Thermal stress analysis of DSG solar absorber tube in stratified two-phase regime

When stratified two-phase flow occurs in the DSG solar absorber tube, the tube perimeter contacting with vapor phase experiences poor heat transfer, which results in higher temperature gradient and thermal stress. A flow pattern based heat transfer model is applied in this paper to evaluate the inner surface heat transfer coefficient distribution. Then the temperature, thermal stress and deflection of the absorber tube are calculated using FEM analysis software. The results show that the effective stress and deflection of the absorber tube are much higher, when considering the heat transfer difference of vapor and liquid phases, than that of uniform intube heat transfer coefficient condition.