m extr mass of extract (g)

h axial coordinate (m)

H b length ob bed (m)

J(X,Y) interfacial mass transfer rate (kg oil/m 3 s)

K initial mass of inaccessible oil (g oil)

k extraction parameter (dimensionless)

k Ya fluid-phase transfer coefficient (min -1)

k Xa solid-phase mass transfer coefficient (min -1)

P initial mass of easily accessible solute (g)

M CER mass extraction rate for the CER period (g/min)

N mass of cellulosic structure (g)

O mass of solute in solid phase (g)

P pressure (bar)

Q CO2 solvent flow rate (g/min)

S extractor sectional area (cm)

d extr extractor’s diameter (cm)

d par pepper’s diameter (cm)

t extracting time (min)

t CER end of CER (min)

T temperature (°C)

U superficial velocity (m/s)

X O initial solute mass ratio in the solid phase (g/g)

X P mass ratio of easily accessible solute (g/g)

X K mass ratio of solute inside un-ruptured cells

Y mass ratio of solute in solvent phase (g/g)

mean mass ratio difference in bed during the CER period (g/g)

Y in solvent phase solute mass ratio at bed inlet (g/g)

Y CER solvent phase solute mass ratio at bed outlet (g/g)

z W dimensionless coordinate

Z parameter of fast extraction period (dimensionless)

ε total porosity (dimensionless)

p CO2 solvent density (g/cm³)

p S pepper density (g/cm³)