GB2540139B

GB2540139B - Combined ventilation, cooling and humidification system and method

Info

Publication number: GB2540139B
Application number: GB1511731.0A
Authority: GB
Inventors: Beresford Alan
Original assignee: Ecocooling Ltd
Current assignee: Ecocooling Ltd
Priority date: 2015-07-03
Filing date: 2015-07-03
Publication date: 2019-09-11
Anticipated expiration: 2035-07-03
Also published as: GB2567762A; GB201511731D0; GB201901495D0; GB2567762B; GB2540139A

Description

Combined Ventilation, Cooling and Humidification System and Method

The invention relates to a combined ventilation, cooling and humidification system and method, in particular for controlling a temperature and/or a humidity within a system space, such as a data centre or server room or telecommunications facility or any other enclosed space.

There is a need for cost-effective, low-energy cooling of buildings and facilities such as system spaces in the Information Technology (IT) sector such as data centres, server rooms and spaces housing telecommunication equipment.

Such IT equipment or apparatus, which may include computing, telecommunications and other types of equipment, generates heat during normal operation and needs to be appropriately cooled. This may conventionally involve a re-circulating ventilation system cooled by a refrigeration unit, or a ventilation system drawing in ambient air, which may for example be assisted by refrigeration or by evaporative cooling.

In order to reduce the cost of cooling IT facilities, there is a desire to locate new data centres and the like in regions with cold climates, such as northern Europe, Canada and Scandinavia. In such regions, ambient air may be usable for cooling for a large proportion of the year, with additional cooling systems as a back-up to be switched on when ambient temperatures become too high.

System spaces for housing IT equipment are conventionally designed to meet predetermined standards for cooling, such as the ASHRAE (American Society of Heating, Refrigeration and Air-conditioning Engineers) standards, which set out standard-compliant temperature and humidity ranges and recommended temperature and humidity ranges for system spaces housing IT equipment.

While cold ambient air is useful for cooling, the quantity of moisture that can be held by a given quantity of air varies with the temperature of the air, such that cold air can hold much less moisture than warm air. This means that when ambient air is cold, its humidity may be below the allowable or recommended standards. In this case, incoming ambient air must be humidified before delivery to a system space, as sparks can be generated by electronic equipment if the air is too dry. This requirement is conventionally fulfilled by artificial humidifiers or misting systems, which greatly increases the cost, complexity and energy consumption of the system as a whole.

It is desirable to use evaporative cooling systems for controlling the temperature within system spaces, as they are much more energy-efficient than refrigeration-based air-conditioning systems. However, such cooling systems are typically located outside the system space. One reason for this is that they are bulky, and occupy a significant amount of space, because effective evaporative-cooling systems require relatively low air velocities to maintain high coefficients of performance (COP). 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. Further, an evaporative cooler requires a water supply, which is undesirable in a system space containing valuable electronic equipment due to the possibility of flooding.

Summary of the Invention

The invention provides a combined ventilation, cooling and humidification system, and a method of method of controlling the temperature and/or humidity 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 provides a combined ventilation, cooling and humidification system for a system space, comprising: a plurality of evaporative coolers; and a system controller responsive to a temperature and a humidity of air in the system space, which controls the plurality of evaporative coolers to control the air temperature and humidity in the system space; wherein the system controller controls the evaporative coolers selectively either to operate in the same way as each other, so that each cooler delivers air to the system space at the same temperature and humidity, at the same or different flow rates, or to operate differently, so that different coolers deliver air of different temperatures and/or humidities, and/or different flow rates, to the system space.

The system space may be a system space such as a data centre or server room or telecommunications facility or any other enclosed space. The evaporative coolers are preferably installable within the system space.

One or more ofthe coolers ofthe combined ventilation, cooling and humidification system may be an evaporative cooler as described below.

The evaporative cooler may comprise an evaporative-cooling chamber comprising at least one evaporative-cooling element, or pad, coupled to deliver air to an air-mixing chamber. The evaporative-cooling element may be disposed between the evaporative-cooling chamber and the air-mixing chamber such that, in use, air is drawn from the evaporative-cooling chamber, through the evaporative-cooling element, into the air-mixing chamber. The airmixing chamber has an outlet for delivering a supply or flow of air of predetermined or controlled temperature and/or humidity, at a predetermined or controlled flow rate, for controlling the temperature and/or humidity of at least a portion of the system space.

The evaporative cooler may comprise a first damper for controlling a flow of ambient air (from outside the system space) through a first inlet into the evaporative-cooling chamber. The cooler may additionally comprise second and third dampers for controlling a flow of recirculated air from within the system space through a second inlet into the evaporative cooling chamber and a flow of recirculated air from within the system space through a third inlet into the air-mixing chamber.

The second damper may advantageously be disposed across the second inlet, controllable to control the flow of recirculated air through the second inlet into the evaporative-cooling chamber.

The third damper may then be situated upstream of the second and third inlets, controllable to control the flow of recirculated air through both the second inlet and the third inlet. For example, the third damper may be disposed in a recirculation channel in order to control the flow of recirculated air drawn from the system space and directed along the recirculation channel to the second and third inlets. In this arrangement the third inlet preferably provides a resistance, such as a fixed resistance, to the flow of recirculated air into the airmixing chamber. The second damper can then be controlled to offer more or less resistance to the flow of recirculated air into the evaporative-cooling chamber to control the relative rates of flow of recirculated air through the second and third inlets. The resistance of the third inlet may be provided in any convenient manner, for example by passing the flow of air through a constriction, or a narrow or tortuous passage, or through a filter element.

Alternatively, the third damper may be disposed across the third inlet, such that the third damper directly controls air flow through the third inlet.

