modelCooling

Active beam unit for cooling

Information

Model of an active beam, based on the EnergyPlus beam model AirTerminal:SingleDuct:ConstantVolume:FourPipeBeam.

This model operates only in cooling mode. For a model that operates in both heating and cooling mode, use IBPSA.Fluid.HeatExchangers.ActiveBeams.CoolingAndHeating.

For a description of the equations, see the User's Guide.

Performance data are available from IBPSA.Fluid.HeatExchangers.ActiveBeams.Data.

References

DOE(2015) EnergyPlus documentation v8.4.0 - Engineering Reference.

Parameters

Type	Name	Default	Description
Integer	nBeams	1	Number of beams in parallel
Nominal condition
Data.Generic	perCoo		Performance data for cooling
Assumptions
Boolean	allowFlowReversalWat	true	= true to allow flow reversal in water circuit, false restricts to design direction (port_a -> port_b)
Boolean	allowFlowReversalAir	true	= true to allow flow reversal in air circuit, false restricts to design direction (port_a -> port_b)
Dynamics › Nominal condition
Modelica.SIunits.Time	tau	30	Time constant at nominal flow (if energyDynamics <> SteadyState)
Flow resistance
Boolean	from_dpWat	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistanceWat	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaMWat	0.1	Fraction of nominal flow rate where flow transitions to laminar
Advanced
Boolean	homotopyInitialization	true	= true, use homotopy method
MediumWat.MassFlowRate	mWat_flow_small	1E-4*abs(perCoo.mWat_flow_nominal)	Small mass flow rate for regularization of zero flow
MediumAir.MassFlowRate	mAir_flow_small	1E-4*abs(perCoo.mAir_flow_nominal)	Small mass flow rate for regularization of zero flow
Dynamics › Equations
Modelica.Fluid.Types.Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamics.DynamicFreeInitial	Type of energy balance: dynamic (3 initialization options) or steady state
Modelica.Fluid.Types.Dynamics	massDynamics	energyDynamics	Type of mass balance: dynamic (3 initialization options) or steady state
Initialization › Cooling
MediumWat.AbsolutePressure	pWatCoo_start	MediumWat.p_default	Start value of pressure
MediumWat.Temperature	TWatCoo_start	MediumWat.T_default	Start value of temperature
Advanced › Diagnostics
Boolean	show_T	false	= true, if actual temperature at port is computed

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	watCoo_a	Fluid connector watCoo_a (positive design flow direction is from watCoo_a to watCoo_b)
Modelica.Fluid.Interfaces.FluidPort_b	watCoo_b	Fluid connector watCoo_b (positive design flow direction is from watCoo_a to watCoo_b)
Modelica.Fluid.Interfaces.FluidPort_a	air_a	Fluid connector air_a (positive design flow direction is from air_a to air_b)
Modelica.Fluid.Interfaces.FluidPort_b	air_b	Fluid connector air_b (positive design flow direction is from air_a to air_b)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heaPor	Heat port, to be connected to room air

Components

Type	Name	Default	Description
MediumWat.ThermodynamicState	staWatCoo_a	MediumWat.setState_phX(watCoo_a.p, noEvent(actualStream(watCoo_a.h_outflow)), noEvent(actualStream(watCoo_a.Xi_outflow)))	Medium properties in port watCoo_a
MediumWat.ThermodynamicState	staWatCoo_b	MediumWat.setState_phX(watCoo_b.p, noEvent(actualStream(watCoo_b.h_outflow)), noEvent(actualStream(watCoo_b.Xi_outflow)))	Medium properties in port watCoo_b
MediumAir.ThermodynamicState	staAir_a	MediumAir.setState_phX(air_a.p, noEvent(actualStream(air_a.h_outflow)), noEvent(actualStream(air_a.Xi_outflow)))	Medium properties in port air_a
MediumAir.ThermodynamicState	staAir_b	MediumAir.setState_phX(air_b.p, noEvent(actualStream(air_b.h_outflow)), noEvent(actualStream(air_b.Xi_outflow)))	Medium properties in port air_b
Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow	heaToRoo		Heat tranferred to the room (in addition to heat from supply air)
Modelica.SIunits.PressureDifference	dpWatCoo	watCoo_a.p - watCoo_b.p	Pressure difference watCoo_a minus watCoo_b
Modelica.SIunits.PressureDifference	dpAir	air_a.p - air_b.p	Pressure difference air_a minus air_b
FixedResistances.PressureDrop	res

Name	Description
MediumWat	Medium 1 in the component
MediumAir	Medium 2 in the component

Revisions

November 3, 2016, by Michael Wetter:
Set final alpha=0 for prescribed heat flow rate.
September 17, 2016, by Michael Wetter:
Corrected wrong annotation to avoid an error in the pedantic model check in Dymola 2017 FD01 beta2.
This is for issue 557.
June 14, 2016, by Michael Wetter:
Revised implementation.
May 20, 2016, by Alessandro Maccarini:
First implementation.