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Buildings.Fluid.Storage.Validation

Collection of models that validate the storage models

Information

This package contains models that validate the storage models. These model outputs are stored as reference data to allow continuous validation whenever models in the library change.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name Description
Buildings.Fluid.Storage.Validation.HeatExchangerDynamics HeatExchangerDynamics Test model for stratified tank with steady-state and dynamic heat exchanger balance
Buildings.Fluid.Storage.Validation.StratifiedLoadingUnloading StratifiedLoadingUnloading Test model for stratified tank

Buildings.Fluid.Storage.Validation.HeatExchangerDynamics Buildings.Fluid.Storage.Validation.HeatExchangerDynamics

Test model for stratified tank with steady-state and dynamic heat exchanger balance

Buildings.Fluid.Storage.Validation.HeatExchangerDynamics

Information

This validation model compares two tank models. The only difference between the two tank models is that one uses a dynamic energy balance, whereas the other uses a steady-state energy balance for the heat exchanger. The mass flow rate through the heat exchanger is varied from zero to the design flow rate and back to zero to test the model under conditions in which no water flows through the heat exchanger.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

TypeNameDefaultDescription
HeatFlowRateQHex_flow_nominal2000Design heat flow rate of heat exchanger [W]
MassFlowRatem_flow_nominalQHex_flow_nominal/4200/4[kg/s]

Modelica definition

model HeatExchangerDynamics "Test model for stratified tank with steady-state and dynamic heat exchanger balance" extends Modelica.Icons.Example; package Medium = Buildings.Media.Water "Medium model"; constant Integer nSeg = 7 "Number of segments in tank"; parameter Modelica.SIunits.HeatFlowRate QHex_flow_nominal = 2000 "Design heat flow rate of heat exchanger"; parameter Modelica.SIunits.MassFlowRate m_flow_nominal= QHex_flow_nominal/4200/4; Buildings.Fluid.Sources.Boundary_pT watInTan( redeclare package Medium = Medium, use_T_in=false, nPorts=2, T=273.15 + 30, p(displayUnit="Pa")) "Boundary condition for water in the tank"; Sources.MassFlowSource_T mHex_flow1( redeclare package Medium = Medium, use_m_flow_in=true, T=273.15 + 60, nPorts=1) "Mass flow rate through the heat exchanger"; model Tank = StratifiedEnhancedInternalHex ( redeclare package Medium = Medium, redeclare package MediumHex = Medium, hTan=2, dIns=0.3, VTan=0.3, nSeg=nSeg, hHex_a=1, hHex_b=0.2, Q_flow_nominal=QHex_flow_nominal, TTan_nominal=313.15, THex_nominal=333.15, mHex_flow_nominal=m_flow_nominal, show_T=true, m_flow_nominal=m_flow_nominal, energyDynamicsHex=Modelica.Fluid.Types.Dynamics.FixedInitial) "Tank with dynamic heat exchanger balance"; Tank tanDyn "Tank with dynamic heat exchanger balance"; Tank tanSte(energyDynamicsHex=Modelica.Fluid.Types.Dynamics.SteadyState) "Tank with steady-state heat exchanger balance"; Modelica.Blocks.Sources.Trapezoid mHex_flow_in( period=7200, amplitude=m_flow_nominal, offset=0, rising=1800, width=1800, falling=1800, startTime=900) "Control signal for mass flow rate in heat exchanger"; Buildings.Fluid.Sources.Boundary_pT sin( redeclare package Medium = Medium, T=273.15 + 30, p(displayUnit="Pa"), nPorts=2) "Sink boundary condition"; Sources.MassFlowSource_T mHex_flow2( redeclare package Medium = Medium, use_m_flow_in=true, T=273.15 + 60, nPorts=1) "Mass flow rate through the heat exchanger"; Sensors.TemperatureTwoPort senTanDyn( redeclare package Medium = Medium, allowFlowReversal=false, m_flow_nominal=m_flow_nominal, tau=0) "Temperature sensor at tank outlet"; Sensors.TemperatureTwoPort senTanSte( redeclare package Medium = Medium, allowFlowReversal=false, m_flow_nominal=m_flow_nominal, tau=0) "Temperature sensor at tank outlet"; equation connect(mHex_flow_in.y, mHex_flow1.m_flow_in); connect(mHex_flow2.m_flow_in, mHex_flow_in.y); connect(mHex_flow2.ports[1], tanSte.portHex_a); connect(watInTan.ports[1], tanSte.port_a); connect(mHex_flow1.ports[1], tanDyn.portHex_a); connect(watInTan.ports[2], tanDyn.port_a); connect(senTanDyn.port_a, tanDyn.portHex_b); connect(senTanSte.port_a, tanSte.portHex_b); connect(senTanDyn.port_b, sin.ports[1]); connect(senTanSte.port_b, sin.ports[2]); end HeatExchangerDynamics;

