Comparison of the performance of fixed and two-axis movable solar air heaters with different methods

ABSTRACT

Usually, the solar air heater (SAH) is placed in a fixed position based on the tilt angle. This situation adversely affects the thermal performance of the collector, considering the natural motion of the sun. In this experimental study, two SAHs of equal dimensions were designed. A PLC solar tracking system was integrated into one of the SAHs to track the sun in two directions (East-West, North-South). The thermal efficiency values of the SAHs were calculated according to three different mass flow values of the air in the SAH by using the “I” and “II” laws of thermodynamics. It was observed that movable SAH has two times more average heat transfer value, 47.8% more energy efficiency, 2.4 times more exergy efficiency, 20% more coefficient of performance (COP) value, and 23.8% more average collector outlet temperature than fixed SAH. In addition, it was measured that the average irradiance on the absorber plate in the movable SAH is 38% higher than the fixed SAH. After, CFD analysis modeling was carried out for SAH outlet temperature values. The SAH outlet temperature values modeled by CFD analysis were compared with the experimental results. SAH outlet temperature value model was modeled by CFD with less than 1% error value for turbulent flow. As a result of the calculations made with experimental data, it was shown that the PLC tracking feature was an important method to use solar energy more effectively on SAH.

KEYWORDS:

• Solar air heater
• solar tracking
• thermal efficiency
• exergy
• plc
• cfd
• cop

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Firat University Scientific Research Projects Management Unit [2016-MF.16.54].