GB2515378A

GB2515378A - Evaporative cooler apparatus and method

Info

Publication number: GB2515378A
Application number: GB1406088.3A
Authority: GB
Inventors: Alan Beresford
Original assignee: Ecocooling Ltd
Current assignee: Ecocooling Ltd
Priority date: 2013-04-04
Filing date: 2014-04-04
Publication date: 2014-12-24
Anticipated expiration: 2034-04-04
Also published as: GB201306105D0; GB2515378B; GB201316201D0; GB201406088D0

Abstract

An evaporative cooler comprises a housing 2 having an evaporative-cooling chamber 14, an air-mixing chamber 36 located above the evaporative-cooling chamber, and a fan chamber 8 located above the air-mixing chamber. A first inlet 10 in a wall (12, fig 2) of the housing communicates ambient air drawn from outside a system space (fresh external air) and is delivered into the evaporative-cooling chamber. The evaporative-cooling chamber contains an evaporative cooling element 16, 18 arranged such that the ambient air passes through the element before entering the air-mixing chamber. A second inlet 38 in a wall (30) of the housing communicates air drawn from the system space (return / recirculated air) and opens through a variable damper 40 into the air-mixing chamber. A fan 4 at an outlet 6 of the fan chamber draws air through the housing and delivers it to the system space. A controller responsive to a temperature in the system space controls a water supply to the evaporative-cooling element, the variable damper and the fan in order to control an air temperature in the system space. The evaporative cooler is installed in the system space, which may be a data centre.

Description

Evaporative Cooler Apparatus and Method The invention relates to an evaporative cooler apparatus and method, in particular for cooling and controlling a temperature within a system space, such as a data centre or server room or telecommunications facility or any other enclosed space.

It is known to use evaporative cooling systems for controlling the temperature within system spaces, but such a cooling system is typically located outside the system space. There are various reasons for this. One is that evaporative cooling systems are bulky, and occupy a significant amount of space. This is because effective evaporative-cooling systems require relatively low air velocities to maintain high coefficients of performance (COP) and so problems of reduced COP arise in conventional evaporative-cooler designs unless they are large in size. The designer of a system space such as a data centre therefore prefers to maximise use of the available space by installing electronic equipment within the system space rather than evaporative cooling systems.

Also, any noise or heat generated by fans or other parts of the evaporative cooling system are undesirable within the system space. In addition, an evaporative cooler requires a water supply. A system space such as data centre contains valuable and high-performance electronic equipment, and if a water supply for an evaporative cooler is provided within the system space, there is a risk that any water leak or flooding would damage the electronic apparatus. This could be extremely expensive to repair.

Evaporative cooling systems are therefore conventionally installed outside system spaces such as data centres.

An operator may wish to use an evaporative-cooling system rather than a refrigeration-based air-conditioning system, because evaporative cooling systems are very much more energy efficient. But in some situations it may be undesirable or impossible to situate cooling systems outside a system space, and in such cases an operator may conventionally be forced to use a refrigeration-based air-conditioning system, which does not require a water supply and may be less bulky than an evaporative cooling system.

The invention aims to address these problems in the prior art.

Summary of Invention

The invention provides an evaporative cooler and a method for evaporative cooling of a system space as defined in the appended independent claims, to which reference should now be made. Preferred or advantageous features of the invention are set out in dependent subclaims.

In a first aspect, the invention may therefore provide an evaporative cooler, or an evaporative cooling system, installable within a system space, such as data centre or server room or telecommunications facility or any other enclosed space. The evaporative cooler may comprise an external housing which is preferably internally divided to form an evaporative-cooling chamber, an air-mixing chamber positioned, in use, above the evaporative-cooling chamber, a filter positioned, in use, above the air-mixing chamber, and a fan chamber positioned, in use, above the filter. A first inlet for air, preferably ambient air drawn from outside the system space, is defined in a wall of the housing and delivers the air into the evaporative-cooling chamber. A second inlet for air, preferably system-space air drawn from the system space, is defined in a wall of the housing and delivers the air into the air-mixing chamber. The housing preferably has no other air inlets. A fan is preferably arranged at an outlet for air from the fan chamber, such that operation of the fan draws air through the first and second inlets and preferably upwards through the evaporative-cooler housing, and delivers it to the system space.

