modelInjectionTwoWayConstantReturn
Extends from InjectionTwoWayConstant (Model illustrating the operation of an inversion circuit with two-way valve and constant secondary).
Information
This model is almost similar to Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.InjectionTwoWayConstant except that a cooling system is represented, and the valve control logic is based on the consumer return temperature. This model serves mostly as a reference to illustrate the shortcomings of this control option when used with a variable consumer circuit such as in Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.InjectionTwoWayVariableReturn.
In this model the load is not met at partial load due to the sizing of the terminal units that does not take into account the load diversity as required when controlling for the return temperature (see the explanation provided in Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.InjectionTwoWayConstant). In addition, the load model does not guarantee a linear variation of the load with the input signal in cooling mode, see Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.BaseClasses.Load. This amplifies the effect of the unmet load at partial load.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.HydronicConfigurations.Types.Control | typ (from PartialActivePrimary) | Buildings.Fluid.HydronicConfigurations.Types.Control.Heating | Load type |
| Integer | nTer (from PartialActivePrimary) | 2 | Number of terminal units |
| Real | kSizPum (from PartialActivePrimary) | 1.0 | Pump oversizing coefficient |
| Modelica.Units.SI.Pressure | p_min (from PartialActivePrimary) | 200000 | Circuit minimum pressure |
| Modelica.Units.SI.Temperature | TLiqEnt_nominal (from PartialActivePrimary) | if typ == Buildings.Fluid.HydronicConfigurations.Types.Control.Heating then 60 + 273.15 else 7 + 273.15 | Liquid entering temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqLvg_nominal (from PartialActivePrimary) | TLiqEnt_nominal + (if typ == Buildings.Fluid.HydronicConfigurations.Types.Control.Heating then -10 else +5) | Liquid leaving temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqEntChg_nominal (from PartialActivePrimary) | 60 + 273.15 | Liquid entering temperature in change-over mode |
| Modelica.Units.SI.Temperature | TLiqSup_nominal (from PartialActivePrimary) | TLiqEnt_nominal | Liquid primary supply temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqSupChg_nominal (from PartialActivePrimary) | TLiqEntChg_nominal | Liquid primary supply temperature in change-over mode |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | mTer_flow_nominal (from PartialActivePrimary) | 1 | Terminal unit mass flow rate at design conditions |
| Modelica.Units.SI.MassFlowRate | m1_flow_nominal (from PartialActivePrimary) | m2_flow_nominal | Mass flow rate in primary branch at design conditions |
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal (from PartialActivePrimary) | nTer*mTer_flow_nominal | Mass flow rate in consumer circuit at design conditions |
| Modelica.Units.SI.PressureDifference | dpTer_nominal (from PartialActivePrimary) | 3E4 | Terminal unit pressure drop at design conditions |
| Modelica.Units.SI.PressureDifference | dpPip_nominal (from PartialActivePrimary) | 0.5E4 | Pipe section pressure drop at design conditions |
| Modelica.Units.SI.PressureDifference | dpPum_nominal (from PartialActivePrimary) | Pump head at design conditions | |
| Modelica.Units.SI.MassFlowRate | mPum_flow_nominal (from PartialActivePrimary) | m1_flow_nominal | Primary pump mass flow rate at design conditions |
| Modelica.Units.SI.PressureDifference | dp2_nominal (from PartialInjectionTwoWay) | Consumer circuit pressure differential at design conditions | |
| Modelica.Units.SI.Temperature | T2Set_nominal (from InjectionTwoWayConstant) | if con.typVar == Buildings.Fluid.HydronicConfigurations.Types.ControlVariable.SupplyTemperature then TLiqEnt_nominal else TLiqLvg_nominal | Consumer circuit design temperature set point |
| Modelica.Units.SI.Temperature | TAirEnt_nominal (from InjectionTwoWayConstant) | 293.15 | Air entering temperature at design conditions |
| Modelica.Units.SI.MassFraction | phiAirEnt_nominal (from InjectionTwoWayConstant) | 0.5 | Air entering relative humidity at design conditions |
| Modelica.Units.SI.MassFlowRate | mAir_flow_nominal | 6.8 | Air mass flow rate at design conditions |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from PartialActivePrimary) | Modelica.Fluid.Types.Dynamics.FixedInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Configuration | |||
| Boolean | is_bal (from PartialInjectionTwoWay) | false | Set to true for balanced primary branch |
| Boolean | have_resT2 (from InjectionTwoWayConstant) | false | Set to true for consumer circuit temperature reset, false for constant set point |
| Controls | |||
| Modelica.Units.SI.PressureDifference | dp1Set (from PartialInjectionTwoWay) | 1e4 | Pressure differential set point |
Components
Revisions
-
June 30, 2022, by Antoine Gautier:
First implementation.