Performance Enhancement of a Solar Trough Power Plant by Integrating Tower Collectors

Abstract

Parabolic troughs and power towers are state-of-the-art commercial technologies and all of the commercial plants are stand alone. For a solar trough power plant, the operating temperature is limited to 400°C for the stability of oil, which also limits the efficiency of the steam cycle accordingly. In this study, the tower collectors were integrated with the solar trough power plant. The tower collectors with high concentration ratio generate high-temperature heat at 574°C, and the trough collectors with a relative low concentration ratio generate mid-temperature heat at 390°C. The mid-temperature heat from trough collectors generates saturated steam. The steam is then superheated by the high-temperature heat from the tower collectors. Compared with an individual solar trough plant, the temperature of the primary steam is increased from 370°C in the individual trough plant to 540°C, there is a great potential to increase the conversion efficiency from heat to electricity. Based on the simulation results, the thermal efficiency of the integrating system can reach 24.7%, higher by 1.7 percentage points compared with that of the individual trough power plant. The electricity generation cost of the new system can be decreased by 4% compared with that of the individual trough or tower plants. The results obtained in the present study provide a new approach for utilizing solar energy more efficiently and more economically.