Buildings.Fluid.SolarCollectors

Information

Package Content

Name	Description
UsersGuide	User's Guide for Buildings.Fluid.SolarCollectors
EN12975	Model of a concentrating solar collector
ASHRAE93	Model of a flat plate solar thermal collector
Controls	Package for solar thermal collector controllers
Data	Data for solar thermal collectors
Types	Package with type definitions used in solar collector data records
Examples	Examples demonstrating the use of models in the SolarCollectors package
BaseClasses	Package with base classes for Buildings.Fluid.SolarCollectors

Buildings.Fluid.SolarCollectors.EN12975

Information

Overview

This component models a solar thermal collector according to the EN12975 test standard.

Notice

• As mentioned in EnergyPlus 7.0.0 Engineering Reference, the SRCC incident angle modifier equation coefficients are only valid for incident angles of 60 degrees or less. Because these curves behave poorly for angles greater than 60 degrees the model does not calculate either direct or diffuse solar radiation gains when the incidence angle is greater than 60 degrees.
• By default, the estimated heat capacity of the collector without fluid is calculated based on the dry mass and the specific heat capacity of copper.

References

EnergyPlus 7.0.0 Engineering Reference, October 13, 2011.

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Integer	nSeg	3	Number of segments used to discretize the collector model
Angle	lat		Latitude [rad]
Angle	azi		Surface azimuth [rad]
Angle	til		Surface tilt [rad]
Real	rho		Ground reflectance
HeatCapacity	C	385*perPar.mDry	Heat capacity of solar collector without fluid (default: cp_copper*mDry*nPanels) [J/K]
GenericSolarCollector	per		Performance data
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Shading
Boolean	use_shaCoe_in	false	Enables an input connector for shaCoe
Real	shaCoe	0	Shading coefficient. 0.0: no shading, 1.0: full shading
Area declarations
NumberSelection	nColType	Buildings.Fluid.SolarCollect...	Selection of area specification format
Integer	nPanels	0	Desired number of panels in the simulation
Area	totalArea	0	Total area of panels in the simulation [m2]
Configuration declarations
SystemConfiguration	sysConfig	Buildings.Fluid.SolarCollect...	Selection of system configuration
Dynamics
Equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Formulation of energy balance
Dynamics	massDynamics	energyDynamics	Formulation of mass balance
Initialization
AbsolutePressure	p_start	Medium.p_default	Start value of pressure [Pa]
Temperature	T_start	Medium.T_default	Start value of temperature [K]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances
ExtraProperty	C_nominal[Medium.nC]	fill(1E-2, Medium.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Flow resistance
Boolean	computeFlowResistance	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_T	false	= true, if actual temperature at port is computed

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	shaCoe_in	Shading coefficient
Bus	weaBus	Weather data bus

Modelica definition

model EN12975 "Model of a concentrating solar collector"
extends Buildings.Fluid.SolarCollectors.BaseClasses.PartialSolarCollector(final perPar=per);
    parameter Buildings.Fluid.SolarCollectors.Data.GenericSolarCollector per 
    "Performance data";

  BaseClasses.EN12975SolarGain solGai(
    final A_c=TotalArea_internal,
    final nSeg=nSeg,
    final y_intercept=per.y_intercept,
    final B0=per.B0,
    final B1=per.B1,
    final shaCoe=shaCoe,
    final iamDiff=per.IAMDiff,
    final use_shaCoe_in=use_shaCoe_in,
    redeclare package Medium = Medium) 
    "Identifies heat gained from the sun using standard EN12975 calculations";
  BaseClasses.EN12975HeatLoss heaLos(
    final A_c=TotalArea_internal,
    final nSeg=nSeg,
    final y_intercept=per.y_intercept,
    final C1=per.C1,
    final C2=per.C2,
    redeclare package Medium = Medium,
    final G_nominal=per.G_nominal,
    final dT_nominal=per.dT_nominal,
    final m_flow_nominal=per.mperA_flow_nominal*per.A) 
    "Calculates the heat lost to the surroundings using the EN12975 standard calculations";

equation 
  connect(shaCoe_internal, solGai.shaCoe_in);

  connect(weaBus.TDryBul, heaLos.TEnv);
  connect(HDirTil.inc, solGai.incAng);
  connect(HDifTilIso.H, solGai.HSkyDifTil);
  connect(HDirTil.H, solGai.HDirTil);
  connect(shaCoe_in, solGai.shaCoe_in);
  connect(heaLos.TFlu, temSen.T);
  connect(heaLos.QLos, QLos.Q_flow);
  connect(solGai.QSol_flow, heaGai.Q_flow);
  connect(temSen.T, solGai.TFlu);
end EN12975;

Buildings.Fluid.SolarCollectors.ASHRAE93

Information

This component models a solar thermal collector according to the ASHRAE93 test standard.

