GB2555090A

GB2555090A - Air conditioning system

Info

Publication number: GB2555090A
Application number: GB1617237.1A
Authority: GB
Inventors: Donald Foster Pierce Richard; Goss Martin
Original assignee: Foster Pierce Group Ltd
Current assignee: Foster Pierce Group Ltd
Priority date: 2016-10-11
Filing date: 2016-10-11
Publication date: 2018-04-25
Anticipated expiration: 2036-10-11
Also published as: GB2555090B; GB201617237D0

Abstract

An air conditioning system comprises an air inlet 7 through which air is drawn from an external environment 3 by an axial fan 9 and a means (spray humidifier) 15 to add moisture into the air to adiabatically cool the air. A gas separator 21 separates the adiabatically cooled air into an exhaust stream to the external environment 3 via an outlet 33 and a supply stream as output air through a supply conduit 43 to an internal environment 5. The exhaust stream has a higher water vapour content than the supply stream. A first portion of the supply stream is communicated back to the moisture adding means for further adiabatic cooling via a recycling conduit 39 and a second portion of the supply stream is the output air to the internal environment. The ratio of first and second portions may be varied by a mixing valve 35 to control temperature and/or humidity of the output air. A second inlet 49 from the internal environment may supply air to the mixing valve. The gas separator may comprise of a motor 27 driven rotating drum housing 25 having holes 29 for the exhaust stream and holes 31 for the supply stream.

Description

(71) Applicant(s):

Foster Pierce Group Ltd

London House, Shawbury, Shrewsbury, Shropshire, SY4 4EA, United Kingdom (72) Inventor(s):

Richard Donald Foster Pierce Martin Goss (56) Documents Cited:

GB 0331824 A CN 203605618 U

CN 202392918 U (58) Field of Search:

INT CL F24F

Other: Online: WPI, EPODOC, TXTA (74) Agent and/or Address for Service:

Barker Brettell LLP

100 Hagley Road, Edgbaston, BIRMINGHAM, B16 8QQ, United Kingdom (54) Title of the Invention: Air conditioning system Abstract Title: Air conditioning system (57) An air conditioning system comprises an air inlet 7 through which air is drawn from an external environment 3 by an axial fan 9 and a means (spray humidifier) 15 to add moisture into the air to adiabatically cool the air. A gas separator 21 separates the adiabatically cooled air into an exhaust stream to the external environment 3 via an outlet 33 and a supply stream as output air through a supply conduit 43 to an internal environment 5. The exhaust stream has a higher water vapour content than the supply stream. A first portion of the supply stream is communicated back to the moisture adding means for further adiabatic cooling via a recycling conduit 39 and a second portion of the supply stream is the output air to the internal environment. The ratio of first and second portions may be varied by a mixing valve 35 to control temperature and/or humidity of the output air. A second inlet 49 from the internal environment may supply air to the mixing valve. The gas separator may comprise of a motor 27 driven rotating drum housing 25 having holes 29 for the exhaust stream and holes 31 for the supply stream.

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AIR CONDITIONING SYSTEM

The present disclosure relates to an air conditioning system, a controller, and a method for conditioning air.

There is a growing expectation for internal spaces to be maintained to more exacting levels of comfort. For much of the world’s population this means cooling the internal spaces to well below the external ambient temperature for long periods of the annual weather cycle, and controlling humidity levels.

Typically, air conditioning units for cooling air use refrigerant gases. However, there is strong pressure to reduce the use of such gases, because of their high global warming potential and their adverse impact on climate change.

In addition to controlling air temperature and humidity, there is a need to further improve the indoor air quality by reducing levels of pollutants. Pollutants can be generated by activity in the internal space, as well as being found in the external ambient air.

According to a first aspect of the invention there is provided, an air conditioning system having: an inlet for drawing in input air; means for adding moisture in order to adiabatically cool the input air; means for separating the adiabatically cooled air into an exhaust stream and a supply stream, the exhaust stream having higher water vapour content than the supply stream; and means for directing the supply stream, arranged such that a first portion of the supply stream is directed back to the means for adding moisture for further adiabatic cooling, and a second portion of the supply stream is provided as output air.

