.Buildings.Fluid.HydronicConfigurations.ActiveNetworks.SingleMixing .Buildings.Fluid.HydronicConfigurations.ActiveNetworks.SingleMixingThis configuration (see schematic below) is used for variable flow primary circuits and either constant flow or variable flow secondary circuits that have a design supply temperature close or identical to the primary circuit but a varying set point during operation. The control valve should be sized with a pressure drop equal to the primary pressure differential. That pressure drop must be compensated for by the secondary pump which excludes the use of this configuration to applications with a high primary pressure differential.
The following table presents the main characteristics of this configuration.
| Primary circuit | Variable flow |
| Secondary (consumer) circuit | Constant or variable flow |
| Typical applications | Circuits that have a design supply temperature close or identical to the primary circuit but a varying set point during operation. |
| Non-recommended applications | Applications with a high primary pressure differential such as DHC systems due to the constraints on the control valve and secondary pump selection: for those applications use either Buildings.Fluid.HydronicConfigurations.ActiveNetworks.InjectionTwoWay, or Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Decoupling in conjunction with Buildings.Fluid.HydronicConfigurations.PassiveNetworks.SingleMixing. |
| Built-in valve control options | Supply temperature |
| Control valve selection |
β = ΔpA-AB /
(Δp1 + ΔpA-AB) The valve is sized with a pressure drop of Δp1 which yields an authority close to 0.5. |
| Balancing requirement |
The primary balancing valve should compensate for the primary
pressure differential (see additional comments below).
Bypass balancing valve not recommended. |
|
Lumped flow resistances include (With the setting use_lumFloRes=true.)
|
Direct branch: control valve direct branch val.res1
and whole consumer circuit between b2 and a2Bypass branch: control valve bypass branch val.res3
and bypass balancing valve res3
|
The primary pressure differential tends to oppose the bypass flow rate.
It is possible to reach zero bypass flow at partial valve opening and
a negative bypass flow for even lower opening values.
Therefore, a balancing valve in the bypass is not recommended as it
would further reduce the bypass flow rate.
When using that model, one should keep the default setting
dpBal3_nominal=0 Pa.
The balancing procedure should ensure that the primary pressure differential is compensated for by the primary balancing valve. Otherwise, the flow may reverse in the bypass branch and the mixing function of the three-way valve cannot be achieved. The control valve pressure drop must be compensated for by the secondary pump.