Engineering Properties of Biomass - Engineering and Science of Biomass Feedstock Production and Provision - page 31

Fig. 2.5 Moisture sorption isotherms for untreated Douglas fir particles and steam-treated
particles at different temperature and treatment time (solid lines show GAB model). Reprinted
from Bioresource Technology, 116, Lam PS, Sokhansanj S, Bi XT, Jim Lim C, Larsson SH, Drying
characteristics and equilibrium moisture content of steam-treated Douglas fir ( Pseudotsuga men-
ziesii L.), 7, Copyright 2012, with permission from Elsevier

the factors were extinguished when values were recalculated to range from −1 to +1.
Thus, the sign of the modeled coefficients showed if the factors were negatively or
positively correlated to the response. The magnitude of the modeled coefficients
was equivalent to the impact that each factor had on the response. The MLR models
were studied in the range between 200 °C, 5 min and 220 °C, 10 min:

y =+ + bb b x x + + b x + e

i 0 1 i 1 2 i 2 p ip i

(2.11)

for i =¼ 12 ,, , n

where y i are the measured responses, β i are the estimated parameters of the popula-
tion regression line x i , p represents the independent variable of the i th measurement,
and ε i is the model deviation. Further research in this area will develop data on color
versus material properties for a range of feedstock at varying moisture content,
which appears to be a major confounding factor.
Apart from the correlation of color and calorific value, our recent research find-
ings developed an equilibrium moisture content (EMC) database for steam-treated
woody biomass both in ground particles and pellets [ 33 ]. It was found that the EMC
of steam-treated samples decreased with increasing treatment temperature and time