By adiabatic cooling and separation, the total enthalpy of an air stream is reduced as it passes through the system. Therefore, the system provides for cooling of air, and optionally control of humidity levels, without the use of harmful refrigerants. Recycling a portion of the air back through the adiabatic cooling and separation means allows further iterations of cooling, providing a greater overall reduction in temperature. Furthermore, the system is simple to install, since it only requires connection of water and power supplies. In addition, since there is no compressor, noise levels are reduced.

The means for directing the supply steam may be operable to vary the ratio of the first portion of the supply stream to the second portion of the supply stream, to at least in part control the temperature and/or relative humidity of the output air.

The system may include a heat exchange means, for transferring heat from an air conditioning fluid to the output air, to cool the air conditioning fluid.

The heated output air may be provided to the inlet as at least a portion of the input air.

The input air may be ambient air, and the output air may be provided to an internal space.

The system may include a second inlet for drawing in air from the internal space, wherein the means for directing the supply stream is further arranged to mix the air drawn from the second inlet, with the second portion of the supply stream.

The means for directing the supply stream may be operable to control the ratio of the second portion of the supply stream to the air drawn from the second inlet, to at least in part control the temperature and/or relative humidity of the output air.

The system may include a heat exchanger arranged to cool the air drawn in from the second inlet.

The heat exchanger may be arranged to transfer heat from the air drawn in from the second inlet to the exhaust stream.

The system may include filter means arranged to filter the air drawn in at the second inlet.

The system may include filtering means arranged to filter the input air prior to adiabatic cooling.

The filtering means may include a plurality of filters.

At least some of the plurality of filters may be arranged to filter particles of different size, wherein the size of the particles filtered by the plurality of filters decreases away from the inlet.

At least one of the plurality of filters may comprise an active filter for gaseous nonparticulate pollutants.

The means for adding moisture may be connectable to a low pressure water supply.

The low pressure water supply may be a potable water supply.

The means for adding moisture may be operable to control the amount of moisture added, to at least in part control the relative humidity of the output air.

The inlet may include forced air circulation means arranged to create a pressure differential to draw input air into the system.

The forced air circulation means may be operable to control the flow of input air into the inlet, to at least in part control the temperature and/or relative humidity of the output air.

The means for separating may include a rotating gas separation element.

The rotating gas separation element may include parallel and/or cascading air flows.

The rotating gas separation element may include a drum having a central axis about which it rotates, wherein the central axis is arranged vertically.

The rotating gas separation element may include a drum having a central axis about which it rotates, wherein the central axis is arranged horizontally.

The means for separating may be operable to control the speed and degree of separation, to at least in part control the temperature and/or relative humidity of the output air.

The system may include bypass means, wherein when the bypass means is in a closed state, input air is directed from the inlet to the means for adding moisture, and when the bypass means is in an open state, input air bypasses at least the means for adding moisture and means for separating.

The system may include a controller arranged to control the operation of the system to obtain and/or maintain a set temperature and/or relative humidity in the output air and/or an internal space supplied with the output air.

The system may include temperature and humidity sensors to monitor the temperature and/or humidity in the output air and/or the internal space.

The controller may be arranged to maintain a set carbon dioxide level in the output air and/or the internal space.

The controller may be arranged to operate the system to enable a purge of the system and/or the internal space.

According to a second aspect, there is provided a controller arranged to operate the system of the first aspect.

According to a third aspect of the invention, there is provided a method of conditioning an input air supply, the method including: adding moisture to the input air supply, to adiabatically cool the input air; separating the adiabatically cooled air into an exhaust stream and a supply stream, the exhaust stream having higher water vapour content than the supply stream; directing a first portion of the supply stream back to the means for adding moisture for further adiabatic cooling; and directing a second portion of the supply stream as an output air supply.

It will be appreciated that any feature described in relation to one aspect may also be applied to any other aspect.

