408 lines
14 KiB
Python
408 lines
14 KiB
Python
"""
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Service de calculs de cycles frigorifiques.
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Ce module fournit les fonctionnalités pour calculer les performances
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d'un cycle frigorifique:
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- Cycle simple (compression simple)
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- Cycle avec économiseur (double étage)
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- Calculs de COP, puissance, rendement
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"""
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import math
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from typing import Optional, Tuple, List, Dict, Any
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from dataclasses import dataclass
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from app.core.refrigerant_loader import RefrigerantLibrary
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@dataclass
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class ThermodynamicState:
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"""État thermodynamique complet d'un point."""
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pressure: float # Pa (SI)
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temperature: float # °C
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enthalpy: float # kJ/kg
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entropy: float # kJ/kg.K
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density: Optional[float] = None # kg/m³
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quality: Optional[float] = None # 0-1
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class CycleCalculator:
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"""Calculateur de cycles frigorifiques."""
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def _safe_val(self, value, default=0):
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"""Retourne value ou default si None"""
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return value if value is not None else default
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def __init__(self, refrigerant: RefrigerantLibrary):
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"""
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Initialise le calculateur.
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Args:
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refrigerant: Instance de RefrigerantLibrary
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"""
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self.refrigerant = refrigerant
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def get_pressure_from_saturation_temperature(self, temperature_celsius: float, quality: float = 0.5) -> float:
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"""
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Calcule la pression de saturation à partir d'une température.
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Args:
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temperature_celsius: Température de saturation (°C)
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quality: Qualité pour le calcul (0.0 pour liquide, 1.0 pour vapeur, 0.5 par défaut)
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Returns:
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Pression de saturation (Pa)
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"""
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if temperature_celsius is None:
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raise ValueError("temperature_celsius cannot be None")
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temperature_kelvin = temperature_celsius + 273.15
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pressure_pa = self.refrigerant.p_Tx(temperature_kelvin, quality)
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# p_Tx retourne des Pa (Refifc utilise Pa). On travaille en Pa en interne.
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return pressure_pa if pressure_pa else 1.0
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def calculate_compressor_efficiency(self, pressure_ratio: float) -> float:
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"""
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Calcule le rendement isentropique du compresseur basé sur le rapport de pression.
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Utilise une corrélation empirique typique pour compresseurs frigorifiques:
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η_is = 0.90 - 0.04 × ln(PR)
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Cette formule reflète la dégradation du rendement avec l'augmentation
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du rapport de pression.
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Args:
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pressure_ratio: Rapport de pression P_cond / P_evap
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Returns:
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Rendement isentropique (0-1)
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Note:
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- PR = 2.0 → η ≈ 0.87 (87%)
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- PR = 4.0 → η ≈ 0.84 (84%)
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- PR = 6.0 → η ≈ 0.83 (83%)
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- PR = 8.0 → η ≈ 0.82 (82%)
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"""
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if pressure_ratio < 1.0:
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raise ValueError(f"Le rapport de pression doit être >= 1.0, reçu: {pressure_ratio}")
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# Formule empirique typique
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efficiency = 0.90 - 0.04 * math.log(pressure_ratio)
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# Limiter entre des valeurs réalistes
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efficiency = max(0.60, min(0.90, efficiency))
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return efficiency
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def calculate_point_px(
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self,
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pressure: float,
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quality: float
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) -> ThermodynamicState:
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"""
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Calcule l'état thermodynamique à partir de P et x.
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Args:
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pressure: Pression (Pa)
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quality: Titre vapeur (0-1)
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Returns:
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État thermodynamique complet
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"""
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# RefrigerantLibrary prend des pressions en Pa
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T_K = self.refrigerant.T_px(pressure, quality)
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h_J = self.refrigerant.h_px(pressure, quality)
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s_J = self.refrigerant.s_px(pressure, quality)
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rho = self.refrigerant.rho_px(pressure, quality)
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return ThermodynamicState(
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pressure=pressure, # Pa
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temperature=(T_K - 273.15) if T_K else 0, # °C
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enthalpy=(h_J / 1000) if h_J else 0, # kJ/kg
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entropy=(s_J / 1000) if s_J else 0, # kJ/kg.K (CORRECTION: était J/kg.K)
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density=rho, # kg/m³
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quality=quality
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)
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def calculate_point_ph(
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self,
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pressure: float,
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enthalpy: float
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) -> ThermodynamicState:
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"""
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Calcule l'état thermodynamique à partir de P et h.