In that case, the second damper may be situated either at the second inlet as described above, or it may be situated upstream of the second and third inlets, so that the second damper is controllable to control the flow of recirculated air through both the second inlet and the third inlet, the second inlet providing a resistance to the flow of air. The second damper may for example be disposed in a recirculation channel to control the flow of recirculated air through the recirculation channel.

The evaporative cooler may comprise a recirculation channel for air drawn from within the system space. Alternatively, the evaporative cooler may be coupled to a recirculation channel, or a recirculation plenum, forming part of or coupled to the system space. Preferably, the second and third dampers may be controllable to allow a flow of recirculated air from the recirculation channel through the second and third inlets into the evaporative cooling chamber and the air-mixing chamber respectively.

The evaporative cooler preferably comprises a supply fan arranged to draw air, in use, through the evaporative cooler. In use, the supply fan may be arranged to draw air into the cooler through the first, second and third inlets, and to draw air from the evaporative cooling chamber through the evaporative-cooling element to the air-mixing chamber, and to deliver it to, or within, the system space. The supply fan may preferably be arranged in or coupled to or adjacent to an outlet from the evaporative cooler. The supply fan may advantageously be a variable-speed fan.

The evaporative cooler preferably comprises or is coupled to a controller, which may be responsive to a temperature and/or a humidity in the system space to control the first, second and third dampers, the supply fan, and a water supply to the evaporative-cooling element, in order to control the temperature and/or humidity and/or flow rate of air delivered out of the evaporative cooler. By controlling the supply of air to or within the system space, the controller may therefore advantageously control the air temperature and/or humidity in the system space. (References in this document to the delivery of air from a cooler to a system space or to the control of temperature and/or humidity in a system space should be understood as referring to that portion of a system space requiring the delivery of air or the control of temperature and/or humidity, such as the portion of the system space housing IT or other heat-generating equipment.)

The first, second and third dampers may be variable dampers comprising damper blades, the positions, or angles, of which are variable between a closed position, in which no air may flow through the damper, to an open position, for example perpendicular to the closed position, in which the damper blades are fully open and do not impede the air flow through the damper. The damper blades may advantageously be positionable at any angle between the closed position and the open position, so as to control the resistance of the damper to air flow.

The water supply to the evaporative-cooling element may be variable, in use, for example between a closed state in which no water is supplied to the evaporative-cooling element, and a fully-open state in which water is supplied to the evaporative-cooling element at a predetermined maximum flow rate. The flow rate is preferably variable, such that air flowing through the element is evaporatively-cooled or humidified to an extent determined, for example, by the rate at which water is supplied to the element and evaporated by the air flow. The evaporative cooler may be couplable to a water supply, and may comprise a pump, for drawing water from the water supply and delivering it to the evaporative-cooling element.

The evaporative cooler may advantageously comprise, or be operatively connected to, at least one temperature sensor, such that the controller is responsive to an air temperature sensed by the temperature sensor. One or more temperature sensors may advantageously be disposed in the system space (or in a portion of the system space requiring a supply of air of controlled temperature), and/or one or more temperature sensors may advantageously be disposed in the ambient atmosphere outside the system space.

The evaporative cooler may advantageously comprise, or be operatively connected to, at least one humidity sensor, such that the controller is responsive to an air humidity sensed by the humidity sensor. One or more humidity sensors may advantageously be disposed in the system space (or in a portion of the system space requiring a supply of air of controlled humidity), and/or one or more humidity sensors may advantageously be disposed in the ambient atmosphere outside the system space.

Preferably the controller controls the cooler, in use, so as to maintain the air temperature in the system space below a predetermined upper temperature and above a predetermined lower temperature. Preferably the controller controls the cooler, in use, so as to maintain the air humidity in the system space below a predetermined upper humidity and above a predetermined lower humidity. Particularly preferably, the controller controls the cooler, in use, so as to simultaneously maintain the air temperature and the air humidity within predetermined temperature and humidity ranges, for example within appropriate ASHRAE standard ranges.

The system space may be any space, or room, for example within a building. Preferably, the system space may contain heat-generating equipment, such that at least a portion of the system space requires cooling, or a supply of air at a controlled temperature and/or humidity, during normal operation.

Particularly preferably, the system space may contain information technology (IT) equipment, such as computing equipment, data storage equipment or telecommunications equipment. Preferably, air may only enter the system space through an evaporative cooler. The system space may comprise a vent, or an exhaust, so that air may flow out of the system space.

In order to assist with maintenance and cooling, IT equipment is typically arranged in rows, or aisles, within a system space. The system space may advantageously comprise one or more cold aisles, to which controlled temperature and/or humidity air may be delivered by the evaporative cooler, and one or more hot aisles into which the air may pass after flowing through the IT equipment.

If a system space contains IT equipment, typically installed in a lower portion of the system space, on a floor, heat generated by the IT equipment will tend to rise towards the ceiling. Prior art cooling systems have typically been based on the assumption that cooled air should be introduced to the hottest portion of the system space. However, the inventor has found that a greater cooling effect can be obtained by delivering cooled, or controlled-temperature, air to a lower portion of the system space, such as at floor level or at a height below a mid-point of the height of the system space, mid-way between the floor and the ceiling. Thus, the controlled-temperature air may advantageously be delivered by the cooler to a lower portion of the system space, for example below a quarter of the total height of the system space.

In a preferred embodiment of the invention, the evaporative cooler comprises an external housing which is internally arranged to form the evaporative-cooling chamber and the air-mixing chamber, and to house the supply fan. When a cooler housed in such a housing is installed within a system space, controlled-temperature air may be delivered to a lower portion of the system space either by directing an outflow of the cooler downwards, towards the floor, or by delivering air from an outlet defined in a lower portion of the housing, for example below a quarter of the total height of the housing.

In order to provide controlled-temperature air from the evaporative cooler it may be desirable to draw system-space air from the hottest portion of the system space. This is typically near the ceiling. The second and third inlets may therefore advantageously draw air from an upper portion of the system space, for example above three-quarters of the total height of the system space.