Embodiments of the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which:

Figure 1 illustrates an example of an air conditioning system;

Figure 2 illustrates the air conditioning system of Figure 1, with an heat exchange at the exhaust of the gas separator;

Figure 3 illustrates an alternative example of a gas separator for use in the system of Figure 1 or 2; and

Figure 4 illustrates a further alternative example of a gas separator for use in the system of Figure 1 or 2.

Figure 1 illustrates an air conditioning system 1 arranged to draw air from an external environment 3, cool it, and provide it into an internal environment 5, such as the interior of a building. The air drawn in from the external environment 3 is under external ambient conditions, and so may be considered ambient air. The arrows show the flow path of air around the system 1.

The system 1 includes an inlet 7, for drawing in the ambient air. The air is drawn in through the inlet 7 by an axial inline fan 9, which creates a pressure differential to actively draw air into the system 1, rather than passively collecting air.

A filter system 11 is positioned at the inlet 7 to filter out any particulate pollutants. In the example shown, the filter system 11 includes two filters 11a and lib, arranged in series. In the direction of air flow, the first filter 1 la is a coarse filter for filtering out large particulate pollutants, having a size larger than a first threshold size. The second filter lib is a fine filter for filtering out small particulate pollutants, having a size larger than a second threshold size, the second threshold size being smaller than the first threshold size.

After the filter system 11, the ambient air passes through a humidification chamber 13. A spray humidifier 15 is used to add moisture to the ambient air, creating adiabatic cooling. Water is added to the air until it is at or near saturation point.

Water is supplied to the spray humidifier 17 through a potable mains water supply 17, which typically supplies water at relatively low pressure. For example, the pressure may be at 200kPa (2 bar).

From the humidification chamber 13, water is passed through an inlet conduit 19, into a gas separator 21. The fan 9 is positioned downstream of the humidification chamber 13 in order to draw the air in this direction, and the flow of the cooled air through the inlet conduit is controlled by a flow valve 55.

The gas separator 21 includes a rotating drum 23, received in a housing 25. The drum 23 is cylindrical, with a central axis running along it length. The central axis extends vertically. The inlet conduit 19 provides the cooled air stream from the humidification chamber 13 into the centre the drum 23. The drum 23 is rotated about its central axis by a motor 27 driving a shaft 71.

The rotation of the drum 23 creates a centrifugal force, which causes the cooled air to circulate in the drum 23, separating the lighter water vapour gas from the heavier dryer air. The lighter water vapour gas is expelled from holes 29 at the top of the drum 23. This forms an exhaust stream. The heavier, dryer air (mostly oxygen and nitrogen) is expelled from holes 31 in the bottom of the drum 23. This forms a supply stream.

It will be appreciated that different levels of separation can be achieved. For example, perfect separation will result in 100% water vapour in the exhaust stream, and 0% water vapour in the supply stream. Typically, the separation of the air provided to the separator 21 is such that the difference in water content between the supply stream and exhaust stream is 30% or more. The supply stream may include some amount of water vapour by design, to provide humidity to the internal space 5.

The exhaust stream is exhausted from the system 1, through an outlet conduit 37 and an outlet 33 to the ambient external environment 3. Air from the room 5 may also be drawn into a second outlet conduit 41, and exhausted through the outlet 33. The flow of air through this second outlet conduit 41 may be controlled by a flow valve 53.

The supply stream is directed to a mixing valve 35. The mixing valve 35 divides the supply stream into two portions.

A first portion of the supply stream is fed, by a recycling conduit 39, back to the humidification chamber 13, where it repeats the process of humidification and separation. Since the fan 9 is provided after the humidification chamber 13, the fan 9 can help draw this first portion of the air.

There is a limit on the temperature reduction that can be achieved by humidification and separation. However, the air provided by the recycling conduit 39 is colder than the ambient air. Therefore, by repeating the steps of humidification (adiabatic cooling) and separation, a greater overall temperature drop can be achieved.

Hence, it is to be appreciated that in the present invention the process of adiabatic cooling and separation, enables the total enthalpy of the air stream to be reduced as it passes through the system 1.

The second portion of the supply stream is directed out of supply conduit 43, and through an outlet 45 into the internal space 5. A diffuser 47 may be provided at the outlet 45, to diffuse the air into the internal space 5.

The system 1 also includes a room inlet 49 for drawing air from the internal space 5 into the system 1. The inlet may include filters 51, or may not. This air is also fed into the mixing valve 35, where a first portion is directed through the recycling conduit 39 to mix with the first portion of the supply stream, and a second portion is directed through the supply conduit 43, where it is mixed with the second portion of the supply stream.

A controller 57 is provided to control the operation of the system. In particular, the controller 57 is operable to control the circulating fan 9, the flow valves 53, 55, the speed of rotation of the drum 23 in the gas separator 21, the relative proportion of the supply stream that is directed for recycling and directed to the supply conduit 43, and the relative proportion of the air drawn in from the internal space 5 that is directed for recycling and directed to the supply conduit 43.

A temperature sensor 59 and humidity sensor 61 are provided in the internal space 5, or at the room outlet 45. A carbon dioxide sensor (not shown) may also be provided to measure the carbon dioxide levels in the internal space 5. Sensors for other pollutants may also be provided, in some examples.

The measurements of the temperature, humidity and carbon dioxide are provided to the controller 57. At the controller 57, a desired temperature, humidity and carbon dioxide level is set, and the controller operates the system to reach or maintain those set points.

The controller 57 is arranged to modulate a number of parameters to control the conditions in the internal space.

By operating flow valve 55 and fan 9 to vary the speed air is drawn through the inlet , the rate of humidification can be varied to control the amount of adiabatic cooling. Increasing the rate of humidification can decrease the temperature if the set temperature is reduced, or help maintain a constant temperature if the ambient air heats up. Decreasing the rate of humidification can increase the temperature if the set temperature is increased, or help maintain a constant temperature if the ambient air cools down. It should be appreciated that the increase in temperature is not a result of any active heating, for example by an electrical heating means etc. Instead, it will be understood that any increase in temperature arises from a reduction in the amount of cooling provided, and therefore no active heating takes place. Of course, in an alternative embodiment, active heating could be provided to additionally control the temperature if so desired.

Altering the speed of the motor 27 varies the rotation speed of the drum 23, so that the gas separation speed can be varied. Increasing the speed of rotation reduces the water content in the supply stream, and reducing the speed of rotation increases the water content in the supply stream.

Therefore, reducing the rotation speed of the drum 23 can:

Increase the humidity in the internal space if the set humidity is increased, or help maintain the set humidity if the ambient humidity decreases; and/or Since less dry air is available to be recycled and cooled, increase the temperature in the internal space 5 if the set temperature is increased, or help maintain a constant temperature if the ambient air cools down. As above, it will be appreciated that the increase in temperature is not a result of active heating. Instead, the increase in the temperature arises from a reduction in the amount of cooling provided.

Conversely, increasing the speed can:

Decrease the humidity in the internal space if the set humidity is decreased, or help maintain the set humidity if the ambient humidity increases; and/or Since more dry air is available to be recycled and cooled, decrease the temperature in the internal space 5 if the set temperature is decreased, or help maintain a constant temperature if the ambient air heats up.

By varying the flow valve 55, fan 9 and mixing valve 35, the air flow rates through the system 1 can be varied. Increasing the air flow rate can increase the temperature if the set temperature is increased, or help maintain a constant temperature if the ambient air cools down. Conversely, decreasing the air flow rate can decrease the temperature if the set temperature is reduced, or help maintain a constant temperature if the ambient air heats up.

Furthermore, operating the flow valve 53 in the second outlet conduit 41 to increase the flow of air out of the internal space 5, and increasing the flow from the air conditioning system 1 can help to reduce carbon dioxide levels (or maintain carbon dioxide levels if production in the internal space increases), by diluting the carbon dioxide in the internal space 5. Conversely, reducing the flow of air can increase carbon dioxide levels (or maintain carbon dioxide levels if production in the internal space reduces). It should be appreciated that the carbon dioxide will, of course, increase with the number of occupants in the internal space 5, as well as being related to the activities of the occupants (e.g. movement and exercise will increase the carbon dioxide level in the internal space 5).

