Patent Description:
In one aspect, this disclosure features a cooling system according to claim <NUM>.

In aspects, the velocity sensor and the temperature sensor are implemented by an anemometer.

In aspects, the cooling system includes a redundant anemometer.

One or more aspects of this disclosure are particularly pointed out and distinctly claimed as examples in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of this disclosure may be more readily understood by one skilled in the art with reference being had to the following detailed description of several embodiments thereof, taken in conjunction with the accompanying drawings wherein like elements are designated by identical reference numerals throughout the several views, and in which:.

The modular air cooling and distribution systems of this disclosure allow for great flexibility, scalability, ease of installation, and reduced energy consumption for cooling of large, open, indoor areas such as data centers. Combinations of a basic fan/heat exchanger modular assembly may be configured in many ways to best accommodate a given building's overall design.

Embodiments of this disclosure relate to an easy-to-install, low-cost, low-air-pressure-drop, and modular air cooling and distribution system to direct the hot air from the server racks to the heat exchangers. The hot air is then cooled by a liquid, e.g., a refrigerant or chilled water, and cool air is discharged back to open space of the data center. In embodiments, high temperature air from the servers is separated from cooling air all the way to the inlet of heat exchangers by using ceiling or hot aisle containment and short ducts (when needed). By keeping hot air isolated, heat rejection can be done at higher temperatures, thus leading to more "free" cooling, lower liquid flow rate, and higher energy efficiency. The heat exchangers, as disclosed in Provisional Patent Application No. <CIT>, are multi-row-flat-aluminum-tube heat exchangers with low air pressure drop. This factor, combined with the low air pressure drop through the containment/ceiling/plenum, results in low overall pressure drop and fan power. Analysis shows that some embodiments have uniform air temperature distribution across the data center.

While this disclosure uses the term "air", other fluids in the gaseous state may be used in place of air according to embodiments of this disclosure.

<FIG> show various embodiments in which fan and heat exchanger assemblies and airflow arrangement can be applied to fit the details of a given building's structure.

<FIG> shows an embodiment with a lower ceiling <NUM> having a relatively low height. The cooling units or modules <NUM> are located outside and do not require any indoor floor space. The outdoor cooling modules assemblies104 may be assembled at a factory and mounted on a modular slab. The cooling modules or assemblies <NUM> may be disposed within a weather-proofed enclosure. A containment assembly <NUM> is coupled to the server racks <NUM> to contain a hot aisle. A ceiling plenum <NUM> may be defined between the lower ceiling <NUM> and an upper ceiling <NUM>. Alternatively, the upper ceiling <NUM> may be removed and the ceiling plenum <NUM> may be defined between the lower ceiling <NUM> and a pitched roof <NUM>. The ceiling plenum <NUM> is configured to supply return air <NUM> to the cooling modules or assemblies <NUM>.

Redundant anemometers <NUM> are coupled to the containment assembly <NUM> so as to measure the temperature and/or velocity of the air flowing through the containment assembly <NUM>. In other embodiments, another type of fluid velocity sensor and fluid temperature sensor may be used in place of the redundant anemometers <NUM>. For example, the fluid temperature sensor may be replaced by a paddle attached to a mechanical switch so that the fluid flow in the containment assembly <NUM> causes the paddle to move the mechanical switch back and forth and thus sense the direction of fluid flow. The fluid flow direction may alternatively be measured by any other fluid flow direction sensor known in the art. The fluid velocity sensor may be any suitable low velocity-type sensor.

The temperature and/or velocity measurements are used to control the speed of one or more of the fans of the fan and heat exchanger assemblies. For example, the fluid velocity and temperature measurements, which indicate the leakage rate of fluid between the hot aisle to the cold aisle, may be used to modulate the speed of the fans of the fan and heat exchanger assembly to neutralize the pressure inside the containment assembly. In embodiments, the anemometers <NUM> may be hot wire anemometers capable of sensing both air temperature and velocity simultaneously.

In embodiments, the control system may use a temperature set point and a velocity set point. For example, the temperature set point may be calculated according to the following equation:<MAT> The temperature set point is used to command the fans of the fan and heat exchanger assemblies to accelerate or decelerate. The velocity set point may be used to fine tune the fan speed to minimize the air leakage. For example, the velocity set point may be used to decelerate the fan speed.

