Buildings.Fluid.HeatPumps.BaseClasses
Package with base classes for Buildings.Fluid.HeatPumps
Information
This package contains base classes that are used to construct the models in Buildings.Fluid.HeatPumps.
Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
| Name | Description |
|---|---|
 EquationFitReversible
|
Equation fit method to compute the performance of the reversable heat pump |
 PartialWaterToWater
|
Partial model for water to water heat pumps and chillers |
 Validation
|
Collection of validation models |
Buildings.Fluid.HeatPumps.BaseClasses.EquationFitReversible
Equation fit method to compute the performance of the reversable heat pump
Information
Block that implements the equation fit method for the reverse heat pump model Buildings.Fluid.HeatPumps.EquationFitReversible.
Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Generic | per | Performance data | |
| Real | scaling_factor | Scaling factor for heat pump capacity |
Connectors
| Type | Name | Description |
|---|---|---|
| input IntegerInput | uMod | Control input signal, cooling mode= -1, off=0, heating mode=+1 |
| input RealInput | TLoaEnt | Load entering fluid temperature [K] |
| input RealInput | TSouEnt | Source entering fluid temperature [K] |
| input RealInput | mLoa_flow | Mass flow rate at load side [kg/s] |
| input RealInput | mSou_flow | Mass flow rate at source side [kg/s] |
| input RealInput | Q_flow_set | Required heat to meet set point [W] |
| output RealOutput | QLoa_flow | Load heat flow rate [W] |
| output RealOutput | QSou_flow | Source heat flow rate [W] |
| output RealOutput | P | Compressor power [W] |
| output RealOutput | COP | Coefficient of performance, assuming useful heat is at the load side (at Medium 1) [1] |
Modelica definition
block EquationFitReversible
"Equation fit method to compute the performance of the reversable heat pump"
extends Modelica.Blocks.Icons.Block;
parameter Data.EquationFitReversible.Generic per
"Performance data";
parameter Real scaling_factor
"Scaling factor for heat pump capacity";
Modelica.Blocks.Interfaces.IntegerInput uMod
"Control input signal, cooling mode= -1, off=0, heating mode=+1";
Modelica.Blocks.Interfaces.RealInput TLoaEnt(
final unit="K",
displayUnit="degC")
"Load entering fluid temperature";
Modelica.Blocks.Interfaces.RealInput TSouEnt(
final unit="K",
displayUnit="degC")
"Source entering fluid temperature";
Modelica.Blocks.Interfaces.RealInput mLoa_flow(final unit="kg/s")
"Mass flow rate at load side";
Modelica.Blocks.Interfaces.RealInput mSou_flow(final unit="kg/s")
"Mass flow rate at source side";
Modelica.Blocks.Interfaces.RealInput Q_flow_set(final unit="W")
"Required heat to meet set point";
Modelica.Blocks.Interfaces.RealOutput QLoa_flow(final unit="W")
"Load heat flow rate";
Modelica.Blocks.Interfaces.RealOutput QSou_flow(final unit="W")
"Source heat flow rate";
Modelica.Blocks.Interfaces.RealOutput P(final unit="W")
"Compressor power";
Modelica.Blocks.Interfaces.RealOutput COP(
final min=0,
final unit="1")
"Coefficient of performance, assuming useful heat is at the load side (at Medium 1)";
Modelica.Units.SI.Efficiency QRel_flow "Thermal load ratio";
Modelica.Units.SI.Efficiency PRel "Power ratio";
Modelica.Units.SI.HeatFlowRate Q_flow_ava
"Heat (or cooling) capacity available";
Real PLR(min=0, nominal=1, unit="1")
"Part load ratio";
protected
parameter Modelica.Units.SI.HeatFlowRate Q_flow_small(min=Modelica.Constants.eps)
= per.hea.Q_flow*1E-9*scaling_factor
"Small value for heat flow rate or power, used to avoid division by zero";
Real xNor[5] "Normalized inlet variables";
initial equation
assert(per.hea.Q_flow > 0,
"Parameter QheaLoa_flow_nominal must be larger than zero.");
assert(per.coo.Q_flow < 0,
"Parameter QCooLoa_flow_nominal must be lesser than zero.");
assert(Q_flow_small > 0,
"Parameter Q_flow_small must be larger than zero.");
equation
if (uMod == 0) then
xNor=fill(0, 5);
elseif (uMod == -1) then
xNor={ 1,
TLoaEnt/per.coo.TRefLoa,
