GB2459543A

GB2459543A - Cooling systems and methods

Info

Publication number: GB2459543A
Application number: GB0808151A
Authority: GB
Inventors: John Edward Gough
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-05-03
Filing date: 2008-05-03
Publication date: 2009-11-04
Also published as: GB0808151D0

Abstract

A cooling system 112 comprises a refrigerator 114, a fluid vessel 116, a fluid flow driving means such as a pump 146, thermal transfer means such as a heat exchanger 120, and first and second power supplies. The refrigerator is powered by the first power supply, which may be a mains power supply, and is provided for cooling a fluid which is contained in the fluid vessel. The fluid flow driving means is powered by the second power supply, which may be a battery, and is provided for generating a flow of fluid in the system. The thermal transfer means is adapted to exchange heat with an item to be cooled, such as the warm air of a computer server room or another cooling system. The fluid flow driving means operates in response to a loss of the first power supply, perhaps in the event of a power cut or outage, to pump cooled fluid through the thermal transfer means. In further aspects, a cooling system is provided as a secondary or back-up cooling system for cooling at least one primary cooling system, so as to reduce the temperature of coolant in the primary system. In the secondary cooling system, the fluid transport means can operate in response to a signal produced by a sensor. Preferably, the cooling systems are used as part of an uninterruptible power supply (UPS).

Description

Cooling Systems The present invention relates to cooling systems, and relates particularly but not exclusively, to a secondary cooling system for reducing the temperature of a primary cooling system in the event of a power cut.

Computer processors as part of computer systems emit heat whilst operating. The air temperature in a space surrounding a large number of computers, for example in a server room therefore is likely to reach high temperatures reducing the efficiency of operation of the servers.

A currently known cooling system which is suitable for reducing the air temperature in a server room as described above is illustrated in figure 1. The cooling system 1 comprises a 1 5 pump 2, a chiller plant 4 and buffers 6, 8 connected by a plurality of sections of piping 10 containing fluid coolant e.g. water, for reducing the temperature of a load 7. When the system I is in operation the pump 2 pumps coolant into the chiller plant 4 wherein the coolant's temperature is reduced to a predetermined value. The chilled coolant is then pumped from the chiller plant 4 and into flow buffer 6 having a reservoir of chilled coolant. The chilled coolant is then pumped from within the flow buffer 6 into the vicinity of the load 7 e.g. the warm air in a server room. Thernial energy is transferred from the wann air into the chilled coolant, thus cooling the air and warming the coolant which is then pumped from the vicinity of the load 7 and into return buffer 8. -2-.

During normal operation the pump 2, chiller plant 4 and computer systems producing the load 7 are powered by a mains power supply which simultaneously charges a battery pack (not shown) which forms part of a UPS (uninterrupted power supply). In the event of a mains power loss the battery pack provides power to the computer systems until mains power is restored. The battery pack however is unable to supply power to the chiller plant when the mains power is initially cut off. The UPS also includes a generator which is activated as soon as mains power is lost. The generator typically takes 30 seconds to start and to begin producing power at the correct voltage and frequency. The generator also is able to supply sufficient power for the operation of the chiller plant 4 although the chiller plant 4 of the cooling system I does not start immediately. A series of diagnostic tests are required to be performed to ensure that the chiller plant 4 is operational and was not for example the cause of the initial loss of mains power.

The primary pump 2 is able to draw power from the battery pack and so remains operational during the time period that the chiller plant 4 is non operational following an initial loss of mains power. During such a time period, any wann coolant having received thermal energy from the load 7 is not subsequently cooled. Therefore when the reservoir of chilled coolant in the flow buffer 6 is exhausted chilled coolant is no longer pumped into thermal communication with the load 7 causing the temperature of the load to increase.

If the temperature of the load 7 increases too much, computer hardware may become damaged and if the temperature increases beyond a pre determined value the power supply to the computer systems producing the heat may be set to automatically cut off in order avoid the risk of damage. The result of heat damage to computer hardware or of a non controlled shut down to a computer system will be the loss of computer data. It is therefore desirable to have a backup cooling system for reducing the temperature of the load 7 during the time period that the chiller plant 4 of the cooling system 1 is non operational following a loss in mains power supply.

One method currently used to cool the load 7 during the time period that the chiller plant 4 is non operational is to utilise a flow buffer 6 having a capacity sufficiently large to hold a supply of chilled coolant to be pumped to the load 7 such that the supply of chilled coolant is not exhausted before the chiller plant 4 becomes operational following a loss in mains power supply.

A problem with this method is that the volume of chilled coolant required is large if the flow buffer is to supply chilled coolant to the load 7 for a long period of time. In order to hold a large volume of coolant the space occupied by such a flow buffer 6 must therefore alsobelarge.

Preferred embodiments of the present invention seek to overcome the above disadvantages

of the prior art.

According to the present invention there is provided a cooling system comprising: refrigeration means for cooling at least one fluid to a first temperature, said refrigeration means powered by at least oiie first power supply; at least one first vessel for containing said fluid; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system, said fluid flow driving means powered by at least one second power supply; and thermal transfer means adapted to exchange thermal energy, wherein said fluid flow driving means operates in response to loss of said first power supply.

By separating the power supplies of the chiller plant (typically operating on mains power) and the pump (operated by a battery) the chiller plant is able to maintain a reservoir of coolant at a low temperature. Then, in the event of loss of mains power (and therefore the loss of a primary cooling system) the battery powered pump can circulate the coolant and cool the primary cooling system or the air in the room containing computer processors.

