EVAPORATIVE COOLING Strategies for data centres

Damien Power, Sales Manager for Ireland at Condair, looks at the different ways humidifiers can be used in data centres to provide low cost evaporative cooling.

Indirect evaporative cooling

Unlike a regular office temperature of around 23°C, a data centre’s upper temperature condition can be as high as 28°C. As Ireland’s temperature rarely rises above this level, many data centre cooling systems simply use the outdoor air rather than mechanical chillers to cool their data halls. During the warmer months, when the outdoor air becomes too hot to successfully lower the indoor temperature to 28°C or less, evaporative cooling can be used to give an additional boost to an air handling unit’s cooling capacity.

A kilo of cold water, when evaporated into the air, provides 0.68kW of adiabatic cooling. A cold water humidifier can supply around 1,000kg of moisture while operating on less than 1kW of electricity, so they offer great potential for low energy, high capacity cooling. Depending on the condition of the outdoor air, evaporative cooling from cold water humidifiers can offer a temperature reduction of up to 12°C.

More and more air handling units are being developed with an evaporative cooling element to take advantage of this low cost, low energy form of temperature control. Two main strategies have emerged for using cold water humidifiers to provide evaporative cooling in AHUs for data centres; direct and indirect.