Abstract:
An Uninterruptible Power Supply (UPS) for providing power to a computer system. The UPS converts kinetic energy of cooling fluid already being pumped through the computer system to operate a reaction turbine. The turbine drives a flywheel, which in turn can drive a generator in the case of a power failure. A gravity feed may continue to supply cooling fluid to the system, at least for a time, after the power is lost. The turbine can continue to store this energy in the flywheel after power failure thereby extending the ride-through time available.

Description:
FIELD OF INVENTION 
       [0001]    This disclosure relates generally to the field of energy storage, and in particular, to energy storage in an uninterruptible power supply (UPS) for a system of computers. 
       BACKGROUND 
       [0002]    Data centers that host mission critical applications invest significant money in building redundant infrastructure. In the case of power distribution, a server or rack of servers may have redundant power supplies, each with their own distribution line from an independent utility. 
         [0003]    Data centers invest this money because their services can be severely disrupted if their supply of electrical power is interrupted even for a few seconds. In addition to, or as an alternative to redundant power supplies, uninterruptible power supply (UPS) systems are in common use to prevent the disruption of operations when a normally used electric power line falters or fails. UPS systems typically have access to a local power generator (such as internal-combustion engines) to supply electrical power to the load until normal power is restored. 
         [0004]    Often when utility power fails, it takes a few seconds for a back-up generator to start and accelerate to a speed fast enough to produce the desired electrical output. This delay may result in a harmful interruption of power to the load. 
         [0005]    UPS systems typically use either battery power or a flywheel to overcome this delay. A flywheel is a rotating mechanical device used to store rotational energy. Energy is added to the flywheel by increasing its speed (through the application of torque). Typically flywheels are made of heavy materials to increase their moment of inertia, making the flywheel more resistant to change in rotational speed. In a flywheel UPS, during normal operation electrical power is used to spin the flywheel and keep the flywheel spinning at a high speed. Once a flywheel has reached a high speed, due to high moment of inertia, little energy is needed to keep up the speed of the flywheel. During a utility power outage, the flywheel catches gearing (such as a hydraulic transmission) to drive an alternator/generator, which in turn supplies electrical power to the load. The time that a flywheel can deliver power to a system is known as the “ride-through time.” 
         [0006]    Increased work load and smaller parts in data centers also make them susceptible to higher temperatures. State of the art data centers may use liquid cooling technology, where a coolant (often water) is pumped through the various servers and/or racks to efficiently reduce the temperature build-up. 
       SUMMARY 
       [0007]    One aspect of the present invention discloses an uninterruptible power supply (UPS) for providing electrical power to one or more computers. The UPS comprises a turbine and an intake tube that is capable of channeling moving fluid to the turbine. An output tube is capable of channeling moving fluid from the turbine. The UPS further comprises a flywheel for driving a generator capable of providing electrical power to the one or more computers. A turbine shaft is coupled to the turbine and to the flywheel, the turbine shaft is capable of being driven by the turbine and of driving the flywheel. 
         [0008]    A second aspect of the present invention discloses a system for providing power to one or more computers. The system comprises a generator coupled to the one or more computers. A flywheel is coupled to and capable of driving the generator. The system further comprises an uninterruptible power supply (UPS) comprising a fluid-driven turbine coupled to and capable of driving the flywheel. A server rack contains the UPS and at least one of the one or more computers. A liquid-cooling system couples to the UPS and is capable of pushing a fluid to the server rack and to the fluid-driven turbine of the UPS. The generator, when driven by the flywheel, is capable of providing electrical power to the one or more computers. 
         [0009]    A third aspect of the present invention discloses a method for powering a computer. The method comprises an uninterruptible power supply (UPS) receiving a fluid. The UPS channels the fluid to a reaction turbine via an intake tube. The reaction turbine rotates a turbine shaft. The rotating turbine shaft drives a flywheel coupled to the rotating turbine shaft and a generator. In response to the computer losing electrical power, the flywheel drives the generator and the flywheel-driven generator supplies electrical power to the computer system. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]    The following detailed description, given by way of example and not intended to limit the disclosure solely thereto, will best be appreciated in conjunction with the accompanying drawings, in which: 
           [0011]      FIG. 1  depicts a server rack comprising a localized, water-driven flywheel UPS in accordance with an embodiment of the present invention. 
           [0012]      FIG. 2  depicts water flow into the rack of  FIG. 1  in accordance with an embodiment of the present invention. 
           [0013]      FIG. 3  shows a more in depth view of components of an embodiment of the UPS of  FIG. 1 . 
           [0014]      FIG. 4  illustrates a water turbine operational within the UPS of  FIG. 1 , without an outer-encasement, in accordance with an embodiment of the present invention. 
           [0015]      FIG. 5  depicts the working of a Kaplan turbine in accordance with an embodiment of the invention. 