This prevents over heating of the computer systems, with processors emitting heat. The prevention of over heating of such computer servers prevents any uncontrolled shut down operations occurring in the event of the temperature of such computers reaching critical levels. The prevention of overheating also reduces the risk of any computer hardware damage. Uncontrolled shut down operations and hardware damage each carry a risk of losing computer data, and so by preventing the overheating of any computer systems provides the advantage of reducing the risk of loss of computer data.

Using a secondary cooling system allows the overall size of the cooling system (the combination of the primary and secondary systems) can be less than existing systems that only contain a primary system. This is because in a current primary cooling system a significantly sized buffer is generally included to ensure that the apparatus has sufficient capacity of coolant to accommodate power interruptions. At the same time the chiller plant must also have greater capacity (that is be capable of cooling the coolant more than is necessary for standard conditions) in order to ensure that it can rapidly cool large volumes of coolant to rapidly return the coolant to the correct temperature if it becomes heated, for example due to a power outage. The addition of the secondary cooling system allows operators the confidence to know that there is coolant capacity available (preferably a relatively small volume at a very low temperature) that can help the primary system when necessary. The additional size of the secondary plant is small compared to the space saved by reducing the primary system to the minimum necessary for normal operation.

In a preferred embodiment the thermal transfer means is adapted to exchange thermal energy with at least one gas.

In the event of loss of mains power (and therefore the loss of a primary cooling system) the battery powered pump can circulate chilled coolant around the secondary cooling system such that it is able to cool the air surrounding computers in a server room. This is achieved by directing a flow of such air using battery powered fans over a portion of the secondary cooling system wherein chilled coolant flowing through this portion absorbs thermal energy from the air. This prevents over heating of the computer systems, with processors emitting heat, when a primary cooling system for cooling the computer systems becomes unable to cool such computer systems.

In a preferred embodiment the thermal transfer means is adapted to exchange thermal energy with at least one primary cooling system.

In the event of loss of mains power (and therefore the loss of a primary cooling system) the battery powered pump can circulate chilled coolant around the secondary cooling system such that it is able to reduce the temperature of coolant in a primary cooling system used to cool computers in a server room containing processors emitting heat. This is achieved by bringing the coolant with the primary and secondary cooling systems into thermal communication such that the coolant flowing within the secondary cooling system is able to absorb thermal energy from the coolant flowing within the primary cooling system.

This provides the advantage that in the event of primary cooling system becoming unable to reduce the temperature of the coolant flowing within it, the computer systems being cooled by the primary system continue to remain so cooled due to the absorption of thermal energy from the coolant within the primary cooling system by the coolant in the secondary cooling system.

In a preferred embodiment the fluid flow transport means is adapted to direct at least a portion of fluid having received thermal energy from at least one of said gas or said primary cooling system, into at least one second vessel.

The exhaustion of coolant having absorbed thermal energy from at least one of a gas or a primary cooling system into a receiver vessel, separate to and thermally insulated from the battery vessel of the secondary cooling system which contains chilled coolant, ensures that the temperature of any such chilled coolant is not unnecessarily increased due to the backflow of warmed coolant into the secondary cooling system having absorbed thermal energy.

In a preferred embodiment second vessel is thermally insulated from said first vessel.

In another preferred embodiment fluid flow transport means is adapted to direct at least a portion of said fluid having received thermal energy from at least one of said gas or said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from at least one of said gas or said primary cooling system, thereby mixing said fluids.

The reduction in the temperature of coolant in the battery vessel of the secondary cooling system to subzero temperatures requires that the temperature of such chilled coolant may be needed to be increased before coming into thenTnal communication with at least one of a gas or a primary cooling system. As the chilled coolant is so cold, the mixing requirement is met that only a small amount chilled coolant is needed per unit volume of coolant having absorbed thermal energy from at least one of a gas or a primary cooling system to form a 1 5 flow of coolant at a temperature above 0°C yet sufficiently low such that coolant flowing from the secondary cooling system into the heat exchaiiger is able to absorb thermal energy from at least one of a gas or a primary cooling system. This is particularly important if the coolant in a primary cooling system is water in order to prevent it from freezing and in order to prevent condensation and even freezing of airborne moisture. This provides the advantage that the secondary cooling system is able to reduce the temperature of at least one of a gas or a primary cooling system for longer than if the chilled coolant flowed directly into the heat exchanger.

In a preferred embodiment the mixing of said fluid from said first vessel before receiving thermal energy from at least one of said gas or said primary cooling system, and said fluid having received thermal energy from at least one of said gas or said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of at least one of said gas or said primary cooling system in thermal communication with said thermal transfer means.

In another preferred embodiment the refrigeration means is adapted to cool said fluid externally to at least one said vessel.

In a further preferred embodiment the refrigeration means is adapted to cool said fluid within at least one said vessel.

The cooling system may further comprise parameter monitoring means for monitoring a parameter and determining when to initiate said cooling system.

In a preferred embodiment the parameter monitoring means comprises at least one temperature monitoring device for measuring at least one temperature of at least one of said gas or said primary cooling system.

In another preferred embodiment the parameter monitoring means comprises at least one current monitoring device for measuring at least one electrical current.

According to another aspect of the present invention there is provided a method of cooling at least one gas comprising the steps of: refrigerating at least one fluid to a first temperature; storing said fluid in at least one first vessel; and S pumping said fluid from at least one said first vessel into thermal transfer means adapted to exchange thermal energy with at least one gas caused to come into thermal communication with said thermal transfer means, so as to reduce the temperature of the or each said gas.

