modelCoolingCoilHumidifyingHeating
Extends from Buildings.Applications.DataCenters.ChillerCooled.Equipment.BaseClasses.PartialCoolingCoilHumidifyingHeating.
Information
This model can represent a typical air handler with a cooling coil, a variable-speed fan, a humidifier and an electric reheater. The heating coil is not included in this model.
The water-side valve can be manipulated to control the outlet temperature on air side, as shown in Buildings.Applications.DataCenters.AHUs.Example.AirHandlingUnitControl.
It's usually undesired to control the outlet air temperature by simultenanously manipulating the water-valve and reheater, because energy waste could happen in this case. For example, under the part-load condition, the water valve might be in its maximum position with the reheater turning on to maintain the outlet air temperature. To avoid that water-valve and reheater control the outlet temperature at the same time, a buit-in reheater on/off controller is implemented. The detailed control logic about the reheater on/off control is shown in Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat.
The humidfier is an adiabatic spray air washer with a prescribed outlet water vapor mass fraction
in kg/kg total air. During the humidification, the enthalpy remains constant.
Details can be found in
Buildings.Fluid.Humidifiers.SprayAirWasher_X. The humidifer can be turned off
when the prescribed mass fraction
is smaller than the current state at the outlet, for example, XSet=0.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | yValSwi | Switch point for valve signal | |
| Real | yValDeaBan | 0.1 | Deadband for valve signal |
| Modelica.Units.SI.TemperatureDifference | dTSwi | 0 | Switch point for temperature difference |
| Modelica.Units.SI.TemperatureDifference | dTDeaBan | 0.5 | Deadband for temperature difference |
| Modelica.Units.SI.Time | tWai | 60 | Waiting time |
| Valve | |||
| Real | R | 50 | Rangeability, R=50...100 typically |
| Real | delta0 | 0.01 | Range of significant deviation from equal percentage law |
| Dynamics › Electric heater | |||
| Modelica.Units.SI.Time | tauEleHea | 10 | Time constant at nominal flow for electric heater (if energyDynamics <> SteadyState) |
| Electric heater | |||
| Modelica.Units.SI.Efficiency | etaHea | 1.0 | Efficiency of electrical heater |
| Modelica.Units.SI.HeatFlowRate | QHeaMax_flow | Nominal heating capacity of eletric heater,positive | |
| General › Humidifier | |||
| Modelica.Units.SI.MassFlowRate | mWatMax_flow | Nominal humidification capacity for humidifier, positive for humidification | |
| Humidifier | |||
| Modelica.Units.SI.Temperature | THum | 293.15 | Temperature of water that is added to the fluid stream by the humidifier |
| Dynamics › Humidifier | |||
| Modelica.Units.SI.Time | tauHum | 10 | Time constant at nominal flow for humidifier(if energyDynamics <> SteadyState) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealOutput | PHea | Power consumed by electric heater | |
| Modelica.Blocks.Interfaces.RealInput | TSet | Set point temperature of the fluid that leaves port_b | |
| Modelica.Blocks.Interfaces.RealInput | XSet_w | Set point for water vapor mass fraction in kg/kg total air of the fluid that leaves port_b | |
| Modelica.Blocks.Sources.RealExpression | dT | Difference between inlet temperature and temperature setpoint of the reheater | |
| Buildings.Fluid.Humidifiers.SprayAirWasher_X | hum | Humidifier | |
| Buildings.Applications.DataCenters.ChillerCooled.Equipment.ElectricHeater | eleHea | Electric heater | |
| Buildings.Applications.DataCenters.ChillerCooled.Controls.Reheat | heaCon | Reheater on/off controller |
Revisions
-
May 14, 2017 by Yangyang Fu:
First implementation.