modelDualMixing
Extends from BaseClasses.PartialPassivePrimary (Partial model of passive primary network).
Information
This model represents a heating system where the configuration Buildings.Fluid.HydronicConfigurations.PassiveNetworks.DualMixing serves as the interface between a variable flow primary circuit and a constant flow secondary circuit. The secondary supply temperature is constant and lower than the primary circuit.
The fixed bypass of the dual mixing circuit is balanced at design conditions
if kSizBal=1.
Selecting a lower value such as kSizBal=0.6 illustrates
the operation with an oversized balancing valve, yielding
a lower pressure drop.
One can observe that the secondary supply temperature set point cannot
be met despite the control valve being fully open.
The secondary distribution pump operates with sufficient head
as the design flow rate is met in the consumer circuit.
This is the low pressure differential at the boundaries
of the control valve due to the oversized balancing valve
that creates the primary flow shortage and prevents from
serving the load properly.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.HydronicConfigurations.Types.Control | typ (from PartialPassivePrimary) | Load type | |
| Integer | nTer (from PartialPassivePrimary) | 2 | Number of terminal units |
| Modelica.Units.SI.Pressure | p_min (from PartialPassivePrimary) | 200000 | Circuit minimum pressure |
| Modelica.Units.SI.Temperature | TLiqEnt_nominal (from PartialPassivePrimary) | 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 PartialPassivePrimary) | 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 PartialPassivePrimary) | 60 + 273.15 | Liquid entering temperature in change-over mode |
| Modelica.Units.SI.Temperature | TLiqSup_nominal (from PartialPassivePrimary) | TLiqEnt_nominal | Liquid primary supply temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqSupChg_nominal (from PartialPassivePrimary) | TLiqEntChg_nominal | Liquid primary supply temperature in change-over mode |
| Modelica.Units.SI.MassFlowRate | mAir_flow_nominal | abs(loa.loa.Q_flow_nominal)/3/1015 | Air mass flow rate at design conditions |
| Modelica.Units.SI.Temperature | TAirEnt_nominal | 24 + 273.15 | Air entering temperature at design conditions |
| Modelica.Units.SI.MassFraction | phiAirEnt_nominal | 0.5 | Air entering relative humidity at design conditions |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | mTer_flow_nominal (from PartialPassivePrimary) | 1 | Terminal unit mass flow rate at design conditions |
| Modelica.Units.SI.MassFlowRate | m1_flow_nominal (from PartialPassivePrimary) | nTer*mTer_flow_nominal | Mass flow rate in primary circuit at design conditions |
| Modelica.Units.SI.PressureDifference | dpTer_nominal (from PartialPassivePrimary) | 3E4 | Terminal unit pressure drop at design conditions |
| Modelica.Units.SI.PressureDifference | dpPip_nominal (from PartialPassivePrimary) | 0.5E4 | Pipe section pressure drop at design conditions |
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal | nTer*mTer_flow_nominal | Mass flow rate in consumer circuit at design conditions |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from PartialPassivePrimary) | Modelica.Fluid.Types.Dynamics.FixedInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Configuration | |||
| Real | kSizBal | 1.0 | Sizing factor for bypass balancing valve (1 means balanced) |
Components
Revisions
-
June 30, 2022, by Antoine Gautier:
First implementation.