Energetic and exergetic analyses on structural optimized parabolic trough solar receivers in a concentrated solar–thermal collector system

Highlights: • Energetic and exergetic performance of PTC with novel solar receivers is studied. • Mathematical models with spectral radiant distribution are built and validated. • All-day PTC system efficiency in different areas in China is calculated. • The radiation heat loss of the novel receiver is reduced by around 24.0%. • Thermal and exergetic efficiencies of novel receiver are raised by 7.1 and 4.7%. -- Abstract: High collecting temperature in parabolic trough collectors (PTCs) induces considerable radiative heat loss of solar receivers, which causes significant negative effects on heat-collecting efficiency. Structural optimized solar receivers with inner radiation shield achieved superior thermal performance for reducing heat loss. Based on widely commercial EuroTrough and PTR70 solar receivers, the optimized solar receivers are numerically applied to a small thermal-collection field with 72 m loop using molten salt as heat transfer fluid to validate their enhanced overall performance. Mathematical models relying on spectrum parameter calculation and working fluid volume unit method are established to simulate the energetic and exergetic performances of the solar receivers. The influence of solar irradiance on parabolic trough collector system is studied, and all-day system efficiencies in different areas in China are investigated to validate the performance of the proposed solar receivers in real condition. Results show that the PTCs with novel solar receivers exhibit outstanding energetic and exergetic performances compared with conventional receivers. The heat loss reduction percentage of the novel receivers reaches approximately 24.0% when the absorber temperature is 600 °C. The heat-collecting efficiency and exergetic efficiency are effectively raised by 7.1% and 4.7%, respectively, at an inlet temperature of 580 °C.