The method may further comprise the step of directing at least a portion of fluid having received thermal energy from said gas into at least one second vessel.

The method also may further comprise the step of directing at least a portion of said fluid having received thermal energy from said gas, into the flow of fluid from said first vessel before receiving thermal energy from said gas, thereby mixing said fluids.

In a preferred embodiment the mixing of said fluid from said first vessel before receiving thermal energy from said gas, and said fluid having received thermal energy from said gas, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said gas in thermal communication with said thermal transfer means.

The method may further comprise the step of monitoring at least one parameter and determining when to initiate said cooling system.

In a preferred embodiment the monitored parameter is at least one temperature of said gas.

In another preferred embodiment the monitored parameter is at least one electrical current.

According to a further aspect of the present invention there is provided a secondary cooling system for cooling at least one primary cooling system, the secondary cooling system comprising: refrigeration means for cooling at least one fluid to a first temperature; at least one first vessel for containing said fluid; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system; and thermal transfer means adapted to exchange thermal energy with a primary cooling system so as to reduce the temperature of coolant in said primary system.

1 5 The thermal communication of both a primary and secondary cooling system within a heat exchanger ensures that the temperature of coolant in a primary cooling system is able to be reduced, through the absorption of thermal energy by coolant in a secondary cooling system when the temperature of coolant in the first cooling system exceeds a pre-determined value due to the first cooling system being unable to reduce the temperature of coolant. This allows the primary cooliiig system in thermal communication with the load to continue to reduce the temperature of the load even when the chiller plant in that system is non operational. This prevents over heating of the load which may consist of a plurality of computer servers, each comprising a plurality of processors emitting heat. The prevention of over heating of such computer servers reduces the risk of any uncontrolled shut down operations occurring due to the temperature of such computers reaching critical levels. The prevention of overheating also reduces the risk of any computer hardware damage. Uncontrolled shut down operations and hardware damage each carry a risk of losing computer data, and so by preventing the overheating of any computer systems comprising a load provides the advantage of reducing the risk of loss of computer data.

In a preferred embodiment the fluid flow transport means is adapted to direct at least a portion of fluid having received thermal energy from said primary cooling system, into at least one second vessel.

The exhaustion of coolant having absorbed thermal energy from the primary cooling system into a receiver vessel, separate to and thermally insulated from the battery vessel of the secondary cooling system which contains chilled coolant, ensures that the temperature of any such chilled coolant is not unnecessarily increased due to the backflow of warmed coolant into the secondary cooling system having absorbed thermal energy from the primary cooling system.

In another preferred embodiment second vessel is theriially insulated from said first vessel.

In a further preferred embodiment the fluid flow transport means is adapted to direct at least a portion of said fluid having received thermal energy from said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from said primary cooling system, thereby mixing said fluids.

The reduction in the temperature of coolant in the battery vessel of the secondary cooling system to subzero temperatures requires that the temperature of such chilled coolant may be needed to be increased before coming into thermal communication with the primary cooling system in the heat exchanger. As the chilled coolant is so cold, the mixing requirement is met that only a small amount of chilled coolant is needed per unit volume of coolant having absorbed thermal energy from the primary cooling system to form a flow of coolant at a temperature above 0°C yet sufficiently low such that coolant flowing from the secondary cooling system into the heat exchanger is able to absorb thermal energy from the primary cooling system. This provides the advantage that the secondary cooling system is able to reduce the temperature of coolant in the primary cooling system for longer than if the chilled coolant flowed directly into the heat exchanger.

In a preferred embodiment the mixing of said fluid from said first vessel, before receiving thenTnal energy from said primary cooling system, and said fluid having received thermal energy from said coolant in said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said coolant in said primary system entering said thermal transfer means.

The refrigeration means may be adapted to cool said fluid externally to at least one said vessel or within at least one said vessel.

The secondary cooling system may further comprise parameter monitoring means for monitoring a parameter of said primary cooling system and determining when to initiate said secondary cooling system.

In a preferred embodiment the parameter monitoring means comprises at least one temperature monitoring device for measuring at least one temperature of said primary cooling system.

In another preferred embodiment the temperature is the temperature of said coolant in said first cooling system.

In a further preferred embodiment the parameter monitoring means comprises at least one current monitoring device for measuring at least one current flowing within said primary cooling system.

According to an aspect of the present invention there is provided a method of cooling a primary cooling system using a secondary cooling system comprising the steps of: refrigerating at least one fluid to a first temperature; storing said fluid in at least one first vessel; and pumping said fluid from at least one said vessel into thermal transfer means adapted to exchange thermal energy with said primary cooling system, so as to reduce the temperature of coolant in said primary system.

The method may further comprise the step of directing at least a portion of fluid having received thermal energy from said primary cooling system into at least one second vessel.

In a preferred embodiment the step of directing at least a portion of said fluid having received thermal energy from said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from said primary cooling system, thereby mixing said fluids.

In another preferred embodiment the mixing of said fluid from said first vessel, before receiving thermal energy from said primary cooling system, and said fluid having received thermal energy from said coolant in said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said coolant in said primary system entering said thermal transfer means.

The method may further comprise the step of monitoring at least one parameter of said primary cooling system and determining when to initiate said secondary cooling system.

The monitored parameter may be temperature or may be current.

