“…Dochain & Vanrolleghem, 2001) and then transformed into the single dynamic equation that successively can be simplified to the desired form. The second method is directly based on the very general mass or energy conservation considerations written for the whole system in the form of the general mass or heat balance equation (Czeczot, 1998(Czeczot, , 2001(Czeczot, , 2006(Czeczot, , 2006a(Czeczot, , 2008, (Czeczot et al, 2010). Then, after simple recalculations that require only basic knowledge on the physical modelling of dynamic systems, this final dynamic equation can be rewritten to define the known part of Equation (1).…”