It's time to revive some chilling ideas

Over in Australia recently, speaking at a datacentre event, I listened to a few other
presentations where some new ideas were being put across for low-cost, low-carbon approaches to datacentre cooling. Well, I say new ideas, but the two most interesting were actually based on technology that has been around for thousands of years in one case and dozens of years in the other.

Let’s start with the ancient one ­ the use of stove chimneys. When looking at ancient stoves and, in particular, smelting ovens, there is often a chimney topping off an enclosed environment that has an opening at the base to let in air.

Server racks provided by a company called Chatsworth Products take the same approach.

The idea is that the use of fans and forced air is minimised, as the design automatically pulls in cold air at the bottom, uses trunking to distribute it equally within the rack, using the updraft caused by the chimney as the main means of drawing in the cold air. A by-product is that the air used in cooling is highly specific ­ you are not cooling down the air in the datacentre, only the air that passes through the racks. In this way, the datacentre can be run at any temperature you like.

The volume of chilled air required is far less than that needed in typical datacentres, and with power costs for cooling one or more times those of the power costs required for running servers, switches, storage and so on, this could be a major saving.

The other item is from a company called KyotoCooling. Here, a simple rotary heat
exchanger, used since the 1960s as a heating mechanism, is reverse plumbed to give cooling capabilities instead. A “wheel” consisting of coiled corrugated metal sheeting is laid in a room, with a floor in line with the wheel, and a wall in line with its centre, creating four quadrants of space.

To envisage this, try to picture a large square with a horizontal and a vertical line creating four equally sized squares within it. The wheel will then lie along the horizontal line. Cold air is drawn into one quadrant from outside the
building and is passed through the small, high surface area metal channels in the wheel into the quadrant below and vented back to the outside.

The ambient temperature air cools the wheel as it passes through. The wheel turns slowly (about 4-7rpm), taking the mass of cool metal from the outer quadrants into the inner ones. These quadrants work in the same manner as the outer ones, except they deal with the air from and to the datacentre. Hot air from the datacentre is drawn into one quadrant and through the cool metal of the wheel, and is then vented back into the datacentre as the source for cooling the datacentre itself.

With an optimum efficiency at about 22 degrees Celsius, the KyotoWheel is good enough to be used across the majority of the major datacentre communities in the world. That it still works at up to 32 degrees Celsius, but at lower efficiencies, means it can still be used to offset expensive standard air conditioning systems in most datacentres.

So ­ no strange chemicals being pumped around; few moving parts other than a slow-moving wheel and some large air-moving fans; lower maintenance than air conditioning; longer predicted lifetime and fewer problems in recycling or dumping ­ it seems like a pretty good idea.

The downside is that the wheels can be big ­ up to eight metres in diameter and about half a metre thick. Finding space to retrofit such solutions may not be easy but KyotoCooling is worth considering for new-build datacentres.

Combining the two approaches could lead to even greater savings, making these tried-and-tested solutions a pretty attractive prospect at this time of ever-rising energy costs.

Clive Longbottom is service director at analyst Quocirca. Read the blog at: http://quocirca.computing.co.uk