SYSTEMS AND METHODS FOR COOLING COMPUTER DATA CENTERS

Abstract

A data center cooling system is provided to maintain data center temperatures without introducing detrimental conditions into the data center. The computer data center cooling system has a cooling tower that controllably provides cooling water at a temperature in a particular range. The cooling water is then pumped through a series of filtration, treatment, monitoring and separation subsystems to reliably clean the cooling water of particles and treat the cooling water to reduce the harmful effects of corrosion and scaling. Further control subsystems utilize PID loop controllers to maintain the temperature to the air-handler unit cooling coils to within one (1) degree Fahrenheit of a set point that is determined by the computer data center air conditions. The cooling system utilizes either a primary loop or a combination of primary/secondary loops to achieve the highest system efficiency.

Description

BACKGROUND OF THE INVENTION

1. The Field of the Invention

This invention relates to cooling systems that provide cooling to computer data centers.

2. Background and Relevant Art

Generally, modern computer data centers have servers, switches, and networking equipment that are maintained to environmental standards, such as those discussed in ASHRAE TC 9.9, which is hereby incorporated by reference in its entirety. Data centers use a significant amount of energy to operate, and in fact, data center energy use is one of the fastest growing segments of energy consumption in the United States. Experts predict that by the year 2020, data center energy use will surpass the metals industry as the largest segment of energy consumption in the United States. This fact is driving data centers, especially large data centers, to find and use more energy efficient methods and systems.

One way in which data centers may become more energy efficient is through increasing the efficiency of the cooling systems used to cool the data center. Conventional cooling systems may include a chiller, direct expansion gas cooling, water-side economizer, air-side economizer, or some combination of these components. In addition, conventional cooling systems often utilize water or glycol as a cooling medium in closed loop systems. Alternatively, conventional cooling systems may utilize computer room air cooling (CRAC) units placed near the server racks in a data center. In these systems, cooling is accomplished by direct expansion, water-side economizer, or chilled water.

Conventional cooling systems typically use between 0.5 and 1.8 kilowatts per ton of cooling produced. As an example, a conventional large collocation facility may use 400 tons of cooling, and therefore, a data center cooling system that decreases this load would significantly reduce overall energy costs.

Efforts directed at energy efficient cooling systems have focused on efficient air or other fluid distribution. For example, there have been inventions directed towards increasing the efficiency of chillers (US Pub. 20030067745), air distribution (US Pub. 20090168345, US Publ. 20040206101, U.S. Pat. No. 7,112,131, U.S. Pat. No. 6,859,366), hot and cold aisle isolation (US Pub. 20080185446), using outside air (US Pub. 20090210096), and even locating data centers on barges and using seawater to cool them (US Pub. 20080209234).

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention include systems, devices and methods used to increase the energy efficiency of data center cooling systems. In particular, example embodiments of the present invention include an indirect open-loop evaporative cooling system that provides cooling to data centers. By using a unique open-loop system, higher energy efficiencies are obtained because the system cooling water is exposed to ambient air with a low wet bulb temperature. This exposure allows the cooling water to utilize the energy transfer involved in vaporization to cool the cooling water to within approximately three to five degrees Fahrenheit of the dew point. The system therefore, uses the dry ambient air as the ultimate thermal sink of the system.

In this way, embodiments of the present invention can provide cooling systems that produce cooled water at an energy cost ranging from approximately 0.05 to 0.15 kilowatts per ton. At this rate, in a 400-ton conventional large collocation facility, the energy savings would be between approximately 2 and 6 gigawatt hours per year.

Example embodiments of the present invention are advantageous because they provide a significant increase in the operating efficiency compared to conventional data center cooling systems. For example, the use of an open-loop system gains efficiencies in power consumption and water usage. The electrical power is saved through the increases in cooling efficiency, and water consumption is reduced by the elimination of the need to reject large amounts of heat generated by mechanical cooling devices, such as chillers.

In a preferred configuration of the invention, an open-loop cooling system that provides cooling water of a desired cooling temperature is used for cooling environmentally sensitive volumes of air. This system includes an evaporative heat exchanger. Within the evaporative heat exchanger, cooling water is cooled by mixing the cooling water with air that has a low wet bulb temperature.

Also, the system includes a temperature control subsystem which is connected to the evaporative heat exchanger and controls the temperature of the cooling water circulating in the open-loop cooling system. The temperature control subsystem includes a temperature monitor that measures the temperature of the cooling water. The subsystem also includes a mechanical cooler that provides supplementary mechanical cooling to the cooling water when the temperature control subsystem indicates the temperature of the cooling water is hotter than the desired cooling temperature. The subsystem also includes a mixing element that heats the cooling water if the temperature control subsystem indicates the temperature of the cooling water is cooler than the desired cooling temperature.

The open-loop cooling system also includes at least one air-handler unit, which is connected to the evaporative heat exchanger and the temperature control subsystem. The air-handler unit facilitates the transfer of heat from the environmentally sensitive volume of air to the cooling water.

According to another configuration of the invention, an open-loop cooling system used in cooling a data center includes at least one air-handler unit. The air-handler unit is configured to facilitate the transfer of heat from air in the data center to cooling water that circulates through a cooling water system. The cooling water system provides cooling water at a desired cooling temperature.

The cooling water system includes a cooling tower, which is connected to the air-handler unit. Within the cooling tower, the cooling water mixes with air that has a low wet bulb temperature. The mixing cools the cooling water.

The cooling water system also includes a temperature control subsystem, which is connected to the cooling tower and the air-handler unit. The temperature control subsystem controls the temperature of the cooling water circulating in the cooling water system. The subsystem includes a temperature monitor that measures the temperature of the cooling water. The subsystem also includes a mechanical cooler that provides supplementary mechanical cooling to the cooling water if the temperature control subsystem indicates the temperature of the cooling water is hotter than the desired cooling temperature. The subsystem also includes a mixing element that heats the cooling water if the temperature control subsystem indicates the temperature of the cooling water is cooler than the desired cooling temperature.

The invention extends to a method for data center cooling using an open-loop evaporative system that facilitates the production of cooling water at a desired cooling temperature. The method includes the step of mixing heated cooling water with air that has a low wet bulb temperature in a cooling tower. This step utilizes the latent heat of vaporization to cool the cooling water. The cooling water circulates through one or more cooling coils of an air-handler unit. Within the air-handler unit, the air from the data center is forced across the cooling coil such that the air transfers its heat to the cooling water. This step heats the cooling water, which returns to the evaporative cooling tower.

Additional features and advantages of embodiments of the present invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary embodiments. The features and advantages of such embodiments may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such exemplary embodiments as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 illustrates a block diagram of an example of the data center cooling system;

FIG. 2 illustrates a piping diagram of an example of the data center cooling system;

FIG. 3 illustrates a psychometric chart showing the cooling process that can be accomplished by embodiments of the cooling system;

FIG. 4 illustrates an embodiment of the air-handler unit;

FIG. 5 illustrates air entrapment remedies used in an embodiment of the cooling system; and

FIG. 6 illustrates a system that may be used for freeze protection in standby pumps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention include systems, devices and methods used to increase the energy efficiency of data center cooling systems, e.g., computer data centers. In particular, example embodiments of the present invention include an indirect open-loop evaporative cooling system that provides cooling to data centers. By using a unique open-loop system, higher energy efficiencies are obtained because the system cooling water is exposed to ambient air with a low wet bulb temperature. This exposure allows the cooling water to utilize the energy transfer involved in vaporization to cool the cooling water to within approximately three to five degrees Fahrenheit of the dew point. The system therefore, uses the dry ambient air as the ultimate thermal sink of the system.

As an overview, FIG. 1 shows an example of an open-loop cooling system 50 according to one embodiment of the present invention. For example, FIG. 1 illustrates that the open-loop cooling system 50 can include a cooling tower 100, one or more tower pumps 101, one or more system pumps 106, a filtration subsystem 102, a chemical treatment and monitoring subsystem 103, a temperature control subsystem 104, one or more air-handler units 105, a computer data center 140, data center air 145, and cooling water 55 that circulates through the open-loop cooling system 50.

Generally, the open-loop cooling system 50 can include piping sections through which the cooling water 55 circulates and which connect components making up the open-loop cooling system 50. For example, in the embodiment illustrated in FIG. 1, the cooling water 55 circulates through a cooling tower outlet piping section 116, a tower pump inlet piping section 117, a tower pump outlet piping section 136, a chemical treatment inlet piping section 118, a chemical treatment outlet piping section 119, a filter inlet piping section 120, a filter outlet piping section 121, a mechanical cooling inlet piping section 122, a mechanical cooling outlet piping section 123, a mixing element inlet piping section 128, a mixing element outlet piping section 129, a mixing element cross-over piping section 130, a system pump inlet piping section 131, a system pump outlet piping section 132, an air-handler inlet piping section 133, and a system return piping section 135. In alternate embodiments, the configuration of the piping sections as well as the inclusion of various sections may vary from one embodiment to the next depending the cooling requirements of the data center 140.

Notwithstanding the various piping sections configurations, FIG. 1 illustrates that the open-loop cooling system 50 includes cooling tower 100. In one example embodiment, cooling tower 100 has a high efficiency counter-flow design with an induced draft fan. In alternate embodiments, the cooling tower may utilize other designs and configurations that perform the same or similar function as will be described below.

In particular, the cooling tower 100 uses the induced draft fan to draw or blow atmospheric air 51 through an atmospheric air inlet 107. The atmospheric air 51 interacts with the cooling water 55 that exits the system return piping section 135 and enters the cooling tower 100. As the cooling water 55 exiting the return piping section 135 mixes with the atmospheric air 51, the latent heat of vaporization is absorbed from the cooling water 55 and the atmospheric air 51. As a result, the cooling water 55 is cooled.

The rate and amount of cooling performed within the cooling tower 100 may depend on the wet bulb characteristics of the atmospheric air 51. Generally, the lower the wet bulb temperature of the atmospheric air 51, the more cooling that takes place within the cooling tower 100. Thus, the open-loop cooling system 50 can be installed in geographic locations known to have atmospheric air 51 with low wet bulb temperatures, such as deserts or arid climates. In these optimal climates, the cooling tower 100, may cool the cooling water 55 to within three to five degrees Fahrenheit of the dew point. Aside from the optimal climates, the open-loop cooling system 50 can be installed in a wide-range of geographic locations, although the exact efficiencies of the open-loop cooling system 50 may vary with atmospheric characteristics.

Returning to the open-loop cooling system 50, after the atmospheric air 51 is cooled within the cooling tower 100, the atmospheric air 51 is exhausted to the atmosphere through an atmospheric air exhaust 110. For example, FIG. 1 illustrates that the cooling tower 100 includes an atmospheric air exhaust 110. In one example embodiment, the atmospheric air exhaust 110 is located opposite of the atmospheric air inlet 107 to form a defined flow path of the atmospheric air 51 through the cooling tower 100. In alternate embodiments, the location of the atmospheric air exhaust 110 can vary.

Just as the atmospheric air 51 exhausts from the cooling tower 100, the cooling water 55 which has been cooled also exits the cooling tower 100. In one example embodiment, the cooling tower 100 is connected to the tower pumps 101 via the tower outlet piping section 116. In particular, after the cooling water 55 is cooled within the cooling tower 100, the cooling water 55 accumulates within the cooling tower 100 and the tower pumps 101 pump the cooling water 55 through the tower outlet piping section 116, into the tower pump inlet piping section 117, and through the tower pumps 101.

Although one or more tower pumps 101 can be employed in various configurations, FIG. 2 illustrates one example embodiment in which the tower pumps 101a and 101b are configured in parallel. In the parallel configuration, one of tower pumps is designated as the operating tower pump 101a, while the other tower pump is designated as the standby tower pump 101b. Thus, the operating tower pump 101a normally pumps the cooling water 55, while the standby tower pump 101b remains in standby in case the operating tower pump 101a fails or another system condition requires the use of the standby tower pump 101b. In alternate embodiments, the tower pumps 101 may be configured in series or a single pump may be utilized.

The tower pumps 101 are used to circulate the cooling water 55 through various components and subsystems of the open-loop cooling system 50. In one example embodiment, the tower pumps 101 are connected to the chemical treatment and monitoring subsystem 103 and the filtration subsystem 102 via the tower pump outlet piping section 136. In particular, the tower pump outlet piping section 136 can connect to the chemical treatment inlet piping section 118 to circulate water through the chemical treatment and monitoring subsystem 103. The chemical treatment outlet piping section 119 is configured to return cooling water 55 that has been chemically treated to the tower pump outlet piping section 136.

In one embodiment of the open loop cooling system 50, at least a portion of the cooling water 55 may be routed through the chemical treatment and monitoring subsystem 103. For example, in the configuration illustrated in FIG. 1, a portion of the cooling water 55 exiting the tower pumps 101 into the tower pump outlet piping section 136 enters the chemical treatment and monitoring subsystem 103 via the chemical treatment inlet piping section 118. The remainder of the cooling water 55 exiting the tower pumps 101 remains in the tower pump outlet piping section 136 and proceeds to the filter inlet piping section 120. In alternative embodiments, none or all of the cooling water 55 exiting the tower pumps 101 may enter the chemical treatment and monitoring subsystem 103.

The portion of cooling water that enters the chemical treatment and monitoring subsystem 103 can be controlled by one or more valves. The valves can be electronically controlled and coupled with other devices, such as flow rate meters, to direct substantially exact portions of the cooling water 55 to the chemical treatment and monitoring subsystem 103 in order to maintain consistent chemical properties in the cooling water 55.

Additionally, a dedicated chemical subsystem pump may circulate the portion of cooling water 55 that enters the chemical treatment and monitoring subsystem 103. For example in the embodiment illustrated in FIG. 2, a dedicated chemical subsystem pump 210 circulates the cooling water 55 through the chemical treatment and monitoring subsystem 103. In alternate embodiments, the open-loop cooling system 50 may utilize an alternate pressure source to circulate the cooling water 55 through the chemical treatment and monitoring subsystem 103.

In addition to the various components used to direct cooling water 55 to the chemical treatment and monitoring subsystem 103, the chemical treatment and monitoring subsystem 103 can include various components to chemically monitor the cooling water 55 and chemically treat the cooling water 55. For example, FIG. 2 illustrates that the chemical treatment and monitoring subsystem 103 can include a corrosion coupon rack 202. In operation, the corrosion coupon rack 202 includes coupons of known size/weight of a material that can corrode when exposed to the cooling water 55, such as copper. In alternative embodiments, other corrodible materials can be used within the corrosion coupon rack 202.

The coupons are positioned on the corrosion coupon rack 202 such that the coupons interface with the cooling water 55. The rate at which the coupons corrode depends upon the corrosive properties of the cooling water 55. The coupons can then be removed from the corrosion coupon rack 202 and measured and/or weighed to determine and monitor the corrosive properties of the cooling water 55. For example, if the cooling water 55 becomes too corrosive, remedial actions can be taken, such as adding additional chemicals to the cooling water 55 to make the cooling water 55 less corrosive.

In one example embodiment, the chemical treatment and monitoring subsystem 103 includes a chemical injection pump 204, as illustrated in FIG. 2. The chemical injection pump 204 allows an operator to inject chemicals as required into the open-loop cooling system 50 via the chemical treatment and monitoring subsystem 103. In one example, an operator can control the chemical injection pump 204 from a control center. In alternate embodiments, the chemical treatment and monitoring subsystem 103 automatically injects chemicals as required by the open-loop cooling system 50.

In addition to the chemical injection pump 204, the chemical treatment and monitoring subsystem 103 may include additional components. For example, FIG. 2 illustrates an embodiment of the chemical treatment and monitoring subsystem 103 that includes a centrifuge 203. The centrifuge 203 can separate particulate matter contained in the cooling water 55 that is routed to the chemical treatment and monitoring subsystem 103. In alternate embodiments, the chemical treatment and monitoring subsystem 103 can include similar components and processes that separate corrosive particular matter from the cooling water 55.

In addition to the components described above, the chemical treatment and monitoring subsystem 103 can include a wide array of chemical monitoring equipment used to monitor a wide array of chemical properties of the cooling water 55, depending on the desired chemical properties of the cooling water 55. For example, in one embodiment, the cooling water 55 is substantially pure water. In alternative embodiments, however, the cooling water 55 can be chemically treated water, a water-based chemical solution, or another cooling medium with carefully engineered thermodynamic properties.

Once the cooling water 55 or a portion of cooling water 55 is processed through the chemical treatment and monitoring subsystem 103, the cooling water 55 can enter the filtration subsystem 102. For example, as shown in FIG. 1, the chemical treatment and monitoring subsystem 103 is connected to the filtration subsystem 102 via the chemical treatment outlet piping section 119, and the filter inlet piping section 120. The cooling water 55 exiting the chemical treatment and monitoring subsystem 103 via the chemical treatment outlet piping section 119 mixes with the cooling water 55 that did not enter the chemical treatment and monitoring subsystem 103 in the filter inlet piping section 120, and then enters the filtration subsystem 102. In alternative embodiments, the cooling water 55 exiting the chemical treatment and monitoring subsystem 103 via the chemical treatment outlet piping section 119 may mix with the cooling water 55 that did not enter the chemical treatment and monitoring subsystem 103 at another point in the open-loop cooling system 50.

The filtration subsystem 102 filters the cooling water 55 before it enters the filter outlet piping section 121. The filtration subsystem 102 can include, but is not limited to media filters, screen filters, disk filters, slow sand filter beds, rapid sand filters and cloth filters that can be configured to various sizes of particles from the cooling water 55. In at least one embodiment, the filtration subsystem 102 substantially prevents a particle of a predetermined size or larger from circulating with the cooling water 55 through the portion of the open-loop cooling system 50 behind the filtration subsystem 102.

Once the cooling water 55 passes through the filtration subsystem 102, the cooling water 55 can enter one or more subsystems within the open-loop cooling system 50. For example, as shown in FIG. 1, the filtration subsystem 102 is connected to the temperature control subsystem 104 via the filter outlet piping section 121. In alternate embodiments, the connection between the filtration subsystem 102 and the temperature control subsystem 104 can exist in an alternate location in the open-loop cooling system 50.

Generally, the temperature control subsystem 104 provides the cooling water 55 with supplementary temperature control in the event that the cooling tower 100 was unable to produce cooling water 55 with a desired temperature for the cooling cycle. For example, in the event that the atmospheric air 51 becomes humid, the atmospheric air 51 will have a higher wet bulb temperature. This condition reduces the efficiency of the cooling that occurs in the cooling tower 100 and may necessitate supplementary mechanical cooling in the temperature control subsystem 104.

Additionally, the temperature control subsystem 104 can be configured to function only if the cooling water 55 is not at the desired temperature. For example, if the cooling water 55 is at the desired temperature, the cooling water 55 can bypass the temperature control subsystem 104.

Depending on the temperature of the cooling water 55 entering the temperature control subsystem 104, the temperature control subsystem 104 can employ various components to adjust the temperature of the cooling water 55. In one example embodiment, the temperature control subsystem 104 can include a mechanical cooler 137, such as a chiller, that can provide supplementary mechanical cooling to the cooling water 55 as required to produce cooling water 55 with the desired temperature for the cooling cycle.

Thus, the combination of the cooling tower 100 (high efficient cooling) and the mechanical cooler 137 (lower efficient cooling) used to control the temperature of the cooling water 55 is highly energy efficient and may allow temperature control of the cooling water 55 to within one (1) degree Fahrenheit. For example, under certain conditions, the atmospheric air 51 has wet bulb temperature properties that allow the cooling tower 100 to adequately cool the cooling water 55, thus providing the highest efficiency possible as no supplementary mechanical cooling is needed. With other conditions, for example when the atmospheric air 51 has a higher wet bulb temperature, the cooling water 55 can require supplementary mechanical cooling. However, because the cooling tower 100 has provided most of the cooling, the mechanical cooler 137 only needs to lower the temperature of the cooling water 55 a few degrees. Thus, the majority of the work performed in the open loop cooling system 50 is provided by the high efficient cooling component while the lower efficient cooling is only utilized as required and in a limited fashion. Therefore, the temperature of the cooling water 55 is controlled in a highly energy efficient manner.

In addition, FIG. 1 illustrates that the temperature control subsystem 104 can be configured in series with the cooling tower 100. Configuring the temperature control subsystem 104 in series with the cooling tower 100 eliminates the need for an additional cooling tower, heat exchangers, or secondary closed loop for chilled water or glycol, as with conventional systems.

As shown in FIG. 1, the mechanical cooler 137 is connected to the filter outlet piping section 121 via the mechanical cooling inlet piping section 122 and the mechanical cooling outlet piping section 123. A controlled portion of the cooling water 55 exiting the filtration subsystem 102 through the filter outlet piping section 121 enters the mechanical cooling inlet piping section 122. The remainder of the cooling water 55 remains in the filter outlet piping section 121. Depending on the wet bulb temperature of the data center air 145, the amount of cooling water 55 that enters the mechanical cooler 137 can range from none of the cooling water 55 to all of the cooling water 55.

In alternative embodiments, the portion of the cooling water 55 entering the mechanical cooler 137 could be based on other physical conditions in the open-loop cooling system 50. For example, the portion of the cooling water that enters the mechanical cooler 137 from the filter outlet piping section 121 may be controlled such that condensation does not form in the air-handler units 105.

In addition, in the embodiment illustrated in FIG. 1, the cooling water 55 that entered the mechanical cooler 137 via the mechanical cooling inlet piping section 122 is cooled in the mechanical cooler 137 then exits the mechanical cooler 137 via the mechanical cooling outlet piping section 123. The cooling water 55 exiting the mechanical cooler 137 via the mechanical cooling outlet piping section 123 mixes with the portion of the cooling water 55 that exited the filtration subsystem 102 via the filter outlet piping section 121. The result of the mixing of the cooling water 55 exiting the mechanical cooler 137 via the mechanical cooling outlet piping section 123 with the cooling water 55 exiting the filtration subsystem 102 via the filter outlet piping section 121 is the cooling water 55 in the mixing element inlet piping section 128 is cooler than the cooling water 55 exiting the filtration subsystem 102.

In one example embodiment of the temperature control subsystem 104, twenty-five percent of the cooling water 55 exiting the filtration subsystem 102 via the filter outlet piping section 121 enters the mechanical cooler 137 via the mechanical cooling inlet piping section 122. In this example embodiment, the cooling water 55 is cooled twenty degrees Fahrenheit in the mechanical cooler 137. The cooling water 55 then exits the mechanical cooler 137 via the mechanical cooling outlet piping section 123. The cooling water 55 exiting the mechanical cooler 137 via the mechanical cooling outlet piping section 123 mixes with the cooling water 55 that exited the filtration subsystem 102 via the filter outlet piping section 121 and entered the mixing element inlet piping section 128. When this mixing occurs, the cooling water 55 entering the mixing element inlet piping section 128 is cooled five degrees Fahrenheit.

If a ten degree Fahrenheit cooling was needed, fifty percent of the cooling water 55 can be directed into the mechanical cooler 137 to be cooled by twenty degrees. Thus, when the fifty percent portion is mixed with the cooling water 55 that was not mechanically cooled, the overall temperature drop of the cooling water 55 would be ten degrees.

FIG. 2 illustrates another example of a mechanical cooler. In particular, FIG. 2 illustrates a temperature control subsystem 104 that includes a multi-element mechanical cooler 221 consisting of a condenser 223 and a chiller 222. In the embodiment illustrated in FIG. 2, the condenser 223 is connected to the filter outlet piping section 121 via a condenser cooling inlet piping section 126. The condenser 223 is connected to system return piping section 135 via a condenser cooling outlet piping section 127.

In the embodiment illustrated in FIG. 2, a portion of the cooling water 55 exiting the filtration subsystem 102 enters the condenser 223 via the condenser cooling inlet piping section 126. The condenser 223 utilizes the cooling water 55 as the cooling medium for the chiller 222. The cooling water 55 utilized in the condenser 223 as a cooling medium exits the condenser 223 via the condenser cooling outlet piping section 127 and is routed to the system return piping section 135. Thus, the configuration illustrated in FIG. 2 utilizes the cooling capacity of the cooling tower 100 to a maximum extent as well as prevents the heat absorbed in the condenser 223 from being introduced into the open-loop cooling system 50.

In some atmospheric conditions, it may be the case that the cooling tower 100 cooled the cooling water 55 to a temperature below the desired temperature of the cooling cycle. Under these conditions, the cooling water 55 needs to be heated to provide the required cooling of the data center air 145 through the air-handler units 105 (discussed further below). Thus, in one example embodiment, the temperature control subsystem 104 can include a mixing element 138 to increase the temperature of the cooling water 55 if the cooling water 55 is too cold, as illustrated in FIG. 1.

In one example embodiment, the mixing element 138 is a valve that mixes cooling water 55 with a high temperature exiting the air-handler units 105 with the cooling water 55 with a low temperature in the temperature control subsystem 104. For example, FIG. 2 illustrates a mixing element 138 that is a three-way bypass valve 220. In alternate embodiments, the mixing element 138 may be an injection pump. The mixing element 138 can be communicably connected to a control center that automatically controls the mixing element 138 based on the temperature of the cooling water 55 entering the temperature control subsystem 104.

As shown in FIG. 1, the mixing element 138 is connected to the mechanical cooler 137 and the filtration subsystem 102 via the mixing element inlet piping section 128 which is connected to the filter outlet piping section 121 and the mechanical cooling outlet piping section 123. As further illustrated in FIG. 1, the mixing element 138 is connected to the system return piping section 135 via the mixing element cross-over piping section 130. As further illustrated in FIG. 1, the mixing element 138 is connected to the system pump inlet piping section 131 via the mixing element outlet piping 129.

Furthermore, FIG. 1 illustrates that the mixing element 138 mixes the cooling water 55 entering the mixing element 138 via the mixing element inlet piping section 128 with the cooling water 55 in the system return piping section 135 via the mixing element cross-over piping 130 then routes the cooling water 55 that has been mixed to the mixing element outlet piping section 129. By mixing the cooling water 55 entering the mixing element 138 via the mixing element inlet piping section 128 with the cooling water 55 entering the mixing element 138 via the mixing element cross-over piping section 130 from the in the system return piping section 135, the mixing element 138 increases the temperature of the cooling water 55 exiting the mixing element 138 into the mixing element outlet piping section 129.

In addition, in the example embodiment illustrated in FIG. 1, the quantity of cooling water 55 entering the mixing element 138 via the mixing element cross-over piping section 130 from the system return piping section 135 may be determined by the wet bulb temperature of the data center air 145. In alternate embodiments, the quantity of cooling water 55 entering the mixing element 138 is determined by other physical properties of the open-loop cooling system 50. For example, the quantity of the cooling water 55 entering the mixing element 138 via the mixing element cross-over piping section 130 from the system return piping section 135 is determined such that condensation does not form in the one or more air-handler units 105.

In addition, in an embodiment of the invention, the temperature control subsystem 104 may use a dedicated condenser pump and a dedicated chiller pump. For example, in the embodiment illustrated in FIG. 2, the temperature control subsystem 104 includes a dedicated condenser pump 212 and a dedicated chiller pump 211.

In this embodiment, an alternative piping configuration can be utilized. For example, as illustrated in FIG. 2, the condenser cooling inlet piping section 126 is connected to the filter outlet piping section 121. The mechanical cooling inlet piping section 122 is connected to the mixing element outlet piping section 129 rather than the filter outlet piping section 121 as illustrated in FIG. 1. Additionally, in this embodiment, cooling water 55 exiting the chiller 222 circulates into the system pump inlet piping section 131 rather than into the mixing element inlet piping section 128 as illustrated in FIG. 1. In alternate embodiments, the piping configuration between the temperature control subsystem 104 and the open-loop cooling system 50 may take other configurations.

In the embodiment illustrated in FIG. 2, the dedicated condenser pump 212 circulates cooling water 55 through the condenser 223 via the condenser cooling inlet piping section 126. The dedicated condenser pump 212 then circulates the cooling water 55 out of the condenser 223 into the system return piping section 135 via the condenser cooling outlet piping section 127.

As further illustrated in FIG. 2, the dedicated chiller pump 211 circulates cooling water 55 into the chiller 222 via the mechanical cooling inlet piping section 122. The dedicated chiller pump 211 then circulates the cooling water 55 out of the chiller 222 into the system pump inlet piping section 131 via the mechanical cooling outlet piping section 123. In alternate embodiments, the open-loop cooling system 50 may utilize configurations without a dedicated condenser pump and/or a dedicated chiller pump.

As discussed above, the cooling tower 100 is in series with the temperature control subsystem 104. This allows the cooling tower 100 and the temperature control subsystem 104 to cool the cooling water 55 to within a zone of efficient cooling. For example, FIG. 3 illustrates a zone of efficient cooling 301 for the example embodiment illustrated in FIG. 1 at average atmospheric conditions at approximately 4200 feet above sea level. In alternate embodiments, the zone of efficient cooling would shift due to atmospheric conditions.

The open-loop cooling system 50 would be most efficient below a given atmospheric wet bulb temperature. For example, the open-loop cooling system 50 illustrated in FIG. 1 may be most efficient in areas of the world with a maximum atmospheric wet bulb temperature of 70 degrees Fahrenheit. FIG. 3 illustrates the psychometric properties below the maximum wet bulb temperature of 70 degrees Fahrenheit 302. This physical condition produces the highest efficiencies in the cooling tower 100. In alternate embodiments, the maximum atmospheric wet bulb temperature producing the highest efficiencies may vary with the particular system configuration, ambient atmospheric conditions, and elevation.