According to a further aspect of the present invention there is provided secondary cooling system for operating in conjunction with a primary cooling system, the secondary system comprising:-a first vessel for containing a volume of at least one fluid; refrigeration means for reducing the temperature of said fluid in said vessel at a temperature lower than the temperature of fluid in the primary cooling system; sensor means for producing at least one signal in response to alteration of a condition; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system in response to at least one said signal; and thermal transfer means adapted to exchange thermal energy of fluid.

By providing a secondary cooling system with a vessel of very chilled coolant, essentially a battery of coolant, to operate when needed the advantage is provided that this secondary system can be very small and the primary system can be reduced in size to one just sufficient to operate under normal conditions. In the event that the primary system is overloaded the backup of the secondary system is available. The combination of primary and secondary is smaller in size than a primary system of the prior art that has capacity to deal abnormal conditions.

Preferred embodiments of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which:-Figure 1 is a schematic view of a cooling system of the prior art; Figure 2 is a schematic view of a secondary cooling system of the present invention adapted to cool a gas; and Figure 3 is a schematic view of a secondary cooling system of the present invention adapted to reduce the temperature of coolant within a primary cooling system.

As illustrated in figure 2, a secondary cooling system according to an aspect of the present invention, may be adapted to reduce the temperature of a body of gas in the event of a primary cooling system used to cool the gas becoming unable to cool such gas. Such a gas may be the air surrounding one or a plurality of computers in a server room wherein the processors within such computers emit heat, thus heating the surrounding air which is required to be kept at a sufficiently low temperature to avoid the risk of hardware damage.

Such a secondary cooling system 112 has a plurality of parts described below, wherein such parts are connected by and are in fluid communication with piping 11 8. Fluid like coolant in the secondary cooling system 112 is transferred between components of the cooling system by flowing through such pipes 118. The coolant, which could for example be an aqueous glycol solution familiar to those skilled in the art, is chosen appropriate to the operating temperatures in the secondary system. These temperatures are preferably below 0°C and are ideally around -20°C to -30°C.

The secondary cooling system 112 has a refrigeration plant 114 for reducing the temperature of coolant flowing within the secondary cooling system 112. The secondary cooling system 112 also has a battery vessel 116 for storing chilled coolant having been so chilled by the refrigeration plant 114.

The secondary cooling system 112 can be adapted to exchange thermal energy with a body of gas by ensuring that the gas to be cooled is brought into thermal communication with a heat exchanger 120 through which the coolant of the secondary cooling system 112 is adapted to flow, wherein such gas is preferably but not necessarily blown towards the heat exchanger 120 by one or a plurality of fans 168.

While the mains power supply is available the refrigeration plant 114 draws power from such mains supply and acts to reduce the temperature of coolant within the secondary cooling system 112. This is achieved by pumping coolant within the secondary cooling system 112, using pump 132, from within the battery vessel 11 6, through a non return valve 133, through the refrigeration plant 114 and back into the battery vessel 116. Valve 134 which is preferably but not necessarily a solenoid valve, and valve 136 which is preferably but not necessarily a flow control valve, remain closed during the cooling process of the coolant of the secondary cooling system 112 therefore isolating the sections of piping 118 connecting the refrigeration plant 118 and battery vessel 116. This cooling process takes place only when the mains power supply is available, wherein the pump 132 as well as the refrigeration plant 114 draws its power from such a power supply.

Further, during this cooling procedure valve 142 which is preferably but not necessarily a modulation control valve, is in full circulation mode and valve 144 which is preferably but not necessarily a solenoid control valve is closed. Pump 146, which also draws power from the mains power supply when available, pumps coolant within the secondary cooling system 112 through the heat exchanger 1 20, through a reverting portion 148 of piping 11 8, through modulation control valve 142 and back through the heat exchanger 120, wherein the pump 146 is between the modulation control valve 142 and heat exchanger 120.

Coolant flowing around this particular circuit in the piping 118 of the secondary cooling system 112 is in thermal equilibrium with gas in thermal contact with the heat exchanger due to the exchange of thermal energy between the gas and the secondary cooling system 112. Pump 146 has a greater flow capacity than pump 132 to enable coolant from batter vessel 116 to mix with fluid from heat exchanger 120 via reverting pipe 148. To prevent the thermal load from the pump 146 impacting on the operation of the primary cooling plant it is operational only to a predetermined temperature monitored at sensors 143 and 145.

Preferably but not necessarily, the temperature of coolant within the battery vessel 116 is reduced to a temperature below 0°C. A temperature measuring device 1 38 is used to monitor the temperature of coolant within the battery vessel 116 and activate the refrigeration plant 114 if the temperature of fluid rises above a predetermined value. A level monitoring device 140 is also used to monitor the level of coolant within the battery vessel 116 for safe usage, wherein the level monitoring device 140 may de-activate the pump 132, or open or close any of the valves 134, 136 and 144 if the level of such coolant does not meet a predetermined value.

When a mains power failure occurs the cooling plant of the primary cooling system (not shown) and the refrigeration plant 11 4 of the secondary cooling system 1 1 2 become non operational and, as a result of a restart procedure involving self diagnostic tests, remains non operational for a period of time when power is restored using e.g. generators. During the time period that the cooling plant of the primary cooling system (not shown) is non operational the secondary cooling system 112 is used to keep the temperature of gas being so cooled by the primary cooling system below a pre-determined temperature. How the secondary cooling system 112 achieves this result shall now be described.

Temperature monitoring devices 152, 154 monitor the temperature of the gas constituting the load. When the temperature of such gas is measured to increase above a pre-determined value valve 134, 144 within the secondary cooling system 112 are energised.

