Optimization of concentration performance at focal plane considering mirror refraction in parabolic trough concentrator

ABSTRACT

Parabolic trough solar thermal technology is the most cost-effective approach for concentrated solar energy applications. The concentrator thickness significantly affects the performance of the parabolic trough collector. To examine the effect of mirror refraction in the concentrator, the focal plane concentration for different concentrator thicknesses was studied using theoretical calculations, simulations, and experimental verification. A longitudinal offset of the focal plane is proposed to optimize the focal plane concentration. The deviation of the reflected sunlight depending on the concentrator thickness was found to strongly affect the concentration in the focal plane. When the concentrator thickness was increased by a factor of 5, the focal plane was 5 times as wide, the maximum energy flux density in the focal plane decreased by a factor of 5, and the optical efficiency decreased by 0.24%. The longitudinal offset of the absorber plane position was introduced to avoid local overheating of the absorber and low collector temperature by maintaining the focal plane width and maximum energy flux density in the focal plane within appropriate ranges. The experimental results showed that with optimization, the maximum energy flux density, uniformity, and optical efficiency increased by 5.75%, 3.35%, and 2.43%, respectively.

KEYWORDS:

• Geometric optics
• concentrator thickness
• concentration characteristics
• parabolic trough concentrator
• concentration optimization

Acknowledgments

This study was sponsored by the National Natural Science Foundation of China (52166016), the Natural Science Foundation of the Inner Mongolia Autonomous Region (2020LH05016), Inner Mongolia University of Technology Scientific Research Project (ZZ201907), and Doctoral Fund of Inner Mongolia University of Technology (BS201932).

Disclosure statement

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

Nomenclature and abbreviations

Table

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (52166016), the Inner Mongolia Natural Science Foundation of China (2020LH05016), Inner Mongolia University of Technology Scientific Research Project (ZZ201907, BS201932).

Notes on contributors

Wenwu Chan

Wenwu Chan was born in 1996 and is currently a master’s candidate at the Inner Mongolia University of Technology, China. His main research interests include ray concentration and heat collection in trough solar systems.

Zhimin Wang

Zhimin Wang was born in 1982 and is currently a professor at the Inner Mongolia University of Technology, China. She received her PhD degree from the Inner Mongolia University of Technology, China, in 2018. Her main research interests include solar energy utilization technology, refrigeration, and power machinery design and optimization.

Chang Yang

Chang Yang was born in 1994 and is currently a master’s candidate at the Inner Mongolia University of Technology, China. His main research interests include the concentrator dust.

Tuo Yuan

Tuo Yuan was born in 1998 and is currently a master’s candidate at the Inner Mongolia University of Technology, China. His main research interests include dust removal technology for trough solar energy systems.

Rui Tian

Rui Tian was born in 1956 and is currently a professor and PhD supervisor at the Inner Mongolia University of Technology, China. He received his PhD degree from the Inner Mongolia University of Technology, China, in 2008. His main research interests include the development and utilization of wind and solar energy.