Air vs. Water Cooled Chillers: Which is Best for Data Centers? - Trane

Which chiller type is best for data centers: air cooled, or water cooled? There’s no single answer. HVAC system designers need to ask a lot of questions before advocating one type of chiller over another. The obvious equipment choice is sometimes over-ruled by unique project factors including the available square footage, backup power strategies, local regulations limiting power and water use, or the owner’s sustainability priorities.

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Ideally, data centers will consult with the HVAC company on the front end of the design process to make sure the solution meets short- and long-term objectives. If you’re the one making the decision on behalf of a data center, it helps to understand the pros and cons that are inherent to each type of chiller.

Capacity: Packaged air-cooled chillers are typically available in sizes ranging from 7.5 to 500 tons [25 to 1,580 kW]. Packaged water-cooled chillers are typically available from 10 to 4,000 tons [35 to 14,000 kW]. In other words, water-cooled chillers can deliver higher cooling capacity with fewer units and a smaller footprint.

Maintenance: Air-cooled chillers eliminate the need for cooling towers. Water-cooled chillers require cooling towers, which have critical maintenance demands: water treatment, chiller condenser-tube cleaning, tower mechanical maintenance, and freeze protection. Systems that use open cooling towers must have a water treatment program to prevent contaminants such as bacteria and algae. Cooling towers also evaporate water so you will need access to a large supply of make-up water to replace the evaporated volume.

Location: The pursuit of cheap power and lower taxes is changing the face of the data center industry, placing huge facilities in remote locations far removed from the users. If placed in location where temperature drop below freezing, air-cooled chillers can be easier to operate , because they eliminate the problems associated with operating a cooling tower in severe winter conditions. Cooling towers may require special control sequences, basin heaters, or even an indoor sump for safe operation in freezing weather.

Energy efficiency: Water-cooled chillers are typically more energy efficient than air-cooled chillers. The refrigerant condensing temperature in an air-cooled chiller is dependent on the ambient dry-bulb temperature. The condensing temperature in a water-cooled chiller is dependent on the condenser-water temperature, which is dependent on the ambient wet-bulb temperature. Since the wet-bulb temperature is often significantly lower than the dry-bulb temperature, the refrigerant condensing temperature (and pressure) in a water-cooled chiller can be lower than in an air-cooled chiller. The lower condensing temperature, and therefore lower condensing pressure, means that the compressor needs to do less work and, subsequently, consumes less energy. This efficiency advantage may lessen during nighttime operation because the dry-bulb temperature tends to drop faster than the wet-bulb temperature when the sun goes down.

Delivery & Installation: Most air-cooled chillers are “packed systems.” The system, including the condenser, compressor, and evaporator, is designed and configured at the factory for optimal performance and reliability, which reduces design and delivery time and simplifies installation. Water-cooled chillers have the added complexities of condenser-water piping, pumps, cooling towers, and controls.

Longevity: With the continued technology advances and growth in more data processing, the data center infrastructure needs to be able to support these advancements while delivering consistent performance. In general, air-cooled chillers last 15 to 20 years while water-cooled chillers last 20 to 30 years.

Partially, it’s because water-cooled chillers are typically installed indoors and operate at lower condenser fluid pressure, while air-cooled chillers operate outdoors, at higher condenser pressure.

Water conservation: Water availability, cost, treatment requirements as well as potential additional construction complexity all play a role in system selection. Since air-cooled chiller do not require water, they are often a preferred choice especially in locations where there is a water shortage, or the water is very expensive.

Water is one of two major resources data centers consume [1] . Combined, US data centers were responsible for consumption of 626 billion liters of water in , which includes both water consumed directly at data center sites and water used to generate the electricity that powered them that year. However, as the report points out, far more water is used to generate electricity that powers data centers than to cool them so chiller efficiency again comes back into consideration.

In summary, air-cooled chiller advantages include lower maintenance costs, a prepackaged system for easier design and installation, and better performance in freezing temperature. Water-cooled chiller advantages include greater energy efficiency, larger capacities, and longer equipment life. Yet, the best choice for the project may also depend on an entirely different set of decisions criterial. It’s important for data centers and system designers to take all factors into consideration to make sure the chiller that ultimately gets specified balances all the objectives over the long term.

Chillers play an important role in many industries. They help keep medical machines running consistently, and they keep milk cool until it goes to markets. They assist in the pharmaceutical industry, the brewery industry, and in meat and poultry processing. If you’re looking for a chiller for your business, one of the things you’ll have to decide is whether you need an air-cooled chiller or a water-cooled chiller. To assist in your research, here are the main advantages and disadvantages of water cooled chillers.

Advantages of Water Cooled Chillers

Life expectancy longer

Water cooled chillers do not usually need to be replaced as often as air cooled chillers. They are unaffected by outdoor factors such as rain, snow, ice, and heat and make them less vulnerable.

Quiet operation

Although air cooled chillers have pipes and vents producing noise, water cooled chillers work quietly. Water flows through the system does not create the same noise in the air cooled cooler, causing expansion and contraction. Quiet operation is especially important in the environment where passengers and passengers may experience noise such as hospitals and schools.

Energy efficiency

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In water-cooled chillers, the film factor is 10 to 100 times better than air-cooled chillers. This means that water-cooled refrigerators deliver heat more efficiently. The result of the business is to save energy costs.

Safety

It use water as a refrigerant instead of toxic chemicals. This makes items and people safer who comes in contact with it.

Disadvantage of Water cooled Chillers

Higher Cost

Air cooled chillers are cheaper than water cooled chillers because they don’t require parts like cooling towers and condenser water pumps. Many companies feel that the longer lifespan and savings on energy costs make water-cooled chillers worth the initial high investment, however.

More Maintenance

Since water cooled chillers have more parts, they require more maintenance. Companies should prepare to pay for periodic inspections, water treatments to remove impurities, and regular cleaning of the chiller’s machinery. More maintenance also means more downtime for the chiller. The more parts a machine has, the more things there are that can go wrong with the machine, which means water cooled chillers are more likely to require repairs than air cooled chillers.

Complicated Installation

The extra parts in water cooled chillers also make installation more of a hassle. This can mean higher labor costs for installation of water-cooled chillers as opposed to air-cooled chillers.

Requires Mechanical Room

Businesses need to have a mechanical room to house a water cooled chiller. This is to ensure that the chiller will function properly with its cooling tower and extra components.

Not Ideal For Drought-Stricken Areas

Since they use a good amount of water, water-cooled chillers aren’t great in regions that have water shortages. Companies that pay water costs can expect these bills to rise with the use of a water-cooled chiller. Some drought-stricken areas also have restrictions on water-cooled chiller use.

Less Efficient in Humidity

Although water cooled chillers are overall more efficient than air-cooled chillers, they'll operate less efficiently in humid environments. This is because humidity raises the wet-bulb temperature, which indicates how efficiently water absorbs heat. Water-cooled chillers in humid environments may also make building occupants feel cold and clammy.

About Kaydeli  

Kaydeli designs, researches and developes, operates “Kaydeli” brand chiller, heat recovery unit, environmental chiller, laser chiller, cold oil machine, mold temperature chiller, low temperature freezer, we are professional in the engineering and manufacturing cooling and temperature control equipment. We are among top 10 in the cooling equipment field in China, introduce a lot of advanced technology from America, Japan, Germany, and also develop our own technologies, achieve several patents over the past decades.

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