into the cabin at a level generally adjacent to and in a direction generally parallel to the floor, the Coandã effect may cause the air to move across the floor before moving upwardly.

The method may comprise distributing air from the air inlet along a plurality of substantially parallel paths, each path being substantially parallel to the floor.

The method may comprise radially distributing the air from the air inlet in directions substantially parallel to the floor.

S

The method may comprise diffusing air drawn through the inlet to distribute the air across the floor of the cabin. For example, the method may comprise providing a perforated diffuser located downstream of the inlet. The diffuser may be integrafly formed with the inlet. In some embothments the diffuser may define the inlet. The diffuser may be partiay curved. The diffuser may define a cylindrical surface, such as a part cylindrical surface. The use of a cylindrical surface may provide a radial distribution of the air from the air inlet in directions parallel to the floor. This may assist to distribute the inlet air across the cabin floor.

The diffuser may comprise one or more flow ports, such as slots, apertures, perforations or the like. The flow ports may be of a common dimen&on, or &ternatively may be of differing dimensions.

The air outlet may define a fixed outlet dimension.

The air outlet may feature a flow control arrangement.

The air outlet may define a variable outlet dimension. The variable outlet dimension may be varied to assist in the provision of a desired cooling rate within the cabin.

The air outlet may comprise an air damping arrangement. The outlet may comprise an outer cowling.

The method may comprise controlling both inlet and outlet rates to provide a desired cooling rate. For example, the method may comprise controlling a variable inlet fan and outlet dampers to achieved a desired cooling rate. This may permit more advanced control over a desired cooling rate.

The method may comprise forcing air into the cabin through the inlet during a first period and interrupting the forced air flow during a second period. This arrangement may permit forced air transportation within the cabin to be achieved during the first period, and then utilising inertial effects of the air and natural air movement during the second period. This may permit a reduction in energy expenditure.

The method may comprise fiftering air forced into the cabin. One or more air filters may be provided upstream of the air inlet, One or more air fUters may be provided within an inlet cowling configured for drawing in external air to be filtered and then deilvered into the cabin via the air inlet. The typical use of low air flow rates with the present invention may permit longer use of such filter arrangements.

The method may comprise cooling a single zone within a cabin.

The method may comprise cooling multiple zones within a cabin, in this arrangement the method may be configured for cooling different zones having different cooling requirements, for example due to containing different equipment in different zones.

The method may comprise independenUy cooling different zones. The method may comprise using individual cooling systems according to the invention for each zone. The different zones may be isolated from each other. For example, the cabin may contain an internal chamber, wherein the internal chamber defines a first zone, and the remaining cabin defines a second zone.

The ability to cool different zones may permit the present invention to advantageously he used in circumstances where a cabin contains multiple types of equipment having different cooling requirements. For example, in some uses a cabin may comprise electrical or electronic equipment having a preferred upper operating environment limit of 35 3C, and also further electrical equipment having a preferred upper operating environment limit of 20 C. The present invention therefore permits a zoned cooling arrangement which assists to reduce energy consumption. Such circumstances may occur when a cabin is used to contain or house electronic equipment and battery units for emergency power supply. In such an arrangement the battery arrangement may be contained within an internal chamber, The method may comprise forcing external air into a thermafly insulated zone wkhin the cabin during a first period and interrupting the forced air flow into the thermay insulated zone during a second period.

The method may comprise permitting air to escape from the thermally insulated zone during the first period. This may allow cooler air to be forced into the thermally insulated zone and warmer air to be displaced from the thermally insulated zone during the first period The method may comprise preventing air from escaping from the thermally insulated zone during the second period. This may prevent cooler air from escaping from the thermafly insulated zone during the second period.

The method may comprise forcing external air into the thermally insulated zone during a first period of cooler external temperatures and interrupting the forced air flow into the thermally insulated zone dudng a second period of warmer external temperatures. This may ensure that the thermaUy insulated zone remains at a temperature below the warmer external temperatures during the period of the warmer external temperatures. Such a method may be employed to ensure that the thermally insulated zone remains at a temperature within a predetermined temperature range, for example, a storage or operating temperature range of any equipment located within the thermally insulated zone. For example, such a method may ensure that the thermally insulated zone remains at a temperature within a storage or operating temperature range of a battery such as a 12 V or 6 V battery located wfthin the thermally insulated zone. In particular, this may ensure that the thermally insulated zone remains at a temperature of between 10 and 35 C, at a temperature of between 15 and 30 °C or at a temperature of between 20 and 25 C. By maintaining the temperature of the thermally insulated zone over a storage or operating temperature range of equipment located within the thermally insulated zone, the lifetime of the equipment located within the thermally insulated zone may be extended or at least guaranteed under any warranfles provided wfth the equipment. This may be particidady advantageous where the equipment located within the thermafly insSted zone comprises at least part of an uninterruptable power supply, for example an uninterruptable power supply for providing power to the heat generating equipment located within the cabin but externay to the thermafly insulated zone in the event of failure of a main power supply to the heat generating equipment.

