RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No. 15/782,034, filed on Oct. 12, 2017, which is a continuation of U.S. patent application Ser. No. 14/685,524, filed on Apr. 13, 2015, which is a continuation of U.S. patent application Ser. No. 13/410,558, filed on Mar. 2, 2012, now U.S. Pat. No. 9,010,141 issued on Apr. 21, 2015, which is a non-provisional of U.S. patent application Ser. No. 61/595,989, filed on Feb. 7, 2012. The present application is also related to U.S. patent application Ser. No. 61/451,214, filed on Mar. 10, 2011, U.S. patent application Ser. No. 13/308,208, filed on Nov. 30, 2011, U.S. patent application Ser. No. 61/422,564, filed on Dec. 13, 2010, and U.S. patent application Ser. No. 12/762,898, filed on Apr. 19, 2010. The full disclosure of each of these references is herein incorporated by reference.

TECHNICAL FIELD

The present invention relates to systems and methods for cooling computer systems.

BACKGROUND

Arrays of electronic computers or components, such as those found in data centers, generate a great deal of heat. An example central processing unit of a personal computer (“CPU”) generates over 100 watts of heat (some can generate much more than this) and has a maximum case temperature of about 60 C. An example array (or rack) of 88 CPUs may generate 9 kW of heat.

The standard way to keep data centers cool is to use expensive and relatively inefficient vapor-compression refrigeration systems at least part of the time. These conventional cooling or “air conditioning” systems often use more power that the computers themselves, all of which is discharged to the environment as waste heat. These systems use air as the heat transfer medium, and it is due to the low heat capacity and low thermal conductivity of air that refrigeration must be used to remove the heat generated by multiple air heat exchangers. Some operators use evaporation of cooling liquid to cool liquid-to-air heat exchangers. While this is more thermally efficient than refrigeration, the computers run hotter, reducing their reliability, decreasing their efficiency and making the data center uncomfortable for human occupants.

Water is used as the coolant throughout this disclosure, but it will be known to those in the art that other coolants may be used. Water has approximately 4000 times more heat capacity than air of the same volume, so water is a theoretically ideal heat transfer agent for direct heat transfer from heat-generating components. Other coolants offer similar performance. For example, the coolant may consist essentially of water, including tap water, or may comprise one or more perfluorocarbons or avionics cooling liquids. Liquid cooling is recognized as a thermally efficient way to cool computer CPUs due to their high concentration of power and heat generation in a small space, but the rest of a computer's electronics generate heat at a lower rate and temperature, so air-cooling may be more appropriate for much of the associated hardware.

Current systems may use liquid cooling to move the heat from the CPU to a radiator mounted close to the CPU, or they may use an air-to-liquid heat exchanger to remove heat from the computer enclosure. These systems suffer from the high thermal resistance and the bulkiness of air-to-liquid or liquid-to-air heat exchangers. Other systems use a chilled coolant loop to cool the computer, but these systems require complex and expensive connectors and plumbing to connect the server to the building coolant supply while ensuring that no leaks occur, which may be devastating in or near a computer. Accordingly, operators of server systems are rightly concerned about leaks and reliability of using liquids to cool computers. Furthermore, chillers require a large amount of power. Additionally, for operation in a data center, servers, particularly blade servers, need to be compact.

Therefore, what is needed is a compact cooling solution adaptable to cooling a large number of computers.

SUMMARY

The present invention provides an elegant solution to the needs described above and offers numerous additional benefits and advantages, as will be apparent to persons of skill in the art. A cooling system for a computer server is disclosed. The system includes a flow divider within the server enclosure interior constructed to create a continuous flow path. At least one fan is positioned within the flow path. An inlet air valve is positioned to regulate airflow across the server input air vent. Likewise, an outlet air valve is positioned to regulated airflow across the server output air vent. A controller is connected to the at least one fan, and the systems has two configurations. The first is a closed-loop configuration wherein (1) the inlet air valve is closed, preventing airflow across the input air vent; (2) the outlet air valve is closed, preventing airflow across the output air vent; and (3) the at least one fan is actuated to propel air, thereby circulating air throughout the continuous flow path. The second is an open-loop configuration wherein (1) the inlet air valve is opened, allowing airflow across the input air vent; and (2) the outlet air valve is opened, allowing airflow across the output air vent, thereby drawing air through the input air vent and propelling air out the output air vent.

The system may have at least two fans within the flow path, such that the closed-loop configuration further includes actuating the fans to propel air in different directions, thereby circulating air through the continuous flow path; and the open-loop configuration further includes actuating the two fans to propel air in the same direction.

The system may have a temperature sensor within in the server enclosure interior, which is connected to the controller, which may change the system configuration based on the temperature detected by the temperature sensor. The controller may actuate the open-loop configuration when the temperature detected by the sensor exceeds a predetermined value.

The server is liquid-cooled, and the system may have a temperature sensor constructed to detect the temperature of the liquid coolant. The sensor is connected to the controller, and the controller may change the system configuration based on the temperature detected by the temperature sensor. The controller may actuate the open-loop configuration when the temperature detected by the sensor exceeds a predetermined value.

The server includes a liquid-cooled cold plate that is coupled to a heat-generating device, such as a CPU, and is also coupled to an air heat exchanger, such as a set of fins on top of the cold plate.

The controller may change the system configuration by controlling the speed and direction of the at least one fan.

The inlet air valve and outlet air valve may be passively opened and closed based on the speed of the at least one fan. The inlet air valve and outlet air valve may be actuated by servos controlled by the controller. The inlet air valve and outlet air valve may be a butterfly air valve, a magnetic check air valve, a servo-actuated air valve, a spring check air valve, a weighted check air valve, and combinations thereof.

Additional aspects, alternatives and variations as would be apparent to persons of skill in the art are also disclosed herein and are specifically contemplated as included as part of the invention. The invention is set forth only in the claims as allowed by the patent office in this or related applications, and the following summary descriptions of certain examples are not in any way to limit, define or otherwise establish the scope of legal protection.