Alternatively, a cooler may draw recirculated air from a hot aisle and deliver it to a cold aisle.

In general, the supply fan may be arranged to draw air in a generally-downward direction through the evaporative cooler. The supply fan is preferably arranged at an outlet from the air-mixing chamber or, in an alternative embodiment, in or adjacent to a fan chamber, which is preferably arranged adjacent to or below the air-mixing chamber. The outlet from the airmixing chamber preferably comprises one or more outlet filter elements, which may be filter bags, such that air drawn, in use, through the supply fan passes through the filter elements before being delivered to the system space. A first inlet for ambient air drawn into the evaporative cooler from outside the system space may advantageously be defined in a wall of the housing such that the first inlet can be aligned with or coupled to an opening to the environment outside the system space, such as a vent or window. Thus, the first inlet may conveniently be defined in a side wall of the housing. The first damper may advantageously be disposed in, or across, the first inlet.

The first inlet may advantageously comprise an inlet filter element, such that, in use, ambient air passes through the filter before being delivered to the evaporative-cooling chamber.

The first inlet may open directly into the evaporative-cooling chamber. Alternatively, the first and second inlets may open into an inlet chamber adjacent the evaporative-cooling chamber, or into an inlet portion ofthe evaporative-cooling chamber separate from the evaporative-cooling element, so that, in use, air drawn through the first and second inlets is mixed before reaching the evaporative-cooling element. This may be particularly preferable when the ambient air is at a low temperature, for example below 0°C, or below the freezing point of water. At such a temperature, ambient air may freeze any water in the evaporative cooler, for example water contained in the water supply or held in the evaporative-cooling element, potentially damaging the cooler. An inlet chamber, or inlet portion, may be preferable in this situation so that ambient air is mixed, in use, with warm or hot recirculated air to raise the air temperature above 0°C before being drawn through the evaporative-cooler element.

Evaporative cooling involves passing air through a wet evaporative-cooling element or pad, so that the water in the pad obtains its latent heat of evaporation from the air flow and evaporates, cooling the air in the process. Air cooled by evaporative cooling is therefore also humidified. The inventor has appreciated that, if both temperature and humidity are appropriately controlled, such a system is highly appropriate for facilities in cold regions, where the low humidity of cold ambient air means that ventilation alone cannot supply air with suitable characteristics (for example with sufficient humidity) for cooling IT equipment.

If the supply fan is positioned downstream of the air-mixing chamber and the first, second and third inlets, control of the first, second and third dampers may advantageously control the air flows drawn by the fan through the first, second and third inlets. The evaporative-cooling element presents a predetermined, fixed resistance to the flow of air drawn from the first second inlets into the airmixing chamber. The resistance of the evaporative-cooling element does not vary significantly depending on whether the element is wet or dry.

By controlling the positions, or openings, of the dampers, the proportions of ambient and system-space air mixed in the air-mixing chamber may be controlled, in use, to control the temperature and humidity of the air delivered from the evaporative cooler. The temperature of the air delivered from the cooler into the system space may be controlled between the temperatures of the (optionally-cooled) ambient air and the re-circulated system-space air.

The evaporative cooler is preferably controllable to operate differently depending on the temperature and/or humidity of the ambient air. Preferably the cooler is operable in different modes or, particularly preferably, the cooler may be controllable to operate in a continuous range of modes, depending on a temperature and/or a humidity in the system space, or a temperature and/or a humidity in the ambient atmosphere, so as to deliver air to the system space at any desired temperature and/or humidity and/or flow rate.

The cooler may be operable in a ventilation mode, in which the second and/or third dampers are controlled to allow no recirculated air into the cooler through the second or third inlets, the first damper is controlled to allow a flow of ambient air into the cooler through the first inlet, and no water is supplied to the evaporative-cooling element, so that ambient air is delivered to the system space without being evaporatively cooled. In this mode, the ambient air temperature may be below 0°C. There is no risk of freezing because water is not provided to the evaporative-cooling element.

The evaporative cooler may be operable in a cooling mode when the ambient air temperature is sufficiently high to avoid freezing the water in the evaporative-cooling element. In this mode the second and/or third dampers are controlled to allow no recirculated air into the cooler through the second or third inlets, the first damper is controlled to allow a flow of ambient air into the cooler through the first inlet, and water is supplied to the evaporative-cooling element, so that the ambient air drawn into the cooler is evaporatively cooled for delivery to the system space.

The evaporative cooler may be operable in an attemperation mode, in which ambient and recirculated air are mixed for delivery to the system space. In this mode, the second and/or third dampers are controlled to allow a flow of recirculated air into the cooler, and the first damper is controlled to allow a flow of ambient air into the cooler through the first inlet, so that ambient air and recirculated air are mixed before supply to the system space. In this embodiment, recirculated air may flow only into the air-mixing chamber and not into the evaporative-cooling chamber. There is no need to supply water to the evaporative-cooling element in this mode.

In order to further control the temperature and/or humidity of the air delivered to the system space in a second variant of the attemperation mode, the second and/or third dampers may optionally be controlled to allow a flow of recirculated air into the evaporative-cooling chamber (either in addition to or instead of a flow of recirculated air into the air-mixing chamber). In this attemperation mode, water may or may not be supplied to the evaporative-cooling element, so that air drawn through the evaporative-cooling element may optionally be evaporatively-cooled.

In a preferred embodiment in which the third damper is disposed in a recirculation channel upstream of the second and third inlets, with the first damper open and the second damper closed to prevent air flow through the second inlet, the evaporative-cooling element and the third damper may act as the primary resistive elements in the evaporative cooler. In this configuration, in an attemperation mode, the third damper may be controlled relative to the airflow resistance of the evaporative-cooling pad, to control the proportions of ambient and recirculated air flowing into in the air-mixing chamber, so that the controlled-temperature air delivered from the cooler into the system space may have a temperature between the temperatures ofthe (optionally cooled) ambient air and the recirculated air. This configuration may be appropriate when the humidity of the ambient air is within the desired humidity limits for the system space, or when the humidity of the ambient air is less than the target humidity ofthe system space such that, after being evaporatively cooled, the humidity of the ambient air is within the desired humidity limits for the system space.