The method may comprise forcing external air into a thermally insulated zone within the cabin during the night and interrupting the forced air flow into the thermally insulated zone during the dayS The method may comprise using a cooling system according to the invention for cooling the thermally insulated zone.

The method may comprise heating inlet air, for example using an electrical heater.

The method may comprise use of a controller unit. The controller unit may be configured to communicate with various system components, such as sensors, including pressure sensors, temperature sensors and the like, The controller unit may be configured to communicate and control system components such as inlet fans, outlet dampers and the like. The controller unit may comprise a solid state control unit According to a second aspect of the present invention there is provided a system for cooling heat generating equipment housed within a cabin, comprising: an air inlet adapted to be located with a lower region of the cabin; an air outlet adapted to be located within an upper region of the cabin; an arrangement for fordng air into the cabin through the air inlet; and an arrangement for distributing the air across a floor of the cabin.

The system may be configured to facilitate the method according to the first aspect. As such, all features identified above in relation to the first aspect may form part of the system according to the second aspect.

Accordhig to a thfrd aspect of the present invention there is provided a cabin for houng heat generating equipment, comprising: a floor for supporting heat generaUng eqthpment; and a cooling system, said cooling system compri&ng: an air inlet located in a lower region of the cabin; an air outlet located in an upper region of the cabin; an arrangement for forcing air into the cabin through the air inlet; and an arrangement for distributing the air across a floor of the cabin.

The coollng system may be provided in accordance with the third aspect The cabin may comprise a single zone.

The cabin may comprise multiple zones. In one embodiment the cabin may comprise an internal enclosure configured to be substantiaHy isolated from the remaining cabin space.

The cabin may comprise at least two cooling systems, a first system for cooling the internal enclosure, and a second system for cooling the remaining cabin space.

According to a fourth aspect of the present invention there is provided a cabin configured to house electrical equipment, comprising: an intern chamber configured to store a battery arrangement; and a cooling arrangement configured to cool the battery arrangement within the internal chamber, said cooling arrangement comprising: an air inlet located in a lower region of the internal chamber; an air ouflet located in an upper region of the internal chamber; an arrangement for forcing air into the internal chamber through the air inlet; and an arrangement for distributing the air across a floor of the internal chamber.

The internal chamber may be defined by a thermaHy insulated endosure. Such an endosure may reduce the transfer of heat between the internal chamber and an interior region of the cabin external to the internal chamber.

One or more of the opfional features disclosed in relation to the first aspect may apply alone or in any combinafion in relation to the fourth aspect.

GRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invenflon will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an illustraflon of a cabin for housing electrical equipment in accordance with an embodiment of the present invention, shown from above; Figure 2 is a view of the cabin of Figure 1 from one side; Figure 3 is a perspective view of an inlet assembly of a cooling system according to the present invenfion; Figures 4 and 5 are vertical and hohzontal crosssectional views, respectively, through the inlet assembly of Figure 3; Figure 6 is a perspective view of an inlet assembly of a cooling system according to an alternative embodiment of the present invention; Figure 7 is a vertical crosssectionaI view through the inlet assembly of Figure 6; and Figure 8 is a plan view of the cabin of Figure 1 having an additional thermally insulating enclosure for hou&ng batteries.

DETAILED DESCRIPTION OF THE DRAWINGS

Upper and side views, respectiv&y, of a cabin, generally designated 10, are shown in Figures 1 and 2, wherein the cabin 10 is used for housing heat generating equipment such as electrical equipment 12. The cabin 10 may be used in many appHcations, such as for housing electrical equipment associated with telecommunicahon antenna and the Uke, It is wefi known in the art that to maximise the fife of contained &ectrical eqiüpment it is desfrable to provide a controfied temperature within the cabin. This has typicafly been achieved in the art by use of air condifloning systems, which have significant energy requirements. The present invention has proposed methods and systems for providing improved temperature control in en economical and efficient manner, as wifi be described in detail below.

The cabin 10 in the embodiment shown includes two Inlet arrangements 14 which each comprise an air inlet 16 located within a lower region of the cabin 10. As wifi be described in further detail below: each inlet arrangement 14 comprises a fan (not shown in Figures 1 and 2) which functions to force external air, via a cowling 18, into the cabin 10 through the lower air inlets 16 to be distributed across the floor 20 of the cabin 10 in the direction of arrows 22. Distributing the inlet air across the cabin floor 20 in this manner establishes a substantially uniform layer or blanket of air which is permitted to move upwardly through the cabin in the direction of arrows 24. This upward moving mass or blanket of air functions as an air piston to displace the air within the cabin 10 which has been heated by the electrical equipment 12 while causing minimum recirculation of the heated air. The cabin further comprises outlet units 26 each having outlet vents 28 located in an upper region of the cabin which permit the displaced heated air to be expelled from the cabin 10. The outlet units 26 also comprise external cowlings 27 which assist to provide weather protection.