Buildings.Fluid.Storage.Validation.StratifiedLoadingUnloading Buildings.Fluid.Storage.Validation.StratifiedLoadingUnloading

Test model for stratified tank

Buildings.Fluid.Storage.Validation.StratifiedLoadingUnloading

Information

This test model compares two tank models. The only difference between the two tank models is that one uses the third order upwind discretization scheme that reduces numerical diffusion that is induced when connecting volumes in series.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

TypeNameDefaultDescription
MassFlowRatem_flow_nominal1*1000/3600/4[kg/s]

Modelica definition

model StratifiedLoadingUnloading "Test model for stratified tank" extends Modelica.Icons.Example; package Medium = Buildings.Media.Water "Medium model"; constant Integer nSeg = 7 "Number of segments in tank"; parameter Modelica.SIunits.MassFlowRate m_flow_nominal= 1*1000/3600/4; Buildings.Fluid.Sources.Boundary_pT sou_1( p=300000 + 5000, T=273.15 + 40, redeclare package Medium = Medium, use_T_in=false, nPorts=2); Sources.MassFlowSource_T sin_1( redeclare package Medium = Medium, T=273.15 + 20, m_flow=-0.028, use_m_flow_in=true, nPorts=1); Buildings.Fluid.Storage.StratifiedEnhanced tanEnh( redeclare package Medium = Medium, hTan=3, dIns=0.3, VTan=0.1, nSeg=nSeg, show_T=true, m_flow_nominal=m_flow_nominal) "Tank"; Sources.MassFlowSource_T sin_2( redeclare package Medium = Medium, T=273.15 + 20, m_flow=-0.028, use_m_flow_in=true, nPorts=1); Buildings.Fluid.Storage.Stratified tan( redeclare package Medium = Medium, hTan=3, dIns=0.3, VTan=0.1, nSeg=nSeg, show_T=true, m_flow_nominal=m_flow_nominal) "Tank"; Modelica.Blocks.Sources.Pulse pulse( amplitude=2*m_flow_nominal, offset=-m_flow_nominal, period=7200); Buildings.Fluid.Sensors.EnthalpyFlowRate HIn_flow(redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal) "Enthalpy flow rate"; Buildings.Fluid.Sensors.EnthalpyFlowRate HOut_flow(redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal) "Enthalpy flow rate"; Buildings.Fluid.Sensors.EnthalpyFlowRate HInEnh_flow(redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal) "Enthalpy flow rate"; Buildings.Fluid.Sensors.EnthalpyFlowRate HOutEnh_flow(redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal) "Enthalpy flow rate"; Modelica.Blocks.Math.Add add(k2=-1); Modelica.Blocks.Continuous.Integrator dHTanEnh "Difference in enthalpy (should be zero at steady-state)"; Modelica.Blocks.Math.Add add1( k2=-1); Modelica.Blocks.Continuous.Integrator dHTan "Difference in enthalpy (should be zero at steady-state)"; equation connect(sou_1.ports[1], HIn_flow.port_a); connect(HIn_flow.port_b, tan.port_a); connect(tan.port_b, HOut_flow.port_a); connect(HOut_flow.port_b, sin_2.ports[1]); connect(sou_1.ports[2], HInEnh_flow.port_a); connect(HInEnh_flow.port_b, tanEnh.port_a); connect(tanEnh.port_b, HOutEnh_flow.port_a); connect(HOutEnh_flow.port_b, sin_1.ports[1]); connect(HInEnh_flow.H_flow, add.u1); connect(HOutEnh_flow.H_flow, add.u2); connect(add.y, dHTanEnh.u); connect(HIn_flow.H_flow, add1.u1); connect(HOut_flow.H_flow, add1.u2); connect(add1.y, dHTan.u); connect(pulse.y, sin_1.m_flow_in); connect(pulse.y, sin_2.m_flow_in); end StratifiedLoadingUnloading;

Buildings.Fluid.Storage.Validation.HeatExchangerDynamics.Tank Buildings.Fluid.Storage.Validation.HeatExchangerDynamics.Tank

