Ventilation – Electronic cabinet
Reexamination Certificate
2001-11-08
2003-09-09
Joyce, Harold (Department: 3749)
Ventilation
Electronic cabinet
C062S419000, C062S426000, C361S678000, C361S696000, C454S186000, C454S306000, C454S903000
Reexamination Certificate
active
06616524
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an air handling system. More particularly, it relates to an air conditioning/heating system for use in computer rooms and data centers to provide climate control for electronic equipment such as computers, servers, routers, switches and other networking equipment.
BACKGROUND OF THE INVENTION
Operators, managers, designers, and developers of large data centers and computer rooms are constantly striving to put as much computer hardware into their available space as they can. This has led to tall, compact, double-sided rack systems set atop raised computer room floors. At the same time, computing speed is increasing per Moore's law due to the demand for and development of more complex software and interfaces. This also leads to more heat generation. These two factors combined have greatly reduced the effectiveness of traditional cooling systems, such as Computer Room Air Conditioners (CRACs), Computer Room Air Handlers (CRAHs), In Space Units (ISUs), etc.
In the past, most large data centers and computer rooms have utilized many small packaged CRACs or CRAHs located atop the raised floor amongst the computer and server equipment. Both of these systems pull warm air in at the top (~5-6′ above the raised floor), condition the air (per temperature and humidity setpoints), and provide cool air to an underfloor plenum (under the raised floor). Air is then passively allowed out of the underfloor plenum through the use of perforated floor tiles.
The heat that is pulled out of the air is then transferred out of each of the CRACs or CRAHs via underfloor condenser or chilled water piping systems to cooling towers and/or chillers located outside of the data center. Each CRAC or CRAH is also served by condensate and makeup water piping for humidity control. All of this piping interferes with the cool air that is being distributed under the floor and decreases the air supply or static pressure. Also, if the condenser water piping is not insulated, the heat in the condenser water can be transferred to the air under the floor before it has a chance to cool the servers and computers, thus providing warm air supply to the servers and computers.
Since the cool air is passively allowed out of the underfloor plenum, the distance that the air moves out of the perforated tiles relies on the pressure from the CRACs or CRAHs, the number of perforated tiles, the size/quantity of perforations, and the amount of space served by the CRACs and CRAHs. However, even if high pressure blowers were utilized in the CRACs, there can still be areas where there is not enough cool air coming out of the floorspace.
Also, since warm air rises and cool air drops, natural convection typically overpowers the trickle of cool air from the floor tiles. Without active circulation in place (natural or otherwise), the air stratifies into different temperature layers. This results in higher supply and operating temperatures on servers at the tops of the racks. With a traditional data center cooling system, temperatures of 80 to 90° F. (or more) have been seen at the intake of servers from the middle to the tops of the racks versus the 60 to 70° F. available under the raised floor.
At elevated temperatures, electronic components can fail catastrophically or the electrical characteristics of the chips can undergo intermittent or permanent changes. Manufacturers of processors and other computer components specify a maximum operating temperature for their products. Most devices are not certified to function properly beyond 50° C.-80° C. (122° F.-176° F. However, a loaded server/computer with standard cooling can easily experience operating temperatures that exceed the limits. The result can be memory errors, hard disk read-write errors, faulty video, and other problems not commonly recognized as heat related.
There have been many studies by public and private agencies over the years that have found that the life of an electronic device is directly related to its operating temperature. These studies, based on empirical data, were used to create models/standards for determining electronic equipment reliability. (MIL-HDBK-217, Bellcore TR-332, and the Arrhenius equation are examples.) Based on the Arrhenius equation, it can be seen that each 10° C. (18° F.) temperature rise reduces component life by 50%. Conversely, each 10° C. (18° F.) temperature reduction increases component life by 100%. Therefore, it is recommended that computer components be kept as cool as possible for maximum reliability, longevity, and return on investment.
It is the objective of this invention to provide cool air evenly to the electronic equipment, eliminate the air stratification, extend the life and increase the reliability of electronic equipment while minimizing the impact on the floorspace, since space on a computer room or server room floor is typically a commodity.
SUMMARY OF THE INVENTION
The present invention takes the form of raised floor air handling units. The units actively pull cool air from the underfloor plenum through a custom raised floor tile with bulkhead fittings to flexible anti-static fabric ductwork supported vertically (or other air distribution systems). This ductwork then directs the cool air equally across the face of all electronic equipment on each rack or cabinet via nozzles, reinforced linear slots, or other air distribution methods. This, coupled with a properly designed computer room cooling system, eliminates heat added to the room and the associated stratification. Therefore, with a cooler air supply to all of the servers from the raised floor air handling units, the annual cost for server replacement (not including interruption of service) could be reduced by as much as 50%. Note that additional savings can also be achieved by the elimination of problems from customer dissatisfaction associated with the equipment overheating issues, which is typically more valuable than the replacement costs. Financial losses from possible disruption in service due to overheating would also be reduced.
By implementing the raised floor air handling units, the typical computer room air conditioning units can be eliminated and centralized air handling or air conditioning systems can be installed remotely on roof or in a mechanical room to handle the climate control, move the cool air under the floor, and pull the warm air back from above the racks. In new construction, it not only eliminates the installation cost of the CRACs, CRAHs, and ISUs, but also the associated piping and wiring under the floor. This would, in turn, save on energy costs associated with the losses in the piping and electrical.
Also, since the raised floor air handling units can be installed in walkways in front of the server racks and allow a person to still use the walkway, the additional floorspace freed up by the elimination/relocation of the computer room air conditioning units can be used to generate additional revenue and/or allow the installation of more computer racks.
REFERENCES:
patent: 5345779 (1994-09-01), Feeney
patent: 5403232 (1995-04-01), Helm et al.
patent: 6318113 (2001-11-01), Levy et al.
patent: 2002/0025775 (2002-02-01), Herbreteau
Ray Jay D.
Storck, Jr. Gary A.
Weigel Wesley W.
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