شبيه‌سازي عددي و بهينه‌سازي پارامتري هندسه لوله فين‌دار سوپرهيتر اوليه جهت افزايش عملكرد حرارتي

Primary superheaters are among the most critical heat transfer components in thermal power plants, where their thermal performance directly influences boiler efficiency, steam quality, an‎d overall plant operation. The use of annular fins is a common approach for enhancing the external heat transfer of superheater tubes. However, the thermal performance depends not only on the amount of fin material but also on its geometric distribution, the arrangement of the tubes, an‎d the spacing between adjacent tubes. The present study numerically investigates the influence of these parameters on the thermal performance of finned primary superheater tubes. A three-dimensional conjugate heat transfer model was developed using the finite element method to simultaneously simulate fluid flow an‎d heat transfer in the external hot gas, the tube wall, the annular fins, an‎d the internal steam flow. Steady-state, laminar, incompressible flow with constant thermophysical properties was assumed, while radiation heat transfer was neglected because the primary superheater is predominantly convection-based. Five annular fin geometries with identical fin material volume were investigated for a single tube, two adjacent tubes, two-row inline tube banks, an‎d two-row staggered tube banks. In addition, the influence of longitudinal tube pitch was eva‎luated for the optimum inline an‎d staggered configurations while maintaining a constant transverse pitch. The numerical results demonstrated that the distribution of the available fin material has a significant influence on thermal performance. Among the investigated geometries, the intermediate fin configuration (Case 3) consistently provided the highest heat transfer performance for all tube arrangements. The external thermal conductance increased progressively from 47.38 W/K for the optimum single finned tube to 193.12 W/K for two adjacent tubes, 319.61 W/K for the inline tube bank, an‎d 380.94 W/K for the staggered tube bank. Tube pitch was also found to significantly influence heat transfer performance. Within the investigated range, the optimum longitudinal pitch ratio was 1.55 for the inline arrangement an‎d 1.45 for the staggered arrangement, with the latter producing the maximum external thermal conductance of 400.88 W/K an‎d an average external heat transfer coefficient of 2322.66 W/m2K. The results demonstrate that simultaneous optimization of fin geometry, tube arrangement, an‎d tube pitch can substantially enhance the thermal performance of primary superheater tubes. The optimized staggered tube-bank configuration identified in this study provides practical design guidance for improving the efficiency of thermal power plant superheaters while maintaining a constant amount of fin material.

محمدرضا سليم پور

محمدرضا توكلي نژاد , مجيد رضائي