Model selection must consider accuracy and required resources. Thus, the simplest model with sufficiently accurate results is indicated ). In the literature, there are several detailed studies on lumped model selection criteria for different types of moving bed heat exchangers . In the context of processes involving chemical reactions in the solid phase, the literature is less extensive: Pyle and Zaror (1984) studied the pyrolysis of solids at low temperatures and proposed the use of small 𝐵 and small Py 7 as selection criterion to lumped parameter model for the solid phase. In their modeling, the temperature of the fluid was assumed constant and equal to that of the furnace wall. This assumption makes the model simpler than that discussed in the present study. Another work to be considered is that of . These authors, studying the biomass fast pyrolysis, proposed 𝐵 1 < 0.1 as selection criterion to lumped parameter model for the solid phase, where 𝐵 1 is calculated at the initial conditions of the process.