Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase

Information

Package Content

Name	Description
dp_twoPhaseChisholm_DP	Frictional pressure loss of straight pipe for two phase flow according to Chisholm correlation | calculate pressure loss | overall flow regime
dp_twoPhaseFriedel_DP	Frictional pressure loss of straight pipe for two phase flow according to Friedel correlation | calculate pressure loss| overall flow regime
dp_twoPhaseGeodetic_DP	Geodetic pressure loss of straight pipe for two phase flow | calculate pressure loss
dp_twoPhaseMomentum_DP	Momentum pressure loss of straight pipe for two phase flow | calculate pressure loss
TwoPhaseMultiplierFriedel	Calculation of two phase multiplier according to Friedel | constant mass flow rate quality | horizontal flow | vertical upflow and downflow
TwoPhaseMultiplierChisholm	Calculation of two phase multiplier according to Chisholm | constant mass flow rate quality
TwoPhaseDensity	Calculation of mean density for two phase flow
VoidFraction	Calculation of (cross sectional) void fraction for two phase flow
SlipRatio	Calculation of (analytical/empirical) slip ratio

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.dp_twoPhaseChisholm_DP

Information

Inputs

Name	Description
Constant inputs
IN_con
Variable inputs
IN_var
Input
m_flow	Mass flow rate [kg/s]

Outputs

Name	Description
DP	Output for function dp_twoPhaseChisholm_DP [Pa]

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.dp_twoPhaseFriedel_DP

Information

Inputs

Name	Description
Constant inputs
IN_con
Variable inputs
IN_var
Input
m_flow	Mass flow rate [kg/s]

Outputs

Name	Description
DP	Output for function dp_twoPhaseFriedel_DP [Pa]

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.dp_twoPhaseGeodetic_DP

Information

Inputs

Name	Description
voidFractionApproach	Choice of void fraction approach
crossSectionalAveraged	true == cross sectional averaged void fraction | false == volumetric
Geometry
length	Length in fluid flow direction [m]
phi	Tilt angle to horizontal [rad]
Fluid properties
rho_g	Density of gaseous phase [kg/m3]
rho_l	Density of liquid phase [kg/m3]
x_flow	Mass flow rate quality

Outputs

Name	Description
DP_geo	Geodetic pressure loss [Pa]

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.dp_twoPhaseMomentum_DP

Information

Inputs

Name	Description
Choices
voidFractionApproach	Choice of void fraction approach
massFlowRateCorrection	Consider heterogeneous mass flow rate correction
Geometry
A_cross	Cross sectional area [m2]
perimeter	Perimeter [m]
Fluid properties
rho_g	Density of gas [kg/m3]
rho_l	Density of liquid [kg/m3]
x_flow_end	Mass flow rate quality at end of length
x_flow_sta	Mass flow rate quality at start of length
Input
m_flow	Mass flow rate [kg/s]

Outputs

Name	Description
DP_mom	Momentum pressure loss [Pa]

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.TwoPhaseMultiplierFriedel

Information

Inputs

Name	Description
Constant inputs
IN_con
Variable inputs
IN_var
Input
m_flow	Mass flow rate [kg/s]

Outputs

Name	Description
phi	Two phase multiplier w.r.t. Friedel

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.TwoPhaseMultiplierChisholm

Information

Inputs

Name	Description
Constant inputs
IN_con
Variable inputs
IN_var
Input
m_flow	Mass flow rate [kg/s]

Outputs

Name	Description
phi	Two phase multiplier w.r.t. Chisholm

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.TwoPhaseDensity

Information

The gaseous and the liquid part of a fluid in a two phase flow are often discontinuously distributed. This complex behaviour is simplified for engineering calculations. The two phase flow of different fluid flow situations (e.g., bubble or stratified flow) is modelled as if the gaseous and the liquid phase are continuously distributed.

A mean density assuming a continuous distribution out of a discontinuous two phase fluid flow situation can be calculated with a homogeneous or a heterogeneous approach (see dp_twoPhaseOverall_DP).

The following modelling approaches can be used to calculate the mean density of two phase flow:

• homogeneous density (homogeneous approach)
• momentum flux density (heterogeneous approach)
• kinetic energy flow density (heterogeneous approach)

The heterogeneous approaches are analytically derived by minimising the momentum flux or the kinetic energy flow assuming implicitly that the two-phase flow will tend towards the minimum of this quantity.

References

VDI:

VDI - Wärmeatlas: Berechnungsblätter für den Wärmeübergang. Springer Verlag, 10th edition, 2006.

Inputs

Name	Description
rho_g	Density of gaseous phase [kg/m3]
rho_l	Density of liquid phase [kg/m3]
epsilon_A	Void fraction (cross sectional averaged)
x_flow	Mass flow rate quality
Choices
voidFractionApproach	Choice of void fraction approach
massFlowRateCorrection	Consider heterogeneous mass flow rate correction

Outputs

Name	Description
rho_2ph	Mean density of two phase flow [kg/m3]

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.VoidFraction

Information

Inputs

Name	Description
crossSectionalAveraged	true == cross sectional averaged void fraction | false == volumetric
rho_g	Density of gaseous phase [kg/m3]
rho_l	Density of liquid phase [kg/m3]
x_flow	Mass flow rate quality
Choices
voidFractionApproach	Choice of void fraction approach

Outputs

Name	Description
epsilon	Void fraction
slipRatio	Slip ratio

Modelica.Fluid.Dissipation.Utilities.Functions.PressureLoss.TwoPhase.SlipRatio

Information

Inputs

Name	Description
rho_g	Density of gaseous phase [kg/m3]
rho_l	Density of liquid phase [kg/m3]
x_flow	Mass flow rate quality
Choices
voidFractionApproach	Choice of void fraction approach

Outputs

Name	Description
SR	Slip ratio