The EnergyPlus Indirect Research Special is similar in principal to the Indirect CelDekPad and Indirect WetCoil evaporative coolers, but it provides some additional flexibility. It is provided for advanced users who will export the model to EnergyPlus and edit further there.
Important note: DesignBuilder does not fully implement this component. To access the extra flexibility you should export the model to EnergyPlus. This will allow you to a) to specify the source of secondary air if this is not standard outside air and b) control the amount of cooling based on node setpoints, controlled by Setpoint managers avoiding problems from over cooling when conditions are such that loads are low and cooling power is high.
The cooler effectiveness with respect to wet-bulb depression is allowed to go beyond 1. Fan power is assumed to vary linearly when the cooler is operating at less than full capacity.
A unique name for an instance of an evaporative cooler which is predetermined by DesignBuilder.
This field specifies the maximum effectiveness that is applied to the wet-bulb depression to determine the conditions leaving the cooler. This effectiveness is a complicated function of the efficiency with which heat and mass are transferred on the secondary side and the efficiency of heat exchange between the secondary and primary flows. The model assumes that the effectiveness is constant.
This field specifies an effectiveness that is applied to the dew-point depression to determine a bound for the conditions leaving the cooler. The model uses the warmer of the two temperatures determined from wet-bulb depression and dew-point depression.
This field is optional and can be used to model additional water consumed by the cooler from drift. Drift is water that leaves the cooling media as droplets and does not evaporate into the process air stream. For example, water may get blown off the evaporative media by winds and escape the air system. The value entered here is a simple fraction of the water consumed by the cooler for normal process evaporation. The amount of drift is this fraction times the water evaporated for the normal cooling process. This field can be left blank and then there will be no added water consumption from drift.
This field is used to specify the power consumed by the water pump that circulates water (in W). The pump power and energy consumption is reduced by cycling when the amount of cooling needs to be restricted for control purposes.
This field is used to specify the secondary fan flow rate and is specified in m3/s or ft3/min.
This field is used to specify the total efficiency of the fan and is used to calculate the power consumed by the evaporative cooler secondary fan. Input values should be between 0 and 1.
This field is used to specify the delta pressure across the secondary stage of the evaporative cooler (in Pa or in H2O).
Select this option to model additional water consumed by the cooler from blowdown. Blowdown is water that is intentionally drained from the cooler’s sump to offset the build up of solids in the water that would otherwise occur because of evaporation.
The value entered here is dimensionless. It can be characterized as the ratio of solids in the blowdown water to solids in the make up water. Typical values are 3 to 5. The default is 3.0.
Schedule that defines when the coil is available, i.e. whether the evaporative cooler can run during a given time period. A schedule value greater than 0 (usually 1 is used) indicates that the unit can be on during a given time period. A value less than or equal to 0 (usually 0 is used) denotes that the unit is off.