Cooling equipment can account for 30 to 50% of total energy consumption in a data center. As today’s data centers look to utilize the most efficient cooling methods possible, direct evaporative cooling (DEC) offers an advantageous solution. The effectiveness of a DEC system can be directly attributed to the evaporative media selected to power the fixed evaporative cooling system.
Evaporative media selection is a process that should encompass meeting short-term needs while accounting for long-term goals. There are a few guidelines to consider when selecting the best evaporative media for the demands of data centers while specifically keeping in mind a sustainably savvy solution for years of good PUE.
As you begin researching manufacturers, make sure the media you’re considering is made of flame-retardant, inert materials fortified to provide superior strength and longevity. Why is this important? Given that data centers frequently experience fast startups and changes in demand, it is paramount the media is designed to follow fire codes and withstand the demands of the toughest HVAC environment. Additionally, selecting media with superior water absorption properties and saturation efficiency is important. This element allows the evaporative media to respond rapidly and provide the enhanced cooling performance required in data center environments.
Do you need evaporative media to operate at a high velocity? Review your options to ensure the design of the media is developed with increased rigidity to withstand the higher velocities demanded by the market while providing excellent performance at a low pressure drop and longevity without bowing or sagging. Well-designed evaporative media can absorb as much as five times its own weight in water, enabling efficient transfer of water molecules — the basis of good evaporative cooling technology. Media with low pressure drop and effective cooling performance optimizes PUE.
Today’s cutting-edge drift eliminators ensure that droplet carry-over is never a problem. Choosing an evaporative media with excellent drift elimination will ensure the air leaving the air-handling unit (AHU) remains clean and free from entrained water-mineral dust. With high-performing drift eliminators, cooling pumps may be switched on at maximum system airflows without the risk of water entrainment. This provides the benefit of allowing higher velocities, which means AHUs can be more compact.
It is also advantageous to confirm where the media you are selecting is manufactured. Product availability is a key attribute that many take for granted until they are in a crunch to get the mission critical supplies needed to meet a facility deadline. Turnaround time in today’s warp speed environment is crucial. Do not let the availability of media keep you from finalizing a vital changeout or installation — research the manufacturers.
Maintenance Considerations for Optimal PUE Over a Longer Period of Time
To ensure optimal PUE over a long period of time, some considerations must be made regarding the following areas.
The health and sustainability of evaporative media are directly affected by the water that is being used to generate cooling. Monthly water maintenance checks are recommended, with a specific focus on the pH level as well as other constituents of the water. Water contains minerals and scaling salts and is either acidic or basic. The pH and constituents of water are extremely important aspects of water quality used for DEC best practices. Generally, a high pH coupled with calcium and other dissolved salts will cause calcium scale deposits on evaporative media. High pH water is not only damaging to water pumps and distribution system performance because of scale formation, but a pH higher than 9 is damaging to the materials found in the evaporative media. Reducing the pH of the supply water is an option, as this reduces the point at which scale forms. It’s recommended to keep the pH levels between 6.5 and 8.5. Avoiding scale formation assists with the low pressure drop that's linked to a lower PUE.
There are a number of best practices to follow in order to keep evaporative media running optimally, which, in turn, results in a long-lasting, sustainable cooling solution. As you make your final decision on the partner to choose for media, look at it as just that: a partner. Research the manufacturer to see how involved the company is in helping customers during the early design phase, assisting with water quality advice, and troubleshooting equipment after installation.
Optimal cooling is both a short- and long-term process. Selecting the right evaporative media and following best practices can ensure reliable and sustainable data center operation.
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