           [0016]      FIG. 6  depicts an embodiment of a planetary gear. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Detailed embodiments of the present invention are disclosed herein with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely illustrative of potential embodiments of the invention and may take various forms. In addition, each of the examples given in connection with the various embodiments is also intended to be illustrative, and not restrictive. This description is intended to be interpreted merely as a representative basis for teaching one skilled in the art to variously employ the various aspects of the present disclosure. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments. 
         [0018]    Embodiments of the invention provide a computer system utilizing one or more localized flywheel UPS systems, where the flywheel UPS systems use the kinetic energy of pumped coolant to drive a turbine, which in turn drives the flywheel. As an alternative to pumped coolant, a gravity feed may supply the coolant to the turbine subsequent to a power failure, thereby extending the ride-through time. 
         [0019]      FIG. 1  depicts a server rack in which a localized, water-driven flywheel UPS may be implemented. Rack  102  is a server rack of a data center. Rack  102  may hold any number of rack-mountable units. A rack-mountable unit is any enclosure designed to fit in rack  102 . In the depicted example, rack-mountable unit  104  is a server computer unit. In one embodiment, rack-mountable unit  104  holds Blade® servers  106 . In another embodiment, rack-mountable unit  104  is a single server computer. The capability to expand a datacenter by only the server computers needed, and do so one rack at time, allows for an efficient use of space and resources. Every rack-mountable unit may connect to mounting bars  108 . 
         [0020]    Rack  102  is designed with rack-based real estate, which allows a local (rack-mountable) UPS, such as UPS  110 , to be installed directly in the rack. Distributing UPS systems among the racks allows the UPS function to scale upwards with the size of the overall datacenter and to scale it proportionally with the additional servers. The sides of the enclosure for UPS  110  include mounting bars  112  to couple with one set of mounting bars  108  on rack  102 . UPS  110  may slide into its designated space. 
         [0021]      FIG. 2  depicts water flow into rack  102  in accordance with an embodiment of the present invention. 
         [0022]    Rack  102  is depicted from a rear view. At the bottom of rack  102 , UPS  110  has been installed. The enclosure of UPS  110  is shown opaque here to show an embodiment of a water-driven flywheel UPS. The water-driven flywheel UPS comprises flywheel  114 , water turbine  116 , and alternator  118 . Water (or other coolant liquid) is supplied to water turbine  116  of UPS  110  via coolant piping  120 . After passing through water turbine  116 , the water is expelled through exit piping  122  which channels the water to server computer  104  to perform its normal cooling function. 
         [0023]    In a second embodiment, water may run through one or more server computers prior to UPS  110 . In a third embodiment, a separate piping line may exist for supplying water to server computers. 
         [0024]    Coolant piping  120  connects to rack  102  through quick-connect terminal  123 . Racks using liquid cooling typically already have such terminals to facilitate running water to them. Generally, existing quick-connect terminals are near the bottom of a rack, making a bottom slot a preferred location for UPS  110 . Additionally, housing UPS  110  at the bottom of rack  102  avoids having moving mechanical parts with a high flow of water positioned above sensitive electronic equipment. Piping  120  is preferably a high pressure flex pipe. 
         [0025]    Liquid cooling system  124  uses pump  126  to push the water through piping  120 . In a preferred embodiment, liquid cooling system  124  also maintains a water reservoir  128 . Reservoir  128  may be coupled to a pressure tank so that in a scenario where pump  126  gives out (e.g. for lack of electrical power), water can still be supplied to rack  102  for a short amount of time. Alternatively, reservoir  128  may be elevated to feed the water through liquid cooling system  124  through gravitational force in a scenario where pump  126  does not work. This embodiment may be preferred as the extended length of time for running water is determined by the amount of water stored in the reservoir and not an amount of pressure stored. 
         [0026]      FIG. 3  shows a more in depth view of components of UPS  110 . 
         [0027]    As mentioned earlier, the central components to UPS  110  include flywheel  114 , water turbine  116 , and alternator  118 . 
         [0028]    Flywheel  114  is preferably a thick-walled empty cylinder oriented to spin horizontally. Using an empty cylinder, as opposed to a solid cylinder or disk, allows water turbine  116  to fit within the hollow of flywheel  114  and conserve space. The thick walls allow for flywheel  114  to have a greater mass and hence a greater moment of inertia. Additionally, the walls of the cylinder forming flywheel  114  will preferably extend as far out as the enclosure of UPS  110  will allow, keeping the mass as far away from the center of the cylinder as possible, also increasing the moment of inertia. The moment of inertia can be determined using the following equation, where I is the moment of inertia, m is the mass of flywheel  114  and r is the radius to either the outer wall or the inner wall of flywheel  114 . 