As the cooling water 55 circulates through the open-loop cooling system 50 the cooling water 55 is subject to psychometric changes. A psychometric change of cooling water 55 in a cooling tower 100 includes an initial physical state, a final physical state, and a change line illustrating the intermediate physical states between the initial and final physical state. For example, FIG. 3 illustrates a cooling tower psychometric change 303 of the cooling water 55 in the cooling tower 100. The cooling tower psychometric change 303, for example, includes an initial physical state 304, a final physical state 305, and a change line 306.

The cooling tower psychometric change 303 represents the psychometric changes of the cooling water 55 as the cooling water 55 circulates from the system return piping section 135 through the cooling tower 100 and into the cooling tower outlet piping section 116. The initial physical state 304 represents the physical properties of the cooling water 55 in the system return piping section 135. The final physical state 305 represents the physical properties of the cooling water 55 in the cooling tower outlet piping section 116. The change line 306 represents the cooling occurring in the cooling tower 100 due to the mixing of the cooling water 55 with the atmospheric air 51 with a low wet bulb temperature. In alternate embodiments, the cooling tower psychometric change 303 will vary with physical properties of the system and the ambient conditions of the atmospheric air 51.

As illustrated in FIG. 3, the final physical state 305 is located in the zone of efficient cooling 301. This illustrates that in the embodiment illustrated in FIG. 1 during the cooling tower psychometric change 303 the cooling tower 100 normally has the ability of to provide sufficient cooling to the cooling water 55 for circulation in the open-loop cooling system 50.

Alternatively, if adverse ambient conditions exist such as atmospheric air 51 with a high wet bulb temperature, the cooling tower 100 may produce a cooling tower psychometric change in which the final physical state of the cooling water 55 is outside the zone of efficient cooling 301. For example, FIG. 3 illustrates an inadequate cooling tower psychometric change 303a. The inadequate cooling tower psychometric change 303a includes the initial physical state 304, an intermediate physical state 305a, and an intermediate change line 306a.

The inadequate cooling tower psychometric change 303a represents the psychometric changes of the cooling water 55 as the cooling water 55 circulates from the system return piping section 135 through the cooling tower 100 and into the cooling tower outlet piping section 116. The initial physical state 304 represents the physical properties of the cooling water 55 in the system return piping section 135. The intermediate physical state 305a represents the physical properties of the cooling water 55 in the cooling tower outlet piping section 116. The intermediate change line 306a represents the cooling occurring in the cooling tower 100 due to the mixing of the cooling water 55 and atmospheric air 51 with a higher-than-optimal wet bulb temperature. In alternate embodiments, the inadequate cooling tower psychometric change 303a will vary with physical properties of the system and the ambient conditions of the atmospheric air 51.

As illustrated in FIG. 3, the intermediate physical state 305a is located outside of the zone of efficient cooling 301. This illustrates that in the embodiment illustrated in FIG. 1 during the inadequate cooling tower psychometric change 303a when adverse atmospheric conditions exist, the cooling tower 100 may be unable to provide sufficient cooling to the cooling water 55 for circulation in the open-loop cooling system 50.

In this situation, additional cooling may be necessary. For example, FIG. 3 illustrates a mechanical cooler psychometric change 307 of the cooling water 55 in the mechanical cooler 137. In this situation, the open-loop cooling system 50 embodied in FIG. 1 introduces the cooling water 55 into a mechanical cooler 137. Within the mechanical cooler 137, the cooling water 55 undergoes psychometric changes. For example, FIG. 3 illustrates a mechanical cooler psychometric change 307 of the cooling water 55 in the mechanical cooler 137.

As with the cooling tower psychometric change 303, the mechanical cooler psychometric change 307 can include an initial psychometric state, a final psychometric state, and a trend line illustrating the intermediate psychometric states between the initial and final psychometric states. For example, in FIG. 3, the mechanical cooling psychometric change 307 includes an initial psychometric state 308 (which may coincide with intermediate physical state 305a), a final psychometric state 310, and a trend line 309.

The mechanical cooler psychometric change 307 represents the psychometric changes of the cooling water 55 as the cooling water 55 circulates from the filter outlet piping section 121 through the mechanical cooler 137 and into the mixing element inlet piping section 128. The initial psychometric state 308 represents the physical properties of the cooling water 55 in the filter outlet piping section 121. The final psychometric state 310 represents the physical properties of the cooling water 55 in the mixing element inlet piping section 128. The trend line 309 represents the cooling occurring due to the mechanical cooler 137. In alternate embodiments, the mechanical cooler psychometric change 307 will vary with physical properties of the mechanical cooler 137 and the system configuration.

As illustrated in FIG. 3, the final psychometric state 310 is located within the zone of efficient cooling 301. Thus, the cooling water 55 mechanically has been cooled from a physical state outside the zone of efficient cooling 301, such as the intermediate physical state 305a that resulted from the inadequate cooling tower psychometric change 303a, to be within the zone of efficient cooling 301. This illustrates that during the mechanical cooling psychometric change 307 the mechanical cooler 137 has the ability to provide supplemental mechanical cooling to the cooling water 55 for circulation in the open-loop cooling system 50.

Returning to FIG. 1, the remaining components of the open-loop cooling system 50 will be described. As shown in FIG. 1, the mixing element 138 is connected to the one or more system pumps 106 via the mixing element outlet piping section 129 and the system pump inlet piping section 131. In the example embodiment illustrated in FIG. 1, after the cooling water 55 exits the mixing element 138 via the mixing element outlet piping section 129, the one or more system pumps 106 pump the cooling water 55 in through the system pump inlet piping section 131, out through the system pump outlet piping section 132, and into the air-handler inlet piping section 133. In alternate embodiments, the particular configuration of these components may vary.

In addition to the system pumps 106 pumping the cooling water exiting the mixing element 138, the system pumps 106 can have various configurations. For example, in the embodiment illustrated in FIG. 2, the system pumps 106a and 106b are configured in parallel. In this configuration, one of system pumps is designated as the operating system pump 106a, and the other system pump is designated as the standby system pump 106b. That is, the operating system pump 106a pumps the cooling water 55 while the standby system pump 106b remains in standby. In alternate embodiments, the system pumps 106 may be configured in series or a single pump may be utilized.