The modulation control valve 142 also modulates to allow coolant leaving the battery vessel 116 to mix with warmer coolant flowing from the heat exchanger 120 and through the reverting portion 148 of piping 118. The result is a coolant at a controlled temperature which is sufficiently low enough for the coolant of the secondary cooling system 112 flowing within the heat exchanger 120 to absorb thermal energy from the gas constituting the load in thermal contact with the heat exchanger 120.

A temperature monitoring device 143 is used to monitor the temperature of coolant flowing into the heat exchanger 120 from within the secondary cooling system 112 and another temperature monitoring device 145 is used to monitor the temperature of coolant flowing out of the heat exchanger 120 and into the secondary cooling system 112. The temperature measured by the temperature measuring device 143 is used to determine the extent of the portion of the total flow of coolant flowing from the heat exchanger 120 which is to be allowed to flow along the reverting portion 148 of piping 118 and be mixed with chilled coolant flowing from the battery vessel 116 to ensure that the temperature of coolant flowing into the heat exchanger 120 is at the predetermined temperature.

When valve 144, which is preferably but not necessarily a modulation control valve, is opened only a portion of coolant flowing from the heat exchanger 120 within the secondary cooling system 112 is reverted along reverting portion 148 of piping 118. The same volume of coolant that flows through the valve 134 as flows through valve 144 and the volume of coolant that flows through the reverting portion 148 is controlled to maintain the temperature at sensor 143. The temperature of coolant in the receiving vessel is too high to be useful and so such coolant is stored in the receiving vessel 1 56until the cooling plant in the primary cooling system (not shown) becomes operational.

When the cooling plant in the primary cooling system becomes operational following an initial loss of mains power, the temperature of gas being blown towards the heat exchanger begins to decrease. When the temperature of such gas is measured by temperature monitoring device 1 54 to decrease below a pre-deterrnined value modulation control valve 142 reverts back to full circulation mode and prevents any further coolant flowing from the 1 5 battery vessel 116 mixing with coolant flowing from within the reverting portion 148 of piping 118.

At this time if the level control monitoring device 140 determines a relatively high level of coolant within the battery vessel 116 a delay sequence is activated. In this delay sequence the temperature monitoring device 154 monitors the temperature of gas flowing into the heat exchanger 120 from within the primary cooling system (not shown) for a pre-determined period of time. If the temperature so measured rises above a pre-determined value within the pre-detennined time of the delay sequence the modulation control valve 142 is again modulated so as to allow chilled coolant to flow from the battery vessel 116, providing further cooling to the primary cooling system (not shown) as described above wherein the delay sequence pre-determined monitoring time period is reset. If the pre-determined time period of the delay sequence passes without the temperature being measured by temperature control device 154 rising above the pre-determined value, the S delay sequence expires.

When the receiver vessel is full, as indicated by level monitoring device 1 58 or where the pre-determined time period of the delay sequence has expired as previously described, valves 134, 144 close. At this time, valve 136 is energised allowing warmer fluid to flow from the receiver vessel 156 and into the battery vessel 116 wherein it is again closed after the level monitoring device 140 of the battery vessel 116 indicates that it is full.

Vents 163, 164 within the secondary cooling system 112 allow coolant to move freely under controlled operation. An expansion vessel 162 is required if the system has to operate closed circuit wherein it is preferably located with the battery vessel 116.

When mains power is available all electrical components of both the primary and secondary cooling systems draw their power from this supply. The computer systems causing the gas to heat up also draw their power from this supply. Further, when the mains supply is available, a battery pack is charged up. When mains power is unavailable the computers causing the increase in temperature of the gas, and all of the components which require electricity to operate discussed in this description, of both the primary and secondary cooling systems draw their power from the battery pack except the cooling plant of the primary cooling system (not shown) and the refrigeration plant 114 of the secondary cooling system 112 which draw their power from the mains supply when available only.

As illustrated in figure 3 a secondary cooling system according to an aspect of the present invention, may be adapted to cool a primary cooling system in the event of mains power failure.

With reference to figure 3, wherein all parts in likeness with figure 1 are numbered with similar reference numerals increased by 200 and all parts in likeness with figure 2 are numbered with similar reference numerals increased by 100, a secondary cooling system 212 ill accordance with the present invention can be adapted to cool a primary cooling system 200 in the event of mains power failure. Such a secondary cooling system 212 has a plurality of parts herein described below, wherein such parts are connected by and are in fluid communication with fluid transfer means in the form of piping 218. Fluid coolant in the secondary cooling system 212 is transferred between components of the cooling system by flowing through such pipes 218.

The secondary cooling system 212 has a refrigeration plant 214 for reducing the temperature of coolant flowing within the secondary cooling system 212. The secondary cooling system 21 2 also has a battery vessel 216 for storing chilled coolant having been so chilled by the refrigeration plant 214.

The secondary cooling system 212 and a primary cooling system 200 can be adapted to exchange thermal energy and are brought into thennal communication by the use of a heat exchanger 220 through which coolant of both the primary and secondary cooling systems is adapted to flow without mixing. The heat exchanger 220 is adapted to be in fluid communication with a primary cooling system 200 by incorporating in fluid communication with, pipe portions 222, 224 at different lengths along the section of piping 210 in the primary cooling system 200, wherein such pipe portions 222, 224 are also in fluid communication with one another within the heat exchanger 220. A valve 226, 228, 230 which is preferably but not necessarily an isolation valve, is incorporated along the length of each pipe portion 222, 224 and the section of piping 210 in the primary cooling system 200 connecting the flow buffer 206 and load 207 between the two connected pipe portions 222, 224. Closing valve 226 and opening valves 228, 230 directs coolant within the primary cooling system 200 into the heat exchanger such that the secondary cooling system 21 2 may act to reduce the temperature of coolant within the primary cooling system in the event of a mains power failure. Closing valves 228, 230 and opening valve 226 prevents coolant within the primary cooling system 200 from flowing through the heat exchanger 220 in the event that the secondary cooling system 212 is required to be removed, for example to perform any necessary repairs to the system.

