| There are various designs of Adiabatic or hybrid cooler, which are basically dry coolers that have a spray or water trickle system to precool the air prior to it reaching the coil through which the cooling water flows. Precooling of the air is only required at higher ambient temperatures so for much of the time the unit operates as a standard dry cooler. They are generally less energy efficient than open evaporative cooling towers but have similar power requirements to evaporative closed-circuit towers. Adiabatic coolers are typically able to cool water to within 6 deg C of the prevailing wet-bulb giving minimum design cold water temperatures for the UK of 24-26 deg C. Whilst there may not currently be a requirement to register this type of system under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992. It is important to assess the risk of legionella in such systems and take appropriate measures. It is likely that some form of water treatment of the equipment will be required and the equipment monitored and risk assessed for legionella. |
