CFD Analysis of the Effect of Geometric Modifications in the Furnace and Flue Pipes on Heat Transfer in a Pyrotubular Boiler

This study presents a Computational Fluid Dynamics (CFD)-based analysis of heat transfer in an 80 BHP fire-tube boiler, aimed at evaluating the impact of internal geometric modifications on thermal efficiency. Multiple scenarios were simulated, including the implementation of MORISON-type corrugations in the furnace and the incorporation of internal elements such as helical strips and conical rings within the fire tubes, with the objective of enhancing turbulence and thus improving convective heat transfer. Simulations were conducted under steady-state conditions and calibrated using experimental data collected under non-phase-change conditions to facilitate validation. The average percentage error between simulated and experimental outlet gas temperatures was consistently below 10%. Among the tested configurations, the inclusion of helical strips achieved a reduction in flue gas outlet temperatures of up to 7%, representing an advantageous trade-off between improved heat transfer and moderate pressure drop. Additionally, the combined application of helical strips and conical rings further reduced outlet temperatures by 9%, although accompanied by a significant increase in flow resistance. These findings provide valuable practical insights for the design and optimization of industrial fire-tube boilers, promoting enhanced thermal performance and improved operational efficiency.