The BIG Data Center Debate - Air vs Water Cooling

So, the BIG question for many consulting engineers today: "Should I choose Evaporative Air or Water Cooling for my Data Center?"

At QCooling our feet are firmly in the Water Cooling camp and here’s the reasons why………

The volumetric heat capacity of water is 3317.63 times more than air, making it far more efficient when it comes to transferring heat. You can cool one 8KW rack with just 1.8m3/hr of water. You’d need 3200 m³/hr of air to achieve the same effect. To put that into context, it’s equivalent to 47 x 40ft trucks of air going through the Data Center every hour!

You then need to consider how you move that amount of air around your White Space. So, your isles need to be wide enough to move the cool air into the racks, which in turn loses rack density and subsequent revenue loss. Alternatively, you have huge raised floors within the Data Center which obviously has an associated cost.

In addition, ensuring that either the last rack gets enough air, with an open louvred wall system, or the bottom or top U’s in each rack in a raised floor system, is always difficult when you’re battling commonly occurring hot spots. If you use the raised floor option, transferring loads from racks to racks as they fire up is impossible and therefore air flows all the times, even when it’s not needed. This then dilutes the return air temperatures and reduces the efficiency of your system.

Other Data Center Cooling Options

In fairness, there are other options. For example, you could have a raised floor with a contained cold isle although the flip side is that the rest of the Data Center would be at 95°F plus (with any higher than normal density this could be over 104°F) so health and safety and the well-being of employees become issues – just think, would you really want to work in a high temperature hurricane!?

If you opt for a louvered wall system, large hot air removal plenums above the room are required but, again, getting the air to the racks requiring it still remains an issue. You can add ancillary items, such as exhaust hoods to “help the air flow”, but in reality these use up capital unnecessarily and additional energy is required by the fans in the chimney systems.

Water cooling is so much more efficient at removing and transferring heat than air is – fact!

Modern Data Center Cooling

The majority of modern Data Center Cooling air systems rely on large amounts of external air, or adiabatically cooled air, which is drawn over large air to air heat exchangers. Two issues become created here, the power of the fans to achieve this and the cost and amount of maintenance of the filters involved which is time consuming and also costly.

The adiabatic water spray systems can drain lakes in high summer temperatures which means large volumes of water need to be made available as a contingency for around 48 or 72 hours. This contingency is very sizeable and weighs thousands of pounds. Or, if this is unacceptable, a refrigerant dx back up system has to be installed, with its own costs and refrigerant systems that are asked to run in emergency.

The potential issue here however is that you can’t guarantee the reliability of equipment if it’s been stood idle for months, perhaps only ever switched on during maintenance.

A Water-Cooled system combines the best of both worlds, much more efficiently and effectively and requiring less space and real estate. Maximum rack density is ensured with a guarantee of Hot Spot removal. This results in increased resilience, with efficiencies at least the same as with an Air to Air system, all for no extra cost. If you then look at natural source cooling, such as bore holes or river/sea water, efficiencies and savings go through the roof.

If you already have an air system in place but are experiencing problems with air flow or Hot Spots, a Water-Cooled system can be retro fitted to a live Data Center environment. This rejuvenates your existing system, removes problematic Hot Spots and increases density and efficiency of your set up!

Call QCooling on 1-866-307-7333 today if you have a requirement for Data Center cooling!