As shown in FIG. 1, the one or more system pumps 106 are connected to the one or more air-handler units 105 via the system pump outlet piping section 132 and the air-handler inlet piping section 133. As further shown in FIG. 1, the air-handler units 105 are connected to the cooling tower 100 via the system return piping section 135.

Generally, the air-handler units 105 provide an interface between the cooling water 55 cooled by the open-loop cooling system 50 and data center air 145 that has been heated in the computer data center 140. For example, FIG. 1 illustrates that the data center air 145 is moved into the air-handler units 105 though ducting. Specifically, FIG. 1 illustrates the air-handler units 105 connected to the computer data center 140 via inlet ducting 141 and outlet ducting 142.

Because the cooling water 55 entering the air-handler units 105 via the air-handler inlet piping section 133, is cooler than the data center air 145 entering the air-handler units 105 via the inlet ducting 141, the heat in the data center air 145 transfers to the cooling water 55, thus cooling the data center air 145. The data center air 145 having been cooled, returns to the computer data center 140 via the outlet ducting 142, while the cooling water 55 which has been heated enters the system return piping section 135 to be directed to the cooling tower 100 to begin the cooling cycle as described above.

In one example embodiment of the air-handler units 105, the air-handler units 105 contain a cooling coil 401. For example, FIG. 4 illustrates an air-handler unit 105 containing a cooling coil 401. In the embodiment illustrated in FIG. 4, the air-handler inlet piping section 133 connects to the cooling coil 401. The system pumps 106 pump the cooling water 55 into the cooling coil 401 via the air-handler inlet piping section 133. The cooling water 55 circulates through the cooling coil 401 then exits the cooling coil 401 into the system return piping section 135.

In the example embodiment of the air-handler unit 105 illustrated in FIG. 4, the data center air 145 enters the air-handler unit 105 via the inlet ducting 141 then moves across the cooling coil 401. As the data center air 145 moves across the cooling coil 401, the data center air 145 transfers heat to the cooling water 55 moving through the cooling coil 401. The data center air 145 exits the air-handler unit 105 through the outlet ducting 142.

As shown in FIG. 1, the inlet ducting 141 may contain a humidification element 143. In the embodiment illustrated in FIG. 1, the humidity of the data center air 145 may be controlled by the humidification element 143. For example, if the humidity level needs to be increased to maintain the correct data center environment, the humidification element 143 may inject water into the inlet ducting 141 as the data center air 145 enters the air-handler units 105. In alternate embodiments, the humidity of the data center air 145 could be controlled through use of an evaporative media section, or directly in the data center 140.

In an example embodiment of the open-loop cooling system 50, an air removal subsystem 500 may be included to remove atmospheric air 51 from the cooling water 55. For example, FIG. 5 illustrates an example of an air removal subsystem 500 that may be included in an embodiment of the open loop cooling system 50 to remove atmospheric air 51 from the cooling water 55. In the embodiment illustrated in FIG. 5, the air removal subsystem 500 includes a supply piping port 502, a vent piping section 504, and a return piping port 505.

As shown in FIG. 5, the supply piping port 502 is provided on the top of the air-handler inlet piping section 133. The return piping port 505 is provided on the top of the system return piping section 135. The supply piping port 502 is connected via the vent piping section 504 to the return piping port 505. In alternate embodiments, the supply piping port 502 may be located on a different section or multiple piping sections of the open-loop cooling system 50.

In addition, in the embodiment illustrated in FIG. 5, the air removal subsystem 500 may function due to a differential pressure between the air-handler inlet piping section 133 and the system return piping section 135. The differential pressure forces atmospheric air 51 in the air-handler inlet piping section 133 through the supply piping port 502, through vent piping section 504, and through the return piping port 505. The atmospheric air 51 is mixed with the cooling water 55 in the system return piping section 135 and is directed back to the cooling tower 100. The air removal subsystem 500 illustrated in FIG. 5 can be located at a high point of the open-loop cooling system 50. In alternate embodiments, multiple air removal subsystems 500 may be located throughout the system.

In an example embodiment of the open-loop cooling system 50, air prevention subsystems 510 and 510a may be included to prevent air from entering the air-handler units 105. For example, FIG. 5 illustrates examples of air prevention subsystems 510 and 510a that may be included in an embodiment of the open loop cooling system to prevent atmospheric air 51 remaining in the cooling water 55 from entering the air-handler units 105.

As illustrated in FIG. 5, the air prevention subsystems 510 and 510a include the air-handler inlet piping section 133 connected to the system pump outlet piping section 132 at the bottom (illustrated in 510) or the side (illustrated in 510a) of the piping and a vent valve 511. In alternate embodiments, the specific piping sections utilized to prevent air from entering the air-handler units 105 may vary.

As illustrated in FIG. 5, the cooling water 55 is allowed to exit the system pump outlet piping section 132 and enter the air-handler inlet piping section 133 without the atmospheric air 51 entering the air-handler inlet piping section 133. Therefore, the cooling water 55 enters the air-handler units 105 without the atmospheric air 51. The atmospheric air 51 is vented via the vent valve 511. In alternate embodiments, the air remaining may be disposed of through other means known in the art.

In an example embodiment illustrated in FIG. 2 of the open-loop cooling system 50, the system pumps 106a and 106b and the tower pumps 101a and 101b are configured in parallel (as discussed above, FIG. 2 specifically illustrates examples of the operating tower pump 101a and standby tower pump 101b along with the operating system pump 106a and the standby system pump 106b configured in parallel) that may require a freeze protection subsystem 600 to prevent damage if the parallel pumps are exposed to temperatures below thirty-two degrees Fahrenheit. For example, FIG. 6 illustrates an embodiment of a freeze protection subsystem 600. The freeze protection subsystem 600 includes a standby pump 602, a standby pump check valve 603, a freeze protection cross-over piping section 606, a standby pump outlet piping section 607, an operating pump 601, an operating pump outlet piping section 605, and a temperature sensor 604.