The evaporative-cooling chamber preferably contains an evaporative-cooling element or pad arranged such that the ambient air drawn through the first inlet passes through the element before entering the air-mixing chamber. System-space air drawn through the second inlet preferably passes through a variable damper to enter the air-mixing chamber. Control of the variable damper may advantageously vary the air flow rate through the damper, or the pressure drop across the damper, so as to control the proportions of ambient air and system-space air, drawn through the first and second inlets respectively, which enter the air-mixing chamber.

The ambient air drawn through the first inlet is at ambient temperature, i.e. the temperature outside the system space, and may be cooled in the evaporative-cooling chamber if or as required. The system-space air entering the second inlet is at the air temperature within the system space adjacent to the cooler.

Controllably mixing these two air flows can therefore produce a flow of mixed air of a desired temperature for delivery through the filter and through the fan to the system space.

The air passing through the evaporative-cooling chamber may or may not be cooled, depending on whether water is delivered to the evaporative-cooling element as the ambient air passes through the evaporative-cooling chamber.

Air from the air-mixing chamber preferably passes through the filter into the fan chamber, for delivery through the fan to the system space.

A controller or control unit responsive to a temperature in the system space preferably controls the variable damper, the fan, and a water supply to the evaporative-cooling element, in order to control an air temperature in the system space.

The evaporative cooler is advantageously designed with the fan chamber, the filter, the air-mixing chamber and the evaporative-cooling chamber positioned vertically above one another in use. This allows particularly efficient packaging and design of the evaporative cooler, both in terms of the physical size of the cooler and its total energy consumption for a given cooling capacity, and therefore its coefficient of performance (COP). The COP of a cooler is the ratio of cooling provided (heat removed from the cooled air) to the power consumption of the cooler. Thus, in a preferred embodiment, the evaporative cooler of the invention may have a cooling capacity of 10, 20, 30 or even kW, and a maximum electrical power consumption of less than 500 W or 300W. For example the fan may consume 300W or 200W or less and other functions such as the evaporative-cooling element's water pump may consume a maximum of 100W or less. Depending on the operating requirements of the cooler at any time the controller may control the fan and/or the pump to operate at less than their full power, further reducing the power consumption of the cooler.

The advantageously small size of the evaporative cooler may, in a preferred embodiment, be provided by a housing enclosing less than 2 m3 of volume, or in which the housing is less than 2 m or 1.8 m in height and/or has a minimum horizontal dimension of less than 1 m or less than 0.8 m. This may conveniently allow the evaporative cooler to pass through a conventional doorway. The cooler may be mounted on wheels or casters for ease of transportation.

Nevertheless, the inventor has found that due to the advantageous structure, or packaging, of the cooler as described herein a COP of 25:1, or 30:1 or more, may be achieved.

Advantageously, an evaporative cooler embodying the invention may be implemented as a modular unit. A designer or operator of a system space may therefore install any number of modular evaporative-cooler units within the system space in order to achieve a desired level of cooling, or temperature control. Advantageously, evaporative-cooler units installed within a system space may be couplable to a water supply of the system space, or to a water supply installed within the system space.

The preferred cuboid shape of the housing of the modular cooler, preferably with the longest dimension of the cuboid vertically oriented, advantageously allows space-efficient installation of evaporative coolers within a system space, which is typically a room of conventional height of, say, 2.5 m. A 2 m high cooler can be positioned in such a space with its outlet advantageously situated in an upper surface of the cooler housing, with sufficient space above the cooler to allow cooled air to be delivered from the outlet into the system space. The narrow width of the cooler housing may then advantageously allow two or more coolers to be installed next to each other, in a space-efficient row, occupying a minimum amount of the floor area in the system space.

The space-efficient design of evaporative coolers embodying the invention may be implemented in coolers of other sizes. For example, smaller units such as coolers between 1 m and 1.8 m, or between 1.3 m and 1.6 m high, preferably of volume 1.5 m3 or 1 m3 or 0.8 m3 or 0.6 m3 or less, may be provided, advantageously retaining COP values of 25:1 or more. Such units may be wall-mountable, for example positioned adjacent to a window of the system space, through which ambient air may be drawn into the first inlet.

