Abstract Helical tubes are known for their ability to enhance heat and mass transfer due to secondary flow effects. However, their application in pyrolysis reactors remains underexplored. This study presents a three-dimensional numerical model coupling fluid flow, heat transfer, and pyrolysis reaction kinetics in a helical reactor. The model is implemented in ANSYS Fluent with validated turbulence and species transport equations. Parametric studies were conducted to evaluate the effects of inlet velocity, helical pitch (100-500 mm), coil diameter (400-800 mm), and tube inner diameter (19-59 mm) on thermal and reaction performance. Results show that increasing velocity improves heat transfer (Nu increases, f decreases) but reduces conversion due to shorter residence time. Pitch variation has a negligible impact. Increasing coil diameter reduces Nu by ~8% but raises conversion from 63% to 96% due to longer tube length. For inner diameter, the optimal value is 39 mm, maintaining > 95% conversion while balancing pressure drop and heat transfer. These findings provide practical design guidance for helical pyrolysis reactors.
Zhang et al. (Fri,) studied this question.