The evaporative cooler may be operable in a humidification mode, in which the second and/or third dampers are controlled to allow a flow of recirculated air into the evaporative-cooling chamber, the first damper is controlled to allow no ambient air into the cooler, and water is supplied to the evaporative-cooling element so that the recirculated air drawn through the second damper is evaporatively cooled, or humidified, for delivery to the system space.

In a preferred embodiment in which the third damper is disposed in a recirculation channel upstream of the second damper and the third inlet, then air flowing through the third damper into the recirculation channel is divided between the second inlet and the third inlet. The third inlet presents a resistance to air flow, such as a fixed resistance, as described above and so the division of the recirculated air between the second and third inlets is achieved by controlling the resistance of the second damper relative to the resistance of the third inlet.

The controller may advantageously be programmed to control the evaporative cooler to operate in either the cooling mode, the ventilation mode, the attemperation mode, or the humidification mode. Particularly preferably, the controller may control the evaporative cooler to operate in a selected mode depending on one or more temperatures and/or a humidities sensed inside and/or outside the system space.

The evaporative cooler may comprise, or be operable with, an exhaust outlet through which air may flow, in use, through an exhaust damper and out of the system space, and an exhaust fan. Both the exhaust damper and the exhaust fan are preferably controllable by the controller, so that the air pressure inside the system space may be controlled by the controller.

The system controller controls the evaporative coolers independently of one another to deliver air to the system space at a desired temperature and/or humidity. For example, the system controller may control one or more evaporative coolers to operate in the same way, so that each cooler delivers air to the system space at the same temperature and humidity, or the system controller may control different evaporative coolers to operate differently, so that different coolers deliver air flows of different temperatures and/or humidities and/or flow rates to the system space.

The different air flow delivered by different coolers may be mixed before delivery to or within the system space.

The plurality of evaporative coolers may advantageously comprise evaporative coolers as described above. Preferably the system controller may be operatively linked to the controllers of the evaporative coolers, such that the system controller may control the controllers of the evaporative coolers according to a predetermined control protocol.

References to a system controller and evaporative-cooler controllers may be taken as references to controller functionality rather than controller location. In a system comprising multiple evaporative coolers, the system-controller functions and the evaporative-cooler controller functions may all, for example, be performed by the system controller, suitably programmed and connected to the evaporative coolers.

The system controller may then advantageously control any fans, variable dampers and water supplies of the plurality of evaporative coolers. Preferably the system controller may control the supply fan, the third damper, the first damper, the second damper, and the supply of water to the evaporative-cooling element of each of the plurality of evaporative coolers. Particularly preferably the system controller may determine whether each evaporative cooler operates in cooling mode, ventilation mode, attemperation mode or humidification mode.

The ability of the system controller to control, in use, the plurality of evaporative coolers independently of one another may allow the system to deliver a desired net air flow to the system space by combining a plurality of air flows delivered by different evaporative coolers at different temperatures and/or humidities and/or flow rates.

The system of the present invention may advantageously allow the delivery of a net air flow, the temperature and/or humidity of which would not be achievable by a single evaporative cooler. For example, when the ambient air is at a temperature well below the freezing point of water, its specific humidity is likely to be less than the target humidity for the system space. However, very cold ambient air cannot be humidified by passing it through wet evaporative-cooling elements, as the ambient air would freeze the elements and cause damage to the system.

One possible solution to this may be to mix the cold ambient air with hot recirculated air, in an evaporative cooler operating in an attemperation mode, so as to raise its temperature before it comes into contact with the wet element. However, in extremely cold ambient temperatures, forexample below -10°C, or below -20°C, it may be difficult to control this mixing with sufficient accuracy in a compact evaporative cooler.

The system of the present invention may advantageously provide a solution to this problem by controlling the plurality of evaporative coolers in a modular fashion. In the scenario above, for example, a first evaporative cooler (or a first group of coolers) may be controlled to provide a flow of cold, low-humidity ambient air to the system in a direct-ventilation mode, while a second evaporative cooler (or a second group of coolers) is controlled to humidify recirculated air to a humidity greater than the target humidity for the system space. The system may advantageously control the first and second evaporative coolers such that, on delivery to the system space, the air delivered from the first and second coolers combines to form air at the target temperature and humidity.

The system may advantageously be configured so that, in use, air delivered from the plurality of evaporative coolers mixes so that the air in the system space has a temperature within a predetermined temperature range, and/or within a predetermined humidity range.

In order to ensure thorough mixing, the combined ventilation, cooling and humidification system may preferably comprise one or more supply chambers or manifolds, each coupled to outlets of a plurality of evaporative coolers, wherein the supply chambers are arranged downstream of the supply fans such that air delivered from one or more evaporative coolers is mixed in the one or more supply chambers before delivery to the system space, for example to a cold aisle of the system space.

Preferably the air delivered to, or within, the system space, in use, conforms to allowable or recommended air standards, such as ASHRAE standards. A combined ventilation, cooling and humidification system according to the present invention may advantageously be installable in a system space. Particularly preferably, the system may be installable in a system space in which at least a portion ofthe system space requires cooling, or requires a supply of air at a controlled temperature and/or humidity and/or flow rate, during normal operation, such as a data centre or a server room or other space containing or consisting of an Information Technology (IT) apparatus.

