modelVAVMultiZone
Multiple-zone VAV
Extends from Buildings.Templates.AirHandlersFans.Interfaces.PartialAirHandler (Interface class for air handler).
Information
Description
This template represents a multiple-zone VAV air handler for a single duct system serving at least two terminal units.
The possible configuration options are enumerated in the table below.
The user may refer to ASHRAE (2021) for further details.
The first option displayed in bold characters corresponds to the default configuration.
| Configuration parameter | Options | Notes |
|---|---|---|
| Outdoor air section |
Single damper for ventilation and economizer, with airflow measurement station Separate dampers for ventilation and economizer, with airflow measurement station Separate dampers for ventilation and economizer, with differential pressure sensor |
|
| Relief/return air section |
Return fan with modulating relief damper Modulating relief damper without fan Relief fan with two-position relief damper |
Nonactuated barometric relief is currently not supported. |
| Supply fan - Blow-through position |
No fan Single fan - Variable speed Fan array - Variable speed |
At least one supply fan must be specified, either in blow-through
or draw-through position. Those two configurations are exclusive from
one another. ASHRAE Guideline 36 does not have any particular logic yet for handling fan arrays. If a fan array is selected, all of the fans are currently controlled together at the same speed, regardless of the number of VFDs. |
| Heating coil - Preheat position |
Hot water coil with two-way valve Modulating electric heating coil No coil |
|
| Cooling coil |
Chilled water coil with two-way valve No coil |
|
| Heating coil - Reheat position | No coil | ASHRAE Guideline 36 does not support heating coils in reheat position yet. |
| Supply fan - Draw-through position |
Single fan - Variable speed Fan array - Variable speed No fan |
At least one supply fan must be specified, either in blow-through
or draw-through position. Those two configurations are exclusive from
one another. ASHRAE Guideline 36 does not have any particular logic yet for handling fan arrays. If a fan array is selected, all of the fans are currently controlled together at the same speed, regardless of the number of VFDs. |
| Return fan |
Single fan - Variable speed Fan array - Variable speed No fan |
The relief fan and the return fan are both optional and they are exclusive from one another. |
| Relief fan |
No fan Single fan - Variable speed Fan array - Variable speed |
The relief fan and the return fan are both optional and they are exclusive from one another. |
| Controller | ASHRAE Guideline 36 controller | An open loop controller is also available for validation purposes only. |
| Exhaust fan | Not available: see note | All exhaust fans that normally operate with the air handler must be configured separately, by means of a dedicated template. |
| Heat recovery | Not available: see note | Currently no heat recovery equipment is supported. |
Simulation model assumptions and requirements
Pressure reference
The duct static pressure sensors use the outdoor absolute pressure as an approximation of the reference pressure in the mechanical room where the air handler is located.
When a building static pressure measurement is required by the control
sequence
(ctl.typCtlFanRet=AirHandlersFans.Types.ControlFanReturn.BuildingPressure),
the corresponding sensor pBui_rel is instantiated
within the current class.
In this case, an additional variable pBui needs to be
connected to the control bus to pass in the value of the absolute pressure
in a representative space of the building.
This is a modeling requirement, the actual control point remains the
relative building static pressure.
References
- ASHRAE, 2021. Guideline 36-2021, High-Performance Sequences of Operation for HVAC Systems. Atlanta, GA.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Templates.AirHandlersFans.Configuration.PartialAirHandler | cfg (from PartialAirHandler) | Configuration parameters | |
| Buildings.Templates.AirHandlersFans.Data.PartialAirHandler | dat (from PartialAirHandler) | Design and operating parameters | |
| Configuration | |||
| Buildings.Templates.AirHandlersFans.Types.Configuration | typ (from PartialAirHandler) | Type of system | |
| Integer | nZon (from PartialAirHandler) | Number of served zones | |
| String | id (from PartialAirHandler) | dat.id | System tag |
| Boolean | have_porRel (from PartialAirHandler) | typ == Buildings.Templates.AirHandlersFans.Types.Configuration.ExhaustOnly | Set to true for relief (exhaust) fluid port |
| Boolean | have_souChiWat (from PartialAirHandler) | Set to true if system uses CHW | |
| Boolean | have_souHeaWat (from PartialAirHandler) | Set to true if system uses HHW | |
| Buildings.Templates.Components.Types.Fan | typFanSup (from PartialAirHandler) | Type of supply fan | |
| Buildings.Templates.Components.Types.Fan | typFanRet (from PartialAirHandler) | Type of return fan | |
| Buildings.Templates.Components.Types.Fan | typFanRel (from PartialAirHandler) | Type of relief fan | |
| Integer | nFanSup (from PartialAirHandler) | Number of supply fans | |
| Integer | nFanRet (from PartialAirHandler) | Number of return fans | |
| Integer | nFanRel (from PartialAirHandler) | Number of relief fans | |
| Boolean | have_senPreBui | secOutRel.typSecRel == Buildings.Templates.AirHandlersFans.Types.ReliefReturnSection.ReliefDamper or secOutRel.typSecRel == Buildings.Templates.AirHandlersFans.Types.ReliefReturnSection.ReliefFan or secOutRel.typSecRel == Buildings.Templates.AirHandlersFans.Types.ReliefReturnSection.ReturnFan and secOutRel.typCtlFanRet == Buildings.Templates.AirHandlersFans.Types.ControlFanReturn.BuildingPressure | Set to true if building static pressure sensor is used |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | mAirSup_flow_nominal (from PartialAirHandler) | dat.mAirSup_flow_nominal | Supply air mass flow rate |
| Modelica.Units.SI.MassFlowRate | mAirRet_flow_nominal (from PartialAirHandler) | dat.mAirRet_flow_nominal | Return air mass flow rate |
| Modelica.Units.SI.MassFlowRate | mChiWat_flow_nominal (from PartialAirHandler) | Total CHW mass flow rate | |
| Modelica.Units.SI.MassFlowRate | mHeaWat_flow_nominal (from PartialAirHandler) | Total HHW mass flow rate | |
| Modelica.Units.SI.HeatFlowRate | QChiWat_flow_nominal (from PartialAirHandler) | Total CHW heat flow rate | |
| Modelica.Units.SI.HeatFlowRate | QHeaWat_flow_nominal (from PartialAirHandler) | Total HHW heat flow rate | |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from PartialAirHandler) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Assumptions | |||
| Boolean | allowFlowReversalAir (from PartialAirHandler) | true | = true to allow flow reversal, false restricts to design direction - Air side |
| Boolean | allowFlowReversalLiq (from PartialAirHandler) | true | = true to allow flow reversal, false restricts to design direction - CHW and HW side |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialAirHandler) | false | = true, if actual temperature at ports of subcomponents is computed |
Connectors
Components
Revisions
-
September 5, 2023, by Antoine Gautier:
Refactored with a record class for configuration parameters.
This is for #3500. -
February 11, 2022, by Antoine Gautier:
First implementation.