Indirect free cooling in combination with adiabatic humidification – this is the principle of the GEA Adia-DENCO® cooling system.
This system, which has been especially developed for climate control of computer centers, is based on the design of the proven GEA CAIR air-handling units. It offers rated air flow of 25,000 m³/h with cooling duty of 100 kW. The extremely low annual operating costs of the GEA Adia-DENCO® cooling system enable its amortization after a short period.
At outdoor temperatures under 6 °C, the indirect free cooling alone of the GEA Adia-DENCO® is sufficient to completely extract the thermal load produced. At this operating point, all additional cooling sources (adiabatic sources as well as compression-refrigeration cooling) are switched off. The highly efficient EC fans in the outside-air flow operate at their minimum speed and assure that the temperature of the supply air for the computer center does not exceed 25 °C. At outdoor temperatures between 6 and 22 °C, it suffices to control only the EC fans steplessly up to their maximum speed level. It is only at temperatures above 22 °C that adiabatic cooling is required. The integrated open- and closed-loop control system finds the energetic minimum here between the fan output and the required adiabatic cooling. Depending on the output demand from the computer center and at outdoor temperatures over 29 °C, the adiabatic cooling system is supported by an additional peak-load cooler. It can as option be designed for 100 % cooling duty for purposes of redundancy.
The adiabatic cooling system is based on the simple principle that evaporating water removes heat from its surroundings. With the GEA Adia-DENCO®, cooling takes place energy-efficiently in a large double-plate heat exchanger. The warm outdoor air is first humidified, which cools it, and is then sent to the recuperator. This dual recuperator then cools the entering warm return air from the computer center by hermetically sealed heat exchange. The large surface involved here enables highly efficient operation at all operating points, with low pressure drop.
As a result of its performance profile, the new GEA Adia-DENCO® cooling system satisfies the new environmental recommendations for computer centers, which advise maximum supply-air temperatures of 27 °C. The very low number of annual hours with outside temperatures above 29 °C (in moderate climates) reduces the annual energy requirements for compression refrigeration to an absolute minimum – or renders it entirely unnecessary. As a result of this extensive reduction of the compression refrigeration required, operators of computer centers can save up to 70 % of required energy and correspondingly reduce their operating costs. And this applies in all moderate to cold climate regions of the world.