NCI uses an innovative free cooling system to deal with all the heat produced by our supercomputer. This was one of the key design philosophies for the NCI Data Centre, completed in late 2012. The Data Centre’s free cooling system has covered around 74% of our cooling requirements since then, saving more than $200,000 annually.
Running over 80,000 computer cores 24 hours a day produces a lot of heat. In fact, Raijin runs at 95 degrees Celsius, requiring constant cooling. Free cooling is a system that uses the outside air temperature to eliminate the need for noisy, expensive and energy-consuming chillers. Fans are a crucial part of the system, by dissipating the heat produced by the computer through a series of radiators.
The Data Centre equipment racks are installed so that heat generated from the computers is sandwiched within a ‘hot aisle’ corridor between two rows of racks. The hot air is then drawn over cool water radiators and the heat is transferred to the water. The newly cooled air is then drawn back into the Data Centre to continue the cooling process.
Meanwhile, the hot water in the radiators is piped to some evaporative towers on the Data Centre roof. When the water evaporates, the heat inside it is transferred to the outside air. Canberra’s low humidity makes it an ideal place to employ free cooling. If the humidity does get too high for evaporative cooling to work efficiently, we do have some industrial chillers we can use to cool down the water.
Since beginning operation, we have been able to meet on average 74% of our cooling requirements using free cooling. This equates to a saving of around $212,000 in electricity costs annually. Overall, the estimated Power Usage Efficiency for the NCI Data Centre is 1.24, making it 250% more efficient than the average Data Centre in the United States.