Impact of double-axis tracking on thermal performance of the linear Fresnel Collector: An experimental study

Abstract

Due to the concerning trend of fossil fuels destructive effect on the environment, renewables, especially solar energy, can be a promising alternative to meet the world's energy demands. Linear Fresnel Collectors (LFCs) are solar thermal collectors that can effectively provide the required thermal energy for various applications. Despite the low capital cost and non-complicated structure of the LFCs, they have some drawbacks, such as end loss effects that reduce their optical and thermal efficiencies. The current research introduces a mechanical tracking system to enable the system to rotate in the secondary axis to decrease the end loss effect. Four experimental tests at laminar and turbulent flows in two single and double-axis tracking modes have been performed to investigate the non-illuminated length in each scenario. Moreover, a theoretical study was conducted, and the results were compared with the experiments. The results showed that the thermal efficiencies were 8.67 %–22.03 % and 40.97 %–63.5 % for the double-axis tracking mode in laminar and turbulent, respectively. The double-axis tracking system enhanced the system's thermal efficiency by 18.91 % and 6.42 % for laminar and turbulent flows on average, respectively, compared to the single-axis tracking. Furthermore, the difference between the experimental and theoretical non-illuminated length values was calculated as 4.14 % and 8.44 % on average for laminar and turbulent flows, respectively. Finally, according to the economic analysis, 4.78 years was calculated for the payback time of the investigated system.