modelFlow1DDB
1-dimensional fluid flow model for water or steam flow (finite volumes, Dittus-Boelter heat transfer)
Extends from Flow1D (1-dimensional fluid flow model for water/steam (finite volumes)).
Information
This model extends Flow1D by computing the distribution of the heat transfer coefficient gamma and making it available through an extended version of the wall connector.
This model can be used in the case of one-phase water or steam flow. Dittus-Boelter's equation [1] is used to compute the heat transfer coefficient.
References:
- J. C. Collier: Convective Boiling and Condensation, 2nd ed.,McGraw Hill, 1981, pp. 146.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | pi (from Flow1DBase) | Modelica.Constants.pi | |
| Integer | N (from Flow1DBase) | 2 | Number of nodes for thermal variables |
| Integer | Nw (from Flow1DBase) | N - 1 | Number of volumes on the wall interface |
| Integer | Nt (from Flow1DBase) | 1 | Number of tubes in parallel |
| SI.Distance | L (from Flow1DBase) | Tube length | |
| SI.Position | H (from Flow1DBase) | 0 | Elevation of outlet over inlet |
| SI.Area | A (from Flow1DBase) | Cross-sectional area (single tube) | |
| SI.Length | omega (from Flow1DBase) | Perimeter of heat transfer surface (single tube) | |
| SI.Length | Dhyd (from Flow1DBase) | omega/pi | Hydraulic Diameter (single tube) |
| Medium.MassFlowRate | wnom (from Flow1DBase) | Nominal mass flowrate (total) | |
| ThermoPower.Choices.Flow1D.FFtypes | FFtype (from Flow1DBase) | ThermoPower.Choices.Flow1D.FFtypes.NoFriction | Friction Factor Type |
| SI.PressureDifference | dpnom (from Flow1DBase) | 0 | Nominal pressure drop (friction term only!) |
| Real | Kfnom (from Flow1DBase) | 0 | Nominal hydraulic resistance coefficient (DP = Kfnom*w^2/rho) |
| Medium.Density | rhonom (from Flow1DBase) | 0 | Nominal inlet density |
| SI.PerUnit | Cfnom (from Flow1DBase) | 0 | Nominal Fanning friction factor |
| SI.PerUnit | e (from Flow1DBase) | 0 | Relative roughness (ratio roughness/diameter) |
| SI.PerUnit | Kfc (from Flow1DBase) | 1 | Friction factor correction coefficient |
| Boolean | DynamicMomentum (from Flow1DBase) | false | Inertial phenomena accounted for |
| ThermoPower.Choices.Flow1D.HCtypes | HydraulicCapacitance (from Flow1DBase) | ThermoPower.Choices.Flow1D.HCtypes.Downstream | Location of the hydraulic capacitance |
| Boolean | avoidInletEnthalpyDerivative (from Flow1DBase) | true | Avoid inlet enthalpy derivative |
| Boolean | allowFlowReversal (from Flow1DBase) | system.allowFlowReversal | = true to allow flow reversal, false restricts to design direction |
| SI.PerUnit | wnf (from Flow1DBase) | 0.02 | Fraction of nominal flow rate at which linear friction equals turbulent friction |
| SI.Acceleration | g (from Flow1DBase) | Modelica.Constants.g_n | |
| SI.PerUnit | dzdx (from Flow1DBase) | H/L | Slope |
| SI.Length | l (from Flow1DBase) | L/(N - 1) | Length of a single volume |
| SI.Volume | V (from Flow1DBase) | Nt*A*L | Total volume (all Nt tubes) |
| Initialisation | |||
| Choices.FluidPhase.FluidPhases | FluidPhaseStart (from Flow1DBase) | Choices.FluidPhase.FluidPhases.Liquid | Fluid phase (only for initialization!) |
| Medium.AbsolutePressure | pstart (from Flow1DBase) | 1e5 | Pressure start value |