If the amount of carbon dioxide, temperature and humidity in the internal space 5 are stable, the flow rates through the system can also be reduced, to reduce energy consumption. One reason that these levels may change is due to people entering or leaving the internal space 5, or equipment being turned on or off. Therefore, monitoring changes in the carbon dioxide, temperature and humidity levels monitors the occupancy of the room.

Depending on the conditions of the air from the internal space 5, and the air in the supply stream, modulating the mixing valve 35 can control the temperature and humidity of the air provided from the room outlet 45, by changing the mix of the air in the supply conduit 43. Furthermore increasing the portion of the air that is recycled to the humidification chamber 13 can decrease the temperature if the set temperature is reduced, or help maintain a constant temperature if the ambient air heats up. Conversely, decreasing the portion of the supply stream that is recycled to the humidification chamber can increase the temperature if the set temperature is increased, or help maintain a constant temperature if the ambient air cools down. The desired levels may be received at the controller 57 by any suitable manner, for example they may be set at a user interface (not shown) or received from a separate user input device (not shown) over a wired or wireless interface, or pre-programmed.

Humidity and temperature sensors may also be provided at the inlet 7. The maximum temperature reduction that can be achieved by a single iteration of humidification and separation is dependent on the humidity and temperature of the ambient air. Therefore, the controller 57 may be arranged to vary the proportion of the supply stream that is recycled for repeated humidification depending on ambient conditions.

Figure 2 illustrates a second example of an air conditioning system 1. Where features are the same as the first example, the same reference numerals are used. The humidification, and separation are the same as the first example. However, the example shown in Figure 2 includes a heat exchanger 63.

The exhaust stream, which is cooled due to the adiabatic cooling is fed into a first input of the heat exchanger 63. Air drawn in through the room inlet 49 is provided to the second input of the heat exchanger 63. In this example, a circulating fan 65 is provided at the room inlet 49, to draw air into the system 1.

In the heat exchanger 63, heat is transferred from the air drawn in from the internal space 5 to the exhaust stream. The cooled air drawn in from the internal space 5 is then fed to the mixing valve as in the previous example, and the warmed exhaust stream is provided to the outlet 33.

Condensate from the heat exchanger 63 is collected by collector 67, and fed to a soil and waste system 69. In this way, the amount of cooling required from the system 1 can be reduced, and hence the power required is reduced.

As shown in Figure 2, a bypass conduit 107 can also optionally be provided. The bypass conduit 107 is arranged to pass directly from the inlet 7 to the room outlet 45 (including the filter system 11). The bypass conduit 107 can be arranged to be opened (and the inlet conduit 19 shut) so that ambient air is provide directly to the internal space 5. This can be useful when the ambient air does not require cooling or humidification/dehumidification. The bypass 107 can be closed when control of cooling and temperature is required.

In other examples, the bypass may be provided using the existing system 1, and a set of flow valves (including the flow valves 35, 53, 55) to direct air directly from the inlet to the 7 to the room outlet 45, for example via the recycling conduit 39. The bypass may also include some recirculation of the room air through the room inlet 49.

The controller 57 can be arranged to provide a purge feature. When the system 1 is purged, high temperature and/or high humidity and/or high levels of carbon dioxide are cleared from the internal space 5. This may be achieved either by using the bypass 107 or cooling using humidification and separation.

Typically, the purge is done overnight, since the internal space 5 is likely to be unoccupied, and the ambient conditions are likely to require less cooling from the system 1, so the energy consumption of the system 1 is reduced. The energy consumption can be reduced further by purging the internal space 1 over an extended time, and operating the system 1 at a slow speed.

In some examples, the controller 57 may be arranged to automatically purge the system when the internal space 5 is unoccupied.

In the above examples, the system 1 is an open system, because the supply air is provided directly into the internal space 5. In other examples, this may not be the case, and the system 1 may be closed.

In the closed version of the system 1, the air from the supply conduit is used to chill water or another fluid by transferring heat from the fluid to the air.

The cooled fluid can be provided for further uses. For example, the cooled fluid can be transported around a building in small bore pipes, and used in localised cooling systems to cool individual rooms. In this example, the system 1 is used for cooling only, and filtering, humidity and carbon dioxide control are omitted from the system 1, and provided locally.

