Experimental comparison of solar air heater based on single and double-ends open evacuated tube collector

The hot air has a lot of applications like drying, space heating, desiccant air conditioning and desalination, which attracts the attention of researchers towards the system used for producing the hot air. In the present work, two different solar air heaters that is, double-ends open evacuated tube based solar air heater (system 1) and single-end open evacuated tube based solar air heater (system 2) are proposed and compared experimentally. The aperture area of each system is 4.687 m2 and operated under same weather conditions. The experiments are performed at three different mass flow rates of the process air that is, 153.21, 207.94, and 246.24 kg/h. The highest mean air temperature difference is 62.91 and 48.8 degrees C for system 1 and system 2 respectively at mass flow rate of 153.21 kg/h. The highest mean energy and exergy efficiency obtained by the system 1 and system 2 are 81.55%, 6.80%, and 65.45% and 4.25% respectively. The present work is also compared with the work presented in literature and it is observed that double-end open evacuated tube collector has significantly high energy and exergy efficiency with higher hot air temperature.