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HelmValve

pair: idaes.models_extra.power_generation.unit_models.helm.valve_steam;HelmValve

idaes.models_extra.power_generation.unit_models.helm.valve_steam

This is a steam power generation turbine model for the stages between the inlet and outlet.

Example

from pyomo.environ import ConcreteModel, SolverFactory, TransformationFactory

from idaes.core import FlowsheetBlock
from idaes.models_extra.power_generation.unit_models.helm import HelmValve
from idaes.models.properties import iapws95

solver = SolverFactory('ipopt')
solver.options = {'tol': 1e-6}

m = ConcreteModel()
m.fs = FlowsheetBlock(dynamic=False)
m.fs.properties = iapws95.Iapws95ParameterBlock()
m.fs.valve = HelmValve(property_package=m.fs.properties)

hin = iapws95.htpx(T=880, P=2.4233e7)
# set inlet
m.fs.valve.inlet.enth_mol[0].fix(hin)
m.fs.valve.inlet.flow_mol[0].fix(26000/4.0)
m.fs.valve.inlet.pressure[0].fix(2.5e7)
m.fs.valve.Cv.fix(0.01)
m.fs.valve.valve_opening.fix(0.5)
m.fs.valve.initialize(outlvl=1)

Variables

This model adds a variable to account for mechanical efficiency to the base PressureChanger model.

Variable Symbol Index Sets Doc
Cv Cv None Valve coefficient for liquid [mol/s/Pa^0.5] for vapor [mol/s/Pa]
valve_opening x time The fraction that the valve is open from 0 to 1

Expressions

Currently this model provides two additional expressions, with are not available in the pressure changer model.

Expression Symbol Index Sets Doc
valve_function f(x) time This is a valve function that describes how the fraction open affects flow.

Constraints

The pressure flow relation is added to the inherited constraints from the PressureChanger model <reference_guides/model_libraries/generic/unit_models/pressure_changer:Pressure Changer>.

If the phase option is set to "Liq" the following equation describes the pressure-flow relation.

$$\frac{1}{s_f^2}F^2 = \frac{1}{s_f^2}C_v^2\left(P_{in} - P_{out}\right)f(x)^2$$

If the phase option is set to "Vap" the following equation describes the pressure-flow relation.

$$\frac{1}{s_f^2}F^2 = \frac{1}{s_f^2}C_v^2\left(P_{in}^2 - P_{out}^2\right)f(x)^2$$

Initialization

This just calls the initialization routine from PressureChanger, but it is wrapped in a function to ensure the state after initialization is the same as before initialization. The arguments to the initialization method are the same as PressureChanger.

HelmValve Class

HelmValve

HelmValveData Class

HelmValveData