         [0000]        I =½ m ( r   external   2   +r   internal   2 )
 
         [0029]    Flywheel  114  is preferably composed of stainless steel or a ceramic. In addition to mass, these materials can be accurately balanced and lend to stability. 
         [0030]    In an alternate embodiment, flywheel  114  may be any number of shapes. 
         [0031]    Water turbine  116  is preferably centered within the cylinder of flywheel  114 . In a preferred embodiment, water turbine  116  is a reaction turbine. A reaction turbine is acted on by a liquid, which changes pressure as it moves through the turbine, releasing energy. To contain the water pressure, a reaction turbine should be encased. Operation of an exemplary embodiment of water turbine  116  is discussed further in  FIGS. 4 and 5 . 
         [0032]    As water turbine  116  is driven by the flow of water, turbine shaft  128  rotates. Though the torque created by rotating turbine shaft  128  could be applied to flywheel  114  directly, to increase the speed, turbine shaft  128 , preferably, drives planetary gear  130 . Planetary gear  130  uses planetary, or epicyclic, gearing to manipulate gear ratios for a desired output of rotational velocity. An exemplary embodiment of planetary gear  130  is discussed in  FIG. 6 . 
         [0033]    Planetary gear  130  relays its increased rotational velocity to output shaft  132 , which in turn drives flywheel  114 . Output shaft  132  attaches to drive gears  134  which apply torque to flywheel support arms  136 . Flywheel support arms  136  attach directly to flywheel  114 , transferring the torque to flywheel  114 . In one embodiment, flywheel support arms  136  and flywheel  114  may be cast together. In another embodiment, flywheel support arms  136  may be a separate structure than flywheel  114  and be adhesively or mechanically attached. 
         [0034]    Flywheel  114  has the ability to catch gearing and drive alternator (or generator)  118  to produce ride-through power for the load. In a preferred embodiment, the gearing that flywheel  114  catches is drive gears  134  which interconnect with drive gears  140  driving alternator  118 . In such an embodiment, alternator  118  may also be located inside the cylinder of flywheel  114 . Additionally, when the ride-through power is not needed, alternator  118  may supply power in reverse, causing drive gears  140  to rotate drive gears  134  and assist in spinning flywheel  114  up to speed. In this embodiment, after the flywheel is brought up to speed, the minimum energy needed to maintain that speed can be supplied by water turbine  116 . 
         [0035]      FIG. 4  illustrates water turbine  116  without the outer-encasement, in accordance with an embodiment of the present invention. Tubing  142  receives water at the top of water turbine  116 . Tubing  142  wraps around a water driven propeller system (not shown) to convert the kinetic energy into torque. Tubing  142  is open towards the center to allow water to be diverted onto the propeller system. After water has made its way through the propeller system, the water exits tubing  142  near the bottom of water turbine  116 . In a preferred embodiment, tubing  142  maintains a diameter equal to piping  120  (so no pressure is lost) and wraps around the propeller system at least once to make the most use out of the propeller blades. 
         [0036]    As previously discussed, water turbine  116  is preferably a reaction turbine. Exemplary designs for reaction turbines include Kaplan, Francis, Propeller, Bulb, Tyson, etc. Kaplan turbines work well for high-flow, low-head applications (head describes the distance that a given water source has to fall before the point where power is generated) which make them ideal for the water-driven flywheel UPS. 
         [0037]      FIG. 5  depicts the working of a Kaplan turbine in accordance with an embodiment of the invention. 
         [0038]    As noted previously, tubing  142  is open along its inner side to allow water to be diverted. Tubing  142  wraps around wicket gate  144 . Wicket gate  144  comprises a number of angled barriers  146  to direct the water tangentially through wicket gate  144 . This causes the water to spiral on to propeller blades  148  causing the propeller to spin. The propeller is attached to turbine shaft  128 . 
         [0039]      FIG. 6  depicts an embodiment of planetary gear  130 . Planetary gear  130  comprises three outer gears  150  (planet gears) revolving around a center gear  152  (sun gear). In other embodiments, planetary gear  130  may have any number of outer gears. Annulus  154  surrounds and meshes with outer gears  150 . 
         [0040]    Outer gears  150  are tied together by carrier  156 . Turbine shaft  128  connects with carrier  156  so, with annulus  154  held stationary, as turbine shaft  128  rotates, outer gears  150  rotate around center gear  152 , causing center gear  152  to rotate (in the opposite direction) at a ratio of 1+Na/Nc where Na is the number of teeth on annulus  154  and Nc is the number of teeth on center gear  152 . Center gear  152  connects to output shaft  132 . 
         [0041]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
         [0042]    Having described preferred embodiments of a water-driven flywheel UPS (which are intended to be illustrative and not limiting), it is noted that modifications and variations may be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims.