296 lines
10 KiB
Python
296 lines
10 KiB
Python
# -*- coding: utf-8 -*-
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"""Cycle definitions and efficiency calculations."""
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from .components import (
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Compressor,
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Concentrator,
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Condenser,
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Heater,
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Recuperator,
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Turbine,
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)
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from .properties import CO2PropertyCalculator
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class BraytonCycle:
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"""CO2 Brayton cycle calculator."""
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def __init__(self, name, refprop_path="C:/Program Files (x86)/REFPROP 10.0+/REFPROP"):
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self.name = name
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self.compressor = None
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self.turbine = None
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self.recuperator = None
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self.heater = None
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self.condenser = None
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self.concentrator = None
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self.component_masses = None
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self.total_mass = None
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self.refprop_path = refprop_path
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self.property_calculator = CO2PropertyCalculator(self.refprop_path)
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def cycle_eff_calculator(self):
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if isinstance(self.compressor, list):
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Wc = sum(compressor.variables["Wc"] for compressor in self.compressor)
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else:
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Wc = self.compressor.variables["Wc"]
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Wt = self.turbine.variables["Wt"]
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Q_input = self.heater.variables["Q_in"]
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return (Wt - Wc) / Q_input
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def iter_components(self):
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"""Yield initialized component objects in the current cycle."""
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for value in (
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self.compressor,
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self.turbine,
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self.recuperator,
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self.heater,
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self.condenser,
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self.concentrator,
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):
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if value is None:
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continue
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if isinstance(value, list):
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for component in value:
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if component is not None:
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yield component
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else:
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yield value
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def calculate_component_masses(self, mass_model=None, **kwargs):
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"""Calculate mass for each initialized component."""
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component_masses = {}
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for component in self.iter_components():
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if not hasattr(component, "calculate_mass"):
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continue
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mass = component.calculate_mass(mass_model=mass_model, **kwargs)
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key = component.variables.get("name", component.name)
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component_masses[key] = {
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"component_type": component.component_type,
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"mass": mass,
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"mass_variables": component.mass_variables,
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}
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self.component_masses = component_masses
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return self.component_masses
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def cycle_mass_calculator(self, mass_model=None, **kwargs):
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"""Calculate and return total cycle component mass."""
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component_masses = self.calculate_component_masses(
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mass_model=mass_model,
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**kwargs,
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)
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self.total_mass = sum(item["mass"] for item in component_masses.values())
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return self.total_mass
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def calculate_total_mass(self, mass_model=None, **kwargs):
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"""Compatibility alias for cycle_mass_calculator."""
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return self.cycle_mass_calculator(mass_model=mass_model, **kwargs)
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def SC(self, T_low, T_high, p_low, p_high, param=None):
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"""Simple Brayton cycle."""
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defaults = {
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"compressor_eff": 0.98,
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"turbine_eff": 0.95,
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}
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cycle_params = defaults if param is None else {**defaults, **param}
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self.heater = Heater(name="Main heater")
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self.condenser = Condenser(name="Main condenser")
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self.compressor = Compressor(
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name="Main compressor",
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eff=cycle_params["compressor_eff"],
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)
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self.turbine = Turbine(name="Turbine", eff=cycle_params["turbine_eff"])
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self.compressor.calculator(p_low, T_low, p_high, self.property_calculator)
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self.turbine.calculator(p_high, T_high, p_low, self.property_calculator)
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self.heater.calculator(
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self.compressor.variables["outlet_state"],
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self.turbine.variables["inlet_state"],
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)
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self.condenser.calculator(
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self.turbine.variables["outlet_state"],
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self.compressor.variables["inlet_state"],
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)
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return self.cycle_eff_calculator()
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def SRC(self, T_low, T_high, p_low, p_high, param=None, ploss=0.0):
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"""Simple recuperated Brayton cycle."""
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defaults = {
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"compressor_eff": 0.98,
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"turbine_eff": 0.95,
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"recuperator_eff": 0.85,
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}
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cycle_params = defaults if param is None else {**defaults, **param}
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self.heater = Heater(name="Main heater")
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self.condenser = Condenser(name="Main condenser")
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self.compressor = Compressor(
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name="Main compressor",
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eff=cycle_params["compressor_eff"],
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)
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self.turbine = Turbine(name="Turbine", eff=cycle_params["turbine_eff"])
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self.recuperator = Recuperator(
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name="Recuperator",
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eff=cycle_params["recuperator_eff"],
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)
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self.compressor.calculator(p_low, T_low, p_high, self.property_calculator)
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self.turbine.calculator(p_high, T_high, p_low, self.property_calculator)
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self.recuperator.calculator(
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self.compressor.variables["outlet_state"],
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self.turbine.variables["outlet_state"],
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0,
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ploss,
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self.property_calculator,
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)
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self.condenser.calculator(
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self.recuperator.variables["hot_outlet_state"],
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self.compressor.variables["inlet_state"],
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)
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self.heater.calculator(
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self.recuperator.variables["cold_outlet_state"],
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self.turbine.variables["inlet_state"],
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)
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return self.cycle_eff_calculator()
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def RC(self, T_low, T_high, p_low, p_high, ploss, param=None):
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"""Recompression Brayton cycle."""