However, when the secondary cooling system 212 is in use the primary cooling system 200 is made to be in fluid communication with the heat exchanger 220. While the mains power supply is available the refrigeration plant 214 draws power from such mains supply and acts to reduce the temperature of coolant within the secondary cooling system. This is achieved by pumping coolant within the secondary cooling system 212, using pump 232, from within the battery vessel 216, through a non return valve 233, through the refrigeration plant 2 14 and back into the battery vessel 2 16. Valve 234 which is preferably but not necessarily a solenoid valve, and valve 236 which is preferably but not necessarily a flow control valve, remain closed during the cooling process of the coolant of the secondary cooling system 212 therefore isolating the sections of piping 218 connecting the refrigeration plant 218 and battery vessel 216. This cooling process takes place only when the mains power supply is available, wherein the pump 232 as well as the refrigeration plant 214 draw their power from such a power supply.

Further, during this cooling procedure valve 242 which is preferably but not necessarily a modulation control valve, is in full circulation mode and valve 244 which is preferably but not necessarily a solenoid control valve is closed. Pump 246, which also draws power from the mains power supply when available, pumps coolant within the secondary cooling system 212 through the heat exchanger 220, through a reverting portion 248 of piping 21 8, through modulation control valve 242 and back through the heat exchanger 220, wherein the pump 246 is between the modulation control valve 242 and heat exchanger 246.

Coolant flowing around this particular circuit in the piping 218 of the secondary cooling system 212 is in thermal equilibrium with coolant flowing within the primary cooling system 200 due to the exchange of thermal energy between the primary and secondary cooling systems 200, 212 within the heat exchanger 220. To prevent the thermal load from the pump 246 impacting on the operation of the primary cooling plant it is operational only to a predetermined temperature monitored at sensors 243 and 245.

Preferably but not necessarily, the temperature of coolant within the battery vessel 2 1 6 is reduced to a temperature below 0°C. A temperature measuring device 238 is used to monitor the temperature of coolant within the battery vessel 216 and activate the refrigeration plant 214 if the temperature of fluid rises above a predetermined value. A level monitoring device 240 is also used to monitor the level of coolant within the battery vessel 216 for safe usage, wherein the level monitoring device 240 may de-activate the pump 232, or open or close any of the valves 234, 236 if the level of such coolant exceeds a predetermined value.

When a mains power failure occurs the chiller plant 204 of the primary cooling system 200 and the refrigeration plant 214 of the secondary cooling system become non operational and shall remain non operational for a period of time when power is restored using e.g. generators. During the time period before that the chiller plant 204 of the primary cooling system 200 is non operational the secondary cooling system 212 is used to keep the temperature of coolant flowing into thermal communication with the load 207 within the primary cooling system 200 below a pre-determined temperature. How the secondary cooling system 212 achieves this result shall now be described.

Flow switch 250 is used to determine whether there is a flow of coolant within the primary cooling system. This is necessary because the loss of mains power may have been due to malfunction of the pump 202 wherein use of the secondary cooling system 212 will not be required due to the non ability to create a flow of coolant within the primary cooling system 200. When such a flow of coolant is however detected, temperature monitoring devices 252, 254 monitor the temperature of coolant in the primary cooling system on entering and leaving the heat exchanger 220. When the temperature of coolant leaving the heat exchanger and flowing within the primary cooling system towards the load is measured to increase above a pre-deterrnined value, valves 234, 244 within the secondary cooling system 212 are energised. The modulation control valve 242 also modulates to allow coolant leaving the battery vessel 216 to mix with warmer coolant flowing from the heat exchanger 220 and through the reverting portion 248 of piping 218. The result is a coolant at a controlled temperature which is sufficiently low enough for the coolant of the S secondary cooling system 212 flowing within the heat exchanger 220 to absorb thermal energy from the coolant of the primary cooling system 200 also flowing within the heat exchanger 220. The temperature is to be preferably but not necessarily controlled to be above 0°C to avoid the freezing of coolant within the primary cooling system 200 if the coolant used in the primary cooling system 200 is water.

A temperature monitoring device 243 is used to monitor and control the temperature of coolant flowing into the heat exchanger 220 from within the secondary cooling system and another temperature monitoring device 245 is used to monitor the temperature of coolant flowing out of the heat exchanger 220 and into the secondary cooling system 212. The temperature measured by the temperature measuring device 243 is used to determine the extent of the portion of the total flow of coolant flowing from the heat exchanger 220 which is to be allowed to flow along the reverting portion 248 of piping 218 and be mixed with chilled coolant flowing from the battery vessel 216 to ensure that the temperature of coolant flowing into the heat exchanger 220 is at the predetermined temperature.

When valve 244, which is preferably but not necessarily a modulation control valve, is opened only a portion of coolant flowing from the heat exchanger 220 within the secondary cooling system 212 is reverted along reverting portion 248 of piping 218. The same volume of coolant that flows through valve 234 flows through valve 244 and into a receiving vessel 256 which is thermally insulated from the battery vessel. The temperature of coolant in the receiving vessel is too high to be useful and so such coolant is stored in the receiving vessel until the chiller plant 204 in the primary cooling system 200 becomes operational.

