SingularPressureLoss#
Copyright © EDF 2002 - 2026#
ThermoSysPro Version 4.2#
This component model is documented in Sect. 13.4 of the ThermoSysPro book.
Singular pressure loss#
This component represents generic pressure losses in a pipe or a singularity using a single-friction pressure loss coefficient. It can also represent the pressure losses inside a circuit of connected pipes and singularities with a pressure loss coefficient equivalent to the whole circuit. The lumped straight pipe should be used instead to take that effect into account. For water/steam, the flow regime can be single-phase or homogeneous two-phase flow.
Following assumptions are made:
The flow inside pressure losses is adiabatic. Non-adiabatic pipes must be
modeled by connecting pressure losses to volumes.The specific enthalpy inside the components is equal to the specific enthalpy at the inlet.
The properties of the fluid are computed for the average pressure..
Inertia due to momentum inside pipes is neglected.
The singular pressure loss component is similar to the pipe pressure loss, except that inlet and outlet altitudes of the pipe are pre-defined.
To model pressure loss in a bent pipe, see bend.
Modelica component model#
The equations mentioned below are implemented in the component SingularPressureLoss, located in the WaterSteam.PressureLosses sub-library.
This component has 2 connectors:
C1: fluid inlet,
C2: fluid outlet.
Nomenclature#
Symbol |
Description |
Unit |
Definition |
Modelica name |
|---|---|---|---|---|
\(g\) |
Gravity constant |
\(\mathrm{m} / \mathrm{s}^{2}\) |
- |
|
\(h\) |
Fluid specific enthalpy |
\(\mathrm{J} / \mathrm{kg}\) |
h |
|
\(m\) |
Fluid mass flow rate |
\(\mathrm{kg} / \mathrm{s}\) |
Q |
|
\(P_{\mathrm{i}}\) |
Fluid pressure at the inlet |
\(\mathrm{Pa}\) |
C1.P |
|
\(P_{\mathrm{o}}\) |
Fluid pressure at the outlet |
\(\mathrm{Pa}\) |
C2.P |
|
\(z_{\mathrm{i}}\) |
Inlet altitude |
\(\mathrm{m}\) |
- |
|
\(z_{0}\) |
Outlet altitude |
\(\mathrm{m}\) |
- |
|
\(\Delta P\) |
Pressure loss of the fluid between the inlet and the outlet |
\(\mathrm{Pa}\) |
\(P_{\mathrm{i}}-P_{\mathrm{o}}\) |
deltaP |
\(\Delta P_{\mathrm{f}}\) |
Friction pressure loss between the inlet and the outlet |
\(\mathrm{Pa}\) |
- |
|
\(\Delta P_{\mathrm{g}}\) |
Gravity pressure loss between the inlet and the outlet |
\(\mathrm{Pa}\) |
\(\rho \cdot g \cdot\left(z_{\mathrm{o}}-z_{\mathrm{i}}\right)\) |
- |
\(\Lambda\) |
Friction pressure loss coefficient |
\(\mathrm{m}^{-4}\) |
K |
|
\(\rho\) |
Fluid density |
\(\mathrm{kg} / \mathrm{m}^{3}\) |
rho |
Governing equations#
Static momentum balance equation#
Validity domain:
\(\forall \dot{m}\)
Mathematical formulation:
Comments:
In case of a singularity, \(z_{\mathrm{o}}=z_{\mathrm{i}}\) and consequently \(\Delta P_{\mathrm{g}}=0\).
Friction pressure losses#
Validity domain:
\(\forall \dot{m}\)
Mathematical formulation:
Comments:
The pressure loss coefficient \(\Lambda\) is provided by the user or can be obtained by inverse calculation from the mass flow rate.
References#
El Hefni, Baligh and Bouskela, Daniel (2019). Modeling and Simulation of Thermal Power Plants with ThermoSysPro, sect. 13.4. Springer Nature Switzerland AG.