Tank with dynamic heat exchanger balance

Buildings.Fluid.Storage.Validation.HeatExchangerDynamics.Tank

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
VolumeVTan0.3Tank volume [m3]
LengthhTan2Height of tank (without insulation) [m]
LengthdIns0.3Thickness of insulation [m]
ThermalConductivitykIns0.04Specific heat conductivity of insulation [W/(m.K)]
IntegernSegnSegNumber of volume segments
Timetau1Time constant for mixing [s]
Nominal condition
MassFlowRatem_flow_nominalm_flow_nominalNominal mass flow rate [kg/s]
Initialization
MassFlowRatem_flow.start0Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
PressureDifferencedp.start0Pressure difference between port_a and port_b [Pa]
Heat exchanger
replaceable package MediumHexPartialMediumMedium in the heat exchanger
HeighthHex_a1Height of portHex_a of the heat exchanger, measured from tank bottom [m]
HeighthHex_b0.2Height of portHex_b of the heat exchanger, measured from tank bottom [m]
IntegerhexSegMult2Number of heat exchanger segments in each tank segment
DiameterdExtHex0.025Exterior diameter of the heat exchanger pipe [m]
HeatFlowRateQ_flow_nominalQHex_flow_nominalHeat transfer at nominal conditions [W]
TemperatureTTan_nominal313.15Temperature of fluid inside the tank at nominal heat transfer conditions [K]
TemperatureTHex_nominal333.15Temperature of fluid inside the heat exchanger at nominal heat transfer conditions [K]
Realr_nominal0.5Ratio between coil inside and outside convective heat transfer at nominal heat transfer conditions
MassFlowRatemHex_flow_nominalm_flow_nominalNominal mass flow rate through the heat exchanger [kg/s]
PressureDifferencedpHex_nominal2500Pressure drop across the heat exchanger at nominal conditions [Pa]
Assumptions
BooleanallowFlowReversaltrue= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Heat exchanger
BooleanallowFlowReversalHextrue= true to allow flow reversal in heat exchanger, false restricts to design direction (portHex_a -> portHex_b)
Advanced
MassFlowRatem_flow_small1E-4*abs(m_flow_nominal)Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Booleanshow_Ttrue= true, if actual temperature at port is computed
Dynamics
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Formulation of energy balance
DynamicsmassDynamicsenergyDynamicsFormulation of mass balance
Initialization
AbsolutePressurep_startMedium.p_defaultStart value of pressure [Pa]
TemperatureT_startMedium.T_defaultStart value of temperature [K]
MassFractionX_start[Medium.nX]Medium.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyC_start[Medium.nC]fill(0, Medium.nC)Start value of trace substances
Flow resistance heat exchanger
BooleancomputeFlowResistancetrue=true, compute flow resistance. Set to false to assume no friction
Booleanfrom_dpfalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistancefalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaM0.1Fraction of nominal flow rate where flow transitions to laminar
Dynamics heat exchanger
Equations
DynamicsenergyDynamicsHexModelica.Fluid.Types.Dynamic...Formulation of energy balance for heat exchanger internal fluid mass
DynamicsmassDynamicsHexenergyDynamicsHexFormulation of mass balance for heat exchanger
DynamicsenergyDynamicsHexSolidenergyDynamicsHexFormulation of energy balance for heat exchanger solid mass
LengthlHexrTan*abs(segHex_a - segHex_b...Approximate length of the heat exchanger [m]
AreaACroHex(dExtHex^2 - (0.8*dExtHex)^2...Cross sectional area of the heat exchanger [m2]
SpecificHeatCapacitycHex490Specific heat capacity of the heat exchanger material [J/(kg.K)]
DensitydHex8000Density of the heat exchanger material [kg/m3]
HeatCapacityCHexACroHex*lHex*dHex*cHexCapacitance of the heat exchanger without the fluid [J/K]

Connectors

TypeNameDescription
replaceable package MediumMedium in the component
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
output RealOutputQl_flowHeat loss of tank (positive if heat flows from tank to ambient)
HeatPort_aheaPorVol[nSeg]Heat port of fluid volumes
HeatPort_aheaPorSidHeat port tank side (outside insulation)
HeatPort_aheaPorTopHeat port tank top (outside insulation)
HeatPort_aheaPorBotHeat port tank bottom (outside insulation). Leave unconnected for adiabatic condition
FluidPort_aportHex_aHeat exchanger inlet
FluidPort_bportHex_bHeat exchanger outlet
Heat exchanger
replaceable package MediumHexMedium in the heat exchanger

Modelica definition

model Tank = StratifiedEnhancedInternalHex ( redeclare package Medium = Medium, redeclare package MediumHex = Medium, hTan=2, dIns=0.3, VTan=0.3, nSeg=nSeg, hHex_a=1, hHex_b=0.2, Q_flow_nominal=QHex_flow_nominal, TTan_nominal=313.15, THex_nominal=333.15, mHex_flow_nominal=m_flow_nominal, show_T=true, m_flow_nominal=m_flow_nominal, energyDynamicsHex=Modelica.Fluid.Types.Dynamics.FixedInitial) "Tank with dynamic heat exchanger balance";
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