Analysis and Numerical Simulations of Thermofluid Dynamic Characteristics in Duct Systems Under Radiation-Convection Coupling Effects

This paper presents a novel Focused Solar Chimney Generator (FSCG) that addresses the fundamental limitations of conventional Solar Chimney Power Plants through compact design, and enhanced thermal performance. The FSCG system integrates concave mirror concentration, molten salt thermal storage, and optimized heat-dissipating fins. A comprehensive theoretical model incorporating radiation-convection coupling effects, and temperature-dependent viscosity corrections was developed, and validated through three-dimensional CFD simulations using the k-ε turbulence model. The FSCG demonstrates remarkable performance advantages: thermal efficiency of 7.5% compared to 0.1-0.5% in traditional systems, rapid wind generation within 2-5 minutes versus 1-3 hours for conventional designs, and 85-90% reduction in construction costs. The compact 1-meter height design achieves 500-4000 times better space efficiency than traditional solar chimney systems requiring 80-195-meter towers. Numerical simulations agree with theoretical predictions, with maximum deviations below 10%. At 500-1000 °C operating temperatures, radiative heat transfer contributes over 40% of total thermal flux, validating the importance of radiation-convection coupling. The optimized duct inlet velocity ranges from 2.07 to 2.37 m/s, demonstrating effective buoyancy-driven flow generation. This research provides a practical pathway for deploying high-efficiency, cost-effective solar thermal systems in space-constrained environments, offering significant potential for distributed renewable energy applications.