Buildings.DHC.Plants.Cooling.BaseClasses
Package containing base classes
Information
Package containing base classes.Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
Name | Description |
---|---|
IdealUser | Ideal user model |
ParallelJunctions | A pair of junctions in parallel |
ParallelPipes | CHW supply and return pipes in parallel |
ReversibleConnection | A connection that supports reversible flow with a pump and a valve |
TankBranch | Model of the tank branch of a storage plant |
Validation | Package containing validation models |
Buildings.DHC.Plants.Cooling.BaseClasses.IdealUser
Ideal user model
Information
This is a simple ideal user model used by
Buildings.DHC.Plants.Cooling.Examples.StoragePlantDualSource.
The load of the user is described by a varying mass flow rate setpoint.
The valve is controlled to maintain the requested mass flow rate.
The model sets its leaving water temperature to the user-specified temperature
T_CHWR_nominal
.
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package Medium | Modelica.Media.Interfaces.Pa... | Medium package | |
MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
Temperature | T_CHWR_nominal | Nominal temperature of CHW return [K] | |
PressureDifference | dp_nominal | Nominal pressure drop when valve is fully open [Pa] |
Connectors
Type | Name | Description |
---|---|---|
replaceable package Medium | Medium package | |
input RealInput | mPre_flow | Load in terms of flow rate prescription [kg/s] |
output RealOutput | yVal_actual | Consumer control valve actuator position [1] |
output RealOutput | dp | Differential pressure from the sensor [Pa] |
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) |
Modelica definition
Buildings.DHC.Plants.Cooling.BaseClasses.ParallelJunctions
A pair of junctions in parallel
Information
This model provides junction models in parallel on the distribution pipe lines. This model is for breaking algebraic loops only and has no pressure drop.
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package Medium | Modelica.Media.Interfaces.Pa... | Medium package | |
Nominal condition | |||
MassFlowRate | m_flow_nominal | Design mass flow rate (used to approximate dynamics [kg/s] | |
Dynamics | |||
Nominal condition | |||
Time | tau | 30 | Time constant at nominal flow [s] |
Initialization | |||
Temperature | T1_start | Medium.T_default | Start temperature of the volume [K] |
Temperature | T2_start | Medium.T_default | Start temperature of the volume [K] |
Connectors
Type | Name | Description |
---|---|---|
replaceable package Medium | Medium package | |
FluidPort_a | port_a2 | Fluid connector |
FluidPort_b | port_b1 | Fluid connector |
FluidPort_b | port_b2 | Fluid connector |
FluidPort_a | port_a1 | Fluid connector |
FluidPort_a | port_c1 | Fluid connector |
FluidPort_b | port_c2 | Fluid connector |
Modelica definition
Buildings.DHC.Plants.Cooling.BaseClasses.ParallelPipes
CHW supply and return pipes in parallel
Information
This model contains two pipes in parallel that represent the supply and return pipes of a district CHW network. Only pressure drop is considered. This model does not consider heat loss.
Extends from Buildings.Fluid.Interfaces.PartialFourPortInterface (Partial model with four ports and declaration of quantities that are used by many models).
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 Medium | Modelica.Media.Interfaces.Pa... | Medium package | |
Nominal condition | |||
MassFlowRate | m1_flow_nominal | m_flow_nominal | Nominal mass flow rate [kg/s] |
MassFlowRate | m2_flow_nominal | m_flow_nominal | Nominal mass flow rate [kg/s] |
MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
PressureDifference | dp_nominal | Nominal pressure drop [Pa] | |
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 |
Connectors
Type | Name | Description |
---|---|---|
replaceable package Medium1 | Medium 1 in the component | |
replaceable package Medium2 | Medium 2 in the component | |
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 Medium | Medium package |
Modelica definition
Buildings.DHC.Plants.Cooling.BaseClasses.ReversibleConnection
A connection that supports reversible flow with a pump and a valve
Information
This model implements a piping connection for reversible mass flow rate between the storage plant and the district network.
Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models).
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package Medium | PartialMedium | Medium in the component | |
MassFlowRate | mTan_flow_nominal | Nominal mass flow rate for CHW tank branch [kg/s] | |
PressureDifference | dpPum_nominal | Nominal pressure difference for supply pump sizing [Pa] | |
PressureDifference | dpVal_nominal | Nominal pressure difference for return valve sizing [Pa] | |
Nominal condition | |||
MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
Assumptions | |||
Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
Advanced | |||
MassFlowRate | m_flow_small | 1E-4*abs(m_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 |
Initialization | |||
ThermodynamicTemperature | T_start | Start temperature [K] |
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) |
output RealOutput | PEle | Estimated power consumption [W] |
input RealInput | yPum | Normalized speed signal for pump [1] |
input RealInput | yVal | Normalized flow signal for valve [1] |
Modelica definition
Buildings.DHC.Plants.Cooling.BaseClasses.TankBranch
Model of the tank branch of a storage plant
Information
This model is part of a storage plant. This branch has a stratified tank. This tank can potentially be charged remotely by a chiller from the district CHW network, or by a chiller that is local to the energy transfer station that contains this tank.
Extends from Buildings.Fluid.Interfaces.PartialFourPort (Partial model 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 Medium | Modelica.Media.Interfaces.Pa... | Medium package | |
Nominal values | |||
MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
MassFlowRate | mTan_flow_nominal | Nominal mass flow rate for CHW tank branch [kg/s] | |
MassFlowRate | mChi_flow_nominal | Nominal mass flow rate for CHW chiller branch [kg/s] | |
Temperature | T_CHWS_nominal | 7 + 273.15 | Nominal temperature of CHW supply [K] |
Temperature | T_CHWR_nominal | 12 + 273.15 | Nominal temperature of CHW return [K] |
Tank | |||
Volume | VTan | Tank volume [m3] | |
Length | hTan | Height of tank (without insulation) [m] | |
Length | dIns | Thickness of insulation [m] | |
ThermalConductivity | kIns | 0.04 | Specific heat conductivity of insulation [W/(m.K)] |
Integer | nSeg | 5 | Number of volume segments |
Time | tau | 1 | Time constant for mixing [s] |
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 |
Dynamics | |||
Conservation equations | |||
Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance |
Initialization | |||
AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
Temperature | T_start | T_CHWR_nominal | Start value of temperature [K] |
Temperature | TFlu_start[nSeg] | T_start*ones(nSeg) | Initial temperature of the tank segments, with TFlu_start[1] being the top segment [K] |
Connectors
Type | Name | Description |
---|---|---|
replaceable package Medium1 | Medium 1 in the component | |
replaceable package Medium2 | Medium 2 in the component | |
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 Medium | Medium package | |
output RealOutput | mTan_flow | Mass flow rate of the tank [kg/s] |
output RealOutput | Ql_flow | Heat loss of tank (positive if heat flows from tank to ambient) [W] |
HeatPort_a | heaPorTop | Heat port tank top (outside insulation) |
HeatPort_a | heaPorSid | Heat port tank side (outside insulation) |
HeatPort_a | heaPorBot | Heat port tank bottom (outside insulation). Leave unconnected for adiabatic condition |
HeatPort_a | heaPorVol[tan.nSeg] | Heat port that connects to the control volumes of the tank |
output RealOutput | TTan[2] | Temperatures at the tank 1: top and 2: bottom [K] |