The control system may operate in a manual mode and an automatic mode. In the manual mode, the fans are set at a fixed speed, which overrides the automatic settings. For example, the initial velocity set point may be set to a predetermined velocity, e.g., <NUM> ft/min. In the automatic mode, when a low load is applied, the control system may first determine whether the hot aisle and cold aisle set temperature is less than, for example, a predetermined temperature, e.g., <NUM>° F. If the hot aisle and cold aisle set temperature is less than <NUM>° F, the fan speed is maintained at a minimum speed, which may be a predetermined minimum speed. If the calculated total IT load divided by the total number of active fan and heat exchanger assemblies is less than a predetermined percentage (e.g., <NUM>%) or if the temperature differential between the inlet and discharge temperature of the fan and heat exchanger assemblies is less than a predetermined temperature (e.g., <NUM>° F), the fan speed may be calculated according to the following example equation:<MAT>.

If the calculated total IT load divided by the total number of active fan and heat exchanger assemblies is more than a predetermined percentage (e.g., <NUM>%) and the temperature differential between the inlet and discharge temperature of the fan and heat exchanger assemblies is more than a predetermined temperature (e.g., <NUM>° F), the percentage of full fan speed may be determined as follows. If the reading from the anemometer is higher than a temperature set point (e.g., <NUM>° F), the fan speed is increased by a predetermined number of rotations per minute (RPM) (e.g., <NUM> RPM). The fan speed continues to increase until the sensed temperature is less than the temperature set point. If the temperature reading from the anemometer is lower than the temperature set point and the velocity reading from the anemometer is higher than the velocity set point (e.g., <NUM> ft/min), the fan speed is decreased (e.g., the fan speed is decreased by <NUM> RPM or a PID controller for controlling the velocity is applied based on the anemometer's readings).

If the temperature reading from anemometer is lower than the temperature set point and the velocity reading from the anemometer is lower than the velocity set point, which may depend on, for example, the site conditions (e.g., <NUM> ft/min or <NUM> ft/min), the fan speed is not changed. In some embodiments, if the anemometer measurement is unstable for either temperature or velocity, the controller may apply the average measurement over time (e.g., over <NUM>-<NUM> seconds) instead of the instantaneous measurement.

<FIG> shows a cross-sectional view of an optional modular air wall section taken across section A-A in accordance with one example embodiment. The modular air wall section includes twelve guard or louvre sections <NUM> corresponding to twelve fan and heat exchanger modules or assemblies arranged two high and six across. In other words, the guard or louvre sections <NUM> correspond to two rows of fan and heat exchanger assemblies, each having six fan and heat exchanger assemblies. In embodiments, there may be any number of rows of fan and heat exchanger assemblies depending on the capacity requirements and/or configuration of the data center. For example, there may be three rows of fan and heat exchanger assemblies or there may be seven rows of fan and heat exchanger assemblies. Each of the guard or louvre sections <NUM> may include fluid deflectors to direct fluid flow or diffuse fluid at an angle. The angle of the fluid deflectors may be adjustable.

Mechanical and electrical chases <NUM> are disposed between the guard or louvre sections <NUM> and may be disposed between the fans and/or heat exchangers of the fan and heat exchanger assemblies. Wall openings or apertures <NUM> are formed to receive the return air conduits <NUM> and the guard or louvre sections <NUM>. In embodiments, the return air conduits <NUM> may be combined into a single or common return air conduit that feeds into the plenum room <NUM>. The modular air wall section also includes removable return air panels <NUM> which may be removed to receive additional fluid ducts to carry more return air from the ceiling plenum <NUM> into the plenum room <NUM> as further cooling capacity is needed.

<FIG> shows an embodiment of an example data center assembly with under-floor cool air distribution. Return air <NUM> is circulated through a ceiling plenum <NUM> between a ceiling <NUM> and a roof <NUM>, through a fan and heat exchanger assembly having a wire mesh screen <NUM>, through a volume formed between a slab <NUM> and perforated floor tiles <NUM>, and then through the server racks <NUM>.