In order to achieve compact packaging of the evaporative cooler, in a preferred embodiment the first inlet may open into a portion of the evaporative-cooling chamber between two or more evaporative-cooling elements, or pads, which are preferably vertically-oriented. This chamber portion, which is preferably centrally arranged within the evaporative-cooling chamber, is sealed except at the first air inlet and the evaporative cooling elements. Air drawn through the first air inlet is therefore forced to flow out of the chamber portion through the evaporative-cooling element(s). The evaporative-cooling elements may be spaced from side walls of the housing, which are preferably vertical, such that air drawn in through the first inlet may pass through the evaporative-cooling elements and then flow upwards between each evaporative-cooling element and the respective spaced, or adjacent, side wall of the housing to enter the air-mixing chamber. This arrangement may conveniently allow the first inlet to be defined in a vertically-oriented side wall of the housing, which may conveniently be aligned with andlor coupled to a corresponding vent or opening in a side wall of the system space, to provide access to the ambient atmosphere outside the system space. At the same time, the evaporative-cooling elements may be positioned in a vertical orientation, as is conventionally used so that water can be provided to an upper edge of each evaporative-cooling element. Having passed through the evaporative-cooling elements, the air can then flow vertically upwards into the air-mixing chamber as a result of the compact packaging of the evaporative cooler.

In a smaller evaporative cooler, the evaporative-cooling chamber may contain only one evaporative-cooling element. In this case the first inlet may be offset towards one side of the chamber, with the cooling element approximately centrally positioned within the chamber, and the upwards airflow to the air-mixing chamber on the other side of the cooling element.

The controller of the evaporative cooler is preferably responsive to sensors for measuring parameters such as an air temperature and/or humidity in the system space and/or an ambient air temperature and/or humidity outside the system space, and accordingly controls the water supply to the evaporative-cooling element(s), the variable damper and the fan, in order to control an air temperature in the system space. Thus, for example, if it is necessary or desirable to cool ambient air drawn through the first inlet, the controller may control the water supply to deliver water to the evaporative-cooling element(s), but if the ambient air temperature is low enough that it does not need to be cooled before delivery to the system space, then the controller may control the water supply not to deliver water to the evaporative-cooling elements(s). The ambient air then still flows through the evaporative-cooling element(s) but is not cooled by them.

The controller may then control mixing of the optionally-cooled ambient air with system-space air in the air-mixing chamber in order to provide air of a desired temperature to the fan chamber. This is achieved by controlling the variable damper. The damper may be closable such that only air drawn through the first inlet is provided to the system space, and/or the damper may be openable completely, such that a maximum proportion of air (drawn through the second inlet) is recycled from the system space back to the system space. However, the variable damper may also be progressively controllable at partial openings so that (optionally-cooled) ambient air and system-space air, drawn through the first and second inlets respectively, may be mixed in desired or predetermined or controllable proportions in the air-mixing chamber. To achieve this, the pressure drop or flow rate in the air flowing through the variable damper is controlled (by the partial opening of the damper) relative to the pressure drop or flow rate in the air passing through the evaporative-cooling element(s). In addition to being advantageously fully closable, the variable damper is therefore preferably controllably or adjustably openable, for example at partial openings, to produce a pressure drop or flow rate between a lower level of about 5% or 10%, and an upper level of about 200%, or 100%, or 50%, of the pressure drop or flow rate of the air passing through the evaporative-cooling element(s).

As described above, air from the air-mixing chamber may flow through a filter into the fan chamber. In order to maximise the performance of the evaporative cooler, the pressure drop in air flowing through the filter (if present) is advantageously as low as possible, and in paiticular is preferably lower than the pressure drop in air passing through the evaporative-cooling chamber.

This may minimise the required power consumption of the fan and increase the COP of the cooler. Advantageously the cooler is arranged such that the fan need only generate a pressure of less than 300 Pa, so that an efficient axial-flow fan can be used.

A further aspect of the invention provides a method for evaporative cooling of a system space, using an evaporative cooler installable within the system space.

The method advantageously comprises controlling a fan, preferably an axial-flow fan, positioned at (or otherwise positioned so as to drive or draw air through) an outlet from a fan chamber of the evaporative cooler, the outlet opening into the system space, to draw air through first and second inlets of the evaporative cooler. Ambient air may thus be drawn from outside the system space through the first inlet into an evaporative-cooling chamber and through an evaporative-cooling element housed within the evaporative-cooling chamber. The evaporative-cooling chamber is preferably positioned, in use, at a lower portion or end of the evaporative cooler. Air is drawn from the system space through the second inlet and through a variable damper, into an air-mixing chamber. The air-mixing chamber is positioned, in use, above the evaporative-cooling chamber and below the fan chamber. The air-mixing chamber receives air from the evaporative-cooling chamber after it has passed through the evaporative-cooling element.

The variable damper is then controllable to mix, in a desired ratio (which is preferably progressively controllable, or adjustable, within a desired range of possible ratios), the air from the system space with the air which has been drawn through the evaporative-cooling element, preferably to generate mixed air of a desired or predetermined temperature. The mixed air is then drawn from the mixing chamber through a filter into the fan chamber, and may be delivered from the fan chamber into the system space.

Advantageously, such a method may be performed using an evaporative cooler embodying the first aspect of the invention described above.

Descrirtion of Preferred Embodiments and Best Mode of the Invention Specific embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is front view of a modular evaporative-cooling unit according to a first embodiment of the invention, with the front panel of the housing of the unit removed; Figure 2 is a vertical section of the evaporative-cooling unit of Figure 1, on the section line shown in Figure 1; Figure 3 is a three-quarter view of a modular evaporative-cooling unit according to a second embodiment of the invention, with its front doors open; Figure 4 is a horizontal section through an evaporative-cooling chamber of the evaporative-cooling unit of Figure 3, viewed from above; and Figure 5 is a three-quarter view of a frame for supporting two evaporative-cooling elements, or pads, in the embodiment of Figure 3.

In a first embodiment, the modular evaporative-cooling unit, or evaporative cooler, comprises an external housing 2. The housing is cuboid in shape, with the longest dimension of the cuboid vertical, between 1.8 m and 2m high, between 1 m and 1.2 m wide and between 0.7 m and 0.9 m deep.

An axial-flow fan 4 is secured to a horizontal upper wall of the housing at an outlet in the form of an opening 6 defined in the wall. When the evaporative cooler is installed in a system space, operation of the fan draws air upwardly through the evaporative cooler and delivers it through the outlet to the system space.

The fan is housed in a fan chamber 8, occupying an upper end of the housing.

A first air inlet 10 is defined in a vertical rear wall 12 of the housing, and is coupled to an opening or vent in a wall of the system space so that it can draw ambient air from outside the system space. Air entering through the first inlet may pass through a filter, to remove dust and the like. The air inlet 10 opens into a central portion of an evaporative-cooling chamber 14 at a lower end of the housing of the evaporative cooler, defined between two vertically-oriented evaporative-cooling elements 16, 18. Lower ends of the evaporative-cooling elements extend within a sump 20 for receiving water draining from the cooling elements. A pump 22 is positioned within the tank and delivers water through pipes 24 to distributors 26 at upper ends of the evaporative-cooling elements, under the control of a controller (not shown).

The evaporative-cooling elements, the sump and an upper wall 28 of the central portion of the evaporative-cooling chamber extend between front and rear vertical walls 30, 12 of the housing. Ambient air drawn through the first inlet is thus forced to flow laterally outwards through the evaporative-cooling elements 16, 18 and then to flow vertically upwards between the evaporative-cooling elements and vertical side walls 32, 34 of the housing. The air flows upwardly into an air-mixing chamber 36 positioned in a central portion of the housing between the evaporative-cooling chamber 14 and the fan chamber 8.

A second air inlet 38, in which a variable damper 40 is mounted, is defined in the front wall 30, opening into the air-mixing chamber 36. The second inlet is arranged to draw air from the system space into the air-mixing chamber, where it mixes with air from the evaporative-cooling chamber. The mixed air is drawn out of the air-mixing chamber through a bank of filters 42 into the fan chamber, and is then delivered by the fan to the system space.

The controller can control the fan, the variable damper and the pump, in response to sensors measuring parameters such as a system-space air temperature, in order to deliver air from the evaporative cooler at a desired temperature and flow rate into the system space. The rate of flow of air through the cooler is primarily determined by the speed of the fan. If it is appropriate to deliver uncooled ambient air to the system space at a desired rate, the controller can close the variable damper and switch off the pump, so that no water is supplied to the evaporative-cooling elements. Ambient air drawn through the first inlet 10 then passes through the evaporative-cooling elements, without being cooled. It then passes through the air-mixing chamber and the fan chamber and is delivered to the system space. If the ambient temperature is higher, such that it is desirable to cool the ambient air for delivery to the system space, the controller controls the pump 22 to deliver water to the evaporative-cooling elements.

Alternatively, it may be appropriate to recycle air from the system space, with or without mixing the recycled system-space air with optionally-cooled ambient air in the air-mixing chamber. To maximise air recycled from the system space, the variable damper is opened completely. If it is desired to mix recycled system-space air with optionally-cooled ambient air, the controller controls the partial opening of the variable damper such that the system-space air and the optionally-cooled ambient air are mixed in a desired proportion in the air-mixing chamber. To achieve accurate mixing, the controllable partial opening of the variable damper should be able to adjust the pressure drop of air flowing through the variable damper to correspond to a pressure drop of air passing through the evaporative-cooling elements. Thus, for example, the opening of the variable damper should be controllable to generate a pressure drop of between 5% and 200% of the pressure drop for air passing through the evaporative-cooling elements, or between 5% and 100%, or between 5% and 50%, of the pressure drop for air passing through the evaporative-cooling elements.

Although the pressure drops across the evaporative-cooling elements and the variable damper should be adjustable to be comparable to each other as described above, the pressure drops across the evaporative-cooling elements, the variable damper (except when closed) and the filters 42 should be as low as possible. This minimises the power requirement for the fan 4, which is advantageously 200 W or less at maximum output. The only other significant power requirement for the cooler may be the pump, which may advantageously consume 100W or less. Thus, the power consumption of the evaporative coolermay be 300Worless. Minimising thetotal powerconsumption ofthe cooler is highly advantageous as the cooler is designed to be installed within a system space, where its own power consumption adds to the heat generated within the system space. This may provide a very significant advantage over refrigeration-based cooling systems.

Figures 3 to 5 illustrate an evaporative-cooling unit, or cooler, according to a second embodiment of the invention. As in the first embodiment, the unit is a modular evaporative-cooling unit comprising a cuboid-shaped housing, with the longest dimension of the cuboid vertical. The dimensions of the housing may be similar to the dimensions of the first embodiment. Further, the fan chamber and the air-mixing chamber of the second embodiment are similar to those of the first embodiment, and the same reference numerals are used in Figures 3 to 5 to identify the same components as in Figures 1 and 2, where appropriate.

The housing 2 of the second embodiment is constructed with opening doors 50, 52, in a front, vertical wall of the housing. The doors are openable to allow access to the interior of the cooler, for example for replacement of the filter pads 42 and evaporative-cooling elements 54. The doors are shown open in Figure 3. The variable damper 40 is supported in one of the doors 50.

The cooler of the second embodiment differs from the first embodiment in that the evaporative-cooling chamber is arranged to house four, rather than two, evaporative-cooling elements 54. This may advantageously increase the cooling capacity of the cooler. The evaporative-cooling elements are positioned above a sump 20, with provision for supplying water to the evaporative-cooling elements in similar manner to the first embodiment. The four elements are oriented vertically, forming the shape of a "W" when viewed from above. Figure 4 is a horizontal section through the evaporative-cooling chamber of the second embodiment, viewed from above, showing the arrangement of the evaporative-cooling elements 54.

