This paper presents a numerical investigation of the heat transfer and fluid flow phenomena in a tubular reactor using Computational Fluid Dynamics (CFD) simulations. The aim of the study is to develop predictive models to identify optimal operating conditions, which are crucial in order to optimize the reactor performance and product quality in biomass conversion processes. COMSOL Multiphysics software is used to develop a comprehensive 3D model of the tubular reactor, incorporating the geometric features and operating parameters. Particular attention is paid to the accurate representation of boundary conditions, including inlet velocities, temperature gradients, heat fluxes and reactor wall properties, essential in order to capture the complex thermochemical phenomena occurring within the reactor. The organic feedstock is introduced into the CFD model of the tubular reactor and its thermal behaviour is simulated under different operating conditions. Using detailed multiphysics the interactions between heat transfer and fluid flow governing the pyrolysis process are modelled. The results obtained provide valuable insights of the distribution of temperature profiles and and heat transfer within the reactor. Analysis of these data elucidates the key factors influencing the pyrolysis process, allowing the identification of optimal reactor configurations and operating conditions to mitigate endothermic and exothermal uncontrolled phenomena. This research contributes to the advancement of predictive capabilities in biomass pyrolysis technology, facilitating the design and optimisation of tubular reactor systems for improved energy efficiency. The knowledge gained has significant implications for the sustainable use of organic feedstock resources in the bio-based products.