Preferably the system controller is responsive to at least one temperature and/or humidity sensed in the system space, for example at one or more positions in the system space, and/or in the ambient atmosphere outside the system space. Particularly preferably the system controller is responsive to a temperature and a humidity sensed downstream of the supply fans of the evaporative coolers and upstream of the portion of the system space which requires cooling, for example, a temperature and/or a humidity sensed in one of the supply chambers or manifolds or in a cold aisle or in a hot aisle. The system controller may also be responsive to a temperature and/or humidity sensed downstream of the portion of the system space which requires cooling. A further aspect of the invention provides a method of controlling the temperature and/or humidity of a system space using a combined ventilation, cooling and humidification system, comprising the steps of: providing a plurality of evaporative coolers; and controlling the plurality of evaporative coolers in response to a temperature and/or a humidity sensed in the system space, so as to deliver air to the system space at a desired temperature and/or humidity; wherein the plurality of evaporative coolers are controlled to operate in the same way, so that each cooler delivers air to the system space at the same temperature and humidity, or different evaporative coolers are controlled to operate differently, so that different coolers deliver air of different temperatures and/or humidities to the system space.

The evaporative controllers are preferably controlled so that the air delivered to or within the system space has a temperature and/or humidity within a predetermined temperature and/or humidity range.

The method of controlling the temperature and/or humidity of a system space using a combined ventilation, cooling and humidification system may comprise a method of use of a combined ventilation, cooling and humidification system according to the first aspect of the present invention.

Each evaporative cooler may be separately, or independently, controlled to operate in cooling mode, ventilation mode, attemperation mode or humidification mode in response to the temperatures and/or humidities sensed in the system space and outside the system. In addition, different coolers may be controlled to operate in the same mode but with different control parameters, such as different air flow rates or humidication rates or cooling rates. Different coolers in different locations within a system space may also be controlled differently if conditions differ at different locations within the system space.

In the description above, it is stated that one or more evaporative coolers are installed within a system space. Although this is preferred, particularly in cold climates, the coolers may if appropriate be installed outside the system space and be coupled to the system space to operate as described herein.

Description of Specific Embodiments 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 a schematic diagram of an evaporative cooler, or combined evaporative cooler and humidifier, usable in the present invention;

Figures 2, 3 and 4 show the apparatus of Figure 1 in cooling mode, attemperation mode and humidification mode, respectively;

Figures 5 and 6 are perspective views of a system incorporating a plurality of coolers embodying the invention;

Figures 7 to 11 show psychrometric charts illustrating the operation of an embodiment of the invention;

Figure 12 is a vertical section of a cooler usable in the present invention; and

Figure 13 is a section on A-A of the cooler of Figure 12.

Figure 1 is a schematic diagram of an evaporative cooler, or combined evaporative cooler and humidifier, usable in the system of the invention. The cooler 2 is arranged to provide a flow of air of desired temperature and humidity to or within a system space 4. The system space, or the portion of the system space requiring cooling, may be termed a room load. The cooler comprises a first, ambient-air, inlet 6 for admitting a flow of air from the surrounding environment, through a first damper 8 (the ambient-air inlet damper) into an evaporative-cooling chamber 10. The evaporative-cooling chamber comprises one or more evaporative-cooling elements, or pads, 12 through which air may flow into an air-mixing chamber 14. A supply fan 16 at an outlet 18 from the air-mixing chamber draws air through the cooler and delivers it to the system space 4.

The cooler comprises a recirculation channel 20 arranged to allow a flow of recirculated air from the system space (room load) to a second inlet 23 into the evaporative-cooling chamber and to a third inlet 26 into the air-mixing chamber. Recirculated air passing through the second inlet 23 passes through a second, damper 24 (the humidification damper) mounted across the second inlet.

The third inlet 26, for air flowing into the air-mixing chamber, comprises a restriction or narrow passage which offers a fixed resistance to the flow of air.

Recirculated air drawn from the system space through the recirculation channel passes through a third damper 22 (the recirculation damper), upstream ofthe second and third inlets.

An exhaust outlet 28 leads from the system space, through an exhaust damper 30, for exhausting air from the system space. An exhaust fan 32 is arranged to drive exhaust air through the exhaust outlet. The exhaust outlet 28 is typically remote from the cooler, for example at a far end of the system space. A controller (not shown) controls the openings of the first, second and third dampers 8, 24, 22 (the inlet damper, the humidification damper and the recirculation damper), a pump (not shown) for delivering water to the evaporative cooling pad 12, and the supply fan 16. A controller, which may be the same controller, also controls the exhaust damper 30 and the exhaust fan 32.

The controller can control the system described above and illustrated in Figure 1 to operate in several different modes, as follows.

The rate of flow of air through the cooler is primarily determined by the speed of the fan, which draws air through the first, second and third inlets, dependent on the settings of the first, second and third dampers.

The cooler and the exhaust fan and exhaust damper may be controlled by a system controller, in response to outputs from at least one temperature sensor and/or humidity sensor positioned within the system space, and/or at least one temperature sensor and/or humidity sensor positioned in the ambient air. The system controller may control the cooler through a cooler controller, mounted within the cooler, or it may control the first, second and third dampers, and the supply fan, directly.

If the ambient air is at a high temperature and cooling of the system space is required, the controller may operate in a cooling mode, as shown in Figure 2.

In this mode, the controller controls the pump to deliver water to the evaporative-cooling element, the first damper is opened and the second and third dampers are closed, such that ambient air is drawn through the evaporative-cooling elements and evaporatively-cooled to a temperature and humidity appropriate for delivery to the system space. The exhaust damper is opened, and the exhaust fan or fans are set to exhaust air at the same rate as it is delivered by the cooler, or coolers if more than one cooler is in operation, such that air delivered to the system space flows through the portion of the system space that requires cooling and absorbs heat before flowing out of the system space through the exhaust outlets.

