The coolant is usually a mixture of water and glycol with the proportions determined to avoid icing (a function of the absolute minimum temperature that the coolant could experience).  The coolant supplied to the heat exchangers can be supplied by several methods, including mechanically actuated refrigeration cycles (e.g., propane cycles), absorption chillers, and ice storage systems.  In the example provided, the cooling would have an effect of up to a 22% increase in power and a reduction in heat rate of as much as 6.5%, even considering the additional 1 inch of H2O pressure loss introduced by the coils and the mist eliminator.  The actual power increase may be limited so as not to exceed the driver and driver equipment ratings.  The effect of 1 inch of H20 permanent inlet pressure loss has to be taken into account when the unit operates with the chiller off.  The chilling coils are normally placed downstream of the filter cartridges in the clean-air path inside the filter house itself. This will result in a zero fouling factor for the chilling coils and a reduction of maintenance requirements. A mist eliminator is provided downstream of the coils to prevent condensed water droplets from entering the inlet duct and causing erosion or FOD damage to the axial compressor. Moreover, the transition duct between the filter house and the inlet duct is symmetrical in order to ensure flow uniformity over the surface of the coils. This feature, together with the placement of the coils inside the filter house, ensure an airflow speed over the surface of the coils low enough to avoid the risk of water carry-over. The heat exchangers are usually of the plate-and-fin type. These exchangers are characterized by tubes running through plates that cover the entire height of the coil set. The tube material is usually copper and the plate material is aluminum.  The mist eliminator is of the inertial type and will capture most of the condensed water droplets that may have been carried over by the air stream.  In retrofitting existing units, the filter house must frequently be modified by inserting the chilling module and modifying the supporting structures in order to accommodate the transition duct between the filter house and the inlet duct. In the event that the filter house provides both ventilation and combustion air, splitting the two streams may be required in order to avoid wasting cooling power and feeding saturated ventilation air into the enclosures.  Due to the continuous presence of saturated air, a stainless steel inlet duct and plenum are usually needed.