Optical Design of a Novel Two-Stage Dish Applied to Thermochemical Water/CO 2 Splitting with the Concept of Rotary Secondary Mirror

Song Yang, Jun Wang and Peter D. Lund
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Song Yang: Key Laboratory of Solar Energy Science and Technology in Jiangsu Province, School of Energy and Environment, Southeast University, No. 2 Si Pai Lou, Nanjing 210096, China
Jun Wang: Key Laboratory of Solar Energy Science and Technology in Jiangsu Province, School of Energy and Environment, Southeast University, No. 2 Si Pai Lou, Nanjing 210096, China
Peter D. Lund: Key Laboratory of Solar Energy Science and Technology in Jiangsu Province, School of Energy and Environment, Southeast University, No. 2 Si Pai Lou, Nanjing 210096, China

Energies, 2020, vol. 13, issue 14, 1-13

Abstract: In this paper, a novel two-stage dish concentrator (TSD) with a rotary secondary mirror (SM) is presented for solar thermal water/CO 2 splitting. An in-house code for ray-tracing simulation of the concentrator was developed and validated. Among all feasible geometries, a hyperboloid with an upper sheet is the most popular option and is widely used as a secondary reflector, which is mainly discussed here. All para-hyperboloid geometric combinations can be categorized into three typical patterns ( φ 1 < π/2, φ 1 = π/2, φ 1 > π/2, φ 1 = field angle of PM). The initial designs of the TSD, respective to different off-axis levels for each combination, were first designed. Then a new mathematical model was introduced to reshape the SM to reach optimal truncated designs. Finally, a new concept of an off-axis primary mirror (PM) combined with the truncated SM was evaluated by using the in-house ray-tracing code. The results include the optical efficiency, concentration ratio and intercepted radiant flux. The best solutions with the highest optical efficiency fall in the range π/2 ≤ φ 1 ≤ (π − arcsin 0.8) rads and 0.4 ≤ NA 2 ≤ 0.6 ( NA 2 = sin φ 2 , φ 2 = field angle of SM), which vary with the concentration ratio and inclination angle.

Keywords: solar thermal; dish concentrator; ray-tracing method; thermochemical redox (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
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