If the ambient air is at a temperature and humidity appropriate for delivery directly to the system space, the controller may advantageously conserve energy by operating in a ventilation mode. In the ventilation mode, uncooled and unhumidified ambient air may be delivered to the system space at a desired rate by opening the first damper, closing the second and third dampers and switching off the pump, so that no water is supplied to the evaporative-cooling elements. Ambient air drawn through the first inlet then passes through the evaporative-cooling elements without being cooled, and is delivered to the system space at ambient temperature and humidity. At the same time, air is exhausted through the system-space exhaust.

In mild weather conditions where the ambient air is at a temperature and/or humidity such that direct ventilation is not required, the cooler may operate in an attemperation mode, as shown in Figure 3. In attemperation mode, ambient air and recirculated air are mixed for delivery to the system space. In this mode, the controller may open, or partially open, the third damper and open, or partially open, the first damper. The second damper is kept closed. By varying the positions of the first and third dampers, the controller may vary the flow rates of ambient air and warmer recirculated air entering the air-mixing chamber and therefore the temperature and humidity of the air delivered to the system space. Water may be supplied to the evaporative-cooling element in the attemperation mode if cooling or humidification of the ambient air is desired.

To maximise the flow of ambient air in attemperation mode, the first damper is opened completely. To mix recirculated system-space air with the ambient air, the controller controls the partial opening of the third 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 third damper should be able to adjust the resistance to air flowing through the third damper to correspond to a resistance to air passing through the evaporative-cooling element or elements. Thus, for example, the opening of the third damper should be controllable to generate a resistance of between 5% and 200% of the (substantially constant) resistance to air passing through the evaporative-cooling elements, or between 5% and 100%, or between 5% and 50%, of the resistance to air passing through the evaporative-cooling element(s).

To decrease the quantity of ambient air flowing in attemperation mode, the first damper may be partially closed, to introduce additional resistance to the flow of ambient air.

In attemperation mode, the second damper may additionally be opened, in order to allow recirculated air to flow into the evaporative-cooling chamber. If no water is provided to the evaporative-cooling pad, opening the second damper simply increases the quantity of recirculated air flowing through the cooler.

In attemperation mode, it may be desirable to humidify the air flowing through the cooler, for example if the humidity of the ambient air is too low. In that case, water may be supplied to the evaporative-cooling pad, with the second damper closed, partially open or fully open. Care must be taken in this mode, if the ambient air temperature is below O°C, to avoid freezing the water in the evaporative-cooling pad.

The cooler may also operate in a humidification mode, as shown in Figure 4, by closing the first damper, opening or partially opening the third damper, opening, or partially opening, the second damper, and switching on the pump to deliver water to the evaporative-cooling element(s). Heated air from the system space is then recirculated through the recirculation channel, and the portion of air drawn through the second inlet into the evaporative-cooling chamber is cooled and humidified before mixing with the rest ofthe recirculated air in the air-mixing chamber and being delivered to the system space.

Operating a cooler in humidification mode is of primary value when more than one cooler is installed in the same system space, and one or more other coolers is operated in a different mode. In particular, for example, if the ambient air temperature and humidity are both very low, then operating coolers in ventilation mode may provide adequate cooling for the system space but may reduce humidity in the system space to an unacceptably low level (for example outside ASHRAE standards). In that case, one cooler, or group of coolers, may be operated in ventilation mode to provide cooling, while a second cooler or group of coolers is operated in humidification mode to maintain adequate humidity in the system space. When ambient temperature is very low, it is not possible to supply water to the evaporative-cooling pads of coolers operating in ventilation mode, because the cold ambient air would freeze the water in the pads.

The evaporative cooler is preferably constructed as a modular unit so that a plurality of coolers may be installed within a system space. In that case, a row 50 of coolers 2 may advantageously be installed, so as to set up a consistent circulation path for air within the system space. Examples are illustrated in Figures 5 and 6.

The plurality of evaporative coolers 2 advantageously form a combined ventilation, cooling and humidification system, which is controlled by a system controller (not shown), using the modes of operation described above.

The system controller can control the supply fan, the variable dampers and the pump of each evaporative cooler, in response to sensors measuring parameters such as a system-space air temperature and humidity and ambient air temperature and humidity, in order to deliver air to the system space at a desired temperature, humidity and flow rate.

Depending on the temperature and humidity of the ambient air, the system controller may control some or all of the coolers to operate in the same way so that each operating cooler delivers air of the same temperature and humidity. Alternatively, the system controller may control some coolers to operate differently to other coolers, so that different coolers deliver air at different temperatures and humidities. Any coolers that are not required at any time may be switched off, preferably by closing at least the first damper and turning off the supply fan and water supply. By controlling each evaporative cooler independently of the other evaporative coolers, the system controller can advantageously control the system to operate in a modular fashion. This may be particularly advantageous when the temperature and/or humidity of the ambient air is such that a single evaporative cooler cannot deliver air to the system space with both a suitable temperature and a suitable humidity.

One such situation may be in very cold weather, when the ambient air is too cold and too dry for delivery directly to the system space. For delivery to the system space, the ambient air must therefore be warmed to an appropriate temperature, and humidified to an appropriate humidity. However, in an evaporative cooling system, air cannot be humidified without cooling it further, and this is not possible with extremely cold air, as cold air can only hold a small amount of water (corresponding to a low specific humidity). To solve this problem, a first cooler may operate in a ventilation mode, so as to deliver a first air stream of cold, dry ambient air, and a second cooler may operate in a humidification mode, so as to deliver a second air stream of cooled and humidified recirculated air. A third cooler may optionally operate in an attemperation mode to deliver a third air stream at a desired temperature and/or humidity. By controlling the flow rates of these air streams and mixing the air streams before they are delivered to the portion of the system space which requires cooling, the system controller may deliver a net air flow to the system space that is at a desired temperature and humidity.

