The
model fit to the experimental data was made to show the exponential increase in the pelletizing pressure as a function of the compression ratio, as suggested in the published theory[13,14]. Due
to mutual correlations between the three parameters, the friction
coefficient was fixed tol= 0.5 obtain a stable fit. The value of
the friction coefficient was chosen as a typical value for dry wood
on a hard smooth surface, as described in Holm et al.[14]. Keeping
the value of the friction coefficient constant, the other parameters
were left free to vary. The resulting values ofPN0andtare found to
be in the typical range of published values[14].