Chillers for Computer Rooms, Server Rooms & Data Centers
As the data center industry becomes more energy conscious, mechanical chillers have come under fire. The attention is warranted, for chillers represent the most energy intensive component in the entire cooling process.
Despite this pariah status in efficiency circles, chillers are essential to keeping data centers cool. And, through good engineering and planning, they can be optimized.
Chillers use the refrigeration process to create chilled water, supplied through a series of pumps and valves to computer room air conditioners. The water circulates through the cooling coil, where it accepts heat generated by the IT equipment and returns to the chiller to be cooled. This perpetual cycle is supported through a series of interconnected parts in the chiller: an evaporator, a compressor, and a condenser.
Chiller efficiency is measured in kW/ton, a ratio that compares the energy required by the chiller to produce a ton of cooling.
In reality, free cooling is not without costs. But it can be extremely effective. Free cooling uses the environment to produce cooling. And economizers are the tools of the trade. A water side economizer uses outside air, instead of refrigeration, to supply chilled water to computer room air conditioners. An air-side economizer introduces outside air to the data center whenever the temperature is appropriate, replacing continuous air conditioning.
Since data centers work days, nights, weekends, and holidays, nearly all geographies can attain some savings through free cooling. Those with the most temperate environments, however, will see the largest returns.
Chiller Optimization: Maximizing Delta T
Delta T is a key design setpoint for any heat exchanging device. Chillers and air conditioners operate more efficiently as Delta-T equals (or sometimes exceeds) this setpoint. So, how can users impact it?
Air mixing is endemic in many data centers. Cool air often mixes with hot air as it's returning to the air conditioner, which lowers Delta-T on the air side and subsequently affects Delta-T on the water side. Aisle Containment strategies (either hot aisle or cold aisle) prevent these air paths from mixing and allow the cooling system to realize Delta-T benefits from the air conditioners through the chiller.
When the air doesn't have far to travel, you can maximize delta T even further. Close-coupled cooling products immediately capture server exhaust air, ensuring the cooling coil receives the hottest possible air.
Top Chiller Systems