The comprehensive investigation of a pyrolysis reactor has been conducted on the basis of thermal engineering design. The gas dynamics, thermodynamic, and psychrometric behaviour of the producer gas have been thoroughly assessed. The pilot-scale reactor has been programmed to operate at the temperature 973 K in the absence of an inert medium. The concentric casing of the heating filament has been used as an external source of energy. The experimental task is divided into two parts: upgradation of biomass and the decomposition of pellets in a developed small-scale pyrolysis unit for the possible gas, char, and pyrolysis oil generation. The fuel upgradation is performed via quasi-static torrefaction of pine pellets using Joule heating in the presence of nitrogen gas. The volumetric gas of nitrogen flowing across the improvised furnace is 0.70 L.min(-1). The obtained results are compared with the wood pellets. The unsaturated producer gas has been found to vary accordingly to the following gas equation pv(0.25) = C and pv(-0.69) = C for the processed pine pellets and wood pellets, respectively. A relative increase of 21.00% has been seen while running the reactor with the processed pine pellets. The percentage yield of the pyrolytic oil for the processed pine and wood pellets is 10.48% and 30.00% respectively. The flame temperature and adiabatic flame temperature of the producer gas (processed pine) is lowered by 8.10% and 17.00% respectively. The energy yield of processed pinechar is found to be 122.58% higher than that of wood char. (C) 2021 The Author(s). Published by Elsevier Ltd.