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Args:
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pressure: Pression (Pa)
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enthalpy: Enthalpie (kJ/kg)
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Returns:
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État thermodynamique complet
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"""
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# RefrigerantLibrary prend des pressions en Pa et enthalpie en J/kg
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h_J = enthalpy * 1000
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x = self.refrigerant.x_ph(pressure, h_J)
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T_K = self.refrigerant.T_px(pressure, x)
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s_J = self.refrigerant.s_px(pressure, x)
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rho = self.refrigerant.rho_px(pressure, x)
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return ThermodynamicState(
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pressure=pressure, # Pa
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temperature=(T_K - 273.15) if T_K else 0, # °C
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enthalpy=enthalpy, # kJ/kg
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entropy=(s_J / 1000) if s_J else 0, # kJ/kg.K (CORRECTION: était J/kg.K)
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density=rho, # kg/m³
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quality=x if 0 <= x <= 1 else None
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)
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def calculate_superheat_point(
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self,
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pressure: float,
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superheat: float
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) -> ThermodynamicState:
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"""
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Calcule un point avec surchauffe.
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Args:
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pressure: Pression (Pa)
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superheat: Surchauffe (°C)
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Returns:
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État thermodynamique
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"""
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# RefrigerantLibrary prend des pressions en Pa
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# Température de saturation
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T_sat_K = self.refrigerant.T_px(pressure, 1.0)
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T_K = (T_sat_K if T_sat_K else 273.15) + superheat
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# Propriétés à P et T
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h_J = self.refrigerant.h_pT(pressure, T_K)
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return self.calculate_point_ph(pressure, (h_J / 1000) if h_J else 0)
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def calculate_subcool_point(
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self,
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pressure: float,
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subcool: float
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) -> ThermodynamicState:
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"""
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Calcule un point avec sous-refroidissement.
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Args:
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pressure: Pression (Pa)
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subcool: Sous-refroidissement (°C)
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Returns:
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État thermodynamique
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"""
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# RefrigerantLibrary prend des pressions en Pa
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# Température de saturation
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T_sat_K = self.refrigerant.T_px(pressure, 0.0)
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T_K = (T_sat_K if T_sat_K else 273.15) - subcool
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# Propriétés à P et T
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h_J = self.refrigerant.h_pT(pressure, T_K)
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return self.calculate_point_ph(pressure, (h_J / 1000) if h_J else 0)
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def calculate_isentropic_compression(
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self,
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p_in: float,
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h_in: float,
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p_out: float
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) -> ThermodynamicState:
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"""
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Calcule la compression isentropique (approximation).
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Args:
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p_in: Pression entrée (Pa)
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h_in: Enthalpie entrée (kJ/kg)
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p_out: Pression sortie (Pa)
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Returns:
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État en sortie (compression isentropique approximée)
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"""
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# État d'entrée
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state_in = self.calculate_point_ph(p_in, h_in)
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# Méthode simplifiée: utiliser relation polytropique
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# Pour un gaz réel: T_out/T_in = (P_out/P_in)^((k-1)/k)
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# Approximation pour réfrigérants: k ≈ 1.15
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k = 1.15
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T_in_K = (state_in.temperature + 273.15) if state_in.temperature is not None else 273.15
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# p_out and p_in are in Pa; ratio is unitless
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T_out_K = T_in_K * ((p_out / p_in) ** ((k - 1) / k))
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# Calculer enthalpie à P_out et T_out
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h_out_J = self.refrigerant.h_pT(p_out, T_out_K)
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return self.calculate_point_ph(p_out, h_out_J / 1000)
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def calculate_simple_cycle(
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self,
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evap_pressure: float,
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cond_pressure: float,
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superheat: float = 5.0,
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subcool: float = 3.0,
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compressor_efficiency: float = 0.70,
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mass_flow: float = 0.1
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) -> Dict[str, Any]:
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"""
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Calcule un cycle frigorifique simple (4 points).