The flow rate of air through the cabin 10 may be carefully controlled in order to achieve a desired cooling performance and maintain a required internal temperature.

In this respect each inlet unit 14 comprises a variable speed fan (not shown in Figures I and 2) which may he varied to control the inlet air flow rate. For example: in some embodiments flow rates in the region of 0.45 to I rn/s may be used. Furthermore, the outlet unfts 26 comprise air dampers (not shown) which can be varied to as&st in varying the flow rate and movement of air through the cabin. Such control may be achieved in accordance with measured thermodynamic properties, such as the extern air temperature or the like, One embodiment of an inlet unit 14a wifl now be described with reference to Figures 3, 4 and 5. In this embodiment the inlet unit 14a comprises an external cowling ISa mounted on the wall 30 of the cabin 10, wherein an air filter 32a is mounted within the cowling ISa. A variable speed fan unit 34a is mounted upstream of the filter 32a and in use draws external air into the cowling ISa through a cowling inlet 38a and through the filter 32a. A diffuser 35 is mounted internally of the cabin 10 and is arranged to guide and diffuse air delivered by the fan unit 34a towards the lower region of the cabin, through ports ISa formed in the diffuser 36, permitfing the air to be distributed across the cabin floor 20. As shown most clearly in Figure 5, the diffuser 36 defines a curved surface which assists to direct air in a radial manner, thus further assisting to distribute the inlet air across the cabin floor 20.

An alternative arrangement of an air inlet unit, in this case defined by reference numeral 14b, is shown in Figures 6 and 7. In this embodiment the air inlet unit 14b comprises an enlarged exterior cowling lSb which includes a cowling inlet 38b and houses a filter 32b and a fan unit 34b. The inlet unit 14b defines an air inlet 16b which when installed is located below the floor 20 of the cabin 10. In this way the inlet air may be delivered beneath the cabin floor, which may be suspended and includes a number of flow ports (not shown, such as via grates, thus permitting the inlet air to be distributed across the cabin floor 20 to be moved upwardly to effect cooling.

it should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the invention. For example, any number of inlet units and outlet units may be utilised. Also, any configuration of cabin may be used. Further, the inlet unit may comprise an ak heater configured to heat inlet air. Such heatfrig may be required Th some conditions, such as in conditions with extrem&y low exterior air temperatures.

As shown in Figure 8, the cabin 10 may contain a thermafly insulated encbsure 50 which defines an internal chamber 52 for housing a battery arrangement 54 such as a battery arrangement of an uninterruptable power supply for the electrical equipment 12.

The enclosure 50 may comprise an enclosure inlet connected to an exterior of the cabin 10 by an inlet air duct 56 and an enclosure ouflet connected to the exterior of the cabin 10 by an outlet air duct 58. The enclosure 50 may comprise an enclosure fan (not shown) at the enclosure inlet which is used to draw air from the exterior of the cabin 10 through the inlet air duct 56 and force the air into the endosure 50 during cooler periods so as to displace air from within the internal chamber 52 through the outlet air duct 58. The enclosure fan may be switched off during warmer periods so as to interrupt the flow of air through the inlet air duct 56 and the outlet air duct 58 during the warmer periods. The endosure outlet may be configured to be shut off to prevent cooler air in the internal chamber 52 from escaping from the enclosure 50 during the warmer periods. Such an arrangement may permit nocturnal cooling of the internal chamber 52 to ensure that a temperature of the battery arrangement 54 is maintained within a predefined storage or operating temperature range for the battery arrangement 54 day and night, It will be recognised that the features of the present invention may be included within a cabin during initial commissioning. However, it should also be noted that features of the present invention may be retrofitted to an existing cabin.