As described above, temperature and humidity are naturally coupled in systems which employ evaporative cooling. While this is usually not a problem for facilities in temperate climates, it may potentially be problematic in extremely cold regions. By providing a modular system comprising evaporative coolers operable in a number of different modes, the system of the present invention can effectively decouple temperature and humidity considerations in a way that has not previously been possible for systems of this type.

In a preferred embodiment, the system space comprises a cooling channel 52 into which controlled temperature and/or humidity air is delivered from each of the plurality of evaporative coolers, as shown in Figures 5 and 6, in order to mix air streams having different properties prior to delivery into the portion of the system space requiring cooling. Air streams delivered into this channel form mixed air at a desired temperature and humidity before flowing into the portion of the system space which requires cooling.

The system is advantageously in a system space housing IT equipment. In such a system space, air heated by the IT equipment tends to rise towards the ceiling, or towards an upper portion, of the system space. This warmed air may then be drawn into the recirculation inlet 38 of the cooler. Cooled, or temperature-controlled, air is then delivered by the cooler to a lower portion of the system space, where it cools the IT equipment (typically mounted on the floor). The heated air rises within the system space and can be re-circulated through the cooler. Thus, by arranging the cooler to draw air downwardly and to deliver cooled air to the lower portion of the system space, an air-circulation path can be set up within the system space, as illustrated in Figures 5 and 6. This reduces the energy consumption of the cooler, and increases its cooling effect, because the air within the system space and in the cooler is flowing in the same direction around the circulation path. Minimising the energy consumption of the cooler is important because the cooler is housed within the system space, and so its own energy consumption may disadvantageously contribute to heating within the system space. IT equipment in a system space is typically arranged in a series of parallel aisles 54. In order to set up the desired circulation path through the coolers, as described above, the coolers should be arranged at the end of an aisle, so that air circulation can be set up within, or along, the aisles.

The operation of the system controller may be described with reference to the psychrometric charts shown in Figures 7 to 10.

Figure 7 illustrates the ranges of temperature and relative humidity which are within the recommended and allowable ASHRAE Class 1 standards.

Figures 8 to 11 illustrate the operation of an embodiment of the invention when the ambient air temperature is very cold, at about -7°C. Ambient air may therefore be at point A in Figure 9. Because the air is cold, even if its relative humidity is high, its specific humidity is outside (below) the ASHRAE standard.

It is desirable to supply air to a system space at a low temperature and humidity, while remaining within the ASHRAE standard. (This is to minimise total energy consumption and the amount of humidification required.)

Therefore, it may be desirable to supply air to the system space having properties at point D in Figure 8.

If this air is supplied to the system space, its temperature will increase as it absorbs heat from the IT equipment, while its specific humidity remains constant, so that any recirculated air drawn from the system space into a cooler may then be at point B in Figure 8.

If a cooler draws in recirculated air, and operates in a humidification mode (as shown in Figure 4), then the air delivered from the cooler is at point C in Figure 8. A cooler operating in ventilation mode can therefore deliver air to the system space at quality A, a cooler operating in recirculation mode without evaporative cooling can deliver air with quality B, and a cooler operating in humidification mode (or adiabatic recirculation mode) can deliver air with quality C. A cooler operating in attemperation mode (without humidication) can deliver air having any quality on a straight line on the psychrometric chart between points A and B, depending on the relative flow rates of ambient air and recirculated air entering the cooler.

The system controller can therefore operate different coolers in different modes at different flow rates (controlled by the supply fans and by the number of coolers operating in each mode) to deliver the required mixture of these air qualities, to provide a net (or mixed) flow of air having quality D, at a desired flow rate, to the system space.

As illustrated in Figure 9, the required flow rates of each quality of air are a flow rate of X for ambient air, a flow rate of Y for directly recirculated air, and a flow rate of Z for humidified recirculated air. If the temperatures of the three air qualities are termed A, B and C, and the humidities of the three air qualities are termed Μ, N and O, as shown in Figures 9 and 10, then the ratios of the flow rates required to achieve the desired standard-compliant air, of temperature D and humidity P, are shown in Figure 11.

Figures 12 and 13 illustrate a specific embodiment of a modular evaporative-cooling unit, or evaporative cooler. The cooler comprises an external housing, which 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. A fan chamber 60 is defined at a lower end of the housing. A supply fan 16 is located in an inlet to the fan chamber, which separates the fan chamber from an air-mixing chamber 14 (described below).

The supply fan draws air downwardly through the cooler, delivering it into the fan chamber. A cooler outlet 18 is defined in a front, vertical wall of the fan chamber. Four filter bags 44 are housed within the fan chamber, and air driven into the fan chamber by the fan passes through the filter bags before entering the system space through the outlet.

The outlet is defined at a lower portion of the front wall of the housing so that the cooler delivers air to a lower portion of the system space, advantageously at or near floor level. A first air inlet 6, in which a variable first damper 8 is mounted, is defined in a vertical rear wall 62 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. The air inlet 6 opens into a central portion of an evaporative-cooling chamber 10 situated at a middle portion ofthe housing ofthe evaporative cooler, defined between two vertically-oriented evaporative-cooling elements 12. Lower ends of the evaporative-cooling elements extend within a sump 68 for receiving water draining from the cooling elements. A pump 70 is positioned within the tank and delivers water through pipes to distributors at upper ends of the evaporative-cooling elements, under the control of a controller (not shown). A recirculation air inlet, in which a variable third damper 22 is mounted, is defined in the top or uppermost wall 66 of the cooler housing, and opens into a recirculation channel 20 at the top of the cooler, above the evaporative-cooling chamber. A second air inlet, in which a variable second damper 24 is mounted, is defined in a lower wall 72 ofthe recirculation channel, which additionally forms an upper wall ofthe central portion ofthe evaporative-cooling chamber, so that recirculated air can be drawn through the second air inlet from the recirculation channel into the evaporative-cooling chamber.

