Multi-dish configurations for single-shaft and parallel-flow solar-dish Brayton cycles

Abstract

Concentrating solar power combined with parallel-flow Brayton cycles can form a viable solution to generating cleaner and more sustainable energy. Parallel-flow Brayton cycles are not influenced as greatly as traditional single-shaft cycles when solar and/or recuperation components are added to the cycle. To further improve the thermal efficiency of parallel-flow cycles, the solar heat input to the cycles can be increased through introducing a second solar receiver in the setup (a multi-dish setup). This analytical study addresses the viability of incorporating multi-dish configurations in parallel-flow and single-shaft Brayton cycles. The study is based on using off-the-shelf automotive turbochargers to develop a solarised micro gas turbine for power generation. It is determined that a multi-dish cycle setup adds performance improvement to the thermal efficiency results in both single-shaft and parallel-flow recuperated solar cycles. When the best-performing multi-dish recuperated low-temperature turbine (LTT) cycle is considered, the thermal efficiency is 69 % greater than in the best-performing single-dish recuperated LTT cycle. The multi-dish recuperated single-shaft cycle, however, obtains 3.2 % less thermal efficiency than the single-dish recuperated single-shaft cycle. The multi-dish single-shaft power output is greatly restricted by high solar receiver surface temperatures, which is not the case in the multi-dish recuperated LTT cycle. Therefore, more solar heat can be captured in the parallel-flow multi-dish LTT cycle.