Thermal performance and thermal stress analysis of a supercritical CO2 solar conical receiver under different flow directions

To ensure the safe and efficient operation of the receiver in the concentrated solar power system, it is necessary to study its performance characteristics. Different from considering the thermal performance alone, this study comprehensively analyzed the thermal and mechanical performance of the solar receiver by using a coupled thermal-mechanical model. The critical factors including geometric parameters (aspect ratio H/D and angle ratio φ/φmax), operation parameters (mass flow rate, inlet temperature and direct normal irradiance (DNI)) and flow directions (up-flow and down-flow) were investigated. The results demonstrated that the optimum thermal efficiency achieved 85.67% when H/D = 1.5 and φ/φmax = 0.25, and the maximal thermal stress was 87.61 MPa. Increasing the flow rate from 0.01 kg/s to 0.06 kg/s improved the thermal performance, but increased the thermal stress. An opposite trend was observed when the inlet temperature increased from 573 K to 773 K. As the DNI increased from 200 W/m2 to 1000 W/m2, the maximal thermal stress increased by approximately 3 times, when the DNI >800 W/m2, the thermal performance would be deteriorated. Although the thermal performance under up-flow was better, the thermal stress was greater, the receiver should adopt an up-flow flow direction.