blockHVACZones

Declaration of an FMU that exports a simple convective only HVAC system for two zones

Extends from Buildings.Fluid.FMI.ExportContainers.HVACZones (Partial block to export an HVAC system that has no radiative component and that serves multiple zones as an FMU).

Information

This example demonstrates how to export a model of an HVAC system that only provides convective cooling to two thermal zones. The example is similar to Buildings.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone except that is serves two thermal zones rather than one.

The example extends from Buildings.Fluid.FMI.ExportContainers.HVACZones which provides the input and output signals that are needed to interface the acausal HVAC system model with causal connectors of FMI. The instance hvacAda is the HVAC adapter that contains on the left a fluid port, and on the right signal ports which are then used to connect at the top-level of the model to signal ports which are exposed at the FMU interface.

Parameters

Type	Name	Default	Description
Integer	nZon (from HVACZones)		Number of thermal zones served by the HVAC system
Integer	nPorts (from HVACZones)		Number of fluid ports for each zone (must be the same for every zone)
Real	eps	0.8	Heat recovery effectiveness
Modelica.Units.SI.Temperature	TASup_nominal	291.15	Nominal air temperature supplied to room
Modelica.Units.SI.DimensionlessRatio	wASup_nominal	0.012	Nominal air humidity ratio supplied to room [kg/kg] assuming 90% relative humidity
Modelica.Units.SI.Temperature	TRooSet	297.15	Nominal room air temperature
Modelica.Units.SI.Temperature	TOut_nominal	303.15	Design outlet air temperature
Modelica.Units.SI.Temperature	THeaRecLvg	TOut_nominal - eps*(TOut_nominal - TRooSet)	Air temperature leaving the heat recovery
Modelica.Units.SI.DimensionlessRatio	wHeaRecLvg	0.0135	Air humidity ratio leaving the heat recovery [kg/kg]
Real	UA	10E3	Average UA-value of the room
Modelica.Units.SI.HeatFlowRate	QRooInt_flow	1000	Internal heat gains of the room
Modelica.Units.SI.HeatFlowRate	QRooC_flow_nominal	-QRooInt_flow - UA/30*(TOut_nominal - TRooSet)	Nominal cooling load of the room
Modelica.Units.SI.MassFlowRate	mA_flow_nominal	1.3*QRooC_flow_nominal/1006/(TASup_nominal - TRooSet)	Nominal air mass flow rate, increased by factor 1.3 to allow for recovery after temperature setback
Modelica.Units.SI.TemperatureDifference	dTFan	2	Estimated temperature raise across fan that needs to be made up by the cooling coil
Modelica.Units.SI.HeatFlowRate	QCoiC_flow_nominal	mA_flow_nominal(TASup_nominal - THeaRecLvg - dTFan)1006 + mA_flow_nominal(wASup_nominal - wHeaRecLvg)2458.3e3	Cooling load of coil, taking into account outside air sensible and latent heat removal
Modelica.Units.SI.Temperature	TWSup_nominal	285.15	Water supply temperature
Modelica.Units.SI.Temperature	TWRet_nominal	289.15	Water return temperature
Modelica.Units.SI.MassFlowRate	mW_flow_nominal	-QCoiC_flow_nominal/(TWRet_nominal - TWSup_nominal)/4200	Nominal water mass flow rate
Assumptions
Boolean	allowFlowReversal	false	= true to allow flow reversal, false restricts to design direction (inlet -> outlet)

Connectors

Type	Name	Description
Interfaces.Outlet[nZon,nPorts]	fluPor (from HVACZones)	Fluid connectors
Modelica.Blocks.Interfaces.RealInput[nZon]	TRadZon (from HVACZones)	Radiative temperature of the zone
Modelica.Blocks.Interfaces.RealOutput[nZon]	QGaiRad_flow (from HVACZones)	Radiant heat input into the zones (positive if heat gain)
Modelica.Blocks.Interfaces.RealOutput[nZon]	QGaiSenCon_flow (from HVACZones)	Convective sensible heat input into the zones (positive if heat gain)
Modelica.Blocks.Interfaces.RealOutput[nZon]	QGaiLat_flow (from HVACZones)	Latent heat input into the zones (positive if heat gain)
BoundaryConditions.WeatherData.Bus	weaBus	Weather data bus
Modelica.Blocks.Interfaces.RealOutput	TOut	Outdoor temperature

Components

Type	Name	Description
Adaptors.HVAC[nZon]	hvacAda (from HVACZones)	Adapter between the HVAC supply and return air, and its connectors for the FMU
Modelica.Blocks.Sources.Constant[nZon]	zer	Zero output signal
Movers.FlowControlled_m_flow	fan	Supply air fan
HeatExchangers.ConstantEffectiveness	hex	Heat recovery
Buildings.Fluid.HeatExchangers.ConstantEffectiveness	cooCoi
Buildings.Fluid.Sources.Outside	out	Outside air boundary condition
Sources.MassFlowSource_T	souWat	Source for water flow rate
Buildings.Fluid.Sources.Boundary_pT	sinWat	Sink for water circuit
Modelica.Blocks.Sources.Constant	mAir_flow	Fan air flow rate
Sensors.TemperatureTwoPort	senTemHXOut	Temperature sensor for heat recovery outlet on supply side
Sensors.TemperatureTwoPort	senTemSupAir	Temperature sensor for supply air
Modelica.Blocks.Logical.OnOffController	con	Controller for coil water flow rate
Modelica.Blocks.Sources.Constant	TRooSetPoi	Room temperature set point
Modelica.Blocks.Math.BooleanToReal	mWat_flow	Conversion from boolean to real for water flow rate
BoundaryConditions.WeatherData.ReaderTMY3	weaDat	Weather data reader
Modelica.Blocks.Math.Min	min
Movers.FlowControlled_m_flow	fan2	Supply air fan that extracts a constant amount of outside air
Buildings.Fluid.FixedResistances.PressureDrop	res	Fixed resistance for exhaust air duct
Buildings.Fluid.FixedResistances.PressureDrop	resSup1	Fixed resistance for supply air inlet
Buildings.Fluid.FixedResistances.PressureDrop	resSup2	Fixed resistance for supply air inlet
Buildings.Fluid.FixedResistances.PressureDrop	resRet1	Fixed resistance for return air duct
Buildings.Fluid.FixedResistances.PressureDrop	resRet2	Fixed resistance for return air duct

Name	Description
MediumA	Medium for air
MediumW	Medium for water

Revisions

April 9, 2024, by Hongxiang Fu:
Specified nominalValuesDefineDefaultPressureCurve=true in the mover component to suppress a warning. This is for #3819.
September 21, 2021 by David Blum:
Correct supply and return water parameterization.
Use explicit calculation of sensible and latent load to determine design load on cooling coil.
This is for #2624.
May 15, 2019, by Jianjun Hu:
Replaced fluid source. This is for #1072.
April 4, 2017, by Michael Wetter:
Removed import statement.
November 11, 2016, by Michael Wetter:
Made the cooling coil replaceable because the Buildings library uses the model for validation with a cooling coil model that is not in the Annex 60 library.
April 16, 2016 by Michael Wetter:
First implementation.