Experimental Thermal Performance Investigation of Nontracking Multiple Parabolic Trough Collector With a Single Absorber

A parabolic trough collector (PTC) is a system to harness solar energy and hconvert it into usable thermal energy. However, one operational limitation of the PTC is that it requires continuous solar tracking to capture the maximum amount of energy. But adding a solar tracking mechanism complicates the parabolic collector system, increases initial and maintenance costs, and requires substantial energy to operate. This study investigates the performance of a nontracking PTC and proposes a compact nontracking system design using multiple parabolic trough reflectors. It is designed by positioning three distinct parabolic trough reflectors so that the reflected rays are focused on a stationary absorber tube. Experiments were conducted over several days from November 2023 to May 2024, using water as the working fluid flowing through the absorber tube. Throughout the experimental period, nearly constant mass flow rates of 0.3, 0.4, and 0.7 kg/min of working fluid, a slightly variable inlet water temperature, and variable irradiance conditions were maintained. The proposed PTC system could provide a maximum outlet water temperature of 63.3°C at an inlet temperature of 53.2°C when direct solar radiation was 770.25 W/m 2 , with the flow rate maintained at 0.3 kg/min. The system's maximum instantaneous efficiency was 51.78%, which varied with weather conditions and the working fluid's flow rate. Due to the absence of any tracking mechanisms, a considerable performance drop was observed during the early and late phases of the collection period. However, the use of multiple individual reflectors significantly mitigated the loss. This study focuses on simplified design, minimized heat loss, and improved optical performance while maintaining efficiency without the need for any tracking system in PTC.