modelPressDrop
Extends from Icons.Water.PressDrop.
Information
The pressure drop across the inlet and outlet connectors is computed according to a turbulent friction model, i.e. is proportional to the squared velocity of the fluid. The friction coefficient can be specified directly, or by giving an operating point, or as a multiple of the kinetic pressure. In the latter two cases, the correction coefficient Kfc can be used to modify the friction coefficient, e.g. to fit some experimental operating point.
A small linear pressure drop is added to avoid numerical singularities at low or zero flowrate. The wnom parameter must be always specified; the additional linear pressure drop is such that it is equal to the turbulent pressure drop when the flowrate is equal to wnf*wnom (the default value is 1% of the nominal flowrate).
Modelling options
The following options are available to specify the friction coefficient:
- FFtype = 0: the hydraulic friction coefficient Kf is set directly.
- FFtype = 1: the hydraulic friction coefficient is specified by the nominal operating point (wnom,dpnom, rhonom).
- FFtype = 2: the pressure drop is K times the kinetic pressure.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.MassFlowRate | wnom | Nominal mass flowrate | |
| FFtypes | FFtype | FFtypes.Kf | Friction Factor Type |
| Real | Kf | 0 | Hydraulic resistance coefficient (DP = Kf*w^2/rho) |
| SI.PressureDifference | dpnom | Nominal pressure drop | |
| Medium.Density | rhonom | 0 | Nominal density |
| Real | K | 0 | Kinetic resistance coefficient (DP=K*rho*velocity2/2) |
| SI.Area | A | 0 | Cross-section |
| SI.PerUnit | wnf | 0.01 | Fraction of nominal flow rate at which linear friction equals turbulent friction |
| SI.PerUnit | Kfc | 1 | Friction factor correction coefficient |
| Real | Kf_a | Actual hydraulic resistance coefficient | |
| Boolean | allowFlowReversal | system.allowFlowReversal | = true to allow flow reversal, false restricts to design direction |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FlangeA | inlet | ||
| FlangeB | outlet |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.ThermodynamicState | state | Thermodynamic state of the fluid | |
| ThermoPower.System | system | System wide properties | |
| Medium.Density | rho | Fluid density | |
| Medium.MassFlowRate | w | Flow rate at the inlet | |
| Medium.AbsolutePressure | pin | Inlet pressure | |
| Medium.AbsolutePressure | pout | Outlet pressure | |
| SI.PressureDifference | dp | Pressure drop |
Contents
| Name | Description |
|---|---|
 Medium | |
 squareReg |
Revisions
- 16 Dec 2004
by Francesco Casella:
Standard medium definition added. - 18 Nov 2004
by Francesco Casella:
Kfnom removed, Kf can now be set directly. - 18 Jun 2004
by Francesco Casella:
Adapted to Modelica.Media. - 1 Oct 2003
by Francesco Casella:
First release.