Optionally, once the air has been used to cool the fluid, it can then be fed back to the system inlet 7. The air from the exhaust stream may also optionally be fed back to the inlet 7, via a condenser to remove the water vapour, so that the system 1 is fully closed, and no air from the external environment 3 is used. An inlet may be provided to add air from the external environment, to compensate for system losses.

Figure 1 shows a first example of a gas separator 21. Figures 3 and 4 show alternative examples of gas separators 21 that may be used.

The gas separator 21 shown in Figure 1 has a drum 23, arranged with its central axis extending vertically. Figure 3 shows an example of gas separator 21 having a cylindrical drum 23. However, in this example, then central axis extends horizontally.

As with the example shown in Figure 1, the drum 23 is received in a housing 25, and is arranged to rotate on a shaft 71 driven by a motor 27. Seals 79 are provided where the shaft passes through the housing 25 (this may be applied to the example in Figure 1).

The inlet conduit 19 provides adiabatically cooled air to an opening 81 in a lower part of the first end 83 of the housing 25. The outlet conduit 37 is provided in an upper part of the second end 91 of the housing 25, and an outlet 95 to the mixing valve 35 is in the base of the housing 25 at the second end 91.The inlet 81 and outlets 95, 37 of the separator 21 shown in Figure 3 can be provided in the system 1 in the same manner as the separator shown in Figure 1.

The drum 23 is a tight fit inside the housing. The drum 23 has a number of projections 73 on its exterior surface. The projections 73 engage in channels 77 formed by projections 75 formed on the interior of the housing 25. The projections 75, 77 form a multi-chamber labyrinth seal to form a seal between the housing 25 and drum 23, so that the cooled air has to pass through the drum.

The labyrinth seal is just one example of a seal that could be used. In other examples, brush seals or contact rim seals could be used.

The air passes into the drum 23 through openings 85 in the first end 83 of the drum 23. As the air passes along the length the rotating drum 23 it separates into the supply portion and exhaust portion as in the previous example. The exhaust portion passes into the outlet conduit 37 through openings 87 towards the centre of the second end 91 of the drum 23. The supply portion passes through openings 89 towards the outer edge of the second end 91 of the drum 23, and is passed to the mixing valve 35, as discussed in relation to Figures 1 and 2.

Baffles 93 in the drum 23 and between the drum 23 and housing 25help direct the air to the respective openings 37, 87, 89, 95 in the second end 91 of the drum 23 and housing 25.

It will be appreciated that the same principle may be applied to a vertical axis separator 21, and any suitable seal can be formed between the housing 25 and the drum 23.

Figure 4 illustrates a further example of a separator 21. In this example, the separator 21 is formed of a substantially cylindrical housing 25, having a base section 97 that narrows to an outlet 99 to the mixing valve 35. An opening 101 for the inlet conduit 19 is provided near the top of the housing 25. In the example shown in Figure 4, the outlet conduit 37 extends into the centre of the housing 25. The inlet 81 and outlets 95, 37 of the separator 21 shown in Figure 4 can be provided in the system 1 in the same manner as the separator shown in Figure 1.

A plurality of orifices 103 are provided in the section of the outlet conduit within the housing 25.

The cooled air is driven into the housing 25 at high speed by a mixed flow fan 105, or other suitable circulation means. As the air enters the housing 25 it circulates at high speed, creating a cyclone or vortex effect. The exhaust portion of the air is forced to the centre, where it passes into the outlet conduit 37 through the orifices 103, and out of the outlet conduit 37. The supply portion sinks down to the opening 99, from where it is passed to the mixing valve 35, as discussed in relation to Figures 1 and 2.

The examples given above are just three examples of gas separators 21. The gas separation can be achieved using either rotating drums, spinning discs to create vortex separation, pressurised air vortex tubes and cyclonic separation, or membrane films using differential vapour pressures. Indeed, any suitable gas separation technique may be used.

In all the above examples, there is a single air flow through the gas separator 21. However, a plurality of parallel flows may be provided by including multiple drums 23 or the like side by side. This can increase throughput through the system.

