In a recent survey conducted by the Uptime Institute, enterprise data centre managers responded that 39% of them expected that their data centres would run out of cooling capacity in the next 12-24 months and 21% claimed that they would run out of cooling capacity in th next 12-60 months. The study also revealed that bypass airflow is the main culprit in causing this problem. This situation is one in which conditioned air does not reach the equipment.
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| Why Server room cooling is critical? |
The primary cause reported of electronic device failures is overheating. Servers also contain many other electronic and electromechanical components that are susceptible to heat- induced failure. Simply put these machines will crash which means no data flowing to workstations, no e-mail and no access to the life blood of your company. |
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| How’s of server room cooling |
Although there are many aspects that go into the planning and construction of a data centre, cooling the room and maintaining proper humidity to keep static under control and deliver the right combinations to the right places at the right time is an essential part of that plan. There are a variety of methods that can be used to provide cool air for a data centre some are more suitable for floor mounting than others. In some cases, the right solution for a company may be a combination of the following methods :
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Evaporative
Evaporative cooling works by evaporating water into the air. An evaporative cooler must be used with adequate ventilation. The amount of cooling depends upon the area’s humidity. In humid environments cooling will average 8 to 12 degrees and in dry environments 20 to 28 degrees. This type of cooling can alleviate heat problems in large areas but isn’t a good choice for most server rooms but may serve a purpose in very large data centres.
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Split cooling
Split cooling consists of two pieces, a room unit and an outside condenser. Sometimes this is referred to as direct expansion cooling. The units are connected together by a refrigeration pipe that works with refrigerant. The external unit may take one of three forms
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- A heat pump, which consists of a fan, compressor, coil and reversing valve, rejects unwanted heat into the atmosphere during the cooling cycle but can also extract heat from the atmosphere during the heating cycle.
- A condensing unit without a reversing valve provides cooling only.
- A condenser, which consists of a fan and coil. The compressor is contained in the indoor unit. This method is used less often than other split cooling methods.
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Water or liquid cooled
These are refrigeration systems that chill liquids, such as water, oil, brine, alcohol or various air conditioning systems, the devices cools the liquid, typically water and the cooled water chills and dehumidifies incoming circulated air. The system then releases the chilled air back into the atmosphere.
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| Checklist |
Computer equipped cooling air, delivered from a raised floor air source, can be optimized by applying some basic thermal management concepts. This checklist reviews key considerations in applying these principles.
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| Check 1- Manage the air movement under the floor tiles. |
Sealing off all the escape points for bypass air- air that is escaping from under the floor – increasing the static pressure under the raised floor, increasing the air flow (CFM) at the points of need. |
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| Check 2- Manage how the cooled air is actually delivered to equipment |
Do not locate computer room air conditioning units (CRAC) are at right angles to each other. A computer room with all the air and cable running in the same parallel direction is the best way to make air direction both below and above the floor predictable. |
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| Check 3- Apply the same management principles to cabinets. |
If the bypass air elimination produces adequate CFM through all the perforate floor tiles, the cabinet should either have no doors or if required for security, doors with a minimum 60% open mesh for maximum air flow with no top mounted fan kits. |
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| The Right Conditions |
Regardless of the method of cooling incorporated into a server room or data center the temperature and humidity must be properly maintained. Though opinions vary, it is generally accepted that temperature should be between 68 degrees and 75 degrees relative humidity between 40-50%. |
