modelDualMixing
Extends from BaseClasses.PartialPassivePrimary.
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 |
|---|---|---|---|
| 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 |
| Configuration | |||
| Real | kSizBal | 1.0 | Sizing factor for bypass balancing valve (1 means balanced) |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal | nTer*mTer_flow_nominal | Mass flow rate in consumer circuit at design conditions |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.HydronicConfigurations.PassiveNetworks.DualMixing | con | Hydronic connection | |
| ActiveNetworks.Examples.BaseClasses.LoadThreeWayValveControl | loa | Load | |
| Buildings.Controls.OBC.CDL.Integers.Sources.TimeTable | mode | Operating mode (time schedule) | |
| Buildings.Controls.OBC.CDL.Reals.Sources.TimeTable | fraLoa | Load modulating signal | |
| Buildings.Controls.OBC.CDL.Reals.Sources.Constant | T2Set | Consumer circuit temperature set point | |
| Buildings.Controls.OBC.CDL.Reals.Sources.Constant | T1Set | Primary circuit temperature set point | |
| ActiveNetworks.Examples.BaseClasses.LoadThreeWayValveControl | loa1 | Load | |
| FixedResistances.PressureDrop | res2 | Pipe pressure drop | |
| Delays.DelayFirstOrder | del2 | Fluid transport delay |
Revisions
-
June 30, 2022, by Antoine Gautier:
First implementation.