Evaporative Cooling Case Studies
Cooling Cambridge University Data Centre - Phase 2
The project was to provide cooling for a second new data centre within the Engineering Department where high density racks were to be used.Four CRECs were used to provide 90kW of cooling with N+1 redundancy. Air is fed directly into the cold aisle and the supply and extraction is provided by Electrically Commutated (EC) axial fans which provide the lowest energy air flow available.
At full design load these fans consume less than 5kW, which means their use will only add a maximum of 0.05 to the PUE. In addition since the data centre is currently only partly populated the variable speed EC fan exploits this and energy use is further improved. The current energy use is less than 2% of the IT cooling load.
The air is supplied to a ceiling void and then filtered through G4 grade cartridges. This allows a large number of filter elements to be installed with minimum cost and space requirements. This is the first installation of its kind to be used with a fresh air system to provide a dust free environment at a fraction of the cost of normal filters.
The control system designed by EcoCooling using Schneider Crouzet PLC, controls airflow, humidity and temperature within the data centre as well as linking to the fire alarm system. These controls directly interface with a Honeywell Trend BMS for data and fault reporting
The data centre is run at the lower end of the ASHRAE temperature standards at 18.5°C. This costs no more to achieve but gives a more comfortable environment for operators and also reduces temperature related failures. Temperatures within the data centre may rise to up to 24°C on the very hottest days but this is within ASHRAE guidelines. Colder temperatures which can result in server shutdowns are prevented by the use of a patented attemperation system which mixes the hot air from the servers back into the air coming into the server room maintaining the room at the set temperature. The control system dynamically changes the air supply set point automatically to control the maximum RH Level so that ASHRAE compliant conditions (20-80%) are achieved at all times.
The new data centre is currently running at a PUE of less than 1.06 and this has resulted in recurrent savings for the Department of Engineering and also the option to consider expansion of its server capacity in the future.