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defaults = {
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"compressor_eff": 0.98,
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"turbine_eff": 0.95,
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"recuperator_eff": 0.85,
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"recompressor_eff": 0.98,
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"highT_recuperator_eff": 0.85,
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"x": 0.9,
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}
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cycle_params = defaults if param is None else {**defaults, **param}
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self.x = cycle_params["x"]
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self.heater = Heater(name="Main heater")
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self.condenser = Condenser(name="Main_condenser")
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self.turbine = Turbine(
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name="Main Turbine",
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eff=cycle_params["turbine_eff"],
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)
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main_compressor = Compressor(
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name="Main compressor",
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eff=cycle_params["compressor_eff"],
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)
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recompressor = Compressor(
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name="Recompressor",
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eff=cycle_params["recompressor_eff"],
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)
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lrecuperator = Recuperator(
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name="Low Temperature recuprerator",
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eff=cycle_params["recuperator_eff"],
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x=self.x,
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)
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hrecuperator = Recuperator(
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name="High Temperature recuperator",
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eff=cycle_params["highT_recuperator_eff"],
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)
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self.concentrator = Concentrator(name="Concentrator")
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self.recuperator = []
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self.compressor = []
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main_compressor.calculator(p_low, T_low, p_high, self.property_calculator)
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self.turbine.calculator(
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p_high * (1 - ploss) ** 3,
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T_high,
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p_low * (1 - ploss) ** (-3),
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self.property_calculator,
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)
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mw = self.property_calculator.mw
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T_hr_inlet = (
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self.turbine.variables["outlet_state"]["T"]
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+ main_compressor.variables["outlet_state"]["T"]
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) / 2
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max_iter = 300
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relax_fac = 0.4
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for i in range(max_iter):
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hr_inlet_state_hot_mol = self.property_calculator.calculate_properties(
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P=p_high * (1 - ploss),
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T=T_hr_inlet,
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)
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hr_inlet_state_hot = {
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"P": hr_inlet_state_hot_mol["P"],
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"T": hr_inlet_state_hot_mol["T"],
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"h": hr_inlet_state_hot_mol["h"] / mw,
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"s": hr_inlet_state_hot_mol["s"] / mw,
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}
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hrecuperator.calculator(
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hr_inlet_state_hot,
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self.turbine.variables["outlet_state"],
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0,
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ploss,
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self.property_calculator,
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)
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lrecuperator.calculator(
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main_compressor.variables["outlet_state"],
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hrecuperator.variables["hot_outlet_state"],
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1,
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ploss,
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self.property_calculator,
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)
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recompressor.calculator(
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p_in=p_low / (1 - ploss),
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p_out=p_high * (1 - ploss),
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T_in=lrecuperator.variables["hot_outlet_state"]["T"],
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property_calculator=self.property_calculator,
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)
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self.concentrator.calculator(
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recompressor.variables["outlet_state"],
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lrecuperator.variables["cold_outlet_state"],
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self.x,
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self.property_calculator,
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)
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Tc_outlet = self.concentrator.variables["outlet_state"]["T"]
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err = abs(Tc_outlet - T_hr_inlet)
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if err <= 1e-5:
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break
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if i == max_iter - 1:
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raise ValueError(f"Iteration limit exceeded; current error={err:.4f}")
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T_hr_inlet = relax_fac * Tc_outlet + (1 - relax_fac) * T_hr_inlet
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hrecuperator.calculator(
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self.concentrator.variables["outlet_state"],
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self.turbine.variables["outlet_state"],
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0,
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ploss,
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self.property_calculator,
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)
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lrecuperator.calculator(
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main_compressor.variables["outlet_state"],
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hrecuperator.variables["hot_outlet_state"],
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1,
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ploss,
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self.property_calculator,
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)
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main_compressor.variables["Wc"] *= 1 - self.x
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recompressor.variables["Wc"] *= self.x
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self.recuperator.append(lrecuperator)
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self.recuperator.append(hrecuperator)
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self.compressor.append(main_compressor)
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self.compressor.append(recompressor)
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self.condenser.calculator(
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lrecuperator.variables["hot_outlet_state"],
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main_compressor.variables["inlet_state"],
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)
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self.condenser.variables["Q_out"] *= 1 - self.x
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self.heater.calculator(
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hrecuperator.variables["cold_outlet_state"],
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self.turbine.variables["inlet_state"],
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)
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return self.cycle_eff_calculator()
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