The freeze protection subsystem 600 operates by forming a hole in the disc of the standby pump check valve 603. This hole allows a small amount of the cooling water 55 pumped by the operating pump 601 to flow from the operating pump outlet piping section 605, through the freeze protection cross-over piping section 606, down the standby pump outlet piping section 607, through the hole drilled in the disc of the standby pump check valve 603, and into the standby pump 602.

In addition, the freeze protection subsystem 600 may include a temperature sensor 604. The temperature sensor 604 measures the temperature of the cooling water 55 backflowing through the standby pump 602. If the temperature of the cooling water 55 backflowing through the standby pump 602 is below a preset temperature, the standby pump 602 becomes the operating pump 601 and the operating pump 601 becomes the standby pump 602.

The present invention can be embodied in other specific forms without departing from its spirit or essential characteristics. Thus, the described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An open-loop cooling system that provides cooling water for use in cooling environmentally sensitive volumes of air, the open-loop cooling system comprising:

an evaporative heat exchanger that mixes cooling water with air having a low wet bulb temperature to cool the cooling water;

a temperature control subsystem, connected to the evaporative heat exchanger, that controls the temperature of the cooling water circulating in the open-loop cooling system, the temperature control subsystem comprising: a temperature monitor that measures the temperature of the cooling water exiting the evaporative heat exchanger; and a mechanical cooler that provides supplementary mechanical cooling to the cooling water if the temperature monitor indicates the temperature of the cooling water is higher than a desired cooling temperature; and

at least one air-handler unit that facilitates the transfer of heat from the environmentally sensitive volume of air to the cooling water.

2. The open-loop cooling system recited in claim 1, wherein the environmentally sensitive volume is a data center.

3. The open-loop cooling system recited in claim 1, wherein the evaporative heat exchanger is a cooling tower.

4. The open-loop cooling system recited in claim 1, wherein the mechanical cooler comprises:

a chiller, that provides the supplementary mechanical cooling to the cooling water; and

a condenser, wherein the condenser is configured to use cooling water exiting the evaporative heat exchanger as inlet water to cool the mechanical cooler condenser, thereby utilizing the cooling occurring in the evaporative heat exchanger.

5. The open-loop cooling system recited in claim 1, wherein the desired cooling temperature of the cooling water is determined by the wet bulb temperature of air in the data center.

6. The open-loop cooling system recited in claim 1, further comprising a chemical treatment and monitoring subsystem.

7. The open-loop cooling system recited in claim 3, wherein the air utilized in the cooling tower is atmospheric air with a low wet bulb temperature.

8. The open-loop cooling system recited in claim 7, wherein following the cooling of the cooling water, the atmospheric air is exhausted to an ambient atmosphere, thereby using the ambient atmosphere as a heat sink of the open-loop cooling system.

9. The open-loop cooling system recited in claim 1, further comprising a mixing element that heats the cooling water if the temperature control subsystem indicates the temperature of the cooling water is cooler than the desired cooling temperature.

10. The open-loop cooling system recited in claim 9, wherein the mixing element is a three-way valve that mixes warmer cooling water returning from the air-handler with cooler cooling water from the cooling tower.

11. The open-loop cooling system recited in claim 1, further comprising an air removal subsystem having a piping configuration, wherein the air-handler supply piping stems from a bottom or a side of a system pump outlet piping section, such that air is not directed to the air-handler unit.

12. An open-loop cooling system for use in cooling a data center, comprising:

at least one air-handler unit configured to facilitate the transfer of heat from air in the data center to cooling water that circulates through a cooling water system, the cooling water system comprising: a cooling tower connected to the air-handler unit, wherein the cooling tower allows cooling water to mix with air having a low wet bulb temperature; and a temperature control subsystem, connected to the cooling tower and the air-handler unit, that controls the temperature of the cooling water circulating in the cooling water system, the temperature control subsystem comprising: a temperature monitor that measures the temperature of the cooling water exiting the cooling tower; a mechanical cooler that provides supplementary mechanical cooling to the cooling water if the temperature control subsystem indicates the temperature of the cooling water is higher than the desired cooling temperature; and a mixing element that heats the cooling water if the temperature control subsystem indicates the temperature of the cooling water is cooler than the desired cooling temperature.

13. The open-loop cooling system recited in claim 11, wherein the desired cooling temperature of the cooling water is determined by the wet bulb temperature of air in the data center.

14. The open-loop cooling system recited in claim 11, further comprising a chemical treatment and monitoring subsystem.

15. The open-loop cooling system recited in claim 11, wherein the air utilized in the cooling tower is atmospheric air with a low wet bulb temperature.

16. The open-loop cooling system recited in claim 12, wherein following the cooling of the cooling water, the atmospheric air is exhausted to an ambient atmosphere, thereby using the ambient atmosphere as a heat sink of the open-loop cooling system.

17. A method for data center cooling using an open-loop evaporative system that facilitates the production of cooling water at a desired cooling temperature, the method comprising:

mixing heated cooling water with air having a low wet bulb temperature in a cooling tower, thereby utilizing the latent heat of vaporization to cool the cooling water;

circulating at least a portion of the cooling water through a temperature control subsystem, wherein the temperature control subsystem measures the temperature of the cooling water;

comparing the temperature measured in the temperature control subsystem to the desired cooling water temperature;

altering the temperature of the cooling water in the temperature control subsystem if the cooling water temperature is different from the desired cooling temperature;

circulating the cooling water through one or more cooling coils of an air-handler unit, wherein air from the data center is forced across the cooling coil such that the air from the data center transfers its heat to the cooling water; and

returning the heated cooling water to the cooling tower.

18. The method as recited in claim 17, further comprising determining the desired temperature from the wet bulb temperature of air in the data center.

19. The method as recited in claim 16, further comprising:

utilizing atmospheric air having a low wet bulb temperature in the cooling tower; and

exhausting the atmospheric air after cooling the cooling water occurs back to the ambient atmosphere.

20. The method as recited in claim 19, further comprising monitoring the chemical composition of the cooling water.