Evaporative Cooler Data

Evaporative cooler components can be placed within AHUs in much the same way that water and DX cooling coils are placed. They can also be selected as outdoor air pretreatment components within the AHU dialogs.

An evaporative cooler provides cooling to an air stream purely through the evaporation of water. Evaporative cooling differs from typical air conditioning systems which use vapour-compression or absorption refrigeration cycles. Evaporative cooling works by employing water's large enthalpy of vaporisation. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapour, which requires much less energy than refrigeration. In dry climates, it also has the added benefit of conditioning the air with more moisture for the comfort of occupants. Unlike refrigeration, it requires a water source, and must continually consume water to operate.

As water is evaporated, energy is lost from the air, reducing its temperature. The lowest temperature that an evaporative cooler can cool to is the incoming air wet-bulb temperature.

Two types of evaporative cooler are supported by DesignBuilder EnergyPlus: direct and indirect systems.

• Direct evaporative cooling (open circuit) is used to lower the temperature of air by using latent heat of evaporation, changing liquid water to water vapour. In this process, the energy in the air does not change. Warm dry air is changed to cool moist air. The heat of the outside air is used to evaporate water.
• Indirect evaporative cooling (closed circuit) is similar to direct evaporative cooling, but uses some type of heat exchanger. The cooled moist air never comes in direct contact with the conditioned environment.

EnergyPlus provides 5 types of evaporative coolers any of which can be selected when placing the component or from the Evaporative cooler dialog:

• 1-Direct CelDekPad
• 2-Direct Research Special
• 3-Indirect CelDekPad
• 4-Indirect Wet Coil
• 5-Indirect Research Special