Two openings 56 are defined in a rear vertical wall of the housing 2, to allow ambient air to be drawn into the evaporative-cooling chamber. The ambient air is drawn into V-shaped regions between respective pairs of the evaporative-cooling elements. The air flow is shown by arrows "A" in Figure 4. Two frames 58 are provided in the evaporative-cooling chamber, each frame being arranged to support a pair of evaporative cooling elements arranged in a V as shown in Figure 5. An evaporative-cooling element 54 can be removably secured to each side of each frame 58, and an open end of each frame abuts one of the openings 56 in the rear wall of the housing. Upper and lower walls 60, 62 of each frame constrain air drawn through the openings 56 to pass horizontally through the evaporative-cooling elements 54 secured to the frame.

Having passed through the evaporative-cooling elements, the air can flow vertically upwards into the air-mixing chamber 36, as in the first embodiment.

As in the first embodiment, it is important that the arrangement of the evaporative-cooling elements is such that a high rate of air flow can be maintained with the lowest possible pressure drop across the evaporative-cooling chamber, such that the power of the fan required to draw air through the cooler is minimised. Thus, the cross-sectional areas of the passages for air flow should be maximised and the number of corners around which air must flow should be minimised.

In all embodiments of the invention, therefore, it may be advantageous if the air, as it is drawn from the air inlets and delivered to the system space, should never flow downwards, in any part of the cooler. As the air is drawn upwardly through the cooler in the first and second embodiments, it is drawn horizontally through the air inlets and then flows either horizontally or vertically upwards as it passes through the cooler. Avoiding any reversal of the air flow into a downward direction would require significant changes in momentum of the air flow and increase the power required by the fan.

Because it contains four evaporative-cooling elements rather than two, the cooler of the second embodiment may have a greater cooling capacity than the cooler of the first embodiment. The remainder of the cooler may be the same as in the first embodiment or, to optimise the use of the larger number of evaporative-cooling elements, it may be advantageous to employ a more powerful fan in the second embodiment than in the first, and/or for the size of the variable damper to be increased in the second embodiment, in order to maintain a high flow of air through the cooler at low pressure drop, and a high coefficient of performance.

In both the first and second embodiments, the sizes and arrangements of the evaporative-cooling elements, or pads, and the ducts or airways between the evaporative-cooling elements and the air-mixing chamber, are selected so that the air velocity through the elements is less than 1.5 ms1 and the air velocity within the ducts, and all other airways within the cooler, is less than 10 ms* This advantageously allows the coolers to achieve a COP of 25:1 or more.

In each embodiment described above, the tall, thin design of the evaporative cooler provides further advantages in installation within a system space. The height of the cooler is such that there is sufficient clearance between the upper wall of the cooler and the air outlet, and a conventional ceiling height, while the slim housing minimises the floor area required to house the cooler. In addition, the cuboid-shaped housing permits more than one modular evaporative-cooling unit to be installed in a system space next to each other, for example in a row. Thus, any number of modular coolers embodying the invention can be installed conveniently within a system space, depending on the cooling requirements for the space. Each of the coolers may then be coupled to a water supply in the system space. Similar packaging advantages may apply if the cooler is implemented in other sizes, such as a smaller size for cooling small system spaces or for wall mounting.

