Numerical analysis of the effect of baffle length and arrangement on the thermal performance of solar air channels

Improving heat transfer in solar air ducts is crucial to increasing the efficiency of solar heating systems. The addition of baffles is an effective technique for optimizing this heat transfer. This work presents an in-depth analysis of the effect of baffle length and arrangement in an air channel with rectangular baffles to direct and disrupt airflow, thereby increasing the rate of heat transfer. Computational fluid dynamics was employed for the calculations. The Finite volume method was used to discretize the governing equations, and the SIMPLE algorithm was used to the pressure-velocity coupling. A standard k - epsilon turbulence model based on Reynolds number ranges of 8000 <= Re <= 30000 has been used to numerically study flow properties and heat transfer. The results show that adapting baffle length plays a crucial role in controlling flow velocity, which directly influences temperature distribution in the system. In addition, the study reveals that periodic arrangement of baffles (Case C) increases maximum velocity values and optimizes flow by increasing fluid acceleration and dynamic pressure. For a Reynolds number of 30,000, periodic arrangements achieve the highest value for TPF, i.e. 3.267. This indicates that periodic baffles create optimized recirculation zones, improving fluid mixing and heat transfer without excessively increasing flow resistance.