Claims

CLAIMS1. A method for cooUng heat generating equipment housed within a cabin, comprising: forcing external air into the cabin through an aft inlet located in a lower region of the cabin; distributing the air from the air iniet across the floor of the cabin; and permitting the dktributed air to move upwarthy through the cabin towards an air outlet located in an upper region of the cabin.
2. A method according to claim 1, compri&ng forcing external air into the cabin at a level below or adjacent a lower extremity of the equipment.
3. A method according to claim I or 2, comprising permitting the thstributed air to move upwardly through the cabin towards an air ouflet located at a level above or adjacent an upper extremity of the equipment.
4. A method according to any preceding claim, comprising forcing air into the cabin to establish a posftive pressure within the cabin relative to exterior conditions.
5. A method according to any preceding claim, comprising forcing air into the cabin at a speed in the range of 0.1 to 5 m/s, 035 to 2 m/s or 045 to 1 mIs.5. A method according to any preceding claim, comprising varying the inlet flow rate of the inlet air, 7. A method according to any preceding claim: comprising varying the inlet flow rate of the inlet air in accordance with a desired cooling requirement. Is8. A method according to any preceding daim, comprng varying the inlet flow rate of the inlet air in accordance wfth a temperature differential internally and externally of the cabin.9. A method according to any preceding claim, comprising forcing air into the cabin through the inlet at a level generally adjacent to, above or b&ow the floor.10, A method according to any preceding daim, comprising forcing air into the cabin through the inlet in a direction generally paralld to the floor.11. A method according to any preceding claim, comprising distributing air from the air inlet along a phirality of substantially parallel paths, each path being substantially parall& to the floor.12. A method according to any preceding claim, comprising radially distributing the air from the air inlet in directions substantially parallel to the floor.13. A method according to any preceding daim, comprising diffusing air drawn through the inlet to distribute the air across the floor of the cabin.14. A method according to any preceding claim, comprising controlling both inlet and ouflet air flow rates to provide a desired cooling rate.15. A method accorthng to any preceding claim, comprising forcing air into the cabin through the inlet during a first period and interrupting the forced air flow during a second period.16. A method according to any preceding daim, comprising forcing external air into a thermally insulated zone within the cabin during a first period and interrupting the forced air flow into the thermally insulated zone during a second period.17. A method according to daim 1$, comprising permitting air to escape from the thermally insulated zone during the first period.18. A method according to claim 16 or 17, comprising preventing air from escaping from the thermally insulated zone during the second period.19. A method according to any of claims 16 to 18, comprising forcing external air into the thermally insulated zone during a period of cooler external temperatures and interrupting the forced air flow into the thermally insulated zone during a period of warmer external temperatures.20. A method according to any preceding claim, comprising heating air at the air inlet, 21. A method according to any preceding claim, comprising cooling multiple zones within the cabin.22. A method according to claim 21, comprising independently cooling the multiple zones.23. A method according to claim 22, comprising: forcing external air into the cabin through a first air inlet located in a lower region of a first zone of the cabin; forcing external air into the cabin through a second ah inlet located in a bwer region of a second zone of the cabin; thstributing the air from the first air int across the floor of the first zone of the cabfri; distribufing the air from the second air h-flet across the floor of the second zone of the cabin; permitting the distributed air in the first zone to move upwardly through the first zone of the cabin towards a first air outlet located in an upper region of the first zone of the cabin; and permthing the distributed air in the second zone to move upwardly through the second zone of the cabin towards a second air ouflet located in an upper region of the second zone of the cabin.24. A system for coong heat generating equipment housed within a cabin, cornpri&ng: an air inlet adapted to be located with a lower region of the cabin; an air outlet adapted to be located within an upper region of the cabin; an arrangement for forcing air into the cabin through the air inlet; and an arrangement for distributing the air across a floor of the cabin.25. A system according to claim 24, wherein the arrangement for forcing air into the cabin comprises a fan.26. A system according to claim 24 or 25, wherein the arrangement for forcing air into the cabin comprises a variable speed fan, 27. A system according to any of claims 24 to 26, wherein the arrangement for distributing the air across a floor of the cabin comprises a diffuser having one or more flow ports, sbts, apertures and/or perforations.28. A system according to any of claims 24 to 27, wherein the air outlet may define a fixed outlet dimension.29. A system according to any of claims 24 to 27, wherein the air outlet may define a variable outlet dimension.30. A system according to any of claims 24 to 29, comprising one or more air filters provided upstream of the air inlet.31. A system according to any of claims 24 to 30, comprising a thermally insulated enclosure configured for housing equipment within the cabin.32. A system according to any of claims 24 to 31 comprising a heater for heating air at the air inlet.33. A system according to any of claims 24 to 32, comprising a controller unit configured to control the air inlet, the air outlet and/or the arrangement for forcing air into the cabin through the air inlet.34. A cabin for housing heat generating equipment, comprising: a floor for supporting heat generating equipment; and a coollng system, said cooling system comprising: an air inlet located in a lower region of the cabin; an air outlet located in an upper region of the cabin; an arrangement for forcing air into the cabin through the air inlet; and an arrangement for distributing the air across a floor of the cabin, 35. A cabin according to claim 34, wherein the air inlet is located at a level below or adjacent a lower extremity of the equipment.35. A cabin according to claim 34 or 35, wherein the air outlet is located at a level above or adjacent an upper extremity of the equipment.37. A cabin according to any of claims 34 to 36, comprising an internal thermally insulated enclosure for housing electrical equipment.36. A cabin according to claim 37, wher&n the thermally insulated enclosure is configured to house a battery arrangement.