Claims

Claims 1. An evaporative cooler installable within a system space, comprising; an external housing which is internally arranged to form an evaporative-cooling chamber, an air-mixing chamber positioned, in use, above the evaporative-cooling chamber, and a fan chamber positioned, in use, above the air-mixing chamber; in which, a first inlet for ambient air drawn from outside the system space is defined in a wall of the housing and opens into the evaporative-cooling chamber, and the evaporative-cooling chamber contains an evaporative-cooling element arranged such that the ambient air passes through the element before entering the air-mixing chamber; a second inlet for air drawn from the system space is defined in a wall of the housing and opens, through a variable damper, into the air-mixing chamber; a fan is arranged at an outlet for air from the fan chamber, such that the fan draws air through the evaporative-cooler housing and delivers it to the system space; and a controller responsive to a temperature in the system space controls a water supply to the evaporative-cooling element, the variable damper and the fan in order to control an air temperature in the system space.
2. An evaporative cooler according to claim 1, further comprising a filter positioned such that, in use, air passes from the air-mixing chamber through the filter to the fan chamber.
3. An evaporative cooler according to claim 1 or 2, in which the first inlet opens into a portion of the evaporative-cooling chamber between two or more evaporative-cooling elements, and the evaporative-cooling elements are spaced from side walls of the housing such that air drawn in through the first inlet passes through the evaporative-cooling elements and flows upwards between each evaporative-cooling element and the respective spaced side wall of the housing to enter the air-mixing chamber.
4. An evaporative cooler according to claim 1, 2 or 3, in which the evaporative-cooling chamber houses a pump couplable to a water supply of the system space for drawing water from the water supply and delivering it to the evaporative-cooling element(s).
5. An evaporative cooler according to any preceding claim, in which the evaporative-cooling chamber generates a predetermined pressure drop in air flowing therethrough, and the variable damper is progressively controllable such that a pressure drop in air flowing through the variable damper, when partially open, is adjustable between 5% or 10% and up to 200%, or 100%, or 50%, of the predetermined pressure drop so as to control mixing of air entering the air-mixing chamber from the evaporative-cooling chamber and from the system space.
6. An evaporative cooler according to any preceding claim, in which a pressure drop in air flowing through the filter is less than 50%, and preferably less than 30% or less than 10%, of a pressure drop in air passing through the evaporative-cooling chamber.
7. An evaporative cooler according to any preceding claim, forming a modular unit such that one, two or more evaporative-cooler units are installable within the system space.
8. An evaporative cooler according to any preceding claim, in which one, two or more evaporative-cooler units are couplable to a water supply of the system space.
9. An evaporative cooler according to any preceding claim, in which the coefficient of performance of the cooler is greater than 25:1.
10. An evaporative cooler according to any preceding claim in which, at a maximum speed of the fan, the air velocity through the evaporative-cooling element(s) is less than 1.5 ms and the air velocity in all airways or ducts of the cooler is less than 10 ms1.
11. An evaporative cooler according to any preceding claim in which the volume enclosed by the housing is less than 2m3.
12. An evaporative cooler according to any preceding claim, in which the housing is less than 2m in height and/or has a minimum horizontal dimension of less than im.
13. A method for evaporative cooling of a system space using an evaporative cooler installed within the system space, comprising the steps of; controlling a fan positioned at an outlet from a fan chamber, the outlet opening into the system space, to draw air through first and second inlets of the evaporative cooler; drawing air from outside the system space through the first inlet into an evaporative-cooling chamber positioned, in use, at a lower portion of the evaporative cooler, such that the air is drawn through an evaporative-cooling element; drawing air from the system space through the second inlet and through a variable damper into an air-mixing chamber positioned, in use, above the evaporative-cooling chamber and below the fan chamber; controlling the variable damper to mix, in a desired ratio, the air from the system space with the air which has been drawn through the evaporative-cooling element, to generate mixed air of a desired temperature; and delivering the mixed air from the fan chamber into the system space.
14. A method according to claim 13, comprising the step of drawing the mixed air from the mixing chamber through a filter into the fan chamber.
15. A method according to claim 13 or 14, in which the air drawn through the first inlet flows laterally, outwardly from a central portion of the evaporative-cooling chamber, through two or more evaporative-cooling elements, and then upwardly into the air-mixing chamber.
16. A method according to claim 13, 14, or 15, comprising the step of controlling partial opening of the variable damper such that the flow rate of air through the second inlet is progressively adjustable between 5% or 10% and up to 200%, 100%, or 50%, of the flow rate of air through the first inlet.
17. A method according to any of claims 13 to 16, comprising the step of installing one, two or more modular evaporative coolers within the system space.
18. A method according to any of claims 13 to 17, comprising the step of coupling one, two or more modular evaporative coolers to a water supply of the system space.
19. A method according to any of claims 13 to 18, comprising the use of an evaporative cooler as defined in any of claims 1 to 12.
20. An evaporative cooler substantially as described herein, with reference to the accompanying drawings.
21. A method for cooling a system space substantially as described herein, with reference to the accompanying drawings.