General Nomenclature

This page compiles all symbols, parameters, and variables used in the EnergySystemModels library.

Heat Transfer (HeatTransfer)

Geometry and Dimensions

Symbol	Description	Unit	Module
L	Body length	m	ParallelepipedicBody
W	Body width	m	ParallelepipedicBody
H	Body height	m	ParallelepipedicBody
A	Exchange surface area	m²	CompositeWall, ParallelepipedicBody
thickness	Layer thickness	m	CompositeWall
d_hyd	Hydraulic diameter	m	StraightPipe
DN	Nominal diameter	mm	PipeInsulationAnalysis
L_tube	Pipe length	m	PipeInsulationAnalysis

Temperatures

Symbol	Description	Unit	Module
T	General temperature	°C	All modules
Ta	Ambient temperature	°C	ParallelepipedicBody
Tamb	Ambient temperature	°C	PipeInsulationAnalysis
Ti	Interior temperature	°C	CompositeWall
Ti_degC	Inlet temperature	°C	Source, StraightPipe
Te	Exterior temperature	°C	CompositeWall
Tp	Wall temperature	°C	ParallelepipedicBody
T_fluid	Fluid temperature	°C	PipeInsulationAnalysis

Transfer Coefficients

Symbol	Description	Unit	Module
he	External convection coefficient	W/m²·K	CompositeWall
hi	Internal convection coefficient	W/m²·K	CompositeWall
conductivity	Thermal conductivity	W/m·K	CompositeWall

Surface Properties

Symbol	Description	Unit	Module
emissivity	Surface emissivity		PipeInsulationAnalysis
isolated	Face insulation indicator	True/False	ParallelepipedicBody
faces_config	Faces configuration	dict	ParallelepipedicBody

Materials and Insulation

Parameter	Description	Possible Values
material (pipes)	Pipe material	‘steel’, ‘copper’, ‘PVC’, ‘PE’, ‘stainless_steel’, ‘cast_iron’
material (walls)	Construction material	‘Béton’ (Concrete), ‘Brique’ (Brick), ‘Bois’ (Wood), ‘Acier’ (Steel), ‘Aluminium’, ‘Verre’ (Glass), etc.
insulation	Insulation type	‘laine_de_verre’ (glass wool), ‘laine_de_roche’ (rock wool), ‘polystyrène_expansé’ (expanded polystyrene), ‘polyuréthane’ (polyurethane), etc.
insulation_thickness	Insulation thickness	m

Thermodynamic Cycles

Fluids and Refrigerants

Symbol	Description	Unit	Module
fluid	Fluid/refrigerant name	String	Source, StraightPipe
Ti_degC	Inlet temperature	°C	Source
Pi_bar	Inlet pressure	bar	Source, StraightPipe

Available Fluids (CoolProp)

Natural fluids: Water, Air, Nitrogen, Oxygen, CarbonDioxide, Hydrogen, Methane, Ethane, Propane, Butane, IsoButane, Pentane, IsoPentane, Hexane, Heptane, Octane, Nonane, Decane

HFC refrigerants: R134a, R125, R143a, R152a, R32, R245fa, R236fa, R227ea, R365mfc, R404A, R407C, R410A, R507A

Natural refrigerants: R717 (Ammonia), R744 (CO2), R290 (Propane), R600a (Isobutane), R1270 (Propylene)

Others: Benzene, Toluene, Acetone, Ethanol, Methanol, D4, D5, D6, MD2M, MD3M, MD4M, MDM, MM, Neopentane, Cyclohexane, p-Xylene, m-Xylene, o-Xylene

Flow Rates

Symbol	Description	Unit	Module
F	Mass flow rate	kg/s	Source
F_kgs	Mass flow rate	kg/s	Source, StraightPipe
F_kgh	Mass flow rate	kg/h	Source, StraightPipe
F_m3s	Volumetric flow rate	m³/s	Source, StraightPipe
F_m3h	Volumetric flow rate	m³/h	Source, StraightPipe, PipeInsulationAnalysis
F_Sm3s	Standard volumetric flow rate (0°C, 1 atm)	Sm³/s	Source, StraightPipe
F_Sm3h	Standard volumetric flow rate (0°C, 1 atm)	Sm³/h	Source, StraightPipe

Thermodynamic Properties

Symbol	Description	Unit	Module
h	Specific enthalpy	J/kg (kJ/kg)	Source, FreshAir
H_v	Vapor enthalpy	J/kg	Source
H_l	Liquid enthalpy	J/kg	Source
rho (ρ)	Density	kg/m³	Source, StraightPipe
mu (η)	Dynamic viscosity	Pa·s	StraightPipe

Air Handling Units (AHU)

Air State

Symbol	Description	Unit	Module
T	Air temperature	°C	FreshAir, HeatingCoil, Humidifier
RH	Relative humidity	%	FreshAir, HeatingCoil, Humidifier
w	Absolute humidity	g/kg_dry_air	FreshAir, HeatingCoil, Humidifier
h	Specific enthalpy	kJ/kg	FreshAir, HeatingCoil, Humidifier
P	Atmospheric pressure	Pa	FreshAir, HeatingCoil, Humidifier
Pv_sat	Saturation vapor pressure	Pa	FreshAir, HeatingCoil, Humidifier

Air Flow Rates

Symbol	Description	Unit	Module
F_m3h	Volumetric air flow rate	m³/h	FreshAir, HeatingCoil, Humidifier
F	Moist air mass flow rate	kg/s	FreshAir, HeatingCoil, Humidifier
F_dry	Dry air mass flow rate	kg/s	FreshAir, HeatingCoil, Humidifier
F_water	Humidification water flow rate	kg/s	Humidifier

Treatment Parameters

Symbol	Description	Unit	Module
Q_th	Thermal power	kW	HeatingCoil
To_target	Target outlet temperature	°C	HeatingCoil
wo_target	Target outlet absolute humidity	g/kg_dry_air	Humidifier
HumidType	Humidification type	String	Humidifier
humidity	Ambient relative humidity	%	PipeInsulationAnalysis

Hydraulics

Flow

Symbol	Description	Unit	Module
V	Flow velocity	m/s	StraightPipe
Re	Reynolds number		StraightPipe
f	Darcy friction factor		StraightPipe
K	Absolute roughness	m	StraightPipe
alpha (α)	Inclination angle	rad	StraightPipe

Pressure Losses

Symbol	Description	Unit	Module
delta_P (ΔP)	Pressure loss	Pa	StraightPipe
L	Pipe length	m	StraightPipe
A	Pipe cross-section	m²	StraightPipe

Conventions

Units

• Temperatures: °C (unless otherwise stated)

• Pressures: Pa, bar (depending on context)

• Mass flow rates: kg/s, kg/h

• Volumetric flow rates: m³/s, m³/h, Sm³/s (standard: 0°C, 1 atm)

• Lengths: m, mm

• Areas: m²

• Powers: W, kW

Data Types

• String: Character string (e.g., fluid name, material type)

• Float: Decimal number

• Integer: Whole number

• Boolean: True/False

• Dict: Python dictionary (key-value pairs)

Equation Nomenclature

• Darcy-Weisbach: \(\Delta P = f \cdot \frac{L}{d_{hyd}} \cdot \frac{\rho V^2}{2}\)

• Reynolds: \(Re = \frac{\rho V d_{hyd}}{\mu}\)

• Colebrook-White: \(\frac{1}{\sqrt{f}} = -2 \log_{10}\left(\frac{K/d_{hyd}}{3.7} + \frac{2.51}{Re\sqrt{f}}\right)\)

• Vapor quality: \(x = \frac{H - H_l}{H_v - H_l}\)