The evaporative-cooling elements, the sump and the upper wall of the central portion of the evaporative-cooling chamber extend between front and rear vertical walls 61,62 of the housing. Ambient air drawn into the evaporative-cooling chamber through the first inlet, and recirculated air drawn through the second inlet is thus forced to flow laterally outwards through the evaporative-cooling elements 12 and then to flow vertically downwards within vertical channels defined between the evaporative-cooling elements and vertical side walls of the housing. The air thus flows downwardly within an air-mixing chamber 14, which comprises both the vertical channels and a central portion of the housing between the evaporative-cooling chamber 10 and the fan chamber 60.

The recirculation channel also opens through a third inlet 26 into the vertical channels of the air-mixing chamber 14. The recirculation inlet is arranged to draw air from an upper portion of the system space (near the ceiling) into the recirculation channel and from there through the third inlet 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 by the fan and driven through filters 44 in the fan chamber, and is then delivered through the outlet 18 to the system space.

The controller can control the fan, the variable dampers and the pump, in response to sensors measuring parameters such as a system-space air temperature and humidity and ambient air temperature and humidity, in order to deliver air from the evaporative cooler at a desired temperature, humidity 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.

Claims

1. A combined ventilation, cooling and humidification system for a system space, comprising: a plurality of evaporative coolers; and a system controller responsive to a temperature and a humidity of air in the system space, which controls the plurality of evaporative coolers to control the air temperature and humidity in the system space; wherein the system controller controls the evaporative coolers selectively either to operate in the same way as each other, so that each cooler delivers air to the system space at the same temperature and humidity, at the same or different flow rates, or to operate differently, so that different coolers deliver air of different temperatures and/or humidities, and/or different flow rates, to the system space.

2. A combined ventilation, cooling and humidification system according to claim 1, in which the plurality of evaporative coolers comprises an evaporative cooler comprising: an evaporative-cooling chamber, comprising an evaporative-cooling element, coupled to deliver air to an air-mixing chamber, the air-mixing chamber having an outlet through which air is deliverable to the system space; a first damper for controlling a flow of ambient air from outside the system space through a first inlet into the evaporative-cooling chamber; and second and third dampers for controlling a flow of recirculated air from the system space through a second inlet into the evaporative cooling chamber and a flow of recirculated air from the system space through a third inlet into the air-mixing chamber.

3. A combined ventilation, cooling and humidification system according to claim 1 or 2, wherein the system controller controls each evaporative cooler to operate in either a cooling mode, a ventilation mode, an attemperation mode or a humidification mode.

4. A combined ventilation, cooling and humidification system according to any preceding claim, comprising a manifold downstream of two or more evaporative coolers, such that the air delivered from two or more evaporative coolers is mixable in the manifold before delivery to the system space.

5. A combined ventilation, cooling and humidification system according to claim 4, in which the system controller is responsive to a temperature and a humidity in the manifold.

6. A combined ventilation, cooling and humidification system according to any preceding claim, wherein the air delivered from the plurality of evaporative coolers, in use, mixes so that the air in the system space has a temperature within a predetermined temperature range and a humidity within a predetermined humidity range.

7. A combined ventilation, cooling and humidification system according to any preceding claim, in which at least a portion of the system space requires cooling, or a supply of air at a controlled temperature and/or humidity, during normal operation.

8. A combined ventilation, cooling and humidification system according to claim 7, in which the system controller is responsive to a temperature and humidity downstream of outlets ofthe evaporative coolers and upstream ofthe system space which requires cooling.

9. A method of controlling the temperature and/or humidity of a system space using a combined ventilation, cooling and humidification system, comprising the steps of: providing a plurality of evaporative coolers; and controlling the plurality of evaporative coolers in response to a temperature and/or a humidity sensed in the system space, so as to deliver air to the system space at a desired temperature and/or humidity; wherein the plurality of evaporative coolers are controlled to operate in the same way, so that each cooler delivers air to the system space at the same temperature and humidity, or different evaporative coolers are controlled to operate differently, so that different coolers deliver air of different temperatures and/or humidities to the system space.

10. A method of controlling the temperature and/or humidity of a system space according to claim 9, in which the plurality of evaporative coolers comprises an evaporative cooler comprising: an evaporative-cooling chamber, comprising an evaporative-cooling element, coupled to deliver air to an air-mixing chamber, the air-mixing chamber having an outlet through which air is deliverable to the system space; a first damper for controlling a flow of ambient air from outside the system space through a first inlet into the evaporative-cooling chamber; and second and third dampers for controlling a flow of recirculated air from the system space through a second inlet into the evaporative cooling chamber and a flow of recirculated air from the system space through a third inlet into the airmixing chamber.

11. A method of controlling the temperature and/or humidity of a system space according to claim 9 or 10, in which the evaporative controllers are additionally controlled in response to a temperature and/or a humidity of ambient air sensed outside the system space.

12. A method of controlling the temperature and/or humidity of a system space according to claim 9, 10 or 11, in which each evaporative cooler is separately controlled to operate in a cooling mode, a ventilation mode, an attemperation mode or a humidification mode.

13. A method of controlling the temperature and/or humidity of a system space according to any of claims 9, to 12, comprising the step of mixing the air delivered from two or more evaporative coolers so as to generate an air supply at a desired temperature and/or humidity and/or flow rate.

14. A method of controlling the temperature and/or humidity of a system space according to any of claims 9 to 13, in which the evaporative coolers are controlled so that the air delivered to the system space has a temperature and/or a humidity within a predetermined temperature and/or humidity range.

15. A method of controlling the temperature and/or humidity of a system space according to any of claims 9 to 14 comprising the use of a combined ventilation, cooling and humidification system as defined in any of claims 1 to 8.

16. A system controller programmed to control a plurality of evaporative coolers according to the method defined in any of claims 9 to 15.