Alternatively or instead of this, multiple drums 23 or separators 21 or the like may be provided in a series (such that the supply stream of a first separator 21 is provided to the inlet of the next), to increase the levels of gas separation.

In the examples discussed in relation to Figures 1 and 2, air is drawn into the system 1 by an axial inline fan 9. It will be appreciated that this is by way of example only. Any forced air circulation element may be used to draw the air in. For example, there may be two or more inline fans, one or more centrifugal fans, or any other type of fan circulation system. The circulation element may be positioned at any suitable position within the system, to draw in air, and circulate the recycled portion of the cooled supply air. The air may also optionally be drawn in through the room inlet 49, or the second outlet conduit 41by forced air circulation means. Furthermore, the air may be forced out through the room outlet 45.

The filter system 11 given above is given by way of example only. The filter system may have any number of filters 1 la, b arranged to filter any size of particle. It will be appreciated that the finest filter will always be furthest from the inlet 7.

In some examples the ambient air includes high levels of pollutants, such as volatile organic compounds (VOCs), nitrous oxides, sulfur oxides, fungae, spores, bacteria, pollen. The number and/or type of filters may be chosen according to the particular requirements in each situation. For example, in some cases, active carbon filters 11a, b may be included. An active filter is a filter which removes a pollutant or other substance through a chemical reaction.

The filter system 11 at the inlet 7 and the filter system 5 1 at the room inlet 49 may be the same or different. Either or both filter systems 11, 51 may be omitted in some examples, or the filter systems 11, 51 may be provided at a different point in the system 1, such as at the room outlet 45.

Any suitable humidification system can be used to add moisture to the ambient air for adiabatic cooling. For example, instead of a spray humidifier 15, water may be added by a wet medium provided in the chamber 13, Venturi atomisation, or any other suitable means.

Similarly, any suitable water supply may be used. When the system 1 is open, and the humidified air is provided to the internal space 5, the water supply should be clean and/or potable.

Any suitable mixing valve 35 may be used. In some examples, the mixing valve 35 may not mix air form the room inlet 49, and the room inlet 49 may be omitted. In other examples, the main inlet 7 may draw in air from the internal space 5. In some examples, the mixing valve 35 may also mix air from the bypass into the supply conduit 43.

Any suitable type and number of valves may be used to control the flow through the system 1, at any suitable point in the system 1.

The control of carbon dioxide levels is also optional, and may be omitted.

It will be appreciated that the system may be provided in a dedicated housing, having the required ambient inlet 7, room inlet 49, room outlet 45 and outlet 33. This may be fitted inside or outside of a room, and the inlets and outlets may be coupled to ducting as required.

Alternatively, the system may be provided in a plant room, or other suitable space, with ducting as required. In some examples, the gas separation 21 may be in the plant room but the filter systems 11,51 and/or mixing may be elsewhere.

The open and closed versions of the system 1 can find use in a number of different scenarios. By way of example only, it may be used in school classrooms, health care, hospitals etc., domestic housing including residential buildings, offices, higher and further education, or transport (cars, trains, buses etc in the closed loop form).

Claims

1. An air conditioning system having:

an inlet for drawing in input air;

5 means for adding moisture in order to adiabatically cool the input air;

means for separating the adiabatically cooled air into an exhaust stream and a supply stream, the exhaust stream having higher water vapour content than the supply stream; and means for directing the supply stream, arranged such that a first 10 portion of the supply stream is directed back to the means for adding moisture for further adiabatic cooling, and a second portion of the supply stream is provided as output air.

2. The system of claim 1, wherein the means for directing the supply steam is

15 operable to vary the ratio of the first portion of the supply stream to the second portion of the supply stream, to at least in part control the temperature and/or relative humidity of the output air.

3. The system of claim 1 or claim 2, including a heat exchange means, for

20 transferring heat from an air conditioning fluid to the output air, to cool the air conditioning fluid.

4. The system of claim 3, wherein the heated output air is provided to the inlet as at least a portion of the input air.

5. The system of claim 1 or claim 2, wherein the input air is ambient air, and wherein the output air is provided to an internal space.

