This paper emphasises the analogous modelling of hardwood (acacia) pyrolysis. The impacts of physical characteristics of hardwood chips on the pyrolysis are examined through the conservation of biomass solid mass fraction. The ONORM standard chips of sizes ‘G30’ and ‘G50’ and their combination are individually tested in the pyrolysis reactor. In the analogous situation, the fixed bed is assumed to be a wooden slab with a porosity equivalent to the voidage of bed. Bulk density, bed length and porosity are several of the physical attributes of a fixed bed used to examine the variation in the hardwood solid mass across the fixed bed. To measure temperature, the four-temperature sensors separated from each other by 80 mm are fixed along periphery of a reactor. The heating element of 2 kWe is provided to initiate the biomass pyrolysis. The proposed model is also used to establish the relationship between the kinetics of pyrolysis and the structural properties of hardwood.