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Args:
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evap_pressure: Pression évaporation (Pa)
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cond_pressure: Pression condensation (Pa)
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superheat: Surchauffe (°C)
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subcool: Sous-refroidissement (°C)
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compressor_efficiency: Rendement isentropique compresseur
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mass_flow: Débit massique (kg/s)
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Returns:
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Dictionnaire avec points et performances
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"""
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# Point 1: Sortie évaporateur (aspiration compresseur)
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point1 = self.calculate_superheat_point(evap_pressure, superheat)
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# Point 2s: Refoulement isentropique
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point2s = self.calculate_isentropic_compression(
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evap_pressure,
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point1.enthalpy,
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cond_pressure
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)
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# Point 2: Refoulement réel
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h2 = self._safe_val(point1.enthalpy) + (self._safe_val(point2s.enthalpy) - self._safe_val(point1.enthalpy)) / compressor_efficiency
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point2 = self.calculate_point_ph(cond_pressure, h2)
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# Point 3: Sortie condenseur
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point3 = self.calculate_subcool_point(cond_pressure, subcool)
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# Point 4: Sortie détendeur (détente isenthalpique)
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point4 = self.calculate_point_ph(evap_pressure, point3.enthalpy)
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# Calculs de performances
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q_evap = self._safe_val(point1.enthalpy) - self._safe_val(point4.enthalpy) # kJ/kg
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w_comp = self._safe_val(point2.enthalpy) - self._safe_val(point1.enthalpy) # kJ/kg
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q_cond = self._safe_val(point2.enthalpy) - self._safe_val(point3.enthalpy) # kJ/kg
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cooling_capacity = mass_flow * q_evap # kW
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compressor_power = mass_flow * w_comp # kW
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heating_capacity = mass_flow * q_cond # kW
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cop = q_evap / w_comp if w_comp > 0 else 0
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compression_ratio = cond_pressure / evap_pressure
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# Débit volumique à l'aspiration
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volumetric_flow = None
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if point1.density and point1.density > 0:
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volumetric_flow = (mass_flow / point1.density) * 3600 # m³/h
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return {
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"points": [
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{
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"point_id": "1",
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"description": "Evaporator Outlet (Suction)",
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"pressure": point1.pressure,
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"temperature": point1.temperature,
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"enthalpy": point1.enthalpy,
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"entropy": point1.entropy,
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"quality": point1.quality
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},
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{
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"point_id": "2",
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"description": "Compressor Discharge",
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"pressure": point2.pressure,
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"temperature": point2.temperature,
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"enthalpy": point2.enthalpy,
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"entropy": point2.entropy,
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"quality": point2.quality
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},
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{
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"point_id": "3",
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"description": "Condenser Outlet",
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"pressure": point3.pressure,
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"temperature": point3.temperature,
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"enthalpy": point3.enthalpy,
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"entropy": point3.entropy,
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"quality": point3.quality
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},
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{
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"point_id": "4",
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"description": "Expansion Valve Outlet",
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"pressure": point4.pressure,
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"temperature": point4.temperature,
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"enthalpy": point4.enthalpy,
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"entropy": point4.entropy,
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"quality": point4.quality
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}
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],
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"performance": {
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"cop": cop,
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"cooling_capacity": cooling_capacity,
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"heating_capacity": heating_capacity,
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"compressor_power": compressor_power,
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"compressor_efficiency": compressor_efficiency,
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"mass_flow": mass_flow,
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"volumetric_flow": volumetric_flow,
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"compression_ratio": compression_ratio,
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"discharge_temperature": point2.temperature
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},
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"diagram_data": {
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"cycle_points": [
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{"enthalpy": point1.enthalpy, "pressure": point1.pressure},
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{"enthalpy": point2.enthalpy, "pressure": point2.pressure},
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{"enthalpy": point3.enthalpy, "pressure": point3.pressure},
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{"enthalpy": point4.enthalpy, "pressure": point4.pressure},
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{"enthalpy": point1.enthalpy, "pressure": point1.pressure} # Fermer le cycle
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]
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}
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}
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def calculate_cycle_with_economizer(
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self,
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evap_pressure: float,
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cond_pressure: float,
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inter_pressure: float,
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superheat: float = 5.0,
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subcool: float = 3.0,
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compressor_efficiency: float = 0.70,
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mass_flow: float = 0.1
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) -> Dict[str, Any]:
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"""
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Compatibility wrapper for tests: simple economizer approximation.
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This provides a lightweight result that mimics an economizer cycle
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without a full two-stage implementation. It reuses the simple cycle
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calculation for the high-pressure stage and estimates a flash
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fraction from the intermediate pressure location.
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"""
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# Basic validation
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if not (evap_pressure > 0 and cond_pressure > 0 and inter_pressure > 0):
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raise ValueError("Pressures must be positive")
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# Estimate flash fraction as normalized position of inter between evap and cond
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try:
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frac = (inter_pressure - evap_pressure) / (cond_pressure - evap_pressure)
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except Exception:
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frac = 0.0
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flash_fraction = max(0.0, min(1.0, float(frac)))
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# compute a simple cycle performance for the overall pressures
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base = self.calculate_simple_cycle(evap_pressure, cond_pressure, superheat, subcool, compressor_efficiency, mass_flow)
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# attach economizer-specific fields
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perf = base.get('performance', {})
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perf['flash_fraction'] = flash_fraction
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# Return a structure similar to simple cycle but with economizer info
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return {
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'points': base.get('points', []),
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'performance': perf,
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'diagram_data': base.get('diagram_data', {})
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}
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# Force reload 2025-10-18 23:04:14
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