A	absorbance of light as function of wavelength	[-]
AUC	area under the function curve/function integral	[-]
Bo	Bodenstein-number	[-]
c 0	scaling parameter	[*]
c	signal concentration	[*]
d	external screw diameter	[m]
E	residence time density function	[s−1]
I	transmitted light intensity as function of wavelength	[-]
I 0	basic light intensity as function of wavelength	[-]
$\dot{m}$	total mass flow of powder inlet	[kg s−1]
n	screw speed	[kg]
SFL	specific feed load	[-]
t	time	[s]
$t_i$	time to a quantile value of i%	[s]
$\overline{t}$	mean residence time	[s]
T	temperature	[°C]
λ	wavelength	[nm]
ρ	density	[kg m−3]
* unit depends on measured signal