TSouEnt/per.coo.TRefSou,
mLoa_flow/(per.coo.mLoa_flow*scaling_factor),
mSou_flow/(per.coo.mSou_flow*scaling_factor)};
else // uMod == +1
xNor={ 1,
TLoaEnt/per.hea.TRefLoa,
TSouEnt/per.hea.TRefSou,
mLoa_flow/(per.hea.mLoa_flow*scaling_factor),
mSou_flow/(per.hea.mSou_flow*scaling_factor)};
end if;
if (uMod==1) then
QRel_flow = sum(per.hea.coeQ .* xNor);
Q_flow_ava = QRel_flow*per.hea.Q_flow*scaling_factor;
QLoa_flow =Buildings.Utilities.Math.Functions.smoothMin(
x1=Q_flow_set,
x2=Q_flow_ava,
deltaX=Q_flow_small);
PLR = QLoa_flow / Q_flow_ava;
PRel = sum(per.hea.coeP .* xNor);
P = PLR*PRel*per.hea.P*scaling_factor;
QSou_flow = -(QLoa_flow -P);
COP = QLoa_flow/(P+Q_flow_small);
elseif (uMod==-1) then
QRel_flow = sum(per.coo.coeQ .* xNor);
Q_flow_ava = QRel_flow*per.coo.Q_flow*scaling_factor;
QLoa_flow =Buildings.Utilities.Math.Functions.smoothMax(
x1=Q_flow_set,
x2=Q_flow_ava,
deltaX=Q_flow_small);
PLR = QLoa_flow / Q_flow_ava;
PRel = sum(per.coo.coeP .* xNor);
P = PLR*PRel*per.coo.P*scaling_factor;
QSou_flow = -QLoa_flow + P;
COP = -QLoa_flow/(P+Q_flow_small);
else
QRel_flow=0;
PRel = 0;
P = 0;
Q_flow_ava = 0;
QLoa_flow = 0;
QSou_flow = 0;
PLR=0;
COP = 0;
end if;
end EquationFitReversible;
Buildings.Fluid.HeatPumps.BaseClasses.PartialWaterToWater
Partial model for water to water heat pumps and chillers
Information
Partial model for a water to water heat pump, as detailed in Jin (2002). The model for the compressor is a partial model and needs to be replaced by one of the compressor models in Buildings.Fluid.HeatPumps.Compressors.
References
H. Jin. Parameter estimation based models of water source heat pumps. PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002.
Extends from Buildings.Fluid.Interfaces.PartialFourPortInterface (Partial model transporting fluid between two ports without storing mass or energy), Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters (Parameters for flow resistance for models with four ports).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium1 | PartialMedium | Medium 1 in the component | |
| replaceable package Medium2 | PartialMedium | Medium 2 in the component | |
| replaceable package ref | Buildings.Media.Refrigerants... | Refrigerant in the component | |
| Boolean | enable_variable_speed | true | Set to true to allow modulating of compressor speed |
| Real | scaling_factor | 1.0 | Scaling factor for heat pump capacity |
| ThermalConductance | UACon | Thermal conductance of condenser [W/K] | |
| ThermalConductance | UAEva | Thermal conductance of evaporator [W/K] | |
| PartialCompressor | com | redeclare Buildings.Fluid.He... | Compressor |
| Nominal condition | |||
| MassFlowRate | m1_flow_nominal | Nominal mass flow rate [kg/s] | |
| MassFlowRate | m2_flow_nominal | Nominal mass flow rate [kg/s] | |
| PressureDifference | dp1_nominal | Pressure difference [Pa] | |
| PressureDifference | dp2_nominal | Pressure difference [Pa] | |
| Temperature protection | |||
| Boolean | enable_temperature_protection | true | Enable temperature protection |
| Temperature | TConMax | ref.TCri - 5 | Upper bound for condenser temperature [K] |
| Temperature | TEvaMin | 275.15 | Lower bound for evaporator temperature [K] |
| Real | dTHys | 5 | Hysteresis interval width [K] |
| Assumptions | |||
| Boolean | allowFlowReversal1 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Advanced | |||
| MassFlowRate | m1_flow_small | 1E-4*abs(m1_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| MassFlowRate | m2_flow_small | 1E-4*abs(m2_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Medium 1 | |||
| Boolean | computeFlowResistance1 | dp1_nominal > 0 | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp1 | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance1 | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM1 | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Medium 2 | |||