When the chiller plant 204 becomes operational following an initial loss of mains power, the temperature of coolant flowing into the heat exchanger 220 from within the primary cooling system 200 begins to decrease. When the temperature of such coolant is measured by temperature monitoring device 254 to decrease below a pre-determined value modulation control valve 242 reverts back to full circulation mode and prevents any further coolant flowing from the battery vessel 216 mixing with coolant flowing from within the reverting portion 248 of piping 218. Temperature monitoring devices 243 and 245 determine the actual load imposed from the primary circuit load 207 via heat exchanger 200. This together with level monitors 240 and 258 determine the duration of secondary cooling available: This duration is calculated and pass to operator who can decide that the primary cooling will not be operation in time and execute a controlled shutdown of the servers.

At this time if the level control monitoring device 240 detenuines a relatively high level of coolant within the battery vessel 216 a delay sequence is activated. In this delay sequence the temperature monitoring device 254 monitors the temperature of coolant flowing into the heat exchanger 220 from within the primary cooling system 200 for a pre-detet-mined period of time. If the temperature so measured rises above a pre-determined value within the pre-deterrnined time of the delay sequence modulation control valve 242 is again modulated so as to allow chilled coolant to flow from the battery vessel 216, providing further cooling to the primary cooling system 200 as described above wherein the delay sequence pre-deterinined monitoring time period is reset. If the pre-determined time period of the delay sequence passes without the temperature being measured by temperature control device 254 rising above the pre-determined value, the delay sequence expires.

When the receiver vessel is full, as indicated by level monitoring device 258 or where the pre-determined time period of the delay sequence has expired as previously described, valves 234, 244 close. At this time, valve 236 is energised allowing warmer fluid to flow from the receiver vessel 256 and into the battery vessel 216 wherein it is again closed after the level monitoring device 240 of the battery vessel 216 indicates that it is full.

Vents 263, 264, 266 within the system allow coolant to move freely under controlled operation. An expansion vessel 262 is required if the system has to operate closed circuit wherein it is preferably located with the battery vessel 216.

When mains power is available all electrical components of both the primary and secondary cooling systems 200, 212 draw their power from this supply. The computer systems constituting the load 207 also draw their power from this supply. Further, when the mains supply is available, a battery pack is charged up. When mains power is unavailable the computers causing the increase in temperature of the load, and all of the components which require electricity to operate discussed in this description, of both the primary and secondary cooling systems 200, 212, draw their power from the battery pack except the chiller plant 204 of the primary cooling system 200 and the refrigeration plant 214 of the secondary cooling system 212 which draw their power from the mains supply when available only.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. For example insulation may but may not necessarily be provided at any part of the secondary cooling system. The coolant within the secondary cooling system is preferably a liquid but may be in full or at least in part gaseous. The secondary cooling system may be operated with both vents and/or an expansion vessel. More than one expansion vessel may be used at any point within the secondary cooling system. With reference to figure 3, the position of valves 226, 228 and 230, heat exchanger 220 and the associated pipework and sensors relative to buffer can be altered. For example, these components could be located between the chiller plant 204 and buffer 206 instead of between the buffer and the load 207 as shown. Furthennore, in a cruder version of the present invention the valves 226, 228 and 230 could be removed and the pipes feeding to valve 226 removed so that all of the coolant flow in primary cooling apparatus passes through the heat exchanger 220. The heat exchanger will only have an effect on the temperature of coolant in the primary system if coolant from the vessel 216 is passing though it.

Claims

Claims 1. A cooling system comprising: refrigeration means for cooling at least one fluid to a first temperature, said refrigeration means powered by at least one first power supply; at least one first vessel for containing said fluid; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system, said fluid flow driving means powered by at least one second power supply; and thermal transfer means adapted to exchange thermal energy, wherein said fluid flow driving means operates in response to loss of said first power supply.
2. A cooling system according claim 1, wherein said then'nal transfer means is adapted to exchange thermal energy with at least one gas.
3. A cooling system according claim 1, wherein said thermal transfer means is adapted to exchange thermal energy with at least one primary cooling system.
4. A cooling system according claim 2 or 3, wherein said fluid flow transport means is adapted to direct at least a portion of fluid having received thernial energy from at least one of said gas or said primary cooling system, into at least one second vessel.
5. A cooling system according claim 4, wherein said second vessel is thermally insulated from said first vessel.

