Study on the fatigue of vacuum solar receiver

Abstract

Vacuum solar receiver is the key component in parabolic trough solar system. Due to different expansion increment between metal absorber and glass, corrugated expansion joint (metal bellows) is necessary to compensate the extra expansion increment. The mechanical and thermal properties of metal bellows have significant influence on the reliability and heat loss of solar receiver. Recently, China's first high temperature vacuum receiver has been developed and produced by Southeast University and Sanle Electronic Group. This paper analyzes the fatigue properties from displacement compensation, stress assessment and axial elasticity. First, varies stresses of metal bellow when compensating for axial displacement is calculated, and the reliability of bellow is analyzed from the point of stress condition and fatigue life. Because metal bellows will reduce the effective absorbing length, metal bellow should be shortened under the precondition of enough axial compensation. Second, the axial compensation of bellow is a primary factor in design. This paper deduces a simple equation to calculate the maximum axial compensation of single wave for the toroidal bellows, and the calculation proves the compensation of the bellow designed meets the receiver requirement. Finally, the experimental measurements verify it has a good fatigue property.