Enhancing solar air collector performance through optimized entrance flue design: A comparative study

Abstract

The current study examines the effect of entrance flue conditions on the performance of solar air collectors (SAC) with a single pass channel, focusing on two configurations: a front entrance solar air collector (FESAC) and a side entrance solar air collector (SESAC). The FESAC, introduced to optimise air distribution across the absorber plate, demonstrated higher performance, with higher outlet and lower absorber plate temperatures than the SESAC across various mass flow rates. The absorber plate temperatures for FESAC are 86 °C, 82.9 °C, and 75.1 °C, and for SESAC, 90.4 °C, 85.9 °C, and 79.1 °C for tested air flowrate 0.01118 (Case A), 0.01231 (Case B), and 0.01469 kg/s (Case C) respectively. Additionally, the maximum outlet temperatures for FESAC were 45.2 °C, 42.9 °C, and 39.5 °C for Case A, B, and C, respectively, while for SESAC, they were 43.1 °C, 41.4 °C, and 37.8 °C for the same cases. The study also emphasises a proportional relationship between airflow rate and collector efficiency. The observed daily efficiencies of the FESAC were 37.2 %, 40.4 %, and 44.4 % for the corresponding airflow rates mentioned above, while for the SESAC, they were 39.9 %, 43.4 %, and 47.5 % at these same rates. Additionally, the daily efficiency of the FESAC exhibited an enhancement of 3.1 % to 3.7 % relative to the SESAC, highlighting the effectiveness of entrance flue design in optimising SAC performance. These findings indicate the FESAC's enhanced capability in heat removal from the absorber plate and position the FESAC design as a promising avenue for boosting thermal efficiency in SACs. This study highlights the potential of modifying entrance flue configurations as a complementary approach to existing performance enhancement techniques for solar air collectors.

Keywords

• Solar air collector
• Entrance flue
• Thermal efficiency
• Performance enhancement
• Outlet temperature
• Solar air heater