6. The system of claim 5, including a second inlet for drawing in air from the

30 internal space, wherein the means for directing the supply stream is further arranged to mix the air drawn from the second inlet, with the second portion of the supply stream.

7. The system of claim 6, wherein the means for directing the supply stream is

35 operable to control the ratio of the second portion of the supply stream to the air drawn from the second inlet, to at least in part control the temperature and/or relative humidity of the output air.

8. The system of claim 6 or claim 7, including a heat exchanger arranged to cool

5 the air drawn in from the second inlet.

9. The system of claim 8, wherein the heat exchanger is arranged to transfer heat from the air drawn in from the second inlet to the exhaust stream.

10 10. The system of any of claims 6 to 9, including filter means arranged to filter the air drawn in at the second inlet.

11. The system of any preceding claim, including filtering means arranged to filter the input air prior to adiabatic cooling.

12. The system of claim 10 or claim 11, wherein filtering means includes a plurality of filters.

13. The system of claim 12, wherein at least some of the plurality of filters are

20 arranged to filter particles of different size, wherein the size of the particles filtered by the plurality of filters decreases away from the inlet.

14. The system of claim 12 or claim 13, wherein at least one of the plurality of filters comprises an active filter for gaseous non-particulate pollutants.

15. The system of any preceding claims, wherein the means for adding moisture is connectable to a low pressure water supply.

16. The system of claim 15, wherein the low pressure water supply is a potable

30 water supply.

17. The system of any preceding claims, wherein the means for adding moisture is operable to control the amount of moisture added, to at least in part control the relative humidity of the output air.

18. The system of any preceding claim, wherein the inlet includes forced air circulation means arranged to create a pressure differential to draw input air into the system.

5

19. The system of claim 18, wherein the forced air circulation means is operable to control the flow of input air into the inlet, to at least in part control the temperature and/or relative humidity of the output air.

20. The system of any preceding claim, wherein the means for separating includes

10 a rotating gas separation element.

21. The system of claim 20, wherein the rotating gas separation element includes parallel and/or cascading air flows.

15

22. The system of claim 20 or 21, wherein the rotating gas separation element includes a drum having a central axis about which it rotates, wherein the central axis is arranged vertically.

23. The system of claim 20 or 21, wherein the rotating gas separation element

20 includes a drum having a central axis about which it rotates, wherein the central axis is arranged horizontally.

24. The system of any preceding claim, wherein the means for separating is operable to control the speed and degree of separation, to at least in part

25 control the temperature and/or relative humidity of the output air.

25. The system of any preceding claim, including a bypass means, wherein when the bypass means is in a closed state, input air is directed from the inlet to the means for adding moisture, and when the bypass means is in an open state,

30 input air bypasses at least the means for adding moisture and means for separating.

26. The system including a controller arranged to control the operation of the system to obtain and/or maintain a set temperature and/or relative humidity in

35 the output air and/or an internal space supplied with the output air.

27. The system of claim 26, including temperature and/or humidity sensors to monitor the temperature and humidity in the output air and/or internal space.

28. The system of any claim 26 or claim 27, wherein the controller is arranged to

5 maintain a set carbon dioxide level in the output air and/or the internal space.

29. An air conditioning system as described herein with reference to and as illustrated in the accompanying drawings.

25

30. A method of conditioning air as described herein with reference to and as illustrated in the accompanying drawings.

Intellectual

Property

Office

Application No: GB1617237.1 Examiner: Stephen Hart

29. The system of any of claims 26 to 28, wherein the controller is arranged to operate the system to enable a purge of the system and/or the internal space.

10

30. A controller arranged to operate the system of any preceding claim.

31. A method for conditioning an input air supply, the method including:

adding moisture to the input air supply, to adiabatically cool the input air;

15 separating the adiabatically cooled air into an exhaust stream and a supply stream, the exhaust stream having higher water vapour content than the supply stream;

directing a first portion of the supply stream back to the means for adding moisture for further adiabatic cooling; and

20 directing a second portion of the supply stream as an output air supply.