Intelligent Data Centres Issue 1 - Page 42

FEATURE An adiabatic V cooler IT IS VITAL THAT WATER CONSUMPTION RATES ARE TAKEN INTO ACCOUNT NOW, IN ORDER TO PREVENT EXPENSIVE REPLACEMENTS FURTHER DOWN THE LINE. In terms of EER, this difference translates as an approximate EER of 4 (4kWth/1kWe) for a conventional compressor solution and an impressive EER of around 75 (75kWh/1kWe) for the equivalent ambient cooling solution. This of course, translates to substantial energy and cost savings for energy- hungry mission critical environments. But let’s concentrate on the water consumption. Given that cooling towers rely on evaporative cooling throughout the year, achieving little to no sensible cooling, and hybrid systems begin to evaporate water in ambient temperatures as low as 10°C, it will be no surprise that adiabatic coolers consume less than 1% of the water used by traditional cooling towers and approximately 2–4% of that used by wetted surface hybrid coolers. Even when operating in wet mode, adiabatic systems automatically vary the amount of water used to minimise consumption whilst still hitting required water temperatures in varying ambient conditions. If we examine those figures more closely, as water consumed in cubic meters over a one-year period for a 1000kW unit, an adiabatic cooler consumes 92 m³of water, compared to a wetted surface hybrid cooler which requires 8,647 m³ and a conventional 42 Issue 01 cooling tower which is more in the region of a staggering 18,220 m³. innovate technologies which preserve both power and water. Latent heat of evaporation dictates that for every kW of heat that a cooling tower dissipates it must evaporate 1.6kg of water. Without a doubt, water is more abundant here in the UK and for the next few years, the importance of water conservation isn’t likely to reach critical levels for us. On top of this, in order to stop cooling tower base tanks from being clogged with the residual scale left over from the evaporation process, an additional amount of water must be bled off and replenished from a mains water supply. Depending on how hard the water is, this can add an additional 20% to 100% water consumption on top of the water evaporated. At a typical 30% increase this means that the total water consumed is 2.08kg per kW of cooling. But when specifying water-consuming plant designed to last in excess of a decade, it is vital that water consumption rates are taken into account now, in order to prevent expensive replacements further down the line, when the government inevitably regulates water consumption in the data centre market. ◊ For a typical 1,000kW cooling system this gives a cooling tower water consumption of 2,080kg every hour. In contrast, adiabatic coolers, designed with water conservation in mind, would typically consume 350kg every hour and only for 3% of the year rather than 100% of the year. Water-conscious specification Specifiers, whether working on a large- scale data centre project or a smaller facility can uphold their moral obligation by working with manufacturers who Tim Bound, Director for Transtherm Cooling Industries www.intelligentdatacentres.com