Required Objects for Dehumidifier:Desiccant:System

asked 2025-07-10 01:25:27 -0600

Keigo's avatar

updated 2025-07-11 16:29:34 -0600

Aaron Boranian's avatar

I would like to clarify the required objects for Dehumidifier:Desiccant:System.

The Input Output Reference describes as follows.

Currently the only heat exchanger choice for this object is HeatExchanger:Desiccant: BalancedFlow. So to model a Dehumidifier:Desiccant:System located in an air loop, the input data file should include the following objects:

  • Dehumidifier:Desiccant:System (in an air loop (AirLoopHVAC) Branch or AirLoopHVAC:OutdoorAirSystem:EquipmentList for an AirLoopHVAC:OutdoorAirSystem)

  • HeatExchanger:Desiccant:BalancedFlow (desiccant heat exchanger child object)

  • HeatExchanger:Desiccant:BalancedFlow:PerformanceDataType1 (desiccant heat exchanger data object)

  • ZoneControl:Humidistat, and one of:

  • SetpointManager:SingleZone:Humidity:Maximum

  • SetpointManager:MultiZone:Humidity:Maximum

  • SetpointManager:MultiZone:MaximumHumidity:Average

  • (when in an air loop (AirLoopHVAC) Branch), and SetpointManager:OutdoorAirPretreat (when in an AirLoopHVAC:OutdoorAirSystem) to place a maximum humidity ratio set point on the sensor node, typically the process air outlet node

  • Fan:SystemModel, Fan:OnOff, or Fan:ConstantVolume (regeneration air fan)

  • Coil:Heating:Electric or Coil:Heating:Fuel (optional regeneration air heater)

  • Coil:Cooling:DX:SingleSpeed, Coil:Cooling:DX:VariableSpeed, or Coil:Cooling:DX:TwoStageWithHumidityControlMode (optional companion cooling coil)

Does Dehumidifier:Desiccant:System really require ZoneControl:Humidistat and a setpoint manager for zone max humidity?

Desiccant defumidification is often ued for DOAS and it is often controlled by the outdoor air conditions (temperature and humidity) rather than indoor air conditions.

I tested Dehumidifier:Desiccant:System without ZoneControl:Humidistat and with SetpointManager:Scheduled at a sensor node. Control Variable of SetpointManager:Scheduled is set to MaximumHumidityRatio. The simulation completed without relevant warnings, although I need more time to validate the result as not only the max hum setpoint but also the coefficients in HeatExchanger:Desiccant:BalancedFlow:PerformanceDataType1 would affect a lot.

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