Notice

• As mentioned in EnergyPlus 7.0.0 Engineering Reference, the SRCC incident angle modifier equation coefficients are only valid for incident angles of 60 degrees or less. Because these curves behave poorly for angles greater than 60 degrees the model does not calculate either direct or diffuse solar radiation gains when the incidence angle is greater than 60 degrees.
• By default, the estimated heat capacity of the collector without fluid is calculated based on the dry mass and the specific heat capacity of copper.

References

EnergyPlus 7.0.0 Engineering Reference, October 13, 2011.

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Integer	nSeg	3	Number of segments used to discretize the collector model
Angle	lat		Latitude [rad]
Angle	azi		Surface azimuth [rad]
Angle	til		Surface tilt [rad]
Real	rho		Ground reflectance
HeatCapacity	C	385*perPar.mDry	Heat capacity of solar collector without fluid (default: cp_copper*mDry*nPanels) [J/K]
GenericSolarCollector	per
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Shading
Boolean	use_shaCoe_in	false	Enables an input connector for shaCoe
Real	shaCoe	0	Shading coefficient. 0.0: no shading, 1.0: full shading
Area declarations
NumberSelection	nColType	Buildings.Fluid.SolarCollect...	Selection of area specification format
Integer	nPanels	0	Desired number of panels in the simulation
Area	totalArea	0	Total area of panels in the simulation [m2]
Configuration declarations
SystemConfiguration	sysConfig	Buildings.Fluid.SolarCollect...	Selection of system configuration
Dynamics
Equations
Dynamics	energyDynamics	Modelica.Fluid.Types.Dynamic...	Formulation of energy balance
Dynamics	massDynamics	energyDynamics	Formulation of mass balance
Initialization
AbsolutePressure	p_start	Medium.p_default	Start value of pressure [Pa]
Temperature	T_start	Medium.T_default	Start value of temperature [K]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances
ExtraProperty	C_nominal[Medium.nC]	fill(1E-2, Medium.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Flow resistance
Boolean	computeFlowResistance	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_T	false	= true, if actual temperature at port is computed

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	shaCoe_in	Shading coefficient
Bus	weaBus	Weather data bus

Modelica definition

model ASHRAE93 "Model of a flat plate solar thermal collector"
  extends Buildings.Fluid.SolarCollectors.BaseClasses.PartialSolarCollector(final perPar=per);
  parameter Buildings.Fluid.SolarCollectors.Data.GenericSolarCollector per;

  BaseClasses.ASHRAESolarGain solGai(
    final B0=per.B0,
    final B1=per.B1,
    final shaCoe=shaCoe,
    final til=til,
    final nSeg=nSeg,
    final y_intercept=per.y_intercept,
    final use_shaCoe_in=use_shaCoe_in,
    final A_c=TotalArea_internal,
    redeclare package Medium = Medium) 
    "Identifies heat gained from the sun using standard ASHRAE93 calculations";

  BaseClasses.ASHRAEHeatLoss heaLos(
    final nSeg=nSeg,
    final slope=per.slope,
    final y_intercept=per.y_intercept,
    redeclare package Medium = Medium,
    final G_nominal=per.G_nominal,
    dT_nominal=per.dT_nominal,
    final A_c=TotalArea_internal,
    m_flow_nominal=per.mperA_flow_nominal*per.A) 
    "Calculates the heat lost to the surroundings using the ASHRAE93 standard calculations";
    

equation 
  connect(weaBus.TDryBul, heaLos.TEnv);
  connect(HDirTil.inc, solGai.incAng);
  connect(HDirTil.H, solGai.HDirTil);
  connect(HDifTilIso.HGroDifTil, solGai.HGroDifTil);
  connect(HDifTilIso.HSkyDifTil, solGai.HSkyDifTil);
  connect(shaCoe_in, solGai.shaCoe_in);
  connect(solGai.QSol_flow, heaGai.Q_flow);
  connect(temSen.T, heaLos.TFlu);
  connect(temSen.T, solGai.TFlu);
  connect(heaLos.QLos, QLos.Q_flow);
end ASHRAE93;