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6. A cooling system according to any of the preceding clams, wherein said fluid flow transport means is adapted to direct at least a portion of said fluid having received thermal energy from at least one of said gas or said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from at least one of said gas or said primary cooling system, thereby mixing said fluids.
7. A cooling system according to claim 6, wherein the mixing of said fluid from said first vessel before receiving thermal energy from at least one of said gas or said primary cooling system, and said fluid having received thermal energy from at least one of said gas or said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of at least one of said gas or said primary cooling system in thermal communication with said thermal transfer means.
8. A cooling system according to any of the preceding claims, wherein said refrigeration means is adapted to cool said fluid externally to at least one said vessel.
9. A cooling system according to claims I to 7, wherein said refrigeration means is adapted to cool said fluid within at least one said vessel.tO. A cooling system according to any of the preceding claims, ftirther comprising parameter monitoring means for monitoring a parameter and determining when to initiate said cooling system.Ii. A cooling system according to claim 10, wherein said parameter monitoring means comprises at least one temperature monitoring device for measuring at least one temperature of at least one of said gas or said primary cooling system.12. A cooling system according to claim 10, wherein said parameter monitoring means comprises at least one current monitoring device for measuring at least one electrical current.13. A cooling system as herein before described with reference to the accompanying drawings.14. A method of cooling at least one gas comprising the steps of: refrigerating at least one fluid to a first temperature; storing said fluid in at least one first vessel; and 1 5 pumping said fluid from at least one said first vessel into thermal transfer means adapted to exchange thermal energy with at least one gas caused to come into thermal communication with said thermal transfer means, so as to reduce the temperature of the or each said gas.15. The method of claim 14, further comprising the step of directing at least a portion of fluid having received thennal energy from said gas into at least one second vessel.16. The method of claim 14 or 15, further comprising the step of directing at least a portion of said fluid having received thermal energy from said gas, into the flow of fluid from said first vessel before receiving thermal energy from said gas, thereby mixing said fluids.17. The method of claim 16, wherein the mixing of said fluid from said first vessel before receiving thermal energy from said gas, and said fluid having received thermal energy from said gas, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said gas in thermal communication with said thermal transfer means.1 8. The method of any of claims 14 to 17, further comprising the step of monitoring at least one parameter and determining when to initiate said cooling system.19. The method of claim 18, wherein said monitored parameter is at least one temperature of said gas.20. The method of any of claim 18, wherein said monitored parameter is at least one electrical current.21. A method of cooling at least one gas, as herein before described with reference to the accompanying drawing in figure 2.22. A secondary cooling system for cooling at least one primary cooling system, the secondary cooling system comprising: refrigeration means for cooling at least one fluid to a first temperature; at least one first vessel for containing said fluid; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system; and thermal transfer means adapted to exchange thermal energy with a primary cooling system so as to reduce the temperature of coolant in said primary system.23. A secondary cooling system according claim 22, wherein said fluid flow transport means is adapted to direct at least a portion of fluid having received thermal energy from said primary cooling system, into at least one second vessel.24. A secondary cooling system according claim 23, wherein said second vessel is thermally insulated from said first vessel.25. A secondary cooling system according to any of claims 22 to 24, wherein said fluid flow transport means is adapted to direct at least a portion of said fluid having received thermal energy from said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from said primary cooling system, thereby mixing said fluids.26. A secondary cooling system according to claim 25, wherein the mixing of said fluid from said first vessel, before receiving thermal energy from said primary cooling system, and said fluid having received thermal energy from said coolant in said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said coolant in said primary system entering said thermal transfer means.27. A secondary cooling system according to any of claims 22 to 26, wherein said refrigeration means is adapted to cool said fluid externally to at least one said vessel.28. A secondary cooling system according to claims 22 to 26, wherein said refrigeration means is adapted to cool said fluid within at least one said vessel.29. A secondary cooling system according to any of claims 22 to 28, further comprising parameter monitoring means for monitoring a parameter of said primary cooling system and determining when to initiate said secondary cooling system.30. A secondary cooling system according to claim 29, wherein said parameter monitoring means comprises at least one temperature monitoring device for measuring at least one temperature of said primary cooling system.31. A secondary cooling system according to claim 30, wherein said temperature is the temperature of said coolant in said first cooling system.32. A secondary cooling system according to claim 29, wherein said parameter monitoring means comprises at least one current monitoring device for measuring at least one current flowing within said primary cooling system.33. A secondary cooling system for cooling at least one primary cooling system, said secondary cooling system as herein before described with reference to the accompanying drawings in figures 1 and 3.34. A method of cooling a primary cooling system using a secondary cooling system comprising the steps of: refrigerating at least one fluid to a first temperature; storing said fluid in at least one first vessel; and pumping said fluid from at least one said vessel into thermal transfer means adapted to exchange thermal energy with said primary cooling system, so as to reduce the temperature of coolant in said primary system.35. The method of claim 34, further comprising the step of directing at least a portion of fluid having received thermal energy from said primary cooling system into at least one second vessel.36. The method of claim 34 or 35, further comprising the step of directing at least a portion of said fluid having received thermal energy from said primary cooling system, into the flow of fluid from said first vessel before receiving thermal energy from said primary cooling system, thereby mixing said fluids.37. The method of claim 36, wherein the mixing of said fluid from said first vessel, before receiving thermal energy from said primary cooling system, and said fluid having received thermal energy from said coolant in said primary cooling system, provides that said fluid so mixed is at a second temperature greater than said first temperature but lower than said temperature of said coolant in said primary system entering said thermal transfer means.38. The method of any of claims 34 to 37, further comprising the step of monitoring at least one parameter of said primary cooling system and determining when to initiate said secondary cooling system.39. The method of claim 38, wherein said monitored parameter is a temperature.40. The method of any of claim 38, wherein said monitored parameter is a current.41. A method of cooling a primary cooling system using a secondary cooling system, as herein before described with reference to the accompanying drawings in figures 1 and 3.42. A secondary cooling system for operating in conjunction with a primary cooling system, the secondary system comprising:-a first vessel for containing a volume of at least one fluid; refrigeration means for reducing the temperature of said fluid in said vessel at a temperature lower than the temperature of fluid in the primary cooling system; sensor i-neans for producing at least one signal in response to alteration of a condition; fluid transport means in fluid communication with said vessel; fluid flow driving means for driving a flow of fluid in said system in response to at least one said signal; and thermal transfer means adapted to exchange thermal energy of fluid.