Thermal-fluid-mechanical analysis of tubular solar receiver panels using supercritical CO2 as heat transfer fluid under non-uniform solar flux distribution

Abstract

The tubular receiver is one of the most attractive options for the directly heated supercritical CO2 (S-CO2) solar receiver, of which tubular panels are the basic modules. Due to the high working pressure and the non-uniform solar flux distribution, the thermal-fluid-mechanical analysis becomes an important research topic for the S-CO2 solar receiver. In this paper, the thermal-fluid-mechanical characteristics of the S-CO2 tubular receiver panel under non-uniform solar flux distribution using S-CO2 as the heat transfer fluid is numerically studied. The effects of solar flux distribution and flow arrangements on the thermal and mechanical performances are discussed with emphasis. The results indicate that: (1) the non-uniform solar flux of the receiver panel will result in the increase in the thermal loss and the thermal stress; (2) adjusting the flow arrangement to match the solar flux distribution can decrease thermal loss and thermal stress; (3) the proposed matching factor can be used as an indicator for the thermal-mechanical performances, and a larger matching factor means a good performance; (4) although the I-type flow arrangement lead to uneven flow allocation with more fluid in middle tubes, it cannot always yield good performances under Gaussian-shaped solar flux distribution, which is greatly depended on the standard deviation of the Gaussian distribution; (5) an ideal flow allocation can be easily determined by the matching factor being set to 1, which provides guidelines for the design and optimization of the tubular solar receiver panel.