| Boolean | computeFlowResistance2 | dp2_nominal > 0 | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp2 | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance2 | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM2 | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics | |||
| Condenser | |||
| Time | tau1 | 60 | Time constant at nominal flow rate (used if energyDynamics1 <> Modelica.Fluid.Types.Dynamics.SteadyState) [s] |
| Temperature | T1_start | Medium1.T_default | Initial or guess value of set point [K] |
| Evaporator | |||
| Time | tau2 | 60 | Time constant at nominal flow rate (used if energyDynamics2 <> Modelica.Fluid.Types.Dynamics.SteadyState) [s] |
| Temperature | T2_start | Medium2.T_default | Initial or guess value of set point [K] |
| Evaporator and condenser | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPort_a | port_a1 | Fluid connector a1 (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_b | port_b1 | Fluid connector b1 (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_a | port_a2 | Fluid connector a2 (positive design flow direction is from port_a2 to port_b2) |
| FluidPort_b | port_b2 | Fluid connector b2 (positive design flow direction is from port_a2 to port_b2) |
| replaceable package ref | Refrigerant in the component | |
| output BooleanOutput | errLowPre | if true, compressor disabled since evaporator temperature is above upper bound |
| output BooleanOutput | errHigPre | if true, compressor disabled since condenser temperature is below lower bound |
| output BooleanOutput | errNegTemDif | if true, compressor disabled since condenser temperature is below evaporator temperature |
| input RealInput | y | Modulating signal for compressor frequency, equal to 1 at full load condition [1] |
| input IntegerInput | stage | Current stage of the heat pump, equal to 1 at full load condition |
| output RealOutput | QCon_flow | Actual heating heat flow rate added to fluid 1 [W] |
| output RealOutput | P | Electric power consumed by compressor [W] |
| output RealOutput | QEva_flow | Actual cooling heat flow rate removed from fluid 2 [W] |
Modelica definition
partial model PartialWaterToWater
"Partial model for water to water heat pumps and chillers"
extends Buildings.Fluid.Interfaces.PartialFourPortInterface;
extends Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters(
final computeFlowResistance1 = dp1_nominal > 0,
final computeFlowResistance2 = dp2_nominal > 0);
replaceable package ref = Buildings.Media.Refrigerants.R410A
"Refrigerant in the component";
constant Boolean homotopyInitialization = true "= true, use homotopy method";
parameter Boolean enable_variable_speed = true
"Set to true to allow modulating of compressor speed";
parameter Real scaling_factor = 1.0
"Scaling factor for heat pump capacity";
parameter Modelica.Units.SI.ThermalConductance UACon
"Thermal conductance of condenser";
parameter Modelica.Units.SI.ThermalConductance UAEva
"Thermal conductance of evaporator";
parameter Modelica.Units.SI.Time tau1=60
"Time constant at nominal flow rate (used if energyDynamics1 <> Modelica.Fluid.Types.Dynamics.SteadyState)";
parameter Modelica.Units.SI.Time tau2=60
"Time constant at nominal flow rate (used if energyDynamics2 <> Modelica.Fluid.Types.Dynamics.SteadyState)";
parameter Modelica.Units.SI.Temperature T1_start=Medium1.T_default
"Initial or guess value of set point";
parameter Modelica.Units.SI.Temperature T2_start=Medium2.T_default
"Initial or guess value of set point";
parameter Modelica.Fluid.Types.Dynamics energyDynamics=
Modelica.Fluid.Types.Dynamics.DynamicFreeInitial
"Type of energy balance: dynamic (3 initialization options) or steady state";
parameter Boolean enable_temperature_protection = true
"Enable temperature protection";
parameter Modelica.Units.SI.Temperature TConMax=ref.TCri - 5
"Upper bound for condenser temperature";
parameter Modelica.Units.SI.Temperature TEvaMin=275.15
"Lower bound for evaporator temperature";
parameter Real dTHys(unit="K",min=0) = 5
"Hysteresis interval width";
