Geometrical optimisation for turbulence-driven heat transfer enhancement: A techno-environment-economic analysis for solar biomass pyrolysis

Solar-driven biomass pyrolysis holds significant potential in constructing a low-carbon industry and sustainable fuel economy. Nonetheless, existing solar pyrolysis systems face challenges such as high heat loss. Traditional heat transfer enhancement methods for solar systems rely on flow turbulators, which are associated with a high manufacturing cost. Hence, a novel heat transfer enhancement method through variation of the cross-section of the flow path is proposed in this research. A conceptual solar pyrolysis furnace is designed and simulated with the cross-section variation of the coils of its heater using Solidworks Flow Simulation 2023 SP 1.0. Results show that the reduction of the cross-section accelerates the flow, with a range of the Reynolds number increase from 40.10% to 399.62%. This leads to a higher heat transfer coefficient due to higher flow turbulence and fluid mixing, which decreases the start-up time of the pyrolysis furnace by 40%. Owing to an enhanced biomass pyrolysis capability, the CO₂ emission per unit biomass feedstock decreased by 28.6%. The optimised design achieves a 33% increase in the net present value due to a lower capital cost and an increased bio-fuel income. This work establishes the correlation between cross-section variation and heat transfer enhancement, which provides insight for industrial applications, such as optimisation of thermal management and regulation systems.