G. Varhegyi et al., Least squares criteria for the kinetic evaluation of thermoanalytical experiments. Examples from a char reactivity study, J AN AP PYR, 57(2), 2001, pp. 203-222
The mathematical modeling of the chemical processes is a crucial problem of
the thermal analysis. Simple models with few parameters seldom can describ
e the real complexity of the phenomena arising during the heating of the va
rious substances. In the case of more complex models the determination of t
he parameters and the validation of the model require the evaluation of car
efully designed experimental series. The one-by-one evaluation of the exper
iments is a mathematically ill-defined problem at a larger number of unknow
n parameters. The non-statistical experimental errors of the thermal analys
is hinder the determination of a single parameter set by the simultaneous l
east squares evaluation of the experiments. This paper discusses several ev
aluation techniques for the handling of the non-statistical errors during t
he least squares evaluation of experimental series. The methods are illustr
ated by the evaluation of oxidative thermogravimetric experiments of a lign
ite and a coal char. (C) 2001 Elsevier Science B.V. All rights reserved.