General nomenclature

a Specific area (length⁻¹)

A Area (length units square)

AM Ratio of ammonia in unit of mass per mass of biomass

C Concentration (mol per volume unit)

Cat Mass fraction of catalyst added

c_p Heat capacity (energy per unit mass or mol and temperature)

d₃₂ Sauter mean diameter (m)

D Distillate flow rate (molar per unit time)

D_i Diffusion coefficient (length square per second)

D_p Particle diameter (length units)

E Reduction potential (V/mol)

E Evaporated flow rate (see Chapter 4: Water; mass per unit time)

E_c Steam economy

E_e Electrical energy (energy units per unit time)

f_i Feed flow rate of component i (mass or molar per unit time)

f Liquefied fraction

f Separation factor

F Flow rate (of the feed for distillation columns; mass or molar per unit time)

F Faraday constant

FFA Free fatty acid

FAME Fatty acid methyl ester

FAEE Fatty acid ethyl ester

g Air fraction diverted to the expansion machine

G Gas flow rate (mass per unit time)

G Gas flow rate per unit area (Ergun Equation; mass per unit time and area)

G Growth rate in crystallization (length per unit time)

h Liquid enthalpy (energy per unit mass or molar)

H Henry constant (pressure units per molar fraction)

H Enthalpy (energy per unit mass or molar)

I Current intensity (Ampere)

I Initiator in polymerization (moles per unit volume)

K Equilibrium constant (bar^p)

K_La Volumetric mass transfer coefficient (molar per unit time)

k Kinetic constants

k Polytropic coefficient in compressors and expanders

l_i Liquid flow rate of component i (mass or molar per unit time)

L Liquid reflux (molar per unit time)

m/M Mass flow (mass per unit time)

Mw Molar mass (mass per mol)

M Monomer concentration (moles per unit volume)

n Molar flow (kmol per unit time)

n Number of entities per unit volume, crystallization (inverse of volume)

N Number of trays

N Impeller revolutions (see Chapter 8: Biomass; revolutions per unit time)

N_i Flux of species i (mass or molar units per unit time)

P Pressure (mass per unit length and time square)

P Product (see Chapter 8: Biomass; mass per unit volume)

P Impeller power (see Chapter 8: Biomass; energy units)

P_g Impeller power under aerated conditions (see Chapter 8: Biomass; energy units)

P_v Vapor pressure (mass per unit length and time square)

P_T Total Pressure (mass per unit length and time square)

q Specific energy (energy per unit mass)

Q Thermal energy (energy per unit time)

Q_c Gas flow rate (volume per unit time)

R Reflux ratio (L/D)

R Gas constant (energy per unit mol and temperature)

RE Molar ratio of ethanol to oil

RM Molar ratio of methanol to oil

r_i Kinetic rate (molar^q per unit time)

S Entropy (Energy per unit temperature and mass)

S Substrate (see Chapter 8: Biomass; mass per unit volume)

t Time (time units)

T Temperature (K or °C)

T Impeller diameter (length)

u_G Superficial gas velocity (length per unit time)

U Heat transfer global transfer coefficient (energy per unit area and temperature)

U_b Bubble rising velocity (length per unit time)

v Velocity (length per unit time)

v Specific volume of humid air (volume per mass of dry air)

V Vapor flow rate (mass or molar per unit time)

V Potential difference (see Chapter 4: Water)

V Liquid volume (see Chapters 4 and 8: Water and Biomass; volume units)

w_i Mass fraction of component i in FT product distribution

W Residue flow rate in distillation columns (mass or molar per unit time)

W Commercial steam fed to the evaporators (see Chapter 4: Water; mass per unit time)

W Work (energy per unit time)

x Liquid molar fraction or mass fraction

X Conversion

X Solids mass fraction (see Chapter 8: Biomass)

y_i Gas molar fraction

y Specific humidity (mass of vapor per mass of dried air)

z Molar fraction

α_ij Relative volatility between species i and j

α Chain length (see Chapter 5: Syngas)

α Salt dissociation fraction

δ Layer thickness

ε Porosity

ε_G Gas hold up

ϕ Sphericity factor

λ Latent heat (energy per unit mass)

φ Relative moisture

${\mathit{\Phi }}_{\mathrm{L}}$ Liquid fraction in the feed to a distillation column

${\mathit{\Phi }}_{\mathrm{V}}$ Vapor fraction in the feed to a distillation column

η Efficiency

${\mathit{\Theta }}_i$ Stoichiometric coefficient

π Osmotic pressure (mass per unit length and time square)

Δe Ebullioscopic increment (temperature units)

ΔG Gibbs free energy gradient (energy per unit mass or molar)

μ Viscosity (mass per unit length)

μ Biomass growth (per unit time)

τ Shear stress (pressure units)

τ Residence time (time units)

ρ Density (mass per unit volume)

σ Surface tension (pressure · length units)

Subindex

in Inlet

i,j Components

g Gas

o Initial conditions

out Outlet

R Reference

T Total

v Vapor