| Medium.SpecificEnthalpy | hstartin (from Flow1DBase) | if FluidPhaseStart == Choices.FluidPhase.FluidPhases.Liquid then 1e5 else if FluidPhaseStart == Choices.FluidPhase.FluidPhases.Steam then 3e6 else 1e6 | Inlet enthalpy start value |
| Medium.SpecificEnthalpy | hstartout (from Flow1DBase) | if FluidPhaseStart == Choices.FluidPhase.FluidPhases.Liquid then 1e5 else if FluidPhaseStart == Choices.FluidPhase.FluidPhases.Steam then 3e6 else 1e6 | Outlet enthalpy start value |
| Medium.SpecificEnthalpy[N] | hstart (from Flow1DBase) | linspace(hstartin, hstartout, N) | Start value of enthalpy vector (initialized by default) |
| Choices.Init.Options | initOpt (from Flow1DBase) | system.initOpt | Initialisation option |
| Boolean | noInitialPressure (from Flow1DBase) | false | Remove initial equation on pressure |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FlangeA | infl (from Flow1DBase) | ||
| FlangeB | outfl (from Flow1DBase) | ||
| ThermoPower.Thermal.DHT | wall (from Flow1D) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| ThermoPower.System | system (from Flow1DBase) | System wide properties | |
| SI.Power | Q (from Flow1DBase) | Total heat flow through the lateral boundary (all Nt tubes) | |
| SI.Time | Tr (from Flow1DBase) | Residence time | |
| Medium.ThermodynamicState[N] | fluidState (from Flow1D) | Thermodynamic state of the fluid at the nodes | |
| SI.Length | omega_hyd (from Flow1D) | Wet perimeter (single tube) | |
| SI.Pressure | Dpfric (from Flow1D) | Pressure drop due to friction (total) | |
| SI.Pressure | Dpfric1 (from Flow1D) | Pressure drop due to friction (from inlet to capacitance) | |
| SI.Pressure | Dpfric2 (from Flow1D) | Pressure drop due to friction (from capacitance to outlet) | |
| SI.Pressure | Dpstat (from Flow1D) | Pressure drop due to static head | |
| SI.MassFlowRate | win (from Flow1D) | Flow rate at the inlet (single tube) | |
| SI.MassFlowRate | wout (from Flow1D) | Flow rate at the outlet (single tube) | |
| Real | Kf (from Flow1D) | Hydraulic friction coefficient | |
| Real | dwdt (from Flow1D) | Dynamic momentum term | |
| Real | Cf (from Flow1D) | Fanning friction factor | |
| Medium.AbsolutePressure | p (from Flow1D) | Fluid pressure for property calculations | |
| SI.MassFlowRate | w (from Flow1D) | Mass flowrate (single tube) | |
| SI.MassFlowRate[N - 1] | wbar (from Flow1D) | ||
| SI.Velocity[N] | u (from Flow1D) | Fluid velocity | |
| Medium.Temperature[N] | T (from Flow1D) | Fluid temperature | |
| Medium.SpecificEnthalpy[N] | h (from Flow1D) | Fluid specific enthalpy at the nodes | |
| Medium.SpecificEnthalpy[N - 1] | htilde (from Flow1D) | Enthalpy state variables | |
| Medium.Density[N] | rho (from Flow1D) | Fluid nodal density | |
| SI.Mass | M (from Flow1D) | Fluid mass | |
| Real[N - 1] | dMdt (from Flow1D) | Time derivative of mass in each cell between two nodes | |
| Medium.DynamicViscosity[N] | mu | Dynamic viscosity | |
| Medium.ThermalConductivity[N] | k | Thermal conductivity | |
| Medium.SpecificHeatCapacity[N] | cp | Heat capacity at constant pressure |
Revisions
- 24 Mar 2005
by Francesco Casella:
FFtypes package and NoFriction option added. - 16 Dec 2004
by Francesco Casella:
Standard medium definition added. - 26 Jul 2004
by Francesco Casella:
Adapted to Modelica.Media. - 20 Dec 2003
by Francesco Casella:
Function call to f_dittus_boelter updated. - 1 Oct 2003
by Francesco Casella:
First release.