Performance analyses of a novel finned parabolic trough receiver with inner tube for solar cascade heat collection

Designing highly-efficient parabolic trough receiver (PTR) contributes to promoting solar thermal utilization and alleviating energy crisis and environmental problems. A novel finned PTR with inner tube (FPTR-IT), which can provide different grades of thermal energy with two heat transfer fluids (oil and water), is designed to improve thermal efficiency. In this FPTR-IT, an inner tube and straight fins are employed to respectively lessen heat loss at upper and lower parts of the absorber. Based on the design, a numerical model is developed to investigate its performance. Comparisons with other PTRs indicate that the FPTR-IT can combine the advantages of PTR with inner tube and finned PTR and obtain the best performance. Moreover, performance evaluation under broad ranges of direct normal irradiances (300-1000 W/m(2)), flow rates (50-250 L/min) and inlet temperatures (400-600 K) of oil as well as flow rates (3.6-10 L/min) and inlet temperatures (298.15-318.15 K) of water is investigated. Compared with conventional PTR, heat loss is reduced by 20.7%-63.2% and total efficiency is improved by 0.03%-4.27%. Furthermore, the proportions of heat gains for water and oil are located in 8.3%-73.9% and -12.0%-64.3%, while their temperature gains are located in 11.6-37.9 K and -1.2-19.6 K, respectively. Thus, the proposed FPTR-IT may have a promising application prospect in remote arid areas or islands to provide different grades of heat for electricity and freshwater production.

Automated summary

Designing a highly-efficient parabolic trough receiver (PTR), such as a novel finned PTR with inner tube (FPTR-IT), can effectively promote the utilization of solar thermal energy and help alleviate energy crisis and environmental issues. The FPTR-IT is designed to provide different grades of thermal energy using two heat transfer fluids and has improved thermal efficiency compared to conventional PTRs. Performance evaluations show that the FPTR-IT has reduced heat loss and improved total efficiency, making it a promising solution for generating electricity and freshwater in remote arid areas or islands.