Modelica.Blocks.Interfaces.BooleanOutput errLowPre if enable_temperature_protection
"if true, compressor disabled since evaporator temperature is above upper bound";
Modelica.Blocks.Interfaces.BooleanOutput errHigPre if enable_temperature_protection
"if true, compressor disabled since condenser temperature is below lower bound";
Modelica.Blocks.Interfaces.BooleanOutput errNegTemDif if enable_temperature_protection
"if true, compressor disabled since condenser temperature is below evaporator temperature";
Modelica.Blocks.Interfaces.RealInput y(final unit = "1")
if enable_variable_speed == true
"Modulating signal for compressor frequency, equal to 1 at full load condition";
Modelica.Blocks.Interfaces.IntegerInput stage
if enable_variable_speed == false
"Current stage of the heat pump, equal to 1 at full load condition";
Modelica.Blocks.Interfaces.RealOutput QCon_flow(
min = 0,
final quantity="HeatFlowRate",
final unit="W") "Actual heating heat flow rate added to fluid 1";
Modelica.Blocks.Interfaces.RealOutput P(
min = 0,
final quantity="Power",
final unit="W") "Electric power consumed by compressor";
Modelica.Blocks.Interfaces.RealOutput QEva_flow(
max = 0,
final quantity="HeatFlowRate",
final unit="W") "Actual cooling heat flow rate removed from fluid 2";
Buildings.Fluid.HeatExchangers.EvaporatorCondenser con(
redeclare final package Medium = Medium1,
final allowFlowReversal=allowFlowReversal1,
final m_flow_nominal=m1_flow_nominal,
final m_flow_small=m1_flow_small,
m_flow(start=m1_flow_nominal),
final from_dp=from_dp1,
final dp_nominal=dp1_nominal,
final linearizeFlowResistance=linearizeFlowResistance1,
final deltaM=deltaM1,
final tau=tau1,
final T_start=T1_start,
final energyDynamics=energyDynamics,
final homotopyInitialization=homotopyInitialization,
final UA=UACon) "Condenser";
Buildings.Fluid.HeatExchangers.EvaporatorCondenser eva(
redeclare final package Medium = Medium2,
final allowFlowReversal=allowFlowReversal2,
final m_flow_nominal=m2_flow_nominal,
final m_flow_small=m2_flow_small,
m_flow(start=m2_flow_nominal),
final from_dp=from_dp2,
final dp_nominal=dp2_nominal,
final linearizeFlowResistance=linearizeFlowResistance2,
final deltaM=deltaM2,
final tau=tau2,
final T_start=T2_start,
final energyDynamics=energyDynamics,
final homotopyInitialization=homotopyInitialization,
final UA=UAEva) "Evaporator";
replaceable Buildings.Fluid.HeatPumps.Compressors.BaseClasses.PartialCompressor
com
"Compressor";
protected
Modelica.Blocks.Math.IntegerToReal intToRea
if enable_variable_speed == false "Conversion for stage signal";
Modelica.Blocks.Nonlinear.Limiter lim(final uMin=0, final uMax=1)
if enable_variable_speed == false "Limiter for control signal";
Compressors.BaseClasses.TemperatureProtection temPro(
final TConMax=TConMax,
final TEvaMin=TEvaMin,
final dTHys=dTHys) if enable_temperature_protection
"Disables compressor when outside of allowed operation range";
initial equation
assert(homotopyInitialization, "In " + getInstanceName() +
": The constant homotopyInitialization has been modified from its default value. This constant will be removed in future releases.",
level = AssertionLevel.warning);
equation
if enable_temperature_protection then
connect(errLowPre, temPro.errLowPre);
connect(errHigPre, temPro.errHigPre);
connect(errNegTemDif, temPro.errNegTemDif);
end if;
connect(port_a1, con.port_a);
connect(con.port_b, port_b1);
connect(con.Q_flow, QCon_flow);
connect(eva.port_a, port_a2);
connect(eva.port_b, port_b2);
connect(eva.Q_flow, QEva_flow);
connect(com.port_b, con.port_ref);
connect(com.port_a, eva.port_ref);
connect(com.P, P);
if enable_variable_speed then
if enable_temperature_protection then
connect(y,temPro.u);
else
connect(y,com.y);
end if;
else
if enable_temperature_protection then
connect(lim.y, temPro.u);
else
connect(lim.y, com.y);
end if;
end if;
connect(stage, intToRea.u);
connect(intToRea.y, lim.u);
connect(temPro.y, com.y);
connect(temPro.TCon, con.T);
connect(temPro.TEva, eva.T);
end PartialWaterToWater;