<FIG> shows an embodiment of an example data center assembly in a cold aisle containment configuration with a relatively high ceiling <NUM>, which may correspond to another floor of a multi-level building. In embodiments, the high ceiling <NUM> may be formed of concrete T-beams, which may form a portion of the ceiling plenum <NUM>. In embodiments, the high ceiling <NUM> may be constructed so that the high ceiling <NUM> is closer to the low ceiling <NUM>. A vertical baffle <NUM> separates warm return air <NUM> from cool supply air <NUM>. The fan discharge air flow is reversed and cool air <NUM> is distributed in front of the server racks <NUM> via the containment assembly <NUM>, which contains the cold aisle formed by the server racks <NUM>. Also, warm air <NUM> is drawn out of the one or more hot aisles of the server racks <NUM> by the fans of the fan and heat exchanger assemblies. A control module <NUM> and a power module <NUM> are coupled to the anemometers <NUM> in fluid communication with the fluid flowing in the containment assembly <NUM> and the fan and heat exchanger assemblies to provide control signals and power, respectively, to the containment assembly <NUM> and the fan and heat exchanger assemblies, e.g., control signals to control the speed of variable speed fans of the fan and heat exchanger assemblies. The control module <NUM> may be implemented by any suitable controller, which may include a processor and memory, for executing the methods disclosed herein including methods that use fluid temperature and velocity measurements.

<FIG> shows an embodiment of an example data center assembly in a hot aisle containment configuration where the vertical baffle <NUM> is used to separate warm overhead return air <NUM> from cool supply air <NUM>. The direction of the fan discharge air flow (cool supply air <NUM>) is opposite the direction of the fan discharge air flow (warm return air <NUM>) of <FIG>. The fans of the fan and heat exchanger assemblies distribute the cool supply air <NUM> in front of the server racks <NUM>. Also, the warm return air <NUM> flows out of the containment assembly <NUM>.

<FIG> shows an embodiment of a cooling system in which warm return air <NUM> from the hot aisle of the server racks <NUM> is drawn into the outside fan and heat exchanger assemblies at ground level. Cool supply air <NUM> is supplied to the front of the server racks <NUM> from overhead. The one or more hot aisles between the server racks <NUM> are enclosed at the height or top of the server racks <NUM> by a cover and a hot air containment assembly <NUM> is disposed between the right-most server rack of the server racks <NUM> and a wall or panel <NUM> of the building or facility. The hot air containment assembly <NUM> is in air flow communication with the outside fan and heat exchanger assemblies.

<FIG> shows an embodiment of a cooling system in which cool supply air <NUM> is blown in front of the server racks <NUM>. An overhead hot aisle containment assembly is used to draw warm return air <NUM> from the server racks <NUM> to the inlet of the fan and heat exchanger assemblies <NUM>.

<FIG> shows an embodiment of a cooling system with the fan and heat exchanger assemblies 820a, 820b mounted overhead. The cooling system of <FIG> includes a first air containment assembly <NUM> and a second air containment assembly <NUM> disposed on the first air containment assembly <NUM>. The fan and heat exchanger assemblies 820a, 820b are coupled in a tiered configuration to the underside of a right-most portion of the second air containment assembly <NUM> and are in air flow communication with the second air containment assembly <NUM>. The heat exchangers of the fan and heat exchanger assemblies 820a, 820b are coupled to chilled water supply and return piping <NUM> to receive and return chilled water from and to a water cooling system. The fan and heat exchanger assemblies 820a, 820b are coupled to the power module <NUM> and control module <NUM>, which supplies power and control signals, respectively, to the fan and heat exchanger assemblies 820a, 820b.

<FIG> shows another embodiment where the fan and heat exchanger assemblies <NUM> are elevated above the level of the floor <NUM>. Warm return air is drawn from the hot aisles formed by the server racks <NUM> at the level of the floor <NUM>, and cool supply air <NUM> is distributed from above, down to the front of the server racks <NUM>. A containment assembly <NUM> is coupled to the right-most server racks <NUM> and to the underside of the fan and heat exchanger assemblies <NUM>. In this configuration, the fans of the fan and heat exchanger assemblies draw warm air <NUM> from the hot aisles of the server racks <NUM> and through the containment assembly <NUM>.

<FIG> shows another embodiment of a cooling system where the fan and heat exchanger assemblies <NUM> are also elevated above the level of the floor <NUM>. The cooling system includes a first air containment assembly <NUM> and a second air containment assembly <NUM> coupled to the top of the first air containment assembly <NUM> and in air flow communication with the first air containment assembly <NUM>. The fan and heat exchanger assemblies <NUM> are coupled to the underside of the right-most portion <NUM> of the second air containment assembly <NUM> and are in air flow communication with the second air containment assembly <NUM>. The heat exchangers of the fan and heat exchanger assemblies <NUM> are coupled to chilled water supply and return piping, which carries cooling water from and return water to a water cooling system. The fans of the fan and heat exchanger module are coupled to the power and control module, which supplies power and control signals to the fans. Warm return air is drawn from the second air containment structure into an overhead plenum, and cool supply air is blown around the front of the server racks.

<FIG> are side and front views, respectively, showing examples of fan and heat exchanger modules or assemblies assembled to form larger fan and heat exchanger assemblies. In embodiments, two, three, or four fan and heat exchanger assemblies may be stacked to form stacked fan and heat exchanger assemblies <NUM>, <NUM>, and <NUM>, respectively. In embodiments, any number of the stacked fan and heat exchanger assemblies <NUM>, <NUM>, and <NUM> may be connected side-by-side, e.g., six stacks may be connected side-by-side.

<FIG> shows an example "starter enclosure assembly" <NUM>, which may be, for example, one fan and heat exchanger module wide and two fan and heat exchanger modules tall. The starter enclosure assembly <NUM> includes a left wall panel <NUM>, a right wall panel <NUM>, a back wall panel <NUM>, and a roof panel <NUM>. The left wall panel <NUM> and the right wall panel <NUM> may include access doors <NUM> for accessing the stacked fan and heat exchanger modules or assemblies.

<FIG> shows an example "add-on enclosure assembly" <NUM>, which may be, for example, one fan and heat exchanger module wide and two fan and heat exchanger modules tall. The add-on enclosure assembly <NUM> includes a left wall panel <NUM>, a back wall panel <NUM>, and a roof panel <NUM>, which may be appended to the starter enclosure assembly <NUM> of <FIG>.

<FIG> is an exploded view illustrating the assembly of the starter assembly <NUM>, the add-on assembly <NUM>, and the stacked fan and heat exchanger modules or assemblies contained in the starter enclosure assembly <NUM> and the add-on enclosure assembly <NUM>. The stacked fan and heat exchanger assemblies <NUM> include fan guards <NUM> (e.g., three fan guards), variable-speed fans <NUM> (e.g., three variable-speed fans), fan housings <NUM> (e.g., three fan housings configured to be coupled to each other), and heat exchangers <NUM> (e.g., three heat exchangers configured to be coupled to each other). The enclosure assemblies <NUM>, <NUM> and the stacked fan and heat exchanger assemblies <NUM> may be shipped as partially-assembled kits. Then, final assembly may be done in the field.

The speed of the fans may be controlled to match server air flow by using a hot-wire anemometer to ensure a certain air flow rate out of the hot aisle containment area or assembly. <FIG> is a flow diagram illustrating an example method of controlling a fan of a fan and heat exchanger assembly according to embodiments. In block <NUM>, a temperature is read from the anemometer. Then, in block <NUM> it is determined whether the temperature is greater than a predetermined temperature, e.g., <NUM>° F. If the temperature is greater than the predetermined temperature, the fan speed is increased by a predetermined speed, e.g., <NUM> RPM, in block <NUM>.

If the temperature is not greater than the predetermined temperature, it is determined, in block <NUM>, whether the anemometer velocity is greater than a predetermined velocity, e.g., <NUM> ft/min. If the anemometer velocity is greater than the predetermined velocity, the fan speed is decreased by the predetermined speed or another predetermined speed, in block <NUM>. If the anemometer velocity is not greater than the predetermined velocity, the process returns to block <NUM> to read the temperature from the anemometer.

<FIG> is an exploded view of an anemometer module <NUM> used for measuring fluid velocity and fluid temperature according to an embodiment of this disclosure. The anemometer module <NUM> includes an anemometer housing <NUM>, an anemometer retainer <NUM>, a housing nut retainer <NUM>, an anemometer <NUM>, and an anemometer nut retainer <NUM>. The anemometer retainer <NUM> is secured to the anemometer housing <NUM> with the housing nut retainer <NUM>. The anemometer <NUM> is inserted into the anemometer retainer <NUM> so that the two measurement windows of the anemometer <NUM> are located at the center of the anemometer housing <NUM> and are perpendicular to the fluid flow direction <NUM> illustrated in <FIG>. The anemometer <NUM> is secured in place by the anemometer nut retainer <NUM>.

As illustrated in <FIG>, the anemometer module <NUM> of <FIG> is installed at a cutout in the containment assembly wall <NUM>, which separates the hot aisle <NUM> from the cold aisle <NUM>, so that the honeycomb side of the anemometer housing <NUM> is flush with the containment assembly wall <NUM>. The honeycomb design helps straighten the fluid flow to reduce turbulence and thereby increase the accuracy of the anemometer.

Liquid (e.g., glycol and water) flow in the heat exchangers may be modulated to maintain the desired air discharge temperature. Aside from mechanical redundancy when more than one module is used, the entire system employs network redundancy for control by way of any suitable communications network.

Any suitable heat exchanger design may be used in embodiments of this disclosure including embodiments of the heat exchanger disclosed in International Application No. <CIT>.

Any suitable fluid cooler/chiller that provides any suitable fluid, such as a liquid, to heat exchangers may be used in the heat exchangers of the fan and heat exchanger assemblies according to embodiments of this disclosure including embodiments of the fluid cooler/chiller disclosed in <CIT> titled "Cooling Systems and Methods Using Single-Phase Fluid". However, any suitable liquid, such as water or a water/glycol mixture, may be used.

Claim 1:
A cooling system comprising:
a ceiling plenum (<NUM>) formed between a first ceiling (<NUM>) and a second ceiling (<NUM>,<NUM>) of a building;
a containment assembly (<NUM>) disposed above at least one hot aisle formed by a plurality of rows of a plurality of server racks (<NUM>) and extending through an aperture in the first ceiling (<NUM>), the containment assembly (<NUM>) being configured to direct fluid from the hot aisle into the ceiling plenum (<NUM>);
a fluid velocity sensor (<NUM>) configured to measure velocity of fluid flowing in the hot aisle or the containment assembly (<NUM>);
a temperature sensor configured to measure the temperature of the fluid flowing in the hot aisle or the containment assembly (<NUM>);
at least one fan and heat exchanger assembly (<NUM>,<NUM>,<NUM>); and
a controller (<NUM>) configured to adjust a speed of at least one fan (<NUM>) of the at least one fan and heat exchanger assembly (<NUM>,<NUM>,<NUM>) based on the measured temperature and velocity,
wherein at least one fan (<NUM>) of the at least one fan and heat exchanger assembly (<NUM>,<NUM>,<NUM>) causes fluid to flow from the ceiling plenum (<NUM>), through at least one heat exchanger (<NUM>) of the at least one fan and heat exchanger assembly (<NUM>,<NUM>,<NUM>), and to the plurality of server racks (<NUM>); characterized in that the at least one fan and heat exchanger assembly (<NUM>,<NUM>,<NUM>) includes a first row of a plurality of fan and heat exchanger assemblies and a second row of a plurality of fan and heat exchanger assemblies adjacent to the first row of the plurality of fan and heat exchanger assemblies; wherein the at least one heat exchanger assembly (<NUM>,<NUM>,<NUM>) is disposed inside an outdoor cooling assembly (<NUM>) outside of the building and adjacent to a wall (<NUM>) of the building,
wherein a fan and heat exchanger enclosure (<NUM>, <NUM>) is housing the at least one heat exchanger assembly (<NUM>,<NUM>,<NUM>);
wherein the at least one fan (<NUM>) causes fluid to flow through an aperture in the wall (<NUM>) to the plurality of server racks (<NUM>).