Optimal scale of solar-trough powered plants operating with carbon dioxide

Abstract

Undoubtedly, solar energy is one of the most promising renewable sources available. However, the wide range of possible configurations and operational scenarios makes it difficult to decisively select one power plant assembly over another. Therefore, the present analysis proposes a performance-based methodology to assist the design of solar trough power plants. The analysis, which considers carbon dioxide as the only fluid circulating through the cycle, initially determines transition conditions for selecting between transcritical Rankine or transcritical Brayton cycles based on standard thermodynamic performance parameters, such as, the net power delivered and thermodynamic efficiencies. The analysis is followed by a parametric study, which now considers the effect of the collector’s area on the net power delivered and thermodynamic efficiencies. The results clearly show the existence of an optimal collector’s size, which returns the most favorable tradeoffs for some of the performance parameters mentioned above. The analysis also suggests a Brayton/Rankine transition function in terms of pressure and temperature downstream the solar collector aiming to easy the selection between both types of cycles. At the end, the results explore the relative performance of different arrangements of fully supercritical Brayton cycles.