Performance evaluation of both-end open evacuated tube solar air heater: An experimental investigation

Hot air generation is essential for numerous applications, including drying, space heating, desiccant air conditioning, and seawater desalination. This study experimentally investigates a novel solar air heater that utilizes a both-end open evacuated tube collector. The research focuses on the effects of airflow rate, inclination angle, collector area, series, and parallel connection of solar air heater on system performance. The findings reveal that lower airflow rate, i.e. 100 kg/h yield higher hot air temperature (94.7 degrees C), whereas the highest efficiency (78.1%) occurs at higher airflow rate, i.e. 300 kg/h. Additionally, positioning the solar air heater at a 22 degrees angle enhances efficiency and hot air temperature by 47.5% and 27.3%, respectively, in comparison to 45 degrees angle. Expanding the collector area from 4.8 m2 to 14.4 m2 increases the temperature by 44%, though efficiency decreases by 47.7%. The series configuration outperforms the parallel configuration with 22.8% higher efficiency of the system. This study highlights the potential of the both-end open evacuated tube collector in enhancing the efficiency of